JPWO2020039594A1 - Power transmission device - Google Patents

Abstract

Provided is a power transmission device having a simple circuit configuration and can be manufactured at low cost. A primary circuit (2) having a transmission side capacitor (C1) and a transmission side coil (L1), a DC power supply (5) connected to the transmission side capacitor (C1), a transmission side capacitor (C1) and a DC power supply (5). Primary side drive switch (SW1) connected between and, secondary side circuit (3) having power receiving side coil (L2) and power receiving side capacitor (C2) facing the power transmitting side coil (L1), power receiving side capacitor It includes a load element (6) that receives electrostatic energy from (C2), a load side diode (D2) whose anode is connected to a power receiving side capacitor (C2) and whose cathode is connected to the load element (6).

Description

The present invention relates to a power transmission device, and more particularly to a new circuit design of a wireless power transmission device.

Since the 2005 proposal by Karalis et al. Of the Massachusetts Institute of Technology (MIT), research on wireless power transmission has been active (see Patent Documents 1, 2 and 3). The inventions described in Patent Documents 1, 2 and 3 are power transmission techniques using a power source as an AC power source, but as described in Patent Document 2 and the like, power is supplied in a wireless power transmission method based on AC theory. It is said that it is necessary to match the resonance frequency 2π√LC of the side resonance circuit (LC circuit) with the resonance frequency 2π√LC of the power receiving side resonance circuit (LC circuit). However, in reality, the power feeding side resonance circuit and the power receiving side resonance circuit interact with each other, which causes new resonance. It was a technical common sense that it is better not to resonate (double resonance) between the power feeding side resonance circuit and the power receiving side resonance circuit including this new resonance.

According to Patent Document 2, the feeding side resonance circuit and the power receiving side resonance circuit are coupled by a magnetic field component (magnetic field coupling), and a mutual inductance M is formed between the feeding coil and the power receiving coil. The new resonance circuit formed by the mutual inductance M, the feeding side resonance circuit, and the power receiving side resonance circuit _{has a resonance frequency fr 2} different from the resonance frequency fr _1, and double resonance occurs. When trying to make the drive frequency fo of the AC power supplied to the feeding side resonance circuit _{follow the resonance frequency fr 1} , the drive frequency fo follows the _{resonance frequency fr 2} instead of the resonance frequency fr ₁ which is the original target. The resonance frequency fr ₂ is an undesired resonance point, and it is desirable to remove it. In the conventional AC theory, double resonance has been avoided.

Moreover, in the invention described in Patent Document 1, an AC power supply of 10 kHz to 50 GHz is used, in the invention described in Patent Document 2, an AC power supply having a drive frequency of about 100 kHz is used, and in the invention described in Patent Document 3, several hundreds are used. An AC power supply of kHz to several MHz is required. In particular, Patent Document 1 reports experimental data in a frequency band of around 10 MHz. A power supply circuit (0th-order circuit) in the frequency band as described in Patent Documents 1 to 3 complicates a large number of power semiconductor elements after producing an accurate direct current from a commercial power supply by using an expensive switching power supply. Moreover, it is created by precisely switching and making a direct current pulse cut out on a rectangular wave into an alternating current in a pseudo or equivalent manner by PWM (Pulse Width Modulation) or the like. At this time, power loss such as resistance loss that occurs in the power semiconductor element and switching loss that rapidly increases due to an increase in frequency occurs. Further, the switching element is easily destroyed by the induced back electromotive force generated in the coil, and the switching element is easily destroyed by the excessive voltage rise due to resonance. The higher the frequency and the larger the power, the more difficult the circuit design becomes. On the other hand, if you want to send power far, you have to raise the frequency. As described above, the conventional wireless power transmission device based on the AC theory has a problem that the device becomes complicated, the overall power transmission efficiency is low, it is fragile, the reliability is low, and it is expensive. For these reasons, conventional technology cannot realize wireless power transmission that efficiently transmits the power required in the future to a long distance. In other words, the circuit design itself of the power transmission device based on the AC theory is required to be examined.

U.S. Patent Application Publication No. 2008/0278264 Japanese Patent No. 5549745 Japanese Patent No. 5462953

In view of the above problems, an object of the present invention is to focus on a transient response that is not a conventional AC theory, to simplify a circuit configuration, improve power transmission efficiency, and provide an inexpensive power transmission device.

The first aspect of the present invention is as follows: (a) The electrostatic energy sent in parallel with the transmission side capacitor and the transmission side capacitor is stored as magnetic energy, and this magnetic energy is circulated to the transmission side capacitor. A primary side circuit having a transmission side coil, (b) a DC power supply constituting a circuit connecting between one terminal and the other terminal of the transmission side capacitor, and (c) one terminal and a DC power supply of the transmission side capacitor. The primary side drive switch, which is connected between and step-inputs an intermittent DC voltage to the power transmission side capacitor, and (d) the power receiving side coil facing the power transmission side coil and receiving magnetic energy from the power transmission side coil, the power receiving side. A secondary circuit having a power receiving side capacitor that is connected in parallel to the coil and stores the magnetic energy stored in the power receiving side coil as electrostatic energy, and (e) connecting between one terminal and the other terminal of the power receiving side capacitor. Power transmission with a load element that receives electrostatic energy from the power receiving side capacitor and (f) a load side diode whose anode is connected to one terminal of the power receiving side capacitor and whose cathode is connected to the load element. The gist is that it is a device. In the power transmission device according to the first aspect, electric energy can be transmitted from the primary side circuit to the secondary side circuit in a non-contact manner.

A second aspect of the present invention is as follows: (a) A capacitor on the transmission side, electrostatic energy sent from the capacitor on the transmission side connected in parallel to the capacitor on the transmission side is stored as magnetic energy, and this magnetic energy is circulated to the capacitor on the transmission side. A primary side circuit having a transmission side coil, (b) a DC power supply constituting a circuit connecting between one terminal and the other terminal of the transmission side coil, and (c) one terminal and a DC power supply of the transmission side coil. Connect one electrode to one node that is connected between and (d) connects the transmission side capacitor and the transmission side coil in parallel with the primary side drive switch that step-inputs the intermittent DC voltage to the transmission side coil. The first interconnected capacitor, (e) the second interconnected capacitor with one electrode connected to the other node connecting the transmitting side capacitor and the transmitting side coil in parallel, and (f) the first interconnecting. Connect one electrode to the other electrode of the capacitor, connect the other electrode to the other electrode of the second interconnect capacitor, and connect it in parallel to the power receiving side capacitor and the power receiving side capacitor that receive electrostatic energy from the primary side circuit. It constitutes a secondary circuit having a power receiving side coil that stores the electrostatic energy stored in the power receiving side capacitor as magnetic energy, and (g) a circuit that connects between one terminal and the other terminal of the power receiving side coil. The power transmission device is equipped with a load element that receives magnetic energy from the power receiving side coil, and (h) a load side capacitor whose anode is on one terminal side of the power receiving side coil and whose cathode is connected to the load element. It is a summary. The power transmission device according to the second aspect can also transmit electrical energy from the primary side circuit to the secondary side circuit in a non-contact manner, like the power transmission device according to the first aspect.

According to the present invention based on a circuit design that breaks away from the conventional AC theory, it is possible to provide an inexpensive power transmission device that simplifies the circuit configuration and improves the power transmission efficiency by using characteristic harmonized transmission, which is a phenomenon at the time of transient response. ..

FIG. 1A is a circuit diagram showing an outline of an example of a power transmission device according to the first embodiment of the present invention, and FIG. 1B is a terminal of a power transmission side capacitor of the circuit shown in FIG. 1A. It is a waveform diagram of the inter-voltage. FIG. 2A is a waveform diagram of the voltage between the terminals of the power transmission side capacitor and the power reception side capacitor of the power transmission device according to the first embodiment, and FIG. 2B follows the waveform of FIG. 2A. It is a detailed waveform diagram. It is a figure explaining the transient response at the time of step input to the LC parallel circuit. It is a circuit diagram which shows the mounting circuit of the power transmission apparatus which concerns on 1st Embodiment. It is a figure explaining the large signal equivalent circuit of the MOSFET used for the power transmission apparatus which concerns on 1st Embodiment. FIG. 6A is a schematic diagram illustrating the importance of the surface spacing between the coils of the power transmission device according to the first embodiment, and FIG. 6B is for charging a battery of an electric vehicle (EV). It is a bird's-eye view explaining the magnetic coupling degree control mechanism which adjusts the surface spacing between coils when applied. FIG. 7A is a bird's-eye view for explaining the mechanism for adjusting the coil magnetic coupling of the power transmission device according to the first embodiment. FIG. 7A shows a case where the surface spacing between the coils is controlled by using a spacer, and FIG. b) and FIG. 7 (c) show an example of a magnetic coupling degree control mechanism that adjusts the magnetic coupling of the coil using a magnetic plate. FIG. 8 (a) is a block diagram illustrating an example of the hardware configuration of the magnetic coupling degree control mechanism of the power transmission device according to the first embodiment, and FIG. 8 (b) illustrates another example. It is a block diagram. It is a schematic diagram explaining the operation of the power transmission apparatus which concerns on 1st Embodiment by dividing by the timing along the time series. FIG. 10 (a) is a circuit diagram showing an outline of an example of a power transmission device according to a second embodiment of the present invention, and FIG. 10 (b) shows a specific mounting circuit of the circuit of FIG. 10 (a). It is a circuit diagram shown. It is a timing diagram explaining the power supply method of the power transmission apparatus which concerns on 2nd Embodiment. It is the schematic explaining the power supply method of the power transmission apparatus which concerns on 2nd Embodiment, (a) at the time of charging, (b) at the time of characteristic harmonized transmission between a primary side circuit 2 and a secondary side circuit 3, ( c) At the time of transfer, and (d) at the time of characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3. FIG. 13A is a circuit diagram showing an outline of an example of a power transmission device according to a third embodiment of the present invention, and FIG. 13B is a specific implementation of the circuit shown in FIG. 13A. It is a circuit diagram which shows a circuit. It is a flowchart explaining the power supply method of the power transmission apparatus which concerns on 3rd Embodiment. It is a timing diagram explaining the power supply method of the power transmission apparatus which concerns on 3rd Embodiment. 16 (a) is a circuit diagram showing an outline of an example of a power transmission device according to a fourth embodiment of the present invention, and FIG. 16 (b) is a specific implementation of the circuit shown in FIG. 16 (a). It is a circuit diagram which shows a circuit. FIG. 17 (a) is a waveform diagram obtained by simulating the voltage between the terminals of the power transmitting side capacitor and the power receiving side capacitor in the power transmission device according to the fourth embodiment, and FIG. 17 (b) shows the power transmitting side capacitor. It is a waveform diagram obtained by the mounting circuit of the voltage between terminals of the power receiving side capacitor. FIG. 18A is a waveform diagram when the equivalent coupling coefficient K = 0.00 of the voltage between the terminals of the power transmission side capacitor and the power reception side capacitor in the power transmission device according to the fourth embodiment, and FIG. 18B is a waveform diagram. It is a waveform figure when the equivalent coupling coefficient K = 0.1. FIG. 19A is a waveform diagram when the equivalent coupling coefficient K = 0.6 of the voltage between the terminals of the power transmission side capacitor and the power reception side capacitor in the power transmission device according to the fourth embodiment, and FIG. 19B is a waveform diagram. It is a waveform diagram when the equivalent coupling coefficient K = 0.8, and FIG. 19C is a waveform diagram when the equivalent coupling coefficient K = 0.88. FIG. 20A is a waveform diagram when the equivalent coupling coefficient K = 0.6 of the voltage between the terminals of the power transmission side capacitor and the power reception side capacitor in the power transmission device according to the fourth embodiment, and FIG. 20B is a waveform diagram. It is a waveform diagram when the equivalent coupling coefficient K = 0.6 of the current flowing through the power transmission side coil and the power reception side coil. It is a graph which shows the change of the transmission efficiency with respect to the capacity of the capacitor of the power transmission apparatus which concerns on 4th Embodiment. It is a graph which shows the efficiency of the power transmission apparatus which concerns on 4th Embodiment. It is a flowchart explaining the 1st power supply method of the power transmission apparatus which concerns on 4th Embodiment. FIG. 24A is a timing diagram for explaining the first power supply method of the power transmission device according to the fourth embodiment, and FIG. 24B is a timing diagram for explaining the second power supply method. It is a flowchart explaining the 2nd power supply method of the power transmission apparatus in 4th Embodiment. It is a circuit diagram which shows the outline of an example of the power transmission apparatus which concerns on 5th Embodiment of this invention. FIG. 27A is a waveform diagram of the current flowing through the power transmission side coil and the power reception side coil of the power transmission device according to the fifth embodiment, and FIG. 27B is a waveform diagram of the power transmission device according to the fifth embodiment. It is a waveform diagram of the voltage between each terminal of the power transmission side capacitor and the power reception side capacitor. It is a circuit diagram used for the approximate simulation for demonstrating the sawtooth wave of the power transmission apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the transient response characteristic of the sawtooth wave with a knob obtained by the approximate simulation with respect to the circuit of FIG. 28. It is a figure explaining how the sawtooth wave aneurysm obtained by the approximate simulation using the circuit of FIG. 28 changes in a repetition period. It is a simplified circuit diagram by omitting a parasitic capacitance, a parasitic resistance, etc. from the circuit of FIG. 28. It is a figure explaining that the W type transient response characteristic can be obtained by the approximate simulation with respect to the simplified circuit of FIG. It is a circuit diagram used when the transient response characteristic of the power transmission apparatus which concerns on 2nd Embodiment of this invention is simulated by changing a power supply voltage and a load voltage. It is a figure explaining the transfer of electric energy by the transient response characteristic obtained by the approximate simulation for three circuits of FIG. 33. It is a schematic diagram explaining the W type transient response characteristic of the power transmission apparatus which concerns on 1st Embodiment of this invention.

Next, the first to fifth embodiments of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the plane dimensions, the ratio of the thickness of each member, etc. are different from the actual ones. Therefore, the specific thickness and dimensions should be determined in consideration of the following explanation. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios from each other.

Further, the first to fifth embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material of the component parts. , Shape, structure, arrangement, etc. are not specified as follows. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims. Further, the directions of "left and right" and "up and down" in the following description are merely definitions for convenience of explanation, and do not limit the technical idea of the present invention. Therefore, for example, if the paper surface is rotated 90 degrees, "left and right" and "up and down" are read interchangeably, and if the paper surface is rotated 180 degrees, "left" becomes "right" and "right" becomes "left". Of course it will be. Similarly, the direction of the spiral spiral as shown in FIGS. 6 (a) to 7 (c) is merely a selection for convenience of explanation, and depending on the actual design circumstances, right-handed winding is left-handed and left-handed. It is also possible to select right-handed.

(First Embodiment)
As shown in FIG. 1A, the power transmission device according to the first embodiment of the present invention includes a primary side circuit 2 and a secondary side circuit 3. Primary circuit 2, the power-transmitting-side capacitor C ₁ for storing electrostatic _energy, connected in parallel to the power transmission side capacitor C ₁ electrostatic energy transmitted from the power transmitting side capacitor C ₁ accumulated as the magnetic energy, the magnetic energy This is an LC resonance circuit having _{a power transmitting side coil L 1} that magnetically couples to the power receiving side coil L ₂ of the secondary side circuit 3 and transmits and receives magnetic energy at the same time as circulating to the power transmitting side capacitor C _1. Together with the DC power source 5 connected in series with the primary-side drive switch SW1 is connected in parallel to the transmitting capacitor C _1. DC power source 5 supplies a DC voltage to the power transmission side capacitor C _1.

As will be described later, the "primary side drive switch SW1" is a circuit element that limits the free vibration of the primary side circuit 2. By limiting the free vibration, the primary side drive switch SW1 realizes a transient current-voltage change in the primary side circuit 2. The DC power supply 5 may be a pseudo constant voltage source, or may be a DC power supply having a simple structure that is simply rectified and contains a large ripple component. Therefore, the control circuit and peripheral circuits are simple, hard to break, and circuit design is easy. Moreover, an inexpensive DC power supply 5 can be adopted. Secondary circuit 3, spaced in opposition to the power transmission coil L _1, the power transmission side receiving coil L ₂ for receiving magnetic energy from the coil L _1, connected in parallel to the power receiving side coil L ₂ to the power receiving coil L ₂ This is an LC resonant circuit having _{a power receiving side capacitor C 2} that stores the stored magnetic energy as electrostatic energy.

Connected in series with the load-side diode D2 and a load element 6 is connected in parallel to the receiving side capacitor C ₂ to each other. As the load element 6, for example, a rechargeable battery such as an in-vehicle lithium (Li) ion battery of an electric vehicle (EV) can be adopted. In FIG. 1A, an equivalent circuit of a lithium ion battery is schematically shown as a series-parallel circuit of a resistor and a capacitor. Lithium-ion batteries include resistors for current collectors and electric field fluids, and electrical double-layer capacitors and resistors that form at the interface inside the battery. Load side diode D2 has an anode recipient resonator 2 side, a cathode connected to face the load element 6 side to limit the direction of flow of the charging current I _C in one direction.

Figure 1 (a) E a terminal voltage of the DC power source 5 and the equivalent internal resistance _{r 1} at the transmitting side VC ₁ the terminal voltage of the capacitor _{C 1,} the terminal voltage of the power receiving side capacitor _{C 2} VC _2, the load element the charging voltage measured between sixth terminal VC _S, the current flowing through the load-side equivalent stray resistance r _L and the charge current I _C. The equivalent internal resistance r ₁ approximately indicates the internal impedance of the DC power supply 5 as a resistance value. _{Then, the transient response waveform of the inter-terminal voltage VC 1} obtained by the actual measurement when the primary side drive switch SW1 is driven on / off is shown in FIG. 1 (b).

In the first embodiment, it is assumed that _{the value of the charging voltage VC S} of the load element 6 in the initial state is close to the charging completion voltage (close to full charge) and high. At the time t = 0, the power transmission side capacitor C ₁ is not charged and the terminal voltage VC ₁ = 0. When the primary side drive switch SW1 is turned on at t = 0, the inter-terminal voltage E of the DC power supply 5 is step-input. By the step input of t = 0, the charging current flows to the capacitor C1 at first, and its value is E / r1. At this time, the coil L1 generates a counter electromotive force so as to block the inflowing current, so that the current to L1 is zero. As shown in FIG. 1 (b), the power transmission side capacitor C ₁ is charged with _{the equivalent internal resistance r 1} , the capacity C _{1 of the power transmission side capacitor, the inductance L 1} of the power transmission side coil, _{and the time constant τ 1} determined by the mutual inductance M. , The voltage between terminals VC ₁ increases. The time constant τ ₁ is a value that mainly depends on the parameters related to the product C ₁ · r ₁ of the capacitance C _{1 of the transmitting capacitor C 1} and the resistance value C ₁ of the equivalent internal resistance r _1.

The voltage of C1 gradually rises, and as the current becomes smaller, the back electromotive force of L1 becomes smaller and the current to L1 begins to flow. As a result, the voltage across C1 drops slightly. At this point, SW1 is closed (t = t1). The time t1 for closing this switch is a time at which the SW1 is not destroyed by the voltage applied to the SW1 generated by the counter electromotive force generated by turning off the current at the time when the current starts to flow in the coil. When the primary side drive switch SW ₁ is turned off at t = t ₁ , a current flows from the power transmission side capacitor C ₁ to the power transmission coil L ₁ to start full-scale discharge. The electric energy stored in the power transmission side capacitor C ₁ tries to move to the _{power transmission side coil L 1.} At this time, _{the magnetic field generated around L 1} by the current flowing through the _{transmission side coil L 1} generates an electromotive force in the power _{receiving side coil L 2} coupled by the mutual inductance M, and the current flows. As will be described later, if the characteristics of the primary side circuit 2 and the secondary side circuit 3 are in harmony at this time, the power receiving side capacitor C ₂ is charged most efficiently by the transmitted electric power. That is, electric power is most efficiently transmitted from the primary circuit 2 to the secondary circuit 3. An electromotive force is generated in L1 by a magnetic field generated around the power receiving side coil L ₂ by the current flowing through the power receiving side coil L _2. This electromotive force to the original voltage, the voltage of the power transmission coil L ₁ is as sawtooth wave deviates from a sine wave is not a wave in the normal exchange. A little past the lowest voltage part of this sawtooth wave, it becomes a sawtooth wave characteristic with a hump that rises while rising like a hump.

Constant tau ₂ time until swelling occurs as the aneurysm is mainly capacitance C ₁ of the transmitting-side capacitor C _1, the parasitic resistance of the inductance L ₁ and the power transmission coil L ₁ of the power transmission coil L ₁ R _str (L ₁ ) is a value that depends on the parameters shown in a relationship similar to the equation (4) described later. However, it is necessary to consider the mutual inductance M = M (t) of _{the power receiving side coil L 2} which is a value dependent on the time t for the inductance of the power transmitting side coil L _1.

When t = t ₂ , the voltage of the primary side capacitor reaches the maximum peak again, and at this time, the voltage of the secondary side capacitor becomes a value close to the minimum. When the primary side drive switch SW1 is turned on again in accordance with this peak, the inter-terminal voltage E of the DC power supply 5 is step-input again. As before, _{the charging current flows to the capacitor C 1 at} first, and the value is the value obtained by subtracting the voltage of the capacitor C _{1 at t = t 2} from the voltage E between the terminals of the DC power supply 5 and dividing _{it by r 1.} Is. At this time, the coil L ₁ generates a counter electromotive force to block the inflowing current, so the current to _{L 1 is zero.} The voltage of C1 gradually rises, and as the current becomes smaller, the back electromotive force of L1 becomes smaller and the current to L1 begins to flow. As a result, _{the voltage across C 1} drops a little. At this point, SW1 is closed (t = t ₃ ). _{The time t 3} for closing this switch shall be the time when the current starts to flow in the coil and the time during which _{SW 1} is not destroyed by the voltage applied to SW 1 by the counter electromotive force generated _{by the transmission coil L 1 by turning it off.} .. t = t ₃ after turning off the primary-side drive switch SW1 initiates the full-scale discharge is as current flows from the power transmission side capacitor C ₁ to the power transmission coil L _1. The electric energy stored in the power transmission side capacitor C ₁ tries to move to the _{power transmission side coil L 1.} At this time, _{the magnetic field generated around L 1} by the current flowing through the _{transmission side coil L 1} generates an electromotive force in the power _{receiving side coil L 2} coupled by the mutual inductance M, and the current flows. As will be described later, if the characteristics of the primary side circuit 2 and the secondary side circuit 3 are in harmony at this time, the power receiving side capacitor C ₂ is charged most efficiently by the transmitted electric power. That is, electric power is most efficiently transmitted from the primary circuit 2 to the secondary circuit 3. An electromotive force is generated in L1 by a magnetic field generated around the power receiving side coil L ₂ by the current flowing through the power receiving side coil L _2. This electromotive force to the original voltage, the voltage of the power transmission coil L ₁ is as sawtooth wave deviates from a sine wave is not a wave in the normal exchange. A little past the lowest voltage part of this sawtooth wave, it becomes a sawtooth wave characteristic with a hump that rises while rising like a hump.

As a result, _{after t = t 3} , as shown on the right side of FIG. 1 (b), the voltage between terminals VC _{1 of the power transmission side capacitor C 1} decreases and becomes a negative value again. When the terminal voltage VC ₁ of the power transmission capacitor C ₁ becomes a negative value, the electric energy stored in the power transmission coil L ₁ starts refluxed to the power transmission side capacitor C _1, as shown at the right end shown in FIG. 1 (b) In addition, the voltage between terminals VC ₁ of the power transmission side capacitor C ₁ starts to increase due to the recirculation current, becomes a positive value, and further increases. The time up to this point is determined by the time constant τ ₂ determined by _{the capacitance C 1 of the power transmission side capacitor, the inductance L 1} of the power transmission side coil, and the mutual inductance M. _{As shown in FIG. 1 (b), the change in the terminal voltage VC 1} is not a sinusoidal waveform in the usual AC theory due to the step input and interruption of the terminal voltage E of the DC power supply 5 by the primary side drive switch SW1. , Shows the transient response of the repeating waveform of the rising and falling characteristics of the sawtooth wave with a hump.

When the time constant inherent in the circuit characteristics of the primary side circuit 2 and the time constant inherent in the circuit characteristics of the secondary side circuit 3 are in harmony, the electrical energy of the primary side circuit 2 is most efficiently transmitted to the secondary side circuit 3. Then, characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 occurs. Figure a terminal voltage VC ₁ of the primary-side circuit 2, the transient response waveform of terminal voltage VC ₂ of the secondary side circuit 3 when the characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3 occurs It is shown in 2 (a). _{In FIG. 2 (a), as in FIG. 1 (b), the inter-terminal voltage VC 1} has a sawtooth wave due to the step input and interruption of the inter-terminal voltage E of the DC power supply 5 by the primary side drive switch SW1. The repeated transient response waveforms of rising and falling characteristics are shown. In the transient response waveform shown by the solid line in FIG. 2 (a), the inter-terminal voltage VC _{1 of the power transmission side capacitor C 1} starts increasing from a negative value, becomes a positive value, and further increases, t = t. _{It seems} that the primary side drive switch SW1 is turned on by i.

At this time, as shown by the broken line on the left side of FIG. 2A, the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 between the primary side circuit 2 and the secondary side circuit 3 causes the characteristic harmonized transmission. power receiving side capacitor C ₂ of the secondary side circuit 3 is charged, after the terminal voltage of the power receiving side capacitor C ₂ VC ₂ has reached the peak value, the power-receiving-side capacitor C ₂ starts to discharge, the terminal voltage VC ₂ has begun to decrease. When t = t _i to turn on the primary side drive switch SW1, the terminal voltage E of the DC power source 5 is a step input. Terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3 is reduced to a negative value at t = t _i.

The step input t = t _i, as shown near the center left of FIG. 2 (a), the equivalent internal resistance r _1, the capacitance C ₁ of the power transmission _capacitor, the power-transmitting-side coil inductance L _1, determined by the mutual inductance M The power transmission side capacitor C ₁ of the primary circuit 2 is charged by the time constant τ ₁ , and the terminal voltage VC ₁ increases. As shown in FIG. 2A, the voltage between terminals VC ₁ of the primary side circuit 2 starts to decrease after reaching the peak value. When the t = t i + ₁ on the primary side driving switch SW1 is turned off, the power-transmitting-side capacitor C ₁ of the primary-side circuit 2 starts a full-scale discharge, electric energy stored in the power transmitting side capacitor C ₁ is transmission Move to the side coil L _1. The voltage between terminals VC ₂ of the power receiving side capacitor C ₂ of the secondary circuit 3 is a negative value between _{t = t i} and t = t _{i + 1} as shown by the broken line.

After t = t _{i + 1} , as shown by the solid line near the center of Fig. 2 (a), the capacitance C _{1 of the power transmission side capacitor, the inductance L 1} of the power transmission side coil, _{and the time constant τ 2} determined by the mutual inductance M. terminal voltage VC ₁ of the power transmission capacitor C ₁ becomes reduced to a negative value, the electric energy stored in the power transmitting side capacitor C ₁ transfers to the power transmission coil L _1. The electrical energy stored in the transmission side coil L ₁ is transferred from the secondary side circuit 3 by characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 between the primary side circuit 2 and the secondary side circuit 3. It is wirelessly transmitted to the power receiving side coil L _2. The electric energy wirelessly transmitted to the power receiving side coil L ₂ of the secondary side circuit 3 is stored in _{the power receiving side capacitor C 2 of the secondary side circuit 3.}

As a result, after t = t _{i + 1} , the voltage between terminals VC _{2 of the power receiving side capacitor C 2} of the secondary circuit 3 starts to increase, as shown by the broken line near the center of FIG. 2 (a). The voltage between terminals VC ₂ of the power receiving side capacitor C ₂ of the secondary circuit 3 starts to decrease after reaching the peak value, and becomes a negative value as shown by a broken line on the right side of FIG. 2 (a). As a condition in this embodiment, the _{value of the charging voltage VC S} of the load element 6 in the initial state is close to the charging completion voltage (close to full charge) and high, so that the voltage between the terminals of the power _{receiving side capacitor C 2 is high.} Since _{the charging voltage VC S} of the load element 6 is exceeded near the peak value of _{VC 2} , a current flows through the load element 6, and the electric energy stored in the power receiving side capacitor C2 moves to the load element 6 and is transferred to the load element 6. The rechargeable battery of No. 6 is charged.

After t = t _{i + 1} , as shown by the solid line in the center of FIG. 2A, when the voltage between terminals VC _{1 of the power transmission side capacitor C 1} reaches the minimum negative value, the power transmission side coil L ₁ is reached. the stored electric energy is started refluxed to the power transmission side capacitor C _1, the inter-terminal voltage VC ₁ of the power transmission capacitor C ₁ starts to increase by circulating electric current, a positive value, further increases. As shown by the broken line on the right side of FIG. 2A, when the inter-terminal voltage VC ₁ becomes a positive value, the inter-terminal voltage VC _{2 of the power receiving side capacitor C 2} becomes a negative value.

Terminal voltage VC ₁ of the power transmission capacitor C ₁ is increased in a positive value, when t = t i + ₂ in which again turns on the primary side driving switch SW1, the voltage between the terminals E of the DC power source 5 is step input NS. By the step input of t = t _{i + 2 , the power transmission side capacitor C 1} is charged as shown by the solid line on the right side of FIG. 2 (a), and the terminal voltage VC ₁ increases. As shown by the solid line in FIG. 2A, the voltage between terminals VC ₁ starts to decrease again after reaching the peak value E _0. When the primary side drive switch SW1 is turned off at t = t _{i + 3 , the power transmission side capacitor C 1} starts discharging again, and the electric energy stored in the power transmission side capacitor C ₁ moves to the _{power transmission side coil L 1.} .. The voltage between terminals VC ₂ of the power receiving side capacitor C ₂ of the secondary circuit 3 is a negative value between _{t = t i + 2} and t = t _{i + 3} , as shown by the broken line.

The electrical energy stored in the transmission side coil L ₁ is transferred from the secondary side circuit 3 by characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 between the primary side circuit 2 and the secondary side circuit 3. It is wirelessly transmitted to the power receiving side coil L _2. The electric energy wirelessly transmitted to the power receiving side coil L ₂ of the secondary side circuit 3 is stored in _{the power receiving side capacitor C 2 of the secondary side circuit 3. As shown in FIG. 2A, the change in the inter-terminal voltage VC 1} of the primary side circuit 2 due to the step input and cutoff of the inter-terminal voltage E by the primary side drive switch SW1 is the waveform of the sinusoidal wave in the ordinary AC theory. It shows the transient response of the repeating waveform of the rising and falling characteristics of the sawtooth wave with a hump. _{On the other hand, the change in the voltage VC 2} between the terminals of the secondary circuit 3 shows a transient response of a repeating waveform such as a thinned triangular wave, but it is not a sinusoidal waveform in the usual AC theory. As can be seen from FIG. 2A, the "thinned triangular wave" can be interpreted as a waveform in which the polarity of the trapezoidal wave is reversed. In any case, the vibration waveform of the primary side circuit 2 and the vibration waveform of the secondary side circuit 3 are not symmetrical with each other.

_{2 (b) shows the transient response waveforms of the inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ shown in FIG. 2 (a), the inter-terminal voltage E of the DC power supply 5, the inter-terminal voltage VC _{S of the load element 6, and the inter-terminal voltage VC S.} load element is a 6 plus charge current I _C to rechargeable battery is a measured waveform of the transient response. After stored the to charge to the power transmission side capacitor C ₁ of the primary-side drive switch SW1 to the ON state at t = t _i, the t = t i + ₁ on the primary side driving switch SW1 when the OFF state, the primary circuit 2 Characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 to the secondary side circuit 3 occurs. When the primary-side drive switch SW1 in the ON state, the equivalent internal resistance r ₁ of the DC power source 5 is low, the voltage between the terminals E of the DC power source 5 shown by a thick solid line in FIG. 2 (b) is a primary-side circuit 2 terminal It shows the change superimposed on the inter-voltage VC _1.

This description will be focused on the transient response after _{t = t i + 1 in} FIG. 2 (b). As shown by a solid line near the center of FIG. 2B, the voltage between terminals VC _{1 of the power transmission side capacitor C 1} decreases after t = ti _{+ 1} and becomes a negative value. Electrical energy stored in the power transmitting side capacitor C ₁ is transferred to the power transmission coil L _1, it is accumulated in the power transmission coil L _1. The electrical energy stored in the transmission side coil L ₁ is transferred from the secondary side circuit 3 by characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 between the primary side circuit 2 and the secondary side circuit 3. It is transmitted to the power receiving side coil L _2. Electrical energy transmitted to the power receiving coil L ₂ of the secondary side circuit 3 to be accumulated in the power receiving side capacitor C ₂ of the secondary side circuit 3, the voltage between the terminals VC ₂ of the power receiving side capacitor C _2, as shown in FIG. As shown by the broken line near the center of 2 (b), the increase starts from a negative value after _{t = t i + 1.}

The voltage between terminals VC ₂ of the power receiving side capacitor C ₂ of the secondary circuit 3 is a negative value between _{t = t i} and t = t _{i + 1} as shown by the broken line from the left side of the center. .. The voltage between terminals VC ₂ of the power receiving capacitor C ₂ increases from the negative value of t = ti _{+ 1} , becomes a positive value, further increases, and after reaching the peak value, the right side of FIG. 2 (b). As shown by the broken line in, the decrease starts. When the terminal voltage VC ₂ is reduced, the electric energy stored in the power receiving side capacitor C ₂ flows to the load device 6 as the charging current I _C as shown by the dashed line on the right side of FIG. 2 (b), the load element 6 It will be charged. And substantially synchronized with the increase of the charging current I _C indicated by one-dot chain line, also the voltage between the terminals VC _S load element 6 shown by a dotted line on the right side shown in FIG. 2 (b) slightly increases, after being subjected to a peak value, shows a transient response which decreases in synchronization with decreasing of the charging current I _C. When the charging current I _C is reduced to zero, a decrease in inter-terminal voltage VC _S load element 6 stops and turns to an increase, the voltage between the terminals of the load element 6 becomes a steady value. The change of Vcs according to Ic occurs due to the existence of a series-parallel circuit of a resistor and a capacitor as shown in FIG. 1 (a) as an example of an equivalent circuit.

After t = t _{i + 1} , when the inter-terminal voltage VC _{1 of the power transmission side capacitor C 1} reaches the minimum negative value as shown by the solid line in the center of FIG. 2 (b), the power transmission side coil L ₁ is reached. the stored electric energy is started refluxed to the power transmission side capacitor C _1, the inter-terminal voltage VC ₁ of the power transmission capacitor C ₁ starts to increase by circulating electric current, a positive value, further increases. As shown by the broken line on the right side of FIG. 2B, when the inter-terminal voltage VC ₁ becomes a positive value, the inter-terminal voltage VC _{2 of the power receiving side capacitor C 2} becomes a negative value.

Terminal voltage VC ₁ of the power transmission capacitor C ₁ is increased in a positive value, when t = t i + ₂ in which again turns on the primary side driving switch SW1, the voltage between the terminals E of the DC power source 5 is step input NS. By the step input of t = t _{i + 2 , the power transmission side capacitor C 1} is charged as shown by the solid line on the right side of FIG. 2 (b), and the terminal voltage VC ₁ increases. As described above, the equivalent internal resistance r ₁ of the DC power source 5 is small, when the primary-side drive switch SW1 in the ON state, the voltage between the terminals E of the DC power source 5 shown in thick line in FIG. 2 (b) terminal The change is superimposed on the inter-voltage VC _1. As shown by the solid line superimposed on the rightmost terminal voltage E in FIG. 2B, the terminal voltage VC ₁ starts decreasing again after reaching the peak value. When the primary side drive switch SW1 is turned off at t = t _{i + 3 , the power transmission side capacitor C 1} starts discharging again, and the electric energy stored in the power transmission side capacitor C ₁ moves to the _{power transmission side coil L 1.} .. The voltage between terminals VC ₂ of the power receiving side capacitor C ₂ of the secondary circuit 3 is a negative value between _{t = t i + 2} and t = t _{i + 3} , as shown by the broken line.

t = t _i previous behavior is also similar, terminal voltage VC ₂ of the power receiving side capacitor C _2, as shown by the broken line on the left side of FIG. 2 (b), after reaching the peak value, starts decreasing .. When the terminal voltage VC ₂ exceeds Vcs continue to increase, electric energy stored in the power receiving side capacitor C ₂ is the load element 6 as the charging current I _C indicated by one-dot chain line on the left side shown in FIG. 2 (b) Flow, the load element 6 is charged. And substantially synchronized with the increase of the charging current I _C indicated by one-dot chain line, also the voltage between the terminals VC _S load element 6 shown by a dotted line on the left side shown in FIG. 2 (b) slightly increases, after being subjected to a peak value, shows a transient response which decreases in synchronization with decreasing of the charging current I _C. When the charging current I _C is reduced to zero, a decrease in inter-terminal voltage VC _S load element 6 stops and turns to an increase, the voltage between the terminals of the load element 6 becomes a steady value. The change of Vcs according to Ic occurs due to the existence of a series-parallel circuit of a resistor and a capacitor as shown in FIG. 1 (a) as an example of an equivalent circuit.

Then, already when the the t = t i _{+ 1} on the primary side drives the switch SW1 in the OFF state description, Figure 2 central terminal voltage VC ₁ of the power transmission capacitor C ₁ as shown by the solid line is a negative (b) It starts to decrease toward the value. In this way, _{the electrical energy stored in the transmission side coil L 1} is transferred by characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 between the primary side circuit 2 and the secondary side circuit 3. It is wirelessly transmitted to the power receiving side coil L _{2 of the next side circuit 3.} The electric energy wirelessly transmitted to the power receiving side coil L ₂ of the secondary side circuit 3 is stored in _{the power receiving side capacitor C 2 of the secondary side circuit 3. As shown in FIG. 2B, the change in the inter-terminal voltage VC 1} of the primary side circuit 2 due to the step input and interruption of the inter-terminal voltage E by the primary side drive switch SW1 is the waveform of the sinusoidal wave in the ordinary AC theory. The inter-terminal voltage VC ₂ of the secondary side circuit 3 shows a transient response of a repeating waveform such as a thinned triangular wave.

FIG. 3A is a circuit diagram illustrating a step response as a single circuit of the primary side circuit 2 in a state where there is no electromagnetic coupling between the primary side circuit 2 and the secondary side circuit 3. In FIG. 3A, the voltage between the terminals of the DC power supply is E, the voltage between the terminals of the transmission side capacitor C ₁ is VC ₁ , and the current flowing through the transmission side coil L ₁ is the power transmission side coil current IL ₁ . When the primary side drive switch SW1 is turned on at t = 0 ms, the inter-terminal voltage E of the DC power supply 5 is step-input. The step input t = 0ms, as shown in FIG. 3 (b), the capacitance C ₁ of the power transmission _capacitor, the time constant determined by the inductance L ₁ of the power transmission coil transmitting side capacitor C ₁ to charge the rising waveform V _rise The voltage between terminals VC ₁ increases with the rising waveform V _rise. At the same time, the power transmission side coil current _IL1 also starts to increase as shown in FIG. 3 (b).

As shown in FIG. 3 (b), the inter-terminal voltage VC ₁ increases with the rising waveform V _rise , reaches the peak value at t = 0.075 ms, and then starts decreasing. It can be seen that even after the terminal voltage VC ₁ starts to decrease, the power transmission side coil current IL ₁ continues to increase, and the electric energy of the power _{transmission side capacitor C 1 continues to move to the power transmission side coil L 1.} When the primary-side drive switch SW1 is turned off at t = 0.15 ms, the power-transmitting-side capacitor C ₁ begins a full-scale discharge, rapidly decreases with falling waveform V _fall. In this case the power transmission coil current I _L1 is continuing to increase, until it reaches the peak value of the power transmission coil current I _L1 at t = 0.17ms, electrical energy stored in the power-transmitting-side capacitor C ₁ is the transmission side Move to coil L _1.

As a result, after t = 0.15 ms, as shown in FIG. 3 (b), the voltage between the terminals of the power transmission side capacitor C _{1 is a time constant determined by the capacity C 1 of the power transmission side capacitor and the inductance L 1} of the power transmission side coil. VC ₁ decreases, and when the peak value of the transmission side coil current _IL1 is reached at t = 0.17 ms, the terminal voltage VC ₁ becomes zero. Then, after t = 0.17 ms, the voltage between terminals VC _{1 of the power transmission side capacitor C 1} becomes a negative value. When the terminal voltage VC ₁ of the power transmission capacitor C ₁ becomes a negative value, the value of the power transmission coil current I _L1 begins to decrease, the electrical energy stored in the power transmission coil L ₁ is circulating to the power transmission side capacitor C ₁ Begin to. Then, as shown in FIG. 3 (b), when _{the value of the power transmission side coil current IL1} becomes zero at t = 0.29 ms, the inter-terminal voltage VC _{1 of the power transmission side capacitor C 1} increases due to the recirculation current. Start. _{When the value of the coil current IL1} on the power transmission side reaches the minimum negative value at t = 0.4 ms, the terminal voltage VC ₁ becomes zero, and then the terminal voltage VC ₁ becomes a positive value. And further increase.

In the circuit shown in FIG. 3A, after the primary side drive switch SW1 is turned off at t = 0.15 ms, the primary side drive switch SW1 is not turned on again. That is, in the case of the circuit shown in FIG. 3 (a), since it vibrates freely in the region shown by the diagonal line on the right side of FIG. 3 (b), it can be processed by the ordinary AC theory of a sine wave. However, in the circuit shown in FIG. 1 (a), since the primary side drive switch SW1 drives a forced step response that periodically repeats on / off, the region of free vibration shown by the diagonal line in FIG. 3 (b). Is out of the scope of the power transmission device according to the first embodiment. In the case of a forced step response, as shown in FIGS. 1 (b) to 2 (b), the voltage between terminals VC ₁ of the primary side circuit 2 repeats rising / falling characteristics in which a sawtooth wave with a hump is blunted. The transient response of the waveform is shown. Further, the voltage between terminals VC ₂ of the secondary circuit 3 shows a transient response of a repetitive waveform such as a thinned triangular wave.

That is, in the power transmission device according to the first embodiment, the time constant inherent in the circuit characteristics of the primary side circuit 2 and the circuit of the secondary side circuit 3 are not the resonances based on the sine wave in the usual AC theory. When the time constant inherent in the characteristic is harmonized, the electrical energy of the primary side circuit 2 is efficiently transmitted to the secondary side circuit 3 by the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3. .. In order to harmonize the time constant inherent in the circuit characteristics of the primary side circuit 2 with the time constant inherent in the circuit characteristics of the secondary side circuit 3, the product of the transmission side capacitor C1 and the transmission side coil L1 and the power reception side capacitor Basically, the product of C2 and the power receiving side coil L2 must be the same, and the time constants of the transmitting side and the power receiving side, taking into account the parasitic resistance, stray capacitance, etc., must be matched or multiplied by an integral number to be harmonized. The simplest method is to equalize the capacitance of the transmitting side capacitor C1 and the receiving side capacitor C2 including the parasitic resistance of the capacitor, and to make _{the inductance of the transmitting side coil L 1} and the receiving side coil L ₂ including the parasitic resistance of the coil. To be equal. It should also be noted that when the coil and the capacitor have parasitic resistance, the transmission efficiency is maximized when the inductance L of the coil and the capacitance C of the capacitor satisfy the equation (19), as will be described later. be.

As the primary side drive switch SW1 shown in FIG. 1A, in addition to a mechanical switching element such as an electromagnetic contactor, as a more preferable embodiment, a power semiconductor switching element capable of higher speed switching is used. Examples of semiconductor switching elements for electric power include field effect transistors (FETs), static induction transistors (SITs), bipolar transistors (BJTs), gate turn-off thyristors (GTOs), and static induction thyristors (SI thyristors). Suitable. In particular, voltage-driven switching elements such as insulated gate field effect transistors (MISFETs), insulated gate static induction transistors (MISSITs), insulated gate bipolar transistors (IGBTs), and MOS-controlled SI thyristors consume less power. Suitable. From the market availability and the evaluation of the internal resistance of power semiconductor switching elements, at present, MOS field effect transistors (MOSFETs), which are a type of MISFET, are used as shown in the circuit shown in FIG. 4 (a). It is possible to do.

In a power transmission device in which an EV vehicle-mounted rechargeable battery is used as the load element 6, Joule heat is generated significantly due to a large current flowing, and heat generation of several hundred watts or more is accompanied. It becomes a heating device (heater). In the power transmission device according to the first embodiment, since only one power semiconductor switching element is used as the primary side drive switch SW1, it is covered with a heat sink such as a copper block to improve thermal conductivity, and the element is destroyed by heat generation. The structure that prevents the stray resistance can be easily designed, and the generation of stray resistance, stray capacitance, and stray inductance can be minimized. Stray resistance of the power transmission coil L ₁ and the receiver coil L ₂ (parasitic resistance) heating is large due to the power transmission coil L ₁ and the power receiving coil L ₂ air, measures such as water cooling is preferred.

One method of suppressing the generation of Joule heat in a high-power power transmission device such as an EV for automobiles is to increase the voltage of the primary side circuit 2 and adjust the winding ratio of _{the transmission side coil L 1} and the power reception side coil L _{2 to two.} The voltage of the next circuit 3 is set to the optimum voltage of the load element 6. When a power semiconductor switching element is adopted as the primary side drive switch SW1, simple control for turning on / off the power semiconductor switching element is sufficient, so that it is easy to design a circuit for increasing the voltage of the primary side circuit 2. be.

As described above, according to the power transmission device according to the first embodiment, since the primary side drive switch SW1 is a simple design of only one, the voltage of the primary side circuit 2 is increased to joule the primary side circuit 2 side. It is easy to design to minimize the power loss due to heat generation. Since the energy loss due to Joule heat generation can be reduced, the power transmission device according to the first embodiment includes the loss of the power supply circuit (0th order circuit) in the case of high power power transmission such as for an EV in a vehicle. The overall power transmission efficiency will be high, which can contribute to solving the energy problems of humankind.

4 in the mounting circuit shown in (a), the power-transmitting-side first reflux diode considering circulating electric current from the coil L ₁ (freewheeling diode) FWD ₁ is the source of the MOSFET as a first semiconductor switching element Q1 -The drains are connected in parallel as a protective element. Further, in order to prevent the recirculation current from the transmission side coil L ₁ from recirculating to the DC power supply 5, the power supply side diode D1 is connected in series between the DC power supply 5 and the first semiconductor switching element Q1. Figure 4 is a mounting circuit shown in (a) are represented by approximation the equivalent impedance X _Leq load element 6 in the charge capacity C _s.

The AC theory relies on a sine wave of the normal steady state, the mutual inductance M between the power transmission coil L ₁ and the power receiving coil L _2, using the coupling coefficient K _AC:

M = _KAC (L ₁・ L ₂ ) ^1/2 …… (1)

Can be shown. Then, when the mutual induction between the series circuit of the power transmission side capacitor C ₁ and the power transmission side coil L ₁ and the series circuit of the power reception side capacitor C ₂ and the power reception side coil L ₂ uses the mutual inductance M, the following coupling equation is used.

L ₁ di ₁ / dt + (1 / C ₁ ) ∫i ₁ dt + Mdi ₂ / dt = 0 ... (2)
L ₂ di ₁ / dt + (1 / C ₂ ) ∫i ₂ dt + Mdi ₁ / dt = 0 ... (3)

Represented by. In equations (2) and (3), ∫ is an integral symbol. That is, the mounting circuit shown in FIG. 4A can be expressed as shown in FIG. 4B by using a coil having a mutual inductance M according to the AC theory based on a normal steady-state sine wave.

However, since the power transmission device according to the first embodiment is a transient response transmission technique that does not rely on the AC theory of sine waves, the representation of the equivalent circuit in FIG. 4B is for considering an approximate physical model. It is just a schematic diagram in. Maxwell's equation with time variation can be solved analytically if the time variation relies on a sine wave. However, when there is a serrated time change as shown in FIGS. 1 (b) and 2 (b), it is extremely difficult to analytically solve Maxwell's equation. Therefore, the mutual inductance M used in the AC theory is a time-dependent parameter expressed by a function M (t) having t as time in the present invention, and is represented by the equivalent circuit in FIG. 4 (b). Need attention.

FIG. 5 shows an equivalent circuit for a large signal of nMOSFET used as an example of the first semiconductor switching element Q1 in the mounting circuit shown in FIG. 4A. As shown in FIG. 5A, a general nMOSFET faces a p-type substrate 71 with an n ⁺ -type source region 72 and an n ⁺ -type drain region 73 sandwiching the surface of the p-type substrate 71 as a channel region. I'm letting you. A gate electrode 84 is provided above the channel regions of the source region 72 and the drain region 73 via a gate oxide film 81 having a _{thickness of TOX.} The source electrode 82 is in ohmic contact on the source region 72, and the drain electrode 83 is in ohmic contact on the drain region 73.

As shown in FIG. 5A, in a general nMOSFET, the gate-source capacitance C _GS is between the gate electrode 84 and the source region 72, and the gate-drain is between the gate electrode 84 and the drain region 73. There is a capacitance C _GD and a gate-to-board capacitance C _GB between the gate electrode 84 and the substrate 71. Further, there is a source-board capacitance C _{BS between the source region 72 and the substrate 71, and a drain-board capacitance C BD} between the drain region 73 and the substrate 71. In the equivalent circuit shown in FIG. 5B, the drain resistor R _{D connected in series between the drain electrode and the channel region and the source resistor R S} connected in series between the source electrode and the channel region are formed in the channel region. The configuration shown is connected in series to the constant current source of the current _IDS provided in.

_{In the power transmission device according to the first embodiment shown in FIG. 4, the drain resistance R D} and the source resistance R _{S of} the MOSFET shown in FIG. 5, which are the on-resistances of the first semiconductor switching element Q1, have important meanings. It is necessary to select an element having a small on-resistance for the first semiconductor switching element Q1. Accordingly, in mounting the circuit shown in FIG. 4 (a), when moistened with on-resistance of the first semiconductor switching element Q1 to the equivalent internal resistance r ₁ of the DC power source 5, inherent in the circuit characteristics of the primary-side circuit 2 constants Need to be decided.

When the primary side drive switch SW1 is turned off at t = t ₁ in FIG. 1B, the primary side circuit 2 becomes an RLC series circuit. According to the AC theory, if the parasitic resistance of _{the transmission side coil L 1 is R str} (L ₁ ), the attenuation coefficient ζ ₁ of the RLC series circuit is

ζ ₁ = (R _str (L ₁ ) / 2) (C ₁ / L ₁ ) ^1/2 …… (4)

It is expressed as. However, for the inductance of the power transmission side coil L ₁ , it is actually necessary to consider the mutual inductance M = M (t) shown in FIG. 4 (b), but the mutual inductance M = M (t) is analytically taken into consideration. It is difficult to explain.

If the load side diode D2 on the load side of the secondary side circuit 3 and the load element 6 and the like at this time are ignored, it can be regarded as an RLC series circuit. If the AC theory is adopted by ignoring the load side diode D2 and the load element 6 _{, the attenuation coefficient ζ 2} of the secondary side circuit 3 is set _{to R str} (L ₂ ) as the parasitic resistance of _{the power receiving side coil L 2.}

ζ ₂ = (R _str (L ₂ ) / 2) (C ₂ / L ₂ ) ^1/2 …… (5)

It is expressed as. Also in the equation (5), it is necessary to consider the mutual inductance M = M (t) shown in FIG. 4 (b) for the inductance of the power _{receiving side coil L 2.}

According to the AC theory, the resonance frequency of the RLC series circuit configured with the primary side drive switch SW1 turned off at _{t = t 1} in FIG. 1 (b) is determined.

_fo1 = (1 / 2π) (C ₁ , L ₁ ) ^-1/2 …… (6)

Can be approximated to. As described above, it should be noted that in the equation (6), it is actually necessary to consider the mutual inductance M = M (t) shown in FIG. 4 (b) as the inductance of the power _{receiving side coil L 1.} Is. Similarly, according to the AC theory, the resonance frequency of the RLC series circuit when the load side diode D2 on the load side of the secondary side circuit 3 and the load element 6 and the like are ignored is determined.

_fo2 = (1 / 2π) (C ₂・ L ₂ ) ^-1/2 …… (7)

Can be approximated to. Also in the equation (7), it is necessary to consider the mutual inductance M = M (t) shown in FIG. 4 (b) for the inductance of the power _{receiving side coil L 2.}

_{The power transmission side coil L 1} and the power reception side coil L ₂ of the power transmission device according to the first embodiment may be spiral plane coils as shown in FIGS. 6 (a) to 7 (c), for example. can. In the primary side circuit 2 and the secondary side circuit 3, in the steady state where the AC theory is established, as shown in FIG. 4B, the equivalent coupling coefficient K is between _{the power transmission side coil L 1} and the power reception side coil L _2. , It is possible to approximate with a circuit magnetically coupled with mutual inductance M. Here "equivalent coefficient K" is equivalent to the coupling coefficient K _AC derived from the AC theory, a quasi-coupling coefficient in unsteady state defined during a transient response, strictly a parameter dependent on time. Therefore, even in the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 of the time constant inherent in the circuit characteristics of the primary side circuit 2 and the time constant inherent in the circuit characteristics of the secondary side circuit 3, alternating current it can be evaluated in a manner similar to the coupling coefficient of the theoretical K _AC "magnetic coupling degree".

6 (a) to 7 (c) are schematic views showing the structures of _{the power transmission side coil L 1} and the power reception side coil L _{2 of FIG. 4 (a) in a concrete manner.} In the power transmission device according to the first embodiment, for example, ^{nine wiring cables having a conductor cross-sectional area of 16 mm 2} are wound to form a spiral flat coil having a diameter of about 30 Cm. The two spiral plane coils having a diameter of about 30 Cm are arranged in parallel with each other in a non-contact manner with a gap d. Efficiency characteristics harmony transmission between the primary-side circuit 2 and the secondary-side circuit 3 from the primary circuit 2 to the secondary-side circuit 3, the coupling coefficient K _AC similar magnetic coupling degree is defined by alternating theory Depends on the value. The degree of magnetic coupling depends on the distance d between the two spiral plane coils, and it is necessary to control the distance d between the two spiral plane coils.

The degree of magnetic coupling mechanically adjusts the positional relationship between the two spiral plane coils. A magnetic material is inserted between the two spiral plane coils, or a magnetic material is placed around the two spiral plane coils. It can be adjusted by attaching to a preformed coupling using the attractive force or repulsive force acting between the two spiral flat coils to be arranged.

As will be described in the fourth embodiment, the interrelationship between the _{power transmitting side coil L 1} and the power receiving side coil L _{2 having} an equivalent coupling coefficient K that can be approximately approximated to _{the coupling coefficient KAC = 0.6 of the AC theory} It is suitable for characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3. In the case of a spiral flat coil in which 9 wiring cables having a conductor cross-sectional area of 16 mm ² are wound, the interval d needs to be about 0 Cm to 2.0 Cm in order to realize the equivalent coupling coefficient K = 0.6. .. On the other hand, in order to realize the mutual relationship between _{the power transmitting side coil L 1} and the power receiving side coil L _{2 under} the condition that the equivalent coupling coefficient K can be approximately approximated to the coupling coefficient _{KAC = 0.1 of the AC theory, the interval d is 10 Cm.} Degree. As shown schematically in FIG. 6 (b) _{by exaggerating (enlarging) the power transmission side coil L 1} and the power reception side coil L ₂ , the load element 6 which is an EV vehicle-mounted rechargeable battery is the first embodiment. In order to charge using the power transmission device according to the above, the vehicle stop 33 of the rear wheel is used as a magnetic coupling degree control mechanism to control the distance d between _{the power transmission side coil L 1} and the power reception side coil L _{2 to about 10 Cm.} Efficient contactless power supply can be performed.

As a magnetic coupling degree control mechanism for controlling the distance d between the power transmission side coil L ₁ and the power reception side coil L ₂ , as shown in FIG. 7A, there is a thickness between _{the power transmission side coil L 1} and the power reception side coil L _2. By sandwiching the spacer 32 of d ₀ , the distance between _{the power transmission side coil L 1} and the power reception side coil L ₂ can be controlled to _{d = d 0. It should be noted that the transmission side coil L 1} corresponding to the value of the magnetic coupling degree, which is important for the efficiency of characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 from the primary side circuit 2 to the secondary side circuit 3. interrelation of the power receiving coil L _2, it is possible to configure the magnetic coupling of the control mechanism by the power transmission coil L ₁ and the power receiving side parameters other than distance d of the coil L _2.

For example, to configure the magnetic coupling degree control mechanism between the power transmission coil L ₁ and the power receiving side coil L ₂ by inserting the magnetic material plate 31C of the ferrite permeability mu _r as shown in FIG. 7 (b) May be good. The value of the degree of magnetic coupling between the _{power transmission side coil L 1} and the power reception side coil L ₂ can be controlled by the insertion position of the magnetic material plate 31C in the vertical direction or the insertion area of the magnetic material plate 31C. The magnetic plate 31C may be inserted not between the power transmission side coil L ₁ and the _{power transmission side coil L 2 but on the back side of the power transmission side coil L 1} as shown in FIG. 7 (c). do not have. Insertion position in the vertical direction of the magnetic plate 31b, or by the ratio of the insertion area of the magnetic plate 31b to the area of the power transmission coil L _1, a magnetic coupling degree between the power transmission coil L ₁ and the power receiving coil L ₂ The value can be controlled. Although not shown, similarly be inserted magnetic plate on the back of the power receiving coil L _2, it can be controlled value of magnetic coupling degree between the power transmission coil L ₁ and the power receiving coil L ₂ Of course.

Specifically, in order to control the insertion position of the magnetic plate 31C shown in FIG. 7B in the vertical direction and the insertion position of the magnetic plate 31b shown in FIG. 7C in the vertical direction, FIG. 8A ) May be provided on the power feeding device side where the power transmission side coil L _{1 is provided.} The distance measuring unit 41 may provide a magnetic coupling degree control mechanism including a light emitting unit 411 and a light receiving unit 412. If the light receiving unit 412 is a time-of-flight type (TOF type) ranging element d, pulse light is emitted from the light emitting unit 411. For pulse emission, for example, a near-infrared LD (laser diode) or a near-infrared LED is used. The pulsed light reflected from the rear part of the power receiving side coil L ₂ or EV is applied to the light receiving unit 412 through a lens, a BPF (bandpass filter), or the like. The ranging unit 41 may have a configuration such as a laser interferometer.

The distance calculation unit 421 of the logical operation control unit 42 shown in FIG. 8A is connected to the light receiving unit 412 of the distance measurement unit 41. The output of the light receiving unit 412 is input to the distance calculation unit 421 constituting the magnetic coupling degree control mechanism via an output buffer or an interface (not shown), and in the distance calculation unit 421, the transmission side coil L ₁ and the power reception side The arithmetic processing necessary for measuring the distance between the coils L _{2 is performed.} The logical operation control unit 42 contains data necessary for logical operations such as calculation of the value of the degree of magnetic coupling in the logical operation control unit 42 and a magnetic material plate necessary for realizing a desired equivalent coupling coefficient (pseudo-coupling coefficient). A data storage device 45 in which data of the insertion position in the vertical direction of the above is stored is connected. Although not shown, the logical operation control unit 42 may be connected to a program storage device or the like that stores a program that commands the operation of the logical operation control unit 42.

_{The data of the distance between the power transmission side coil L 1} and the power reception side coil L ₂ calculated by the distance calculation unit 421 is transmitted to the coupling coefficient calculation unit 422 of the logical operation control unit 42. The coupling coefficient calculation unit 422 uses the data of the distance between the _{power transmission side coil L 1} and the power reception side coil L ₂ calculated by the distance calculation unit 421 to determine the magnetism between the _{current power transmission side coil L 1} and the power reception side coil L _2. Find the value of the degree of coupling. The coupling coefficient calculation unit 422 further calculates the moving distance of the magnetic plate from the data of the insertion position in the vertical direction of the magnetic plate required to realize the desired equivalent coupling coefficient stored in the data storage device 45. Then, the data is output to the coupling coefficient adjustment drive device 43. The coupling coefficient adjustment driving device 43 of the magnetic coupling degree control mechanism shown in FIG. 8 (a) has the magnetism shown in FIG. 7 (b) from the data of the moving distance of the magnetic material plate sent from the coupling coefficient calculation unit 422. The insertion position of the body plate 31C in the vertical direction and the insertion position of the magnetic body plate 31b shown in FIG. 7C in the vertical direction are driven and controlled to be desired positions. A well-known position control mechanism such as a step motor can be adopted for the coupling coefficient adjusting drive device 43. In this way, feedback control can be performed from the output of the ranging unit 41 so that the insertion position of the magnetic material plate 31C or the magnetic material plate 31b in the vertical direction becomes a desired position.

In the computer system of the magnetic coupling degree control mechanism including the logical calculation control unit 42 shown in FIG. 8A, the data storage device 45 is a group including a plurality of registers, a plurality of cache memories, a main storage device, and an auxiliary storage device. It is also possible to use any combination appropriately selected from the above. Further, the cache memory may be a combination of a primary cache memory and a secondary cache memory, and may have a hierarchy including a tertiary cache memory. The logical operation control unit 42 shown in FIG. 8A can configure a computer system by using a microprocessor (MPU) or the like mounted as a microchip. In addition, as a logical operation control unit 42 that constitutes a computer system of a magnetic coupling degree control mechanism, an embedded device equipped with a digital signal processor (DSP) that enhances arithmetic operation functions and specializes in signal processing, and a memory and peripheral circuits. A microcontroller (microcomputer) or the like for the purpose of control may be used. Alternatively, the main CPU of the current general-purpose computer may be used for the logical operation control unit 42.

FIG. 9 is a diagram showing the operation of the mounting circuit shown in FIG. 4A in chronological order, divided for each timing. As shown in FIG. 9 (a), at the timing of the first semiconductor switching element Q1 as a primary-side drive switch SW1 to the ON state, charges are stored first in the transmission side capacitor C _1. As shown in FIG. 9A, the internal resistance r _on 1 of the first semiconductor switching element Q1 at this time. In the timing of FIG. 9 (a), the inter-terminal voltage VC ₁ of the power transmission capacitor C ₁ begins to increase, a portion of the stored electrical energy to the power transmission side capacitor C ₁ is the transmission side as the power transmission coil current I _L1 moves to the coil L _1, is accumulated in the power transmission coil L _1. Although the electric energy of the transmission side coil L ₁ is small, it is transmitted to the power reception side coil L _{2 of the secondary side circuit 3.} Electrical energy transmitted to the power receiving coil L ₂ of the secondary side circuit 3 is consumed for charging the power receiving side capacitor C ₂ of the power receiving coil current I _L2 as the secondary-side circuit 3. However, the inter-terminal voltage VC ₂ of the power receiving side capacitor C ₂ is a timing shown in FIG. 9 (a) is a negative value.

Then, at the timing shown in FIG. 9 (b), when the first semiconductor switching element Q1 as a primary-side drive switch SW1 to cut off state (OFF state), the voltage between the terminals VC ₁ of the power transmission capacitor C ₁ decreases was started, electric energy stored in the power transmitting side capacitor C ₁ is transferred to the power transmission coil L ₁ as the power transmission coil current I _L1, it is accumulated in the power transmission coil L _1. The electrical energy stored in the transmission side coil L ₁ is transferred from the secondary side circuit 3 by characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 between the primary side circuit 2 and the secondary side circuit 3. It is wirelessly transmitted to the power receiving side coil L _2. Electrical energy transmitted to the power receiving coil L ₂ of the secondary side circuit 3 is stored in the power receiving side capacitor C ₂ of the secondary side circuit 3 as the power receiving coil current I _L2. At the timing of FIG. 9B, the voltage between terminals VC _{2 of the power receiving side capacitor C 2} becomes a positive value. The voltage between terminals VC ₂ of the power receiving side capacitor C ₂ reaches a peak value and then starts to decrease.

When the voltage between terminals VC ₂ decreases, the electrical energy stored in the power receiving side capacitor C _{2 flows to the load element 6 as the charging current ICS} as shown in FIG. 9B, and the load element 6 is charged. .. However, with the decrease of the terminal voltage VC _2, a portion of the accumulated in the power receiving side capacitor C ₂ electrical energy, as shown in FIG. 9 (b), the power receiving side coil current to the power receiving side coil L ₂ I _L2 As a result, electrical energy is also stored in the _{coil L 2} on the power receiving side. As shown in FIG. 9C, the electric energy stored in the power receiving side coil L ₂ is between the primary side circuit 2 and the secondary side circuit 3 between the secondary side circuit 3 and the primary side circuit 2. It is recirculated to the transmission side coil L ₁ of the primary side circuit 2 by the characteristic harmonized transmission.

As shown in FIG. 9 (c), the power transmission coil L ₁ transmitting-coil current was circulated to I _L1, electrical energy stored in the power transmission coil L ₁ starts refluxed to the power transmission side capacitor C _1, the transmission terminal voltage VC ₁ side capacitor C ₁ starts to increase by circulating electric current. Accordingly, as shown in FIG. 9 (c), an ammeter 461 for measuring the power transmission coil current I _L1 which circulated in the power transmission coil L _1, and a voltmeter 462 for measuring the terminal voltage VC _1, the primary side If it is provided in the circuit 2, the magnitude of the electric energy recirculated from the secondary circuit 3 can be measured. That is, it is transmitted from the primary side circuit 2 to the secondary side circuit 3 by the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 by the ammeter 461 and the voltmeter 462 provided in the primary side circuit 2. The efficiency of wireless transmission can be measured.

Therefore, a magnetic coupling degree control mechanism that controls the insertion position of the magnetic plate 31C shown in FIG. 7B in the vertical direction and the insertion position of the magnetic plate 31b shown in FIG. 7C in the vertical direction is provided. To configure the structure, the transmission efficiency measuring unit 46 as shown in FIG. 8B may be provided on the power feeding device side where the power _{transmission side coil L 1 is provided.} As shown in FIG. 9C, the transmission efficiency measuring unit 46 is an ammeter 461 and a voltmeter 462 provided in the primary side circuit 2.

The ammeter 461 and the voltmeter 462 shown in FIG. 9 (c) are connected to the transmission efficiency calculation unit 471 of the logical operation control unit 47 constituting the magnetic coupling degree control mechanism shown in FIG. 8 (b). .. The outputs of the ammeter 461 and the voltmeter 462 are input to the transmission efficiency calculation unit 471 via an output buffer and an interface (not shown), and in the transmission efficiency calculation unit 471, the transmission side coil L ₁ and the power reception side coil L ₂ The arithmetic processing necessary for measuring the transmission efficiency between the two is performed. The logical operation control unit 47 stores data required for logical operations such as transmission efficiency calculation in the logical operation control unit 47 and data on the insertion position of the magnetic plate in the vertical direction necessary for achieving the desired transmission efficiency. The data storage device 45 is connected. Although not shown, the logical operation control unit 47 may be connected to a program storage device or the like that stores a program that commands the operation of the logical operation control unit 47.

_{The transmission efficiency data between the transmission side coil L 1} and the power reception side coil L ₂ calculated by the transmission efficiency calculation unit 471 is transmitted to the coupling coefficient calculation unit 472 of the logical operation control unit 47 constituting the magnetic coupling degree control mechanism. Will be done. The coupling coefficient calculation unit 472 is located between the current power transmission side coil L ₁ and the power reception side coil L _{2 from the transmission efficiency data between the power transmission side coil L 1} and the power reception side coil L ₂ calculated by the transmission efficiency calculation unit 471. The value of the magnetic coupling degree of is obtained. The coupling coefficient calculation unit 472 further calculates the moving distance of the magnetic plate from the data of the insertion position in the vertical direction of the magnetic plate, which is stored in the data storage device 45 and is necessary for realizing the desired transmission efficiency. , Output to the coupling coefficient adjustment drive device 43. From the data of the change in transmission efficiency due to the movement of the magnetic material plate sent from the coupling coefficient calculation unit 472, the coupling coefficient adjusting drive device 43 shows the insertion position and the vertical direction of the magnetic material plate 31C shown in FIG. 7 (b). The insertion position of the magnetic plate 31b shown in 7 (c) in the vertical direction is driven and controlled so as to be a desired position. A well-known position control mechanism such as a step motor can be adopted for the coupling coefficient adjusting drive device 43. In this way, the magnetic coupling degree control mechanism shown in FIG. 8B sets the insertion position of the magnetic material plate 31C and the magnetic material plate 31b in the vertical direction from the output of the transmission efficiency measuring unit 46 to a desired position. Feedback control can be performed as follows.

Similar to that described in FIG. 8A, the data storage device 45, which is a part of the magnetic coupling degree control mechanism shown in FIG. 8B, includes a plurality of registers, a plurality of cache memories, a main storage device, and the like. It is also possible to use any combination appropriately selected from the group including the auxiliary storage device. The logical operation control unit 47 shown in FIG. 8B can configure a computer system by using an MPU or the like mounted as a microchip. Further, as the logical operation control unit 47 constituting the computer system, a DSP specializing in signal processing with enhanced arithmetic operation functions, a microcomputer equipped with a memory and peripheral circuits for the purpose of controlling embedded devices, and the like may be used. .. Alternatively, the main CPU of the current general-purpose computer may be used for the logical operation control unit 47.

Conventionally known "resonance" is that the vibration of the sine wave of the primary side circuit 2 is transmitted to the secondary side circuit 3 which is free-vibrating, and the secondary side circuit 3 has the same frequency as the primary side circuit 2. It is a vibrating concept. The power transmission device according to the first embodiment of the present invention includes a primary side drive switch SW1 that limits the free vibration of the primary side circuit 2 and realizes a transient current-voltage change in the primary side circuit 2. Therefore, it is possible to transmit the serrated transient response characteristic, which is a non-sinusoidal wave, to the secondary circuit 3 by the concept of "characteristic harmonized transmission" proposed by the present inventors for the first time. By using the sawtooth-shaped transient response characteristic which is a non-sinusoidal wave, a complicated and expensive AC power supply circuit that generates a sinusoidal vibration on the primary side circuit 2 side as in the conventional case becomes unnecessary.

As described above, in the power transmission device according to the first embodiment, the time constant inherent in the primary side circuit 2 and the time constant inherent in the secondary side circuit 3 are harmonized with each other to harmonize the electric energy of the primary side circuit 2. Is transmitted to the secondary circuit 3. In the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3, for example, _{the capacities of the power transmission side capacitor C 1} and the power reception side capacitor C ₂ are equalized including the parasitic resistance of the capacitor, and the power transmission side coil L is used. _{The inductance of 1} and the power receiving side coil L ₂ may be equalized including the parasitic resistance of the coil. Therefore, for example, if the on / off repetition period of the primary side drive switch SW1 is set to 500 to 600 μs, the capacitances of the power transmitting side capacitor C ₁ and the power receiving side capacitor C ₂ are set to be the same as each other in the range of, for example, 400 μF to 600 μF. , The inductance of the power transmitting side coil L ₁ and the power receiving side coil L ₂ may be the same as each other in the range of, for example, 5 μH to 20 μH.

The sawtooth-shaped transient response waveform as shown in FIGS. 1 (b) and 2 includes a plurality of bumps in one cycle. It is extremely difficult to analytically solve the transient response waveform of the power transmission device according to the first embodiment. Therefore, although it is approximate, the circuit shown in FIG. 28 will be simulated by the AC theory. In FIG. 28, the capacitance of the capacitor and the inductance of the coil of the primary side circuit 2 and the secondary side circuit 3 are set to the same value. That is, an approximate simulation is performed with C ₁ = C ₂ = 500 μF and L ₁ = L _{2 = 10 μH.} In this case (6) the resonant frequency of the RLC series circuit is given by equation f _o1 = 2.25 kHz, the resonant frequency f _o2 = 2.25 kHz of the RLC series circuit is given by equation (7). The corresponding repetition period is 444 μs.

Turn on the primary side driving switch SW1, when there is a step input, current initially flows to the power transmission side capacitor C _1. The power transmission side coil L ₁ originally has a property of hindering a sudden inflow of current. The voltage of the power transmission side capacitor C ₁ gradually rises, and a current gradually begins to flow in the _{power transmission side coil L 1.} In the meantime, the electric charge accumulated in the power transmission side capacitor C ₁ also flows out to the _{power transmission side coil L 1.} When this happens, the voltage of the power transmission side capacitor C1 drops. Ideally, the time until the primary side drive switch SW1 is turned off is set so that the sum ^{of the electrostatic energy (1/2) CV 2} and the magnetic energy (1/2) LI ^{2 is maximized.} but, with the current I to the power transmission coil L ₁ flows, the primary side driving switch SW1 is turned off so that counter electromotive force is generated in the power transmission coil L _1.

Care must be taken so that the voltage of the counter electromotive force generated in the transmission side coil L ₁ does not exceed the withstand voltage of the first semiconductor switching element Q1 used for the primary side drive switch SW1 shown in FIG. The on / off repetition cycle of the primary side drive switch SW1 is set to be slightly earlier than the timing at which the peak is reached, in consideration of the time until the terminal voltage VC1 of the power transmission side capacitor C1 rises again and reaches its peak.

It indicates an approximate simulation change of the voltage of the power transmission capacitor C ₁ as a result of the Figure 29. The Figure 29 as shown in FIG. 1 (b) and 2, the transient response waveform sawtooth obtain the change of the voltage of the power transmission capacitor C _1. It will be described with reference to FIG. 30 that the sawtooth wave aneurysm is generated because the current of the primary side circuit 2 is reduced by the magnetic flux due to the current induced in the power _{receiving side coil L 2.} The voltage of the secondary circuit 3 is the same as in the mode using the four switches of the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4, which will be described later in the fourth embodiment. Corresponds to the phenomenon that the voltage of the primary side circuit 2 becomes zero when the voltage becomes maximum, and the peak in the middle of the W-shaped transient response waveform shown in FIG.

The W-type transient response waveform shown in FIG. 34 will be described later with reference to FIG. 35. An approximate simulation using the circuit shown in FIG. 31, which is a simplified circuit diagram in which parasitic capacitance and resistance are omitted from the circuit of FIG. 28, shows a W shape as shown in FIG. 32. A transient response waveform is obtained in which the voltage in the valley on the right side of is raised. The mountain in the middle of the W-shaped transient response waveform shown by the dashed circles A ₁ and A ₂ in FIG. 32 is shown in FIGS. 1 (b) and 2 due to the influence of parasitic capacitance and resistance. It can be seen that it appears as a hump in such a sawtooth wave.

In the mode of only the primary side drive switch SW1 in the first embodiment, as shown in FIGS. 30A to 30D, when the ON / OFF repetition cycle of the primary side drive switch SW1 is lengthened, the transient response waveform is generated. The aneurysm becomes smaller and gradually approaches the response waveform of the sawtooth wave as shown in FIGS. 1 (b) and 2. FIG. 29 is an enlarged view of the transient response waveform in the case of the repetition period of 575 μs shown in FIG. 30 (c), and corresponds to the transient response waveform shown in FIGS. 1 (b) and 2. ..

When the on / off repetition period of the primary side drive switch SW1 is 565 μs, it is a W-shaped transient response waveform as shown by _{the circle A a of the broken line in FIG. 30 (a).} Since the repetition period obtained from the resonance frequency of the RLC series circuit defined by the equations (6) and (7) is 444 μs, the repetition period of FIG. 30 (a) takes into consideration the time of turning on SW1 of 100 μs. However, it is longer than the repetition period required by the AC theory. That is, it can be seen that the power transmission device according to the first embodiment vibrates at a repetition period different from the resonance frequency of the RLC series circuit obtained by the AC theory.

In the power transmission device according to the first embodiment, the amplitude is reduced by transmitting electrical energy from the primary side circuit 2 to the secondary side circuit 3 by characteristic harmonized transmission. The repetition period, in the case of repetition period 570μs in Figure 30 was slightly longer (b), as shown enclosed by the dashed circle A _b, the voltage of the right valley of the shape of W showing a transient response waveform Lift up. Further, as shown in FIGS. 1 (b) and 2, a bulge begins to occur on the upper side of the sawtooth wave.

By further transmitting electrical energy from the primary side circuit 2 to the secondary side circuit 3 by characteristic harmonized transmission, the amplitude is further reduced. If the repetition period was longer and the repetition period 575μs in FIG. 30 (c), the one in the shape of W as shown enclosed by the dashed circle A _c, the voltage of the right valley further raised nodular It becomes the shoulder part, and the shape of W disappears from the transient response waveform. Then, as shown in FIGS. 1 (b) and 2, a bump appears on the upper side of the sawtooth wave.

When the amplitude is further reduced by further transmitting electrical energy to the secondary circuit 3 by the characteristic harmonized transmission and the repetition period is further lengthened to the repetition period of 580 μs in FIG. 30 (d), the broken line circle A _As shown by the circled d, the bumpy shoulder showing the transient response waveform is further lifted. Then, as shown in FIGS. 1 (b) and 2, the upper aneurysm of the sawtooth wave also becomes prominent, and a two-stage aneurysm is shown. In this way, among the W shapes showing the transient response waveform, the amplitude gradually becomes smaller, and when the repetition period is lengthened, the voltage in the valley on the right side does not gradually decrease, and the valley on the right side of the W shape rises, and a two-stage bump. It becomes a serrated transient response waveform with.

When the on / off repetition cycle of the primary side drive switch SW1 is lengthened, the voltage in the valley on the right side of the W shape rises because the electrical energy received by the secondary side circuit 3 moves to the load element 6 to be charged. it is conceivable that. The maximum value of the current when the primary side drive switch SW1 is turned on and the maximum value of the current flowing through the load element 6 are the parasitic inductances of the electric wires constituting the actual circuit of the power transmission device according to the first embodiment. Dependent. From the analysis of the waveform measured in the actual circuit, the parasitic inductance is estimated to be about 1 mH to 3 μH. That is, the serrated transient response waveform having a plurality of bumps shown in FIGS. 1 (b) and 2 is generated by the time constant peculiar to the circuit depending on the parasitic resistance, parasitic capacitance, and parasitic inductance. I understand.

Next, using the resonance frequency f _o1 of the RLC series circuit is a conventional AC Theory (6) gives, omega ₀ = 2 [pi] f _o1, and _{ω1 = ω 0 / (1-} k) 1/2, in FIG. 35 As shown, as the energy transfer function f1, the sigmoid function that decays in steps after 2π / ω 1 second, which is the transfer timing:

f1 = V3 / [1 + exp {10 ⁶ (t-2π / ω1)}] + V2 …… (8)

think of. Here, k that defines ω1 = ω ₀ / (1-k) ^1/2 _{is the coupling coefficient KAC of the AC} theory used in the definition of equation (1) (k = _KAC ).

Furthermore, as an arbitrary attenuation function f2, a function that diminishes with an appropriate attenuation constant τ:

f2 = exp (−τt) …… (9)

think of. For example, in a power transmission device according to the first embodiment, the damping function f2 corresponds to a function that decays by a constant τ time due to the parasitic resistance and the capacitor of the maximum value of the voltage VC1 across the primary-side capacitor C _1.

Figure 35 V1, V2, V3 described may be all corresponding to the voltage VC1 at both ends of the capacitor C ₁ of the primary side. V1 can correspond _{to the voltage first charged in the capacitor C 1} on the primary side and the voltage remaining in the capacitor C 1 on the primary side after V2 is transferred to the secondary circuit 3 for electrical energy. V3 shown in FIG. 35 corresponds to those differences. Energy transfer function f1 is a function of the voltage VC1 across the capacitor C ₁ of the primary side is made with the intention that falls V2 from V1.

Using the above-described _{ω 0 = 2πf o1 ω2 = ω} 0 / (1 + k) 1/2 and then mutual induction function φ a (k),

φ (k) = cos (ω1t) + cos (ω2t) …… (10)

If defined as, the function (V1 / 2) φ (k) shows a change as shown by a thin broken line curve after the transfer timing of 2π / ω1 second in FIG. 35. However, it should be noted that the coupling coefficient K of the power transmission device according to the first embodiment is a time-dependent parameter _{and is strictly different from the coupling coefficient KAC of the AC theory.} Thin broken line in FIG. 35 is a waveform before supplying a current to the load circuit 6, corresponding to the waveform of the voltage VC1 across the primary-side capacitor C _1. The thin broken line after the transfer timing of 2π / ω 1 second can be considered as the waveform when the energy of the primary side capacitor C1 is not transferred to the secondary side.

Function (V2 / 2) φ (k ) is a thin dashed curve up to the transfer timing 2 [pi / .omega.1 seconds in FIG. 35, the voltage across the capacitor C ₁ after a current is supplied to the load circuit 6 VC1 It is a waveform of. It corresponds to the waveform when it is considered that the energy of the primary side capacitor C1 has moved to the secondary side from the beginning by the amount transferred to the secondary side. It can be seen that the functions f1, f2, φ (k) shown by the solid line become the voltage VC1 across the _{capacitor C 1 and indicate the W type.}

As described above, in the power transmission device according to the first embodiment, the amplitude is reduced by transmitting the electric energy to the secondary side circuit 3 by the characteristic harmonized transmission. That is, as shown in FIG. 32, the valley on the right side of the W-shaped transient response waveform becomes smaller, gradually rises upward, and does not become dented. This results in a sawtooth-like overall RC time constant, which is attenuated by the dissipation of electrical energy due to parasitic resistance. The approximate simulation of the circuit shown in FIG. 28 by the AC theory is only an approximation, and although there are limits to the AC theory, it should be possible to understand a sawtooth-shaped transient response waveform with roughly two steps of bumps. .. In reality, only the experimental data shown in FIGS. 1B and 2 can explain the effect of the power transmission device according to the first embodiment.

That is, if the same capacitor is used for the power transmitting side capacitor C ₁ and the power receiving side capacitor C ₂ , and the same coil is used for the inductance of the power transmitting side coil L ₁ and the power receiving side coil L ₂ , parasitic resistance is added to the coil and the capacitor. Including, the time constant inherent in the primary side circuit 2 and the time constant inherent in the secondary side circuit 3 can be harmonized.

As described above, since the power transmission device according to the first embodiment of the present invention is a technique that does not rely on the AC theory using a novel concept of characteristic harmonized transmission, it is possible to use an inexpensive DC power supply 5. can. Therefore, the power transmission device according to the first embodiment does not require an expensive switching power supply, simplifies the circuit configuration, and minimizes the power loss on the control circuit side. In particular, when a power semiconductor switching element is used as the primary side drive switch SW1, simple control for turning on / off the power semiconductor switching element is sufficient, so that power loss on the control circuit side is also reduced and the power supply circuit. The overall power transmission efficiency including the loss of the (0th order circuit) can be improved. In particular, since the circuit configuration is simplified, it is hard to break and the circuit design becomes easy. In addition, the limit power of power transmission can be pushed up to a value that exceeds the limit power in the conventional AC theory. The limit power of power transmission can be pushed up to infinity in principle, but the limit distance of power transmission can also be extended to infinity in principle.

As a result, according to the power transmission device according to the first embodiment, the overall configuration of the power transmission device is simplified, the power loss on the control circuit side is minimized, and the weight, size, and efficiency are improved. This makes it possible to inexpensively manufacture wireless power transmission devices with improved overall power transmission efficiency due to power saving. Further, since characteristic harmonized transmission can be realized with a repetition period longer than the repetition period required by the conventional AC theory, a frequency lower than that in the case of multiple resonance in the conventional AC theory may be used. Since a low frequency circuit design is sufficient, it is easy to increase the voltage on the primary side circuit 2 side, and energy loss due to Joule heat generation can be reduced. Therefore, the power transmission device according to the first embodiment is a comprehensive power transmission. A highly efficient power transmission device can be manufactured at low cost. By lowering the parasitic resistance, in principle, it is possible to manufacture a power transmission device in which the power transmission efficiency exceeds 99% and is increased to a value close to 100%.

(Second embodiment)
As shown in FIG. 10A, the power transmission device according to the second embodiment of the present invention adds the power transmission side switch SW2 to the circuit configuration of the power transmission device according to the first embodiment shown in FIG. It has a structure that is Like the primary side drive switch SW1, the “power transmission side switch SW2” is also a circuit element that limits the free vibration of the primary side circuit 2 and realizes a transient current-voltage change in the primary side circuit 2.

As the primary side drive switch SW1 and the transmission side switch SW2 shown in FIG. 10A, thyristors such as a GTO thyristor and an SI thyristor are used in addition to the FET, SIT, and BJT similar to the power transmission device according to the first embodiment. Power semiconductor switching elements including are used. In particular, if a voltage-driven switching element such as a MISFET, MISSIT, IGBT, or MOS-controlled SI thyristor is used, the power consumption is reduced, so that it is suitable for the primary side drive switch SW1 and the power transmission side switch SW2. From the market availability and the evaluation of the internal resistance of power semiconductor switching elements, it is currently possible to adopt MOSFETs as the primary side drive switch SW1 and power transmission side switch SW2 of the circuit shown in FIG. 10B. It is possible.

As already described in the power transmission device according to the first embodiment, Joule heat is generated significantly in a high power power transmission device in which the EV rechargeable battery is used as the load element 6. In the power transmission device according to the second embodiment, only two power semiconductor switching elements are used as the primary side drive switch SW1 and the power transmission side switch SW2, so that a cooling structure for preventing element destruction due to heat generation is simple. It can be designed, and the generation of stray resistance, stray capacitance, and stray inductance can be minimized. Further, since the simple control of turning on / off the primary side drive switch SW1 and the power transmission side switch SW2 is sufficient, it is possible to easily design by increasing the voltage of the primary side circuit 2 and suppressing the generation of Joule heat.

10 in the mounting circuit shown in (b), between the MOSFET source and drain of the power transmission side wheeling diode FWD ₁ considering circulating electric current in the first coil L ₁ is a first semiconductor switching element Q1, the The freewheeling diode FWD _{2 of 2} is connected in parallel as a protection element between the source and drain of the MOSFET as the second semiconductor switching element Q2. Figure 4 similarly to the circuit shown in (a), since the circulating electric current from the power transmission coil L ₁ is prevented from refluxing to the DC power supply 5, the power supply side diode D1 and the DC power source 5 the first semiconductor switching element Q1 Is connected in series between. Even in the mounting circuit shown in FIG. 10B, the equivalent impedance X _Leq of the load element 6 is approximated by the charging capacity C _{s and expressed.}

The wireless power transmission method according to the first embodiment will be described with reference to the timing diagram of FIG. 11 and the time series schematic diagram shown in FIGS. 12 (a) to 12 (d). However, as in the first embodiment, when the equivalent coefficient K in coefficient K _{AC =} 0.6 derived from the AC theory has assumed the value in the initial state of the charge voltage VC _S is almost fully charged It is assumed that the voltage is sufficiently high. First, at the timing shown in FIG. 12 (a), the power-transmitting-side switch SW2 turned off, and the primary-side drive switch SW1 in the ON state, storing electric charge by applying an initial voltage to the power transmission side capacitor C _1. In FIG. 12A, since the first semiconductor switching element Q1 is used for the primary side drive switch SW1, the on state of the primary side drive switch SW1 is shown by _{the on-resistance r on1 of the first semiconductor switching element Q1.} .. Power-transmission-side primary circuit 2 the switch SW2 in an OFF state is not yet formed, as shown in FIG. 12 (a), the on-state of the primary-side drive switch SW1, a DC power source 5, the equivalent internal resistance r _1, the first semiconductor switching elements Q1 and the power supply side circuit 1 by a first freewheeling diode (reflux diode) composed of a parallel circuit and a power-transmitting-side capacitor C ₁ of the FWD ₁ series "circuit is configured.

As shown by a thin broken line in FIG. 11, the inter-terminal voltage VC _{1 of the power transmission side capacitor C 1} is charged to a constant voltage while ringing. Although not shown in FIG. 11, FIG. 12A shows that the voltage between terminals VC ₂ of the power receiving side capacitor C is a negative value at this timing. Next, at a timing shown in FIG. 12 (b), and the primary-side drive switch SW1 in the OFF state, after a certain time, when the power-transmission-side switch SW2 is turned on, electricity stored in the transmission-side capacitor C ₁ energy via a power transmission coil current I _L1, stored in the power transmission coil L _1, further characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3 occurs. Since the second semiconductor switching element Q2 is used for the power transmission side switch SW2 at the timing of FIG. 12B, the on-resistance r _on2 of the second semiconductor switching element Q2 indicates the on state of the power transmission side switch SW2. .. Primary circuit 2 by the power-transmission-side switch SW2 to the ON state is formed, the DC power source 5, the equivalent internal resistance r _1, a first semiconductor switching element Q1 first freewheeling diode (reflux diode) parallel FWD ₁ The power supply side circuit 1 including the circuit and the power transmission side capacitor C _{1 disappears.}

When the electric energy stored in the power transmission side capacitor C _{1 moves to the power transmission side coil L 1 , the inter-terminal voltage VC 1} shown by the thin broken line in FIG. 11 takes a negative maximum value and then becomes 0 V. The characteristic harmonic transmission from the primary side circuit 2 to the secondary-side circuit 3, the electrical energy transmitted to the power receiving coil L ₂ charges the power receiving side capacitor C ₂ by the receiver coil current I _L2. When charging of the power receiving side capacitor C ₂ is started, the terminal voltage VC ₂ of the power receiving side capacitor C takes a negative maximum value as shown by the thick broken line in FIG. 11, and then is shown in FIG. 12 (c). It becomes a positive value as shown. The maximum value is taken when the voltage between terminals VC _{1 becomes 0V.} As can be seen from the change in the thick broken line in FIG. 11, the terminal voltage VC ₂ becomes a positive value after taking a negative maximum value, and when the terminal voltage VC ₁ shown by the thin broken line becomes 0 V. Take the maximum value with.

At the timing shown in FIG. 12 (c), with an increase in inter-terminal voltage VC _2, by a portion of the accumulated in the power receiving side capacitor C electric energy, the charging current I _CS shown in FIG. 11 by a dashed line occurs Then, the electric charge is stored in the rechargeable battery as the load element 6. Another part of the accumulated in the power receiving side capacitor C electrical energy is refluxed as receiver coil current I _L2 to the power receiving coil L _2. At the timing shown in FIG. 12 (d), when the charging current _{I C} becomes 0, the inter-terminal voltage VC ₂ is the same value as the charge voltage VC _S.

When the electric energy stored in the power receiving side capacitor C is _{returned to the power receiving side coil L 2} , characteristic harmonized transmission occurs between the primary side circuit 2 and the secondary side circuit 3, and a part of the electric energy is transferred to the primary side circuit 2. return. When the electric energy stored in the power receiving side capacitor C moves to the load element 6 and the power receiving side coil L _{2 , the power receiving side capacitor C 2} is discharged. When the power receiving side capacitor C _{2 is discharged, the terminal voltage VC 2} shown by the thick broken line on the right side of FIG. 11 takes a negative maximum value and then becomes 0 V. _{At this time, the voltage between terminals VC 1} shown by a thin broken line on the right side of FIG. 11 takes a negative maximum value, then becomes a positive value and increases, and is a constant value when the power transmission side switch SW2 is turned off. Is maintained at. As described in FIG. 9D, _{by measuring the voltage between terminals VC 1} , the transmission efficiency of characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 and the rechargeable type as the load element 6 It can be seen that the charging status of the battery can be monitored. As can be seen from FIG. 11, _{the vibration waveform of the terminal voltage VC 1 of the primary circuit 2 and} the vibration waveform of the terminal voltage VC 2 of the secondary circuit 3 are not symmetrical with each other.

As already mentioned, "resonance" is a concept applied to a system that vibrates freely. On the other hand, in the power transmission device according to the second embodiment of the present invention, the power transmission side switch that limits the free vibration of the primary side circuit 2 and realizes a transient current-voltage change in the primary side circuit 2. It includes SW2 and a primary side drive switch SW1. Therefore, in the power transmission device according to the second embodiment, the transient response characteristic of the non-sinusoidal wave can be transmitted to the secondary side circuit 3 by the new concept "characteristic harmonized transmission". .. Since the non-sinusoidal transient response characteristic that relies on the DC power supply 5 which has a simple and inexpensive control circuit configuration can be used, the primary side circuit 2 is made to generate a sinusoidal vibration higher than the commercial frequency as in the conventional case. It eliminates the need for expensive AC power supply circuits, making it hard to break and facilitating circuit design.

The circuit shown in FIG. 33 is a circuit of the power transmission device according to the second embodiment in the case of performing an approximate simulation by the AC theory, as in the case of the circuit shown in FIG. 28, but is driven on the primary side. It is provided with two switches, a switch SW1 and a power transmission side switch SW2. In FIGS. 33 (a) to 33 (c), the capacitance of the capacitor and the inductance of the coil of the primary side circuit 2 and the secondary side circuit 3 are set to be the same. That is, C ₁ = C ₂ = 500 μF and L ₁ = L ₂ = 10 μH.

FIG. 33A shows a rechargeable battery used as the load circuit 36 by transmitting the electrical energy of the primary side circuit 2 to the secondary side circuit 3 by characteristic harmonized transmission at _{the voltage E 0} = 36V of the DC power supply 5. This is the circuit of the power transmission device according to the second embodiment when the charging voltage V _{cs = 24 V. In FIG. 33 (b), the same voltage E 0} = 36 V of the DC power supply 5 as in FIG. 33 (a) is used, and the electric energy of the primary side circuit 2 is transmitted to the secondary side circuit 3 by characteristic harmonized transmission, but the load circuit _{This is a circuit in which the charging voltage V cs} = 100V of the rechargeable battery adopted as 36 is set and the load circuit 36 is set so that no current flows. FIG. 33 (b) shows a case where the charging voltage V _cs = 100 V of the rechargeable battery adopted as the load circuit 36 is set as in the case of FIG. 33 (b) and the load circuit 36 is set so that no current flows. However, this is a case where _{the voltage E 0} = 26V of the DC power supply 5 is set by subtracting the amount transmitted to the secondary circuit 3 in advance.

FIG. 34 shows a change in the voltage of the power transmission side capacitor C1 as an approximate simulation result. Similar to that shown in FIG. 32, in the approximate simulation of the power transmission device according to the second embodiment by the AC theory, the change in the voltage of the power transmission side capacitor C1 is the same W type as shown in FIG. The transient response waveform is shown. The solid line in FIG. 34 is the result of an approximate simulation for the circuit shown in FIG. 33 (a), the broken line in FIG. 34 is the result of the approximate simulation for the circuit shown in FIG. 33 (b), and the alternate long and short dash line in FIG. 34 is a diagram. It is the result of the approximate simulation for the circuit shown in 33 (c).

At first, as shown by the broken line in FIG. 34, an attempt is made to pass a current through the load circuit 36, but since the charging voltage of the rechargeable battery is set to V _cs = 100V, no current flows through the load circuit 36, which is one point. The change is similar to the curve shown by the chain line. The timing at which the current is to flow through the load circuit 36 is estimated to be around the position of the central peak of the W-shaped transient response waveform in FIG. 34.

As described above, according to the power transmission device according to the second embodiment, the DC power supply 5 having a simple and inexpensive control circuit and peripheral circuits is used as in the power transmission device according to the first embodiment. Therefore, an expensive switching power supply is not required. The circuit configuration of the power transmission device according to the second embodiment is simplified, the power loss on the control circuit side is minimized, it is hard to break, and the circuit design becomes easy. As a result, the overall configuration of the power transmission device has been simplified, making it possible to reduce the weight, size, and efficiency, and to improve the overall power transmission efficiency including the loss of the power supply circuit (0th-order circuit). The transmission device can be manufactured at low cost. Similar to that described in the power transmission device according to the first embodiment, the limit power of power transmission is pushed up to a value exceeding the limit power in the conventional AC theory, and in principle, it is pushed up to infinity, and power transmission is performed. In principle, the limit distance of can be extended to infinity. Further, the power transmission efficiency can be increased to a value close to 100% in principle.

(Third Embodiment)
As shown in FIG. 13A, the power transmission device according to the third embodiment of the present invention has a configuration in which the power receiving side switch SW3 is added to the power transmission device according to the second embodiment. Like the power transmission side switch SW2 and the primary side drive switch SW1, the "power receiving side switch SW3" also limits the free vibration of the secondary side circuit 3 and realizes a transient current-voltage change in the secondary side circuit 3. It is a circuit element to be made to.

As the primary side drive switch SW1, the transmission side switch SW2, and the power reception side switch SW3 shown in FIG. Power semiconductor switching elements including thyristors such as thyristors and SI thyristors are used. Due to the demand for low internal resistance and market availability, it is industrially possible to adopt MOSFETs as the primary side drive switch SW1, the power transmission side switch SW2, and the power reception side switch SW3 of the mounting circuit shown in FIG. 13 (b), respectively. It is considered to be superior in terms of.

As described in the power transmission device according to the first and second embodiments, the Joule heat is generated significantly in the high power power transmission device. In the power transmission device according to the third embodiment, only three power semiconductor switching elements are used as the primary side drive switch SW1, the power transmission side switch SW2, and the power reception side switch SW3, so that the elements are prevented from being destroyed by heat generation. The cooling structure can be easily designed, and the generation of stray resistance, stray capacitance, and stray inductance can be minimized. Further, since the simple control of turning on / off the primary side drive switch SW1 and the power transmission side switch SW2 is sufficient, it is possible to easily design by increasing the voltage of the primary side circuit 2 and suppressing the generation of Joule heat.

In the mounting circuit shown in FIG. 13B, the first freewheeling diode FWD ₁ switches between the source and drain of the MOSFET as the first semiconductor switching element Q1 and the second freewheeling diode FWD ₂ switches the second semiconductor. _{A third freewheeling diode FWD 3} is connected in parallel as a protection element between the source and drain of the MOSFET as the element Q2 and between the source and drain of the MOSFET as the third semiconductor switching element Q3. As shown in FIG. 13 (b), the third freewheeling diode FWD ₃ is provided in the direction in which the recirculation current from the power receiving side coil L _{2 flows, so that the second freewheeling diode FWD 2} is in the opposite direction. It is provided. 4 (a) and similarly to the circuit shown in FIG. 10 (b), since the circulating electric current from the power transmission coil L ₁ is prevented from refluxing to the DC power supply 5, the power supply side diode D1 and the DC power source 5 a It is connected in series between the semiconductor switching elements Q1 of 1. In the mounting circuit shown in FIG. 13B, the equivalent impedance X _Leq of the load element 6 is approximated by the charging capacity C _{s and expressed.}

The wireless power transmission method according to the first embodiment will be described with reference to the flowchart shown in FIG. 14 and the timing diagram shown in FIG. However, as in the first and second embodiments, it is assumed that the characteristic harmonized transmission is performed under the condition corresponding to the _{coupling coefficient KAC = 0.6 according to the AC theory, and the value of the charging voltage VC S in} the initial state is full. It is assumed that the voltage is sufficiently high, which is close to charging.

First, in step S31 of the flowchart of FIG. 14, the power transmission side switch SW2 and the power reception side switch SW3 are turned off, and only the primary side drive switch SW1 is turned on. As shown by a thin broken line in FIG. 15, the inter-terminal voltage VC _{1 of the power transmission side capacitor C 1} is charged to a constant voltage while ringing. Although not shown in FIG. 15, the voltage between terminals VC ₂ of the power receiving side capacitor C is a negative value at this timing. After an electric charge is charged by applying an initial voltage to the power transmission side capacitor C _1, to turn off the primary-side drive switch SW1 as shown in FIG. 15. As described above, it is assumed that _{the charging voltage VC S at this point is high.}

As shown in FIG. 15, after turning off the primary side drive switch SW1, the power transmission side switch SW2 and the power receiving side switch SW3 are turned on at the same time in step S32 after a certain period of time. When the power-transmitting-side switch SW2 is turned on, electric energy stored in the power-transmitting-side capacitor C ₁ via the transmitting-coil current are accumulated in the power transmission coil L _1, further primary circuit 2 and the secondary circuit Characteristic harmonized transmission between 3 occurs. When the electric energy stored in the power transmission side capacitor C _{1 moves to the power transmission side coil L 1 , the inter-terminal voltage VC 1} shown by the thin broken line in FIG. 15 takes a negative maximum value and then becomes 0 V. Since the power receiving side switch SW3 is on, the electric energy transmitted to the power _{receiving side coil L 2} by the characteristic harmonized transmission from the primary side circuit 2 to the secondary side circuit 3 _{causes the power receiving side capacitor C 2} to be driven by the power receiving side coil current. Charge. When charging of the power receiving side capacitor C ₂ is started, the voltage between terminals VC ₂ of the power receiving side capacitor C starts to increase from the negative maximum value as shown by the thick broken line in FIG. 15, and the left in the center of FIG. As shown in the more position, it becomes a positive value. While the inter-terminal voltage VC ₂ has a negative value, the charging current _ICS does not flow, but when the inter-terminal voltage VC ₂ becomes a positive value, the charging current is shown by the alternate long and short dash line in the center of FIG. I _CS begins to rise.

At the timing when the charging current _{I CS} began rising, to turn off the power-transmission-side switch SW2 and the power receiving side switch SW3 at step S33. In the off state of the power transmission side switch SW2 and the power reception side switch SW3, the inter-terminal voltage VC ₂ shown by the thick broken line in FIG. 15 becomes maximum due to the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3. Moreover, it is a time point when the _{voltage between terminals VC 1} shown by a thin broken line becomes 0V. Charging current I _CS indicated by a chain line in the center of FIG. 15, after the power-transmission-side switch SW2 and the power receiving side switch SW3 has reached also an increased peak value after the off state, reduced, to zero in step S34 Become.

As shown in the position of the center of the right of FIG. 15, the thick maximum value between the indicated terminal voltage VC ₂ is a broken line, the charge current I _C begins to decrease, the step becomes constant at value slightly lower ( It becomes a corrugated shape (shoulder). Even after the charging current I _C becomes zero, the value of terminal voltage VC ₂ shown by thick broken lines in FIG. 15, maintains a value lower than the maximum value of the off of the power transmission switch SW2. After off of the power transmission switch SW2, after a lapse of the predetermined time, the maximum value of the inter-terminal voltage VC ₂ is reduced, if a higher charge voltage VC _S at the time of step S31, the charging current I _C between by terminal voltage VC ₂ The amount of decrease in the maximum value of is small, and the influence on the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 is small.

In step S35 in after the charging current I _C becomes 0A, the power-transmission-side switch SW2 and the power receiving side switch SW3 at the same time, when the ON state again, the characteristics between the primary-side circuit 2 and the secondary-side circuit 3 again conditioner transmission Occurs. The on state of the power transmission switch SW2 and the power receiving side switch SW3 at step S35, the inter-terminal voltage VC ₂ indicated by thick broken line on the right side of FIG. 15 starts to decrease, then taking the negative maximum value, it becomes 0V .. _{At this time, the voltage between terminals VC 1} shown by a thin broken line on the right side of FIG. 15 also starts to decrease, takes a negative maximum value, and then increases to a positive value.

Next, in step S36, when the inter-terminal voltage VC ₁ becomes maximum and the inter-terminal voltage VC ₂ becomes 0 V, the power transmission side switch SW2 and the power reception side switch SW3 are turned off. As shown in FIG. 15, the inter-terminal voltage VC _{1 shown by the thin broken line at the time of step S36 is the same value as the inter-terminal voltage VC 2} shown by the thick broken line at the time of step S34, and is the same value as the power transmission side switch SW2 and the power receiving side. The value is maintained at a constant value after the switch SW3 is turned off. NS. Although not shown, the inter-terminal voltage VC ₁ and the inter-terminal voltage of the load element 6 have the same value at the time of step S36. Therefore, as described in FIG. 9D, _{by measuring the terminal voltage VC 1} , the transmission efficiency of the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 and the load element 6 are obtained. It can be seen that the charging status of the rechargeable battery can be monitored. Comparing the timing diagram of the power transmission device according to the second embodiment shown in FIG. 11 and the timing diagram of the power transmission device according to the third embodiment shown in FIG. 15, the power receiving side switch SW3 is increased by one. However, the waveforms showing temporal changes (transient response) such as the _{inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ in the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 are almost the same. I understand.

"Resonance" is a concept used in an AC circuit having free vibration, but in the power transmission device according to the third embodiment, the free vibration of the primary side circuit 2 and the secondary side circuit 3 is limited. It includes a primary side drive switch SW1, a power transmission side switch SW2, and a power reception side switch SW3 that realize a transient current-voltage change in the primary side circuit 2 and the secondary side circuit 3. Therefore, in the power transmission device according to the third embodiment, the transient response characteristic of the primary side circuit 2 can be transmitted to the secondary side circuit 3 by a new concept "characteristic harmonized transmission". be. Since the electrical energy can be transmitted using the non-sinusoidal transient response characteristic that relies on the DC power supply 5 which has a simple and inexpensive control circuit configuration, the sinusoidal wave higher than the commercial frequency is compared to the primary circuit 2. It eliminates the need for expensive AC power circuits that generate vibrations.

Therefore, according to the power transmission device according to the third embodiment of the present invention, the DC power supply 5 having a simple and inexpensive control circuit and peripheral circuits is used as in the power transmission device according to the first and second embodiments. Since it can be used, an expensive switching power supply is not required, the circuit configuration is simplified, and the power loss on the control circuit side is also minimized. As a result, according to the power transmission device according to the third embodiment, the overall configuration of the power transmission device can be simplified, the weight can be reduced, the size can be reduced, and the efficiency can be improved, and the loss of the power supply circuit (0th order circuit) can be achieved. It is possible to inexpensively manufacture a wireless power transmission device with improved overall power transmission efficiency including the above. According to the power transmission device according to the third embodiment as described in the power transmission device according to the first and second embodiments, the circuit configuration is simplified, so that it is hard to break and the circuit design becomes easy. .. In addition, it is possible to push the limit power of power transmission to infinity in principle, extend the limit distance of power transmission to infinity in principle, and increase the power transmission efficiency to a value close to 100% in principle. Is.

(Fourth Embodiment)
As shown in FIG. 16A, the power transmission device according to the fourth embodiment of the present invention has a configuration in which the load control switch SW4 is added to the power transmission device according to the third embodiment. Like the power receiving side switch SW3, the “load control switch SW4” is a circuit element that limits the free vibration of the secondary side circuit 3 and realizes a transient current-voltage change in the secondary side circuit 3.

The primary side drive switch SW1, the transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4 shown in FIG. 16A are FETs and SITs as in the power transmission devices according to the first to third embodiments. , BJT, GTO thyristors, SI thyristors, and other power semiconductor switching elements including thyristors can be used. Considering the demand for low internal resistance, due to the availability on the market at present, the MOSFET has the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3 and the load of the mounting circuit shown in FIG. 16 (b). It is preferable to use each as the control switch SW4.

In the power transmission device according to the fourth embodiment, only four power semiconductor switching elements are used as the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4. The cooling structure that prevents the occurrence of stray resistance can be easily designed, and the occurrence of stray resistance, stray capacitance, and stray inductance can also be minimized. Further, since the simple control of turning on / off the primary side drive switch SW1 and the power transmission side switch SW2 is sufficient, it is possible to easily design by increasing the voltage of the primary side circuit 2 to suppress the generation of Joule heat.

In the mounting circuit shown in FIG. 16B, the first freewheeling diode FWD ₁ switches between the source and drain of the MOSFET as the first semiconductor switching element Q1 and the second freewheeling diode FWD ₂ switches the second semiconductor. Between the source and drain of the MOSFET as element Q2, the third freewheeling diode FWD ₃ is between the source and drain of the MOSFET as the third semiconductor switching element Q3, and the fourth freewheeling diode FWD ₄ is the fourth semiconductor switching. The source and drain of the MOSFET as the element Q4 are connected in parallel as protective elements. As shown in FIG. 16B, the third freewheeling diode FWD ₃ is provided in the direction in which the recirculation current from the power receiving side coil L _{2 flows, so that the second freewheeling diode FWD 2} is in the opposite direction. It is the same as in FIG. 13 (b). FIG. 4 (a), the like the circuit shown in FIG. 10 (b) and 13 (b), since the circulating electric current from the power transmission coil L ₁ is prevented from refluxing to the DC power supply 5, the power supply side diode D1 Is connected in series between the DC power supply 5 and the first semiconductor switching element Q1. In the mounting circuit shown in FIG. _16B , the equivalent impedance X Leq of the load element 6 is approximated by the charging capacity C _{s and expressed.}

As described above, comparing the timing diagram of the power transmission device according to the second embodiment shown in FIG. 11 and the timing diagram of the power transmission device according to the third embodiment shown in FIG. 15, the power receiving side switch SW3 Even if the number increases by one, most of the waveforms showing the temporal change (transient response) such as the _{inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ in the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 It is the same. As shown in FIG. 16A, even if the load control switch SW4 is added to the power transmission device according to the third embodiment, the essence of the characteristic harmonized transmission does not change, and its basic operation and its basic operation are not changed. The waveforms showing temporal changes (transient response) such as the _{inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ in the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 are almost the same.

However, as shown in FIG. 16A, in the configuration having four switches of the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4, the primary side drive switch SW1 and the load control At the timing when the switch SW4 is cut off and the power transmission side switch SW2 and the power reception side switch SW3 are in a conductive state, the circuit on the DC power supply 5 side and the circuit on the load element 6 side are separated from the primary side circuit 2 and the secondary side circuit 3, respectively. Since they are separated, the primary side circuit 2 and the secondary side circuit 3 can freely vibrate. That is, since the LC resonance circuit of the primary side circuit 2 and the LC resonance circuit of the secondary side circuit 3 can be treated as a circuit coupled by the mutual inductance M, the concept of multiple resonance in the AC theory can be adopted. That is, at the timing when the primary side drive switch SW1 and the load control switch SW4 are in the cutoff state and the power transmission side switch SW2 and the power reception side switch SW3 are in the conductive state, the coupling equations of the equations (2) and (3) already described can be used. The efficiency of characteristic harmonized transmission can be examined.

However, in the mounting circuit, it is necessary to consider the on-resistance of the power semiconductor switching element used for each of the four switches, the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4. Therefore, it cannot be described by the coupling equations of equations (2) and (3). Therefore, in the operation at the timing when the primary side drive switch SW1 and the load control switch SW4 are in the cutoff state and the transmission side switch SW2 and the power reception side switch SW3 are in the conduction state, the LCR resonance circuit and the secondary side circuit 3 of the primary side circuit 2 are operated. It is necessary to study as a circuit in which the LCR resonant circuit is coupled by the mutual inductance M.

Further, since it is necessary to consider energy transmission in a transient response such as a step response when the primary side drive switch SW1 and the load control switch SW4 are in a conductive state, the power transmission device according to the fourth embodiment of the present invention. Not all can be interpreted by conventional exchange theory. That is, although the conventional sine wave AC theory can be used in the free vibration region as shown by the diagonal line in FIG. 3B, the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3 and the load can be used. In the operating environment of the power transmission device according to the fourth embodiment in which the boundary conditions of the circuit are changed from moment to moment by using the four switches of the control switch SW4, the sawtooth rise as illustrated in FIG. 2 (b). It is necessary to analyze including the transient response such as characteristics.

(Simulation of characteristic harmonized transmission waveform)
The waveforms of the inter-terminal voltage VC ₁ and the inter-terminal voltage VC _{2 of the power transmitting side capacitor C 1} and the power receiving side capacitor C ₂ in the configuration illustrated in FIG. 16A are obtained by simulation by ordinary AC theory, and the primary side circuit is obtained. Check the characteristic harmonized transmission waveform between 2 and the secondary circuit 3. Primary circuit 2 and the secondary-side circuit 0.6 the coupling coefficient K _AC 3, the power-transmitting-side capacitor C ₁ and both of the capacity of the power receiving side capacitor C ₂ 65MyuF, of the power transmission coil L ₁ and the power receiving coil L ₂ The inductance is set to 60 μH.

First, the power transmission side switch SW2, the power-receiving-side switch SW3 and the load control switch SW4 are turned off, and the primary-side drive switch SW1 in the ON state, by applying an initial voltage of 20V to the power transmission side capacitor C ₁ transmission side capacitor C ₁ Stores electric charge in. Next, when the primary side drive switch SW1 is turned off and the power transmission side switch SW2 and the power receiving side switch SW3 are turned on, it can be expected that characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 will occur. _{The waveforms of the inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ obtained by the simulation are shown in FIG. 17 (a). Both the waveform of the inter-terminal voltage VC _{1 and} the waveform of the inter-terminal voltage VC ₂ are waveforms in which a sine wave with a large amplitude and a sine wave with a small amplitude are combined, which is different from the sine wave in the usual AC theory. ..

In FIG. 17A, the power transmission side switch SW2 and the power reception side switch SW3 are turned on in 0.2 ms. At 0.45 ms, the terminal voltage VC ₁ becomes 0 V, and the terminal voltage VC ₂ becomes 20 V. This indicates that all the energy on the power transmission side is transmitted to the power reception side, and when the power transmission side switch SW2 and the power reception side switch SW3 are turned off at 0.45 ms, the power by characteristic harmonized transmission is efficiently performed. Transmission can be performed.

(Measurement of characteristic harmonized transmission waveform by mounting circuit)
Subsequently, the waveform of the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 is measured by the mounting circuit having the configuration illustrated in FIG. 16A. The equivalent coupling coefficient K of the primary side circuit 1 and the secondary side circuit 2 is 0.6, the capacitances of the power transmission side capacitor C ₁ and the power reception side capacitor C ₂ are both 65 μF, and the power transmission side coil L ₁ and the power reception side coil L ₂ The inductance is 60 μH, and the initial voltage applied to the _{power transmission side capacitor C 1 is 20 V.} These are the same values as in the simulation. Each terminal voltage VC ₁ and terminal voltage VC ₂ waveforms the power transmitting side capacitor C _1, obtained by measuring the power receiving side capacitor C ₂ is shown in FIG. 17 (b), the waveform of the terminal voltage VC ₁ It can be seen that there is no symmetry between the waveforms of the inter-terminal voltage VC _2.

Due to the presence of parasitic resistance in the mounting circuit, the waveform is attenuated with time, unlike the result of the simulation by the usual AC theory shown in FIG. 17 (a). In FIG. 17B, transmission starts from 0.2 ms, and the terminal voltage VC ₂ reaches a maximum of 15 V at 0.45 ms. At this time, the voltage between terminals VC ₁ is -3V, and all the energy on the transmission side is not transmitted to the power receiving side, and some energy remains on the transmission side, but the energy on the transmission side receives power. It can be confirmed that it is transmitted to the side. As described above, even if the load control switch SW4 is added to the power transmission device according to the third embodiment, the temporal change (transient response) such as the _{inter-terminal voltage VC 1} and the inter-terminal voltage VC _{2 is provided.} ) Are almost the same. That is, the waveform of the inter-terminal voltage VC _{1 and} the waveform of the inter-terminal voltage VC ₂ shown in FIG. 17B are diagrams showing macroscopic changes, and the macro is a combination of a large-amplitude sine wave and a small-amplitude sine wave. Although it looks like a waveform like the one shown above, if the time axis is lengthened and viewed in detail, it is similar to the waveform shown in FIGS. 11 and 15, and does not indicate a change in a sine wave.

(Changes in equivalent coupling coefficient and changes in characteristic harmonized transmission)
In the illustrated arrangement in Fig. 16 (a), after accumulated charge to the power transmission side capacitor C _1, and the primary-side drive switch SW1 and the load control switch SW4 off, turned on the power-transmission-side switch SW2 and the power receiving side switches SW3 When set to, characteristic harmonized transmission occurs between the primary side circuit 2 and the secondary side circuit 3. According to the conventional AC theory, this operation is represented by the coupling equations of the equations (2) and (3) already described.

In the conventional AC theory, the voltage between terminals VC _{2 of the power receiving side capacitor C 2} generated by the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 by solving the coupling equations of the equations (2) and (3). Is obtained, using the mutual induction function φ (k) defined by the equation (10),

_{VC 2 = VC 0/2 ×} (L 2 / L 1) (1/2) × φ (k) ...... (11)

Will be. Here, VC ₀ is the initial voltage between the terminals of the power transmission side capacitor C _{1 , ω 0} is the resonance angular frequency, and ω ₀ = L ₁ × C ₁ = L ₂ × C ₂ . When the voltage between terminals VC ₁ of the power transmission side capacitor is 0, equation (11) becomes the maximum value VC ₀ × (L ₂ / L ₁ ) ^(1/2) , and according to the usual AC theory, at this time, the power transmission side This means that all energy has been transmitted to the power receiving side.

In the illustrated arrangement in FIG. 16 (a), the characteristic harmonic transmission waveforms between the primary-side circuit 2 and the secondary-side circuit 3 at the time of changing the coupling coefficient K _AC by conventional AC theory changes, normal Obtained by simulation based on AC theory. The capacitances of the power transmission side capacitor C ₁ and the power reception side capacitor C ₂ are both 500 μF, the inductances of the power transmission side coil L ₁ and the power reception side coil L ₂ are both 10 μH, and the initial voltage applied to the _{power transmission side capacitor C 1 is 25 V.} .. In the following description approximates the coefficient K _AC by the AC theory equal to the equivalent coupling coefficient, the equivalent coefficient K as 0.00,0.1,0.6,0.8,0.88, ordinary respectively A simulation based on AC theory was performed. _{The waveforms of the inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ obtained as a result of the simulation by the ordinary AC theory are shown in FIGS. 18 (a) to 19 (c). As shown in FIG. 18A, when the coupling coefficient K = 0.00 according to the usual AC theory, the primary side circuit 1 and the secondary side circuit do not interact with each other, and the primary side circuit 2 and the secondary side circuit do not interact with each other. Characteristic harmonized transmission between 3 does not occur.

When the equivalent coupling coefficient K = 0.1, 0.6, 0.8, 0.88, characteristic harmonized transmission occurs between the primary side circuit 2 and the secondary side circuit 3. As shown in FIG. 18 (b), when the equivalent coupling coefficient K = 0.1, 2.2 ms, and as shown in FIG. 19 (a), when the equivalent coupling coefficient K = 0.6, 0.28 ms. As shown in 19 (c), when the equivalent coupling coefficient K = 0.88, the inter-terminal voltage VC _{1 of the transmitting side capacitor becomes 0V at 0.3 ms, and the inter-terminal voltage VC 2} of the receiving side capacitor becomes the transmitting side. The initial voltage between the terminals of the capacitor C _{1 is the same as VC 0,} and all the energy on the power transmission side is transmitted to the power reception side. As shown in FIG. 19B, when the equivalent coupling coefficient K = 0.8, _{the maximum value of the inter-terminal voltage VC 2} of the power receiving side capacitor is smaller than the initial voltage VC ₀ between the terminals of the transmitting side capacitor C _1. When the equivalent coupling coefficient K = 0.8, power transmission cannot be performed efficiently as compared with the case where the equivalent coupling coefficient K = 0.1, 0.6, 0.88.

Further, when the equivalent coupling coefficient K = 0.1 is compared with the case where the equivalent coupling coefficient K = 0.6 and 0.88, the time _{until the terminal voltage VC 2 of the} power receiving side capacitor reaches the maximum value. Is long. Equation (11) is expressed as the sum of the two modes.

(1 + k) ^(1/2) / (1-k) ^(1/2) = 2 …… (12)

When, that is, when the equivalent coupling coefficient K = 0.6, terminal voltage VC ₂ of the power receiving side capacitor C ₂ is the shortest time to the maximum value, then a short is given,

(1 + k) ^(1/2) / (1-k) ^(1/2) = 4 …… (13)

That is, when the equivalent coupling coefficient K = 0.88. In the mounting circuit, the _{waveform is attenuated with time by the parasitic resistance r L} = R _str (L ₁ ) = R _str (L ₂ ) of the coil and the parasitic resistance r _{C of the} capacitor, so the equivalent coupling coefficient K = 0.6, 0. At 88, power transmission can be performed most efficiently. Further, when the parasitic resistors r _L and r _C are low, power transmission can be efficiently performed even when the equivalent coupling coefficient K = 0.1. Since the equivalent coupling coefficient K becomes smaller as the interval d is increased _{, it can be said that if the parasitic resistors r L} and r _C are sufficiently low, they can be sent over a long distance.

FIG. 20 (a) shows an enlarged waveform of the _{inter-terminal voltage VC 1} and the inter-terminal voltage VC ₂ when the equivalent coupling coefficient K = 0.6 shown in FIG. 19 (a). Further, the waveforms of the currents I ₁ and I ₂ of the power transmitting side coil L ₁ and the power receiving side coil L ₂ at this time are shown in FIG. 20 (b). At 0.28 ms, the terminal voltage VC ₁ becomes 0 V, the terminal voltage VC _{2 becomes the same value as the initial voltage VC 0} between the terminals of the transmission side capacitor C ₁ , and at the same time, the currents I ₁ and I ₂ become 0 A. ing. When the power transmission side switch SW2 and the power reception side switch SW3 are turned off at 0.28 ms, power transmission can be performed with maximum efficiency, and at this time, the currents I ₁ and I ₂ are 0A, and the power transmission side coil L ₁ Since the counter electromotive force generated in the power receiving side coil L ₂ becomes 0, it is possible to prevent the power transmission side switch SW2 and the power receiving side switch SW3 from being destroyed.

(Optimal combination of inductance L and capacitance C)
In the configuration illustrated in FIG. 16A, the transmission efficiency is the highest when the energy stored on the power transmission side is transmitted to the power reception side by the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3. The combination of the coil inductance L and the capacitor capacitance C is obtained by the following procedure. Transmission efficiency P is the energy to be transmitted in a single P _on C _e-tr, energy P _on which the loss in one by the parasitic resistance r _C of the parasitic resistance r _L and the capacitor of the coil C _e-loss, one if the time required in time and τ _on C _e, it is represented by the formula (14).

_{P = (P on C e-} tr -P on C e-loss) / τ on C e ...... (14)

Energy P _on C _e-tr is ^1/2 × _CV ⁰ 2, energy P _on C _e-loss to the loss in one the _{(r L + r C) /} 2 × C / L × V to be transmitted in one ₀ ^2, since the time tau _on C _e required for one is 2 ^{(1.6) 1/2} [pi ^{(LC) 1/2,} the transmission efficiency P is expressed by equation (15).

_{P = (1/2 × CV} 0 2 - (r L + r C) / 2 × C / L × V 0 2) / (2 (1.6) 1/2 π (LC) 1/2) ...... ( 15)

Here, V ₀ is an initial voltage applied to the power transmission side capacitor C _1.

To parasitic resistance _{r L} and the parasitic resistance r _C of the capacitor of the _{coil, K L = r L / L} , and K _C = _r C × C, and the maximum current flowing through the coil and _{I max I max = (C /} L ) ^1/2 x V, so

^{_{P = I max V {(1.6}} ) -1/2 π -1 - (K L (LC) 1/2 + K C (LC) -1/2)}
……… (16)

Next,

^{_{K L (LC) 1/2 + K}} C (LC) -1/2> = 2 (K L K C) 1/2 ...... (17)

Is.

When the transmission efficiency P is maximized

_{^{K L (LC) 1/2 + K}} C (LC) -1/2 = 2 (K L K C) 1/2 ...... (18)

And at this time

_{LC = K C / K L ......} (19)

Will be. When the inductance L of the coil and the capacitance C of the capacitor satisfy the equation (19), the transmission efficiency is maximized.

In the configuration illustrated in FIG. 16A, the transmission efficiency when the inductance of the coil and the capacitance of the capacitor are changed is obtained by a simulation based on ordinary AC theory. V = 36V, the coupling coefficient _K L = 600 / H, the coupling coefficient ^{_{K C = 3.00 × 10 -6 ΩF}} . FIG. 21 shows the change in transmission efficiency with respect to the capacitance of the capacitor when the coil inductance is 1, 2, 5, 10, 20, and 50 μH, which is obtained as a result of a simulation by ordinary AC theory. As shown in FIG. 21, the combination of the coil inductance L and the capacitor capacitance C that maximizes the transmission efficiency is such that when the coil inductance is 1, 2, 5, 10, 20, and 50 μH, the capacitor capacitance C is different. It is 5000, 2500, 1000, 500, 250, 100 μF, and satisfies the formula (19).

(Power transmission when the voltage between the terminals of the load element is low)
Refer to the flowchart shown in FIG. 23 and the timing diagram shown in FIG. 24A for the first wireless power transmission method according to the fourth embodiment when the voltage between terminals of the load element 6 as a rechargeable battery is low. I will explain. However, when the coupling coefficient K _{AC =} 0.6,0.88 equivalent equivalent coefficient K or the like which is defined by an alternating current theory, the characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3 occurs , The equivalent coupling coefficient K is adjusted so that the maximum value of the terminal voltage VC _{2 becomes the same as the initial voltage VC 0} between the terminals of the _{transmission side capacitor C 1} , and then the terminal voltage VC _{1 becomes 0 V.} It is assumed that

First, in step S11, the power transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4 are turned off, and the primary side drive switch SW1 is turned on. After an electric charge is charged by applying an initial voltage to the power transmission side capacitor C _1, to turn off the primary-side drive switch SW1. At this point, the voltage between the terminals of the load element 6 is assumed to be sufficiently low. Next, in step S12, when the power transmission side switch SW2 and the power reception side switch SW3 are turned on, characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 occurs. Next, in step S13, when the absolute value of the _{inter-terminal voltage VC 2} becomes maximum due to the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3, and the inter- _{terminal voltage VC 1} becomes 0 V, the power transmission side Turn off the switch SW2 and the power receiving side switch SW3.

Next, in step S14, when the load control switch SW4 is turned on, a charging current _ICS is generated and the voltage between terminals VC ₂ is reduced. Next, in step S15, the load control switch SW4 is turned off _{when the charging current ICS becomes 0.} At this time, the voltage between terminals VC ₂ and the voltage between terminals of the load element 6 have the same value. If the voltage between the terminals of the load element 6 is sufficiently low at the time of step S11, the voltage between terminals VC ₂ of the power receiving side capacitor is sufficiently low to be regarded as 0V or 0V _{at the time of step S15, and the power receiving side capacitor C 2} is discharged. It is possible to return to step S11 without doing so.

(Power transmission method when the voltage between terminals of the load element is not low)
The second wireless power transmission method according to the fourth embodiment when the voltage between the terminals of the load element 6 is not low will be described with reference to the flowchart shown in FIG. 25 and the timing diagram shown in FIG. 24 (b). .. However, it is assumed that the equivalent coupling coefficient K is adjusted in the same manner as when the voltage between the terminals of the load element 6 is low.

Steps S21 to S24 are the same as steps S11 to S14. In step S25, the load control switch SW4 is turned off _{when the charging current ICS becomes 0.} The voltage between terminals VC _{2 at} this time has the same value as the charging voltage VC _S. In the next step S26, the power receiving side capacitor is discharged.

When the power transmission side switch SW2 and the power reception side switch SW3 are turned on in step S26, characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 occurs again. _{In step S27, when the absolute value of the terminal voltage VC 1} is maximized by the characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3, and the terminal voltage VC ₂ becomes 0 V, the power transmission side switch SW2 and Turn off the power receiving side switch SW3. Since the inter-terminal voltage VC ₁ at the time of step S27 is the same value as the _{inter-terminal voltage VC 2} at the time of step S25, the inter- _{terminal voltage VC 1} and the charging voltage VC _S are the same values at the time of step S27. Therefore, in this case, the charging voltage VC _S can be monitored by _{the terminal voltage VC 1.}

As described above, according to the power transmission device according to the fourth embodiment of the present invention, the control circuit and the peripheral circuit are simple and inexpensive as in the power transmission device according to the first to third embodiments. Since the DC power supply 5 can be used, an expensive switching power supply is not required, the circuit configuration is simplified, the power loss on the control circuit side is minimized, the circuit is not easily broken, and the circuit design is facilitated. As a result, according to the power transmission device according to the fourth embodiment, the overall configuration of the power transmission device can be simplified, the weight and size can be reduced, and the efficiency can be improved, and the loss of the power supply circuit (0th order circuit) can be reduced. In principle, the overall power transmission efficiency including is increased to a value close to 100%, the limit power of power transmission is pushed up to infinity in principle, and the limit distance of power transmission is extended to infinity in principle. Wireless power transmission equipment can be manufactured at low cost.

(Fifth Embodiment)
In the power transmission device according to the fifth embodiment of the present invention, as shown in FIG. 26, the primary side circuit 2C and the secondary side circuit 3C are composed of a first interconnect capacitor C ₂₃ and a second interconnect capacitor. It is electrostatically coupled at C ₂₄ , and has a configuration in which the coil is replaced with a capacitor and the capacitor is replaced with a coil in the power transmission device according to the first embodiment. From the law of electromagnetic induction and Maxwell's equation, it is possible to replace such a coil and a capacitor. That is, as shown in FIG. 26, the power transmission device according to the fifth embodiment is a power transmission side capacitor that stores electrostatic energy, similarly to the power transmission device according to the first embodiment shown in FIG. 1 (a). C _21, the electrostatic energy transmitted from the power transmitting side is connected in parallel to the capacitor C ₂₁ power-transmitting-side capacitor C ₂₁ accumulates as a magnetic energy, a power transmission coil L ₂₁ to reflux the magnetic energy to the power transmission side capacitor C ₂₁ The primary side circuit 2 is provided.

Then, in the power transmission device according to the fifth embodiment, as shown in FIG. 26, the first electrode is connected to one node that connects the _{power transmission side capacitor C 21} and the power transmission side coil L _{21 in parallel.} mutual coupling capacitor C _23, the power-transmitting-side second interconnection further comprises a point capacitor C ₂₄ of the capacitor C ₂₁ and the power transmission coil L ₂₁ is connected to one electrode to the other nodes connected in parallel, in Figure 1 It is different from the power transmission device according to the first embodiment shown. Then, in the power transmission device according to the fifth embodiment _{, one electrode is connected to the other electrode of the first interconnect capacitor C 23} , and the other electrode is connected to the other electrode of the second interconnect capacitor C _24. connect the power receiving side capacitor C ₂₂ to receive electrostatic energy from the primary side circuit 2, the power receiving side coil accumulates accumulated in the parallel-connected power reception capacitor C ₂₂ to the power receiving side capacitor C ₂₂ electrostatic energy as magnetic energy L A secondary side circuit 3 having _{22 is further provided.}

Further, the power transmission device according to the fifth embodiment, as shown in FIG. 26, a DC power source 5 to a circuit for connecting the one terminal and the other terminal of the power transmission coil L _21, the power transmission coil It is provided with a primary side drive switch SW1 which is connected in series between one terminal of _{L 21 and a DC power supply 5 and step-inputs an intermittent DC voltage to the power transmission side coil L 21.} Further, a circuit is configured to connect between one terminal of the power receiving side coil L _{22 and the other terminal, and the load element 6 that receives magnetic energy from the power receiving side coil L 22} and the anode are one of the power receiving side coil L ₂₂ . A load-side diode D2 whose cathode is connected to the load element 6 is provided on the terminal side. Even with the electrostatic coupling as shown in FIG. 26, the power transmission device according to the fifth embodiment can transmit electric energy from the primary side circuit 2 to the secondary side circuit 3 in a non-contact manner. .. _{The waveform of the current flowing through the power transmitting side coil L 21} and the power receiving side coil L ₂₂ is obtained by a simulation based on ordinary AC theory, and the characteristic harmonized transmission waveform between the primary side circuit 2 and the secondary side circuit 3 is confirmed.

The equivalent coupling coefficient of the primary side circuit 21 and the secondary side circuit 22 is 0, _{the inductance of the power transmission side coil L 21} and the power reception side coil L ₂₂ is 0.1 μH, and the capacitance of the power transmission side capacitor C ₂₁ and the power reception side capacitor C ₂₂ . Both are 400 pF, and the capacitances of the first interconnect capacitor C ₂₃ and the second interconnect capacitor C ₂₄ are both 500 pF. The DC power supply 5 is a constant voltage source as in the case of the first embodiment. The waveform of the current flowing through the power transmitting side coil L ₂₁ and the power receiving side coil L ₂₂ is shown in FIG. 27 (a). Further, the waveforms of the voltage V21 and V22 between the terminals of the power transmitting side capacitor C ₂₁ and the power receiving side capacitor C _{22 are shown in FIG. 27 (b), respectively.} At 0 ns, the _{currents flowing through the power transmitting side coil L 21} and the power receiving side coil L ₂₂ are 30 A and 0 A, respectively, and at 60 ns, the currents flowing through the power transmitting side coil L ₂₁ and the power receiving side coil L ₂₂ are 30 A and 0 A, respectively. Characteristic harmonized transmission between the primary side circuit 2 and the secondary side circuit 3 has occurred.

As described above, according to the power transmission device according to the fifth embodiment of the present invention, even if it is electrostatically coupled, the magnetic power transmission device according to the first to fourth embodiments is magnetic. As in the case of coupling, the control circuit and peripheral circuits are simple and an inexpensive DC power supply 5 can be used, so that an expensive switching power supply is unnecessary. Further, even in the case of electrostatic coupling, the circuit configuration is simplified, hard to break, and circuit design is easy as in the power transmission device according to the first to fourth embodiments, and power loss on the control circuit side. Is also minimized. As a result, according to the power transmission device according to the fifth embodiment of the present invention, the overall configuration of the power transmission device is simplified, the weight and size can be reduced, and the efficiency can be improved, and the power supply circuit (0th order circuit). The overall power transfer efficiency including the loss of Wireless power transmission equipment can be manufactured at low cost.

(Other embodiments)
As mentioned above, the present invention has been described by the first to fifth embodiments, but the statements and drawings that form part of this disclosure should not be understood as limiting the invention. Various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art from this disclosure. For example, in the power transmission device according to the fifth embodiment of the present invention, a circuit configuration including only one primary side drive switch SW1 has been described as an electrostatic coupling method. It is just an example. As described in the power transmission device according to the second embodiment of the present invention, even in the case of the circuit configuration of the electrostatic coupling method, the configuration includes the primary side drive switch SW1 and the power transmission side switch SW2. It is possible.

Similarly, even in the case of an electrostatic coupling type circuit configuration as described in the power transmission device according to the third embodiment of the present invention, the primary side drive switch SW1, the power transmission side switch SW2, and the power reception side The configuration can include the switch SW3. Further, the power transmission device according to the fourth embodiment of the present invention may be configured in the same manner as the power transmission device according to the fourth embodiment of the present invention, including the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3, and the load control switch SW4.

That is, the power transmission device according to the present invention is configured by combining the technical ideas of the respective embodiments as shown in FIGS. 1 (a), 10 (a), 13 (a), 16 (a) and 26. You can also do it. Further, the magnetic coupling degree control mechanism described with reference to FIGS. 6 (a) to 8 (b) in the power transmission device according to the first embodiment of the present invention is related to the second to fourth embodiments. It may be applied to a power transmission device. As described above, the present invention includes various embodiments not described in the present specification and drawings, and the technical scope of the present invention is based on the matters specifying the invention relating to the reasonable claims from the above description. Only defined.

1 ... Power supply side circuit, 2, 2C ... Primary side circuit, 3, 3C ... Secondary side circuit, 5 ... DC power supply, 6 ... Load element, 32 ... Spacer, 33 ... Car stop, 41 ... Distance measuring unit, 411 ... Light emission Unit, 412 ... Light receiving unit, 42, 47 ... Logic calculation control unit, 421 ... Distance calculation unit, 422, 472 ... Coupling coefficient calculation unit, 43 ... Coupling coefficient adjustment drive device, 45 ... Data storage device, 46 ... Transmission efficiency measurement Unit, 461 ... ammeter, 462 ... voltmeter, 471 ... transmission efficiency calculation unit, 71 ... substrate, 72 ... source region, 73 ... drain region, 81 ... gate oxide film, 82 ... source electrode, 83 ... drain electrode, 84 … Gate electrode

Claims (9)

A primary side circuit having a power transmission side capacitor, a primary side circuit having a power transmission side coil connected in parallel to the power transmission side capacitor, storing electrostatic energy sent from the power transmission side capacitor as magnetic energy, and circulating the magnetic energy to the power transmission side capacitor. ,
A DC power supply that constitutes a circuit that connects one terminal and the other terminal of the power transmission side capacitor,
A primary side drive switch connected between the one terminal of the power transmission side capacitor and the DC power supply and step-inputting an intermittent DC voltage to the power transmission side capacitor.
A power receiving side coil that faces the power transmitting side coil and receives the magnetic energy from the power transmitting side coil, and a power receiving side capacitor that is connected in parallel to the power receiving side coil and stores the magnetic energy stored in the power receiving side coil as electrostatic energy. Secondary side circuit with
A load element that constitutes a circuit that connects one terminal and the other terminal of the power receiving side capacitor and receives the electrostatic energy from the power receiving side capacitor.
The anode is provided on the side of the one terminal of the power receiving side capacitor, and the cathode is provided with a load side diode connected to the load element, and electrical energy is transmitted from the primary side circuit to the secondary side circuit in a non-contact manner. A power transmission device characterized by the fact that. The power transmission device according to claim 1, wherein the anode is further provided with the DC power supply, and the cathode is further provided with a power supply side diode connected to the one terminal of the transmission side capacitor. The power transmission device according to claim 1 or 2, wherein the primary side drive switch is a semiconductor switching element. The power transmission device according to claim 3, wherein the primary side drive switch further includes a protection element connected in parallel with the semiconductor switching element. The power transmission device according to any one of claims 1 to 4, further comprising a magnetic coupling degree control mechanism for controlling the magnetic coupling degree between the power transmitting side coil and the power receiving side coil. .. The power transmission device according to any one of claims 1 to 5, further comprising a power transmission side switch connected in series between the one electrode of the power transmission side capacitor and the power transmission side coil. .. The power transmission device according to claim 6, further comprising a power receiving side switch connected in series between the one electrode of the power receiving side capacitor and the power receiving side coil. The power transmission device according to claim 7, further comprising a load control switch connected in series between the one electrode of the power receiving side capacitor and the load side diode. A primary side circuit having a power transmission side capacitor, a primary side circuit having a power transmission side coil connected in parallel to the power transmission side capacitor, storing electrostatic energy sent from the power transmission side capacitor as magnetic energy, and circulating the magnetic energy to the power transmission side capacitor. ,
A DC power supply that constitutes a circuit that connects one terminal and the other terminal of the power transmission side coil,
A primary side drive switch which is connected between the one terminal of the power transmission side coil and the DC power supply and step-inputs an intermittent DC voltage to the power transmission side coil.
A first interconnect capacitor in which one electrode is connected to one node that connects the power transmission side capacitor and the power transmission side coil in parallel, and
A second interconnect capacitor with one electrode connected to the other node connecting the power transmission side capacitor and the power transmission side coil in parallel,
One electrode is connected to the other electrode of the first interconnect capacitor, the other electrode is connected to the other electrode of the second interconnect capacitor, and the electrostatic energy is received from the primary side circuit. A side capacitor, a secondary circuit having a power receiving side coil connected in parallel to the power receiving side capacitor and storing the electrostatic energy stored in the power receiving side capacitor as magnetic energy, and a secondary side circuit.
A load element that constitutes a circuit that connects one terminal and the other terminal of the power receiving side coil and receives the magnetic energy from the power receiving side coil.
The anode is provided with a load-side diode whose cathode is connected to the load element on the side of the one terminal of the power-receiving side coil, and electrical energy is transmitted from the primary-side circuit to the secondary-side circuit in a non-contact manner. A power transmission device characterized by the fact that.

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