WO2020039594A1 - Power transmission device - Google Patents

Abstract

Provided is a power transmission device that has a simple circuit configuration and can be inexpensively manufactured. The device comprises: a primary side circuit (2) comprising a transmitting-side capacitor (C₁) and a transmitting-side coil (L₁); a DC power source (5) connected to the transmitting-side capacitor (C₁); a primary side drive switch (SW1) connected between the transmitting-side capacitor (C₁) and the DC power source (5); a secondary-side circuit (3) comprising a receiving-side coil (L₂) facing the transmitting side coil (L₁) and a receiving-side capacitor (C₂); a load element (6) that receives static energy from the receiving-side capacitor (C₂); and a load-side diode (D2), an anode of which is connected to the receiving-side capacitor (C₂) and a cathode of which is connected to the load element (6).

Description

Power transmission device

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

Since 2005, a 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 technologies using a power supply as an AC power supply. However, as described in Patent Document 2 and the like, in a wireless power transmission method based on AC theory, power is supplied. 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 practice, the power-supply-side resonance circuit and the power-receiving-side resonance circuit interact with each other, thereby generating a new resonance. It has been common technical knowledge that it is better not to cause resonance (double resonance) between the power supply side resonance circuit and the power reception side resonance circuit including this new resonance.

According to Patent Literature 2, the power supply side resonance circuit and the power reception side resonance circuit are coupled by a magnetic field component (magnetic field coupling), and a mutual inductance M is formed between the power supply coil and the power reception coil. Mutual inductance M, a new resonance circuit formed by the power supply side resonance circuit and the receiving resonance circuit, has a different resonant frequency fr ₂ is a resonance frequency fr _1, heavy resonance occurs. If it is intended to follow the drive frequency fo of the AC power supplied to the power supply side resonance circuit in the resonance frequency fr _1, follow towards the drive frequency fo is the resonance frequency fr ₁ rather than the resonance frequency fr ₂ which is the original target The resonance frequency fr ₂ is an undesired resonance point, and it is considered desirable to remove the resonance frequency fr _{2. In} the conventional AC theory, heavy 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 with a driving frequency fo = about 100 kHz is used, and in the invention described in Patent Document 3, several hundreds are used. An alternating current power supply of kHz to several MHz is required. In particular, Patent Document 1 reports experimental data in a frequency band around 10 MHz. A power supply circuit (zero-order circuit) in a frequency band as described in Patent Documents 1 to 3 generates an accurate direct current by using an expensive switching power supply from a commercial power supply and then complicates a large number of power semiconductor elements. In addition, it is created by performing switching accurately and making a DC pulse cut out on a square wave into a pseudo or equivalent alternating current by PWM (Pulse Width Modulation) or the like. At this time, a power loss such as a resistance loss generated in the power semiconductor element and a switching loss that increases rapidly with an increase in frequency occurs. In addition, the switching element is likely to be destroyed due to the induced back electromotive force generated in the coil, and the switching element is likely to be destroyed due to an excessive voltage rise due to resonance. On the other hand, in order to transmit power far away, the frequency must be increased. As described above, the conventional wireless power transmission device based on the AC theory has a problem that the device is complicated, the overall power transmission efficiency is low, the device is fragile, has low reliability, and is expensive. For these reasons, the conventional technology cannot realize wireless power transmission for efficiently transmitting power required in the future to a distant place. That is, the circuit design of the power transmission device based on the AC theory itself has to be studied.

US Patent Application Publication No. 2008/0278264 Japanese Patent No. 5549745 Japanese Patent No. 5462953

In view of the above problems, it is an object of the present invention to provide a low-cost power transmission device that focuses on a transient response that is not a conventional AC theory, simplifies a circuit configuration, increases power transmission efficiency, and is inexpensive.

The first aspect of the present invention is as follows: (a) a power transmission side capacitor, the static energy connected in parallel to the power transmission side capacitor and sent from the power transmission side capacitor is stored as magnetic energy, and the magnetic energy is returned to the power transmission side capacitor. A primary side circuit having a power transmission side coil, (b) a DC power supply constituting a circuit connecting between one terminal and the other terminal of the power transmission side capacitor, and (c) one terminal of the power transmission side capacitor and a DC power supply A primary-side drive switch that is connected between the power-transmitting-side capacitor and a step-input DC voltage to the power-transmitting-side capacitor; and (d) a power-receiving-side coil facing the power-transmitting-side coil and receiving magnetic energy from the power-transmitting-side coil; A secondary-side circuit having a power-receiving-side capacitor connected in parallel with the coil and storing magnetic energy stored in the power-receiving-side coil as electrostatic energy; and (e) a power-receiving-side capacitor. A circuit that connects between one terminal of the sensor and the other terminal is configured, a load element that receives electrostatic energy from the receiving capacitor, (f) the anode is on one side of the receiving capacitor, and the cathode is The gist is to provide a power transmission device including a load-side diode connected to a load element. In the power transmission device according to the first aspect, electric energy can be transmitted from the primary circuit to the secondary circuit in a non-contact manner.

According to a second aspect of the present invention, (a) a power transmission side capacitor, electrostatic energy connected in parallel to the power transmission side capacitor and sent from the power transmission side capacitor is stored as magnetic energy, and the magnetic energy is returned to the power transmission side capacitor. A primary side circuit having a power transmission side coil, (b) a DC power supply constituting a circuit connecting between one terminal and the other terminal of the power transmission side coil, and (c) one terminal of the power transmission side coil and a DC power supply The primary drive switch is connected between the power transmission side coil and the intermittent DC voltage, and (d) one electrode is connected to one node connecting the power transmission side capacitor and the power transmission side coil in parallel. (E) a second interconnection capacitor having one electrode connected to the other node connecting the power transmission side capacitor and the power transmission side coil in parallel, and (f) a first interconnection coupling capacitor. One electrode is connected to the other electrode of the capacitor, the other electrode is connected to the other electrode of the second mutual coupling capacitor, and the receiving side capacitor that receives electrostatic energy from the primary side circuit, is connected in parallel to the receiving side capacitor A secondary circuit having a power receiving coil that stores the electrostatic energy stored in the power receiving capacitor as magnetic energy, and (g) a circuit that connects between one terminal and the other terminal of the power receiving coil. A load element that receives magnetic energy from the power-receiving coil; and (h) a power transmission device including a load-side diode having an anode on one terminal side of the power-receiving-side coil and a cathode connected to the load element. Make a summary. Similarly to the power transmission device according to the first embodiment, the power transmission device according to the second embodiment can transmit electric energy from the primary circuit to the secondary circuit in a non-contact manner.

ADVANTAGE OF THE INVENTION According to this invention by the circuit design which deviated from the conventional AC theory, by using the characteristic harmonic transmission which is a phenomenon at the time of transient response, the circuit configuration can be simplified, the power transmission efficiency can be increased, and an inexpensive power transmission device can be provided. .

FIG. 1A is a circuit diagram schematically illustrating an example of a power transmission device according to a first embodiment of the present invention, and FIG. 1B is a terminal of a power transmission side capacitor of the circuit illustrated in FIG. It is a waveform diagram of an inter-voltage. FIG. 2A is a waveform diagram of the voltage between the terminals of the power transmitting side capacitor and the power receiving side capacitor of the power transmission device according to the first embodiment, and FIG. 2B is a continuation of the waveform of FIG. It is a detailed waveform diagram. FIG. 4 is a diagram illustrating a transient response when a step is input to an LC parallel circuit. FIG. 2 is a circuit diagram illustrating a mounting circuit of the power transmission device according to the first embodiment. FIG. 2 is a diagram illustrating a large-signal equivalent circuit of a MOSFET used in the power transmission device according to the first 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 a diagram illustrating charging of a battery of an electric vehicle (EV). FIG. 13 is a bird's-eye view illustrating a magnetic coupling degree control mechanism that adjusts a surface interval between coils when applied. FIG. 7A is a bird's-eye view illustrating a mechanism for adjusting the coil magnetic coupling of the power transmission device according to the first embodiment. FIG. 7A illustrates a case where the surface interval between coils is controlled using a spacer. FIG. 7B and FIG. 7C show an example of a magnetic coupling degree control mechanism for adjusting the magnetic coupling of the coils using a magnetic plate. FIG. 8A is a block diagram illustrating an example of a hardware configuration of a magnetic coupling control mechanism of the power transmission device according to the first embodiment, and FIG. 8B illustrates another example. It is a block diagram. FIG. 3 is a schematic diagram for explaining the operation of the power transmission device according to the first embodiment separately for each timing in a time series. FIG. 10A is a circuit diagram schematically illustrating an example of a power transmission device according to a second embodiment of the present invention. FIG. 10B is a circuit diagram illustrating a specific implementation circuit of the circuit in FIG. FIG. FIG. 9 is a timing chart illustrating a power supply method of the power transmission device according to the second embodiment. It is a schematic diagram explaining the power supply method of the power transmission device according to the second embodiment, (a) at the time of charging, (b) at the time of characteristic harmonic transmission between the primary side circuit 2 and the secondary side circuit 3, ( c) At the time of transfer, and (d) at the time of characteristic harmonic transmission between the primary side circuit 2 and the secondary side circuit 3. FIG. 13A is a circuit diagram schematically illustrating an example of a power transmission device according to the third embodiment of the present invention, and FIG. 13B is a specific implementation of the circuit illustrated in FIG. It is a circuit diagram showing a circuit. 9 is a flowchart illustrating a power supply method of a power transmission device according to a third embodiment. FIG. 13 is a timing chart illustrating a power supply method of the power transmission device according to the third embodiment. FIG. 16A is a circuit diagram schematically illustrating an example of a power transmission device according to a fourth embodiment of the present invention, and FIG. 16B is a specific implementation of the circuit illustrated in FIG. It is a circuit diagram showing a circuit. FIG. 17A 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. FIG. 9 is a waveform diagram obtained by a mounting circuit of a voltage between terminals of a power receiving side capacitor. FIG. 18A is a waveform diagram when the equivalent coupling coefficient K of the voltage between the terminals of the power transmission side capacitor and the power receiving side capacitor in the power transmission device according to the fourth embodiment is K = 0.00, and FIG. FIG. 9 is a waveform chart when an equivalent coupling coefficient K = 0.1. FIG. 19A is a waveform diagram when the equivalent coupling coefficient K of the voltage between the terminals of the power transmission side capacitor and the power receiving side capacitor in the power transmission device according to the fourth embodiment is K = 0.6, and FIG. FIG. 19C is a waveform diagram when the equivalent coupling coefficient K = 0.88, 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 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 is K = 0.6, and FIG. It is a waveform diagram at the time of the equivalent coupling coefficient K of the electric current which flows into a power transmission side coil and a power receiving side coil = 0.6. 13 is a graph illustrating a change in transmission efficiency with respect to a capacitance of a capacitor of the power transmission device according to the fourth embodiment. 13 is a graph illustrating the efficiency of the power transmission device according to the fourth embodiment. 13 is a flowchart illustrating a first power supply method of the power transmission device according to the fourth embodiment. FIG. 24A is a timing chart illustrating a first power supply method of the power transmission device according to the fourth embodiment, and FIG. 24B is a timing chart illustrating a second power supply method. 13 is a flowchart illustrating a second power supply method of the power transmission device according to the fourth embodiment. It is a circuit diagram showing an outline of an example of a power transmission device according to a fifth embodiment of the present invention. FIG. 27A is a waveform diagram of a current flowing through the power transmission side coil and the power receiving side coil of the power transmission device according to the fifth embodiment, and FIG. 27B is a diagram of the power transmission device according to the fifth embodiment. It is a waveform diagram of each terminal voltage of a power transmission side capacitor and a power receiving side capacitor. FIG. 2 is a circuit diagram used for an approximate simulation for explaining a sawtooth wave with a bump in the power transmission device according to the first embodiment of the present invention. FIG. 29 is a diagram illustrating a transient response characteristic of a sawtooth wave with a bump obtained by an approximate simulation of the circuit of FIG. 28. FIG. 29 is a diagram illustrating how a sawtooth bump obtained by an approximate simulation using the circuit of FIG. 28 changes with a repetition period. FIG. 29 is a simplified circuit diagram in which a parasitic capacitance, a parasitic resistance, and the like are omitted from the circuit of FIG. 28. FIG. 32 is a diagram illustrating that a W-type transient response characteristic is obtained by an approximate simulation of the simplified circuit of FIG. 31. FIG. 9 is a circuit diagram used for performing an approximate simulation of the transient response characteristics of the power transmission device according to the second embodiment of the present invention while changing the power supply voltage and the load voltage. FIG. 34 is a diagram illustrating the transfer of electric energy with transient response characteristics obtained by an approximate simulation for the three circuits in FIG. 33. FIG. 2 is a schematic diagram illustrating a W-type transient response characteristic of the power transmission device according to the first embodiment of the present invention.

Next, first to fifth embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted 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 planar dimension, the ratio of the thickness of each member, and the like are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. In addition, it is needless to say that dimensional relationships and ratios are different between drawings.

The first to fifth embodiments described below exemplify an apparatus and a method for embodying the technical idea of the present invention. The shape, structure, arrangement and the like are not specified as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims. Further, the directions of “left and right” and “up and down” in the following description are simply definitions for convenience of description, and do not limit the technical idea of the present invention. Thus, for example, if the paper is rotated 90 degrees, "left and right" and "up and down" are read interchangeably, and if the paper is rotated 180 degrees, "left" becomes "right" and "right" becomes "left". Of course. Similarly, the direction of the spiral of the spiral as shown in FIGS. 6 (a) to 7 (c) is also merely a choice for convenience of description, and the right-handed is turned to the left-handed and the left-handed is wound according to the actual design circumstances. It is also possible to select right-handed.

(First embodiment)
The power transmission device according to the first embodiment of the present invention includes a primary circuit 2 and a secondary circuit 3 as shown in FIG. The primary side circuit 2 accumulates the electrostatic energy which is connected in parallel to the power transmission side capacitor C ₁ and the power transmission side capacitor C ₁ and which is transmitted from the power transmission side capacitor C ₁ as magnetic energy. and at the same time circulating the transmission side capacitor C _1, magnetically coupled to the power receiving side coil L ₂ of the secondary side circuit 3, an LC resonant circuit having a transmitting coil L ₁ for transmitting and receiving magnetic energy. 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 drive switch SW1” is a circuit element that limits free vibration of the primary 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, and may be a DC power supply having a simple structure that is simply rectified and may be a power supply containing a large ripple component. Therefore, the control circuit and peripheral circuits are simple, are not easily broken, and the circuit design is easy. Moreover, an inexpensive DC power supply 5 can be employed. 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 an LC resonant circuit having a power receiving side capacitor C ₂ for storing 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 a lithium (Li) ion battery mounted on an electric vehicle (EV) can be used. In FIG. 1A, for example, an equivalent circuit of a lithium ion battery is schematically illustrated by a series-parallel circuit of a resistor and a capacitor. Lithium-ion batteries include the resistance of current collectors and electrolytes, and electrical double-layer capacitors and resistors formed at the interface within 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 by a resistance value. We show transient response waveform of terminal voltage VC ₁ obtained by the actual measurement in the case where the on-off driving the primary-side drive switch SW1 in FIG. 1 (b).

In the first embodiment, the value in the initial state of the charge voltage VC _S load elements 6 (closer to the full charge) near the charge completion voltage, assumed to be a high value. At time t = 0, the power-transmitting-side capacitor C ₁ is the voltage VC 1 _{= 0} between not been charging terminal. When the primary-side drive switch SW1 is turned on at t = 0, the terminal voltage E of the DC power supply 5 is step-input. By the step input at t = 0, the charging current to the capacitor C1 flows at first, and its value is E / r1. At this time, since the coil L1 generates a back electromotive force so as to block the flowing current, the current to L1 is zero. As shown in FIG. 1B, the power transmission side capacitor C ₁ is charged with a time constant τ ₁ determined by 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 mutual inductance M. , terminal voltage VC ₁ is increased. The time constant τ ₁ is a value mainly dependent on a parameter related to a product C ₁ · r ₁ of the capacitance C ₁ of the transmission-side capacitor C ₁ and the resistance value C ₁ of the equivalent internal resistance r ₁ .

The voltage of C1 gradually increases, and as the current decreases, the back electromotive force of L1 decreases and the current starts flowing to L1. This causes the voltage across C1 to drop slightly. At this point, SW1 is closed (t = t1). The time t1 at which the switch is closed is a time when the current starts to flow through the coil and such that SW1 is not destroyed by the voltage applied to SW1 generated by the back electromotive force generated by turning off the coil. When t = t ₁ at turning off the primary-side drive switch SW _1, to initiate a full-scale discharge is as current flows through the transmitting coil L ₁ from the power transmission side capacitor C _1. Electrical energy stored in the power transmitting side capacitor C ₁ tries to move to the power transmission coil L _1. The magnetic field generated around the L ₁ by the current flowing to the power transmission coil L ₁ at this time, electromotive force current to flow occurs in the power receiving side coil L ₂ bound in mutual inductance M. As described later, if it was characteristic of when the primary-side circuit 2 the secondary side circuit 3 is harmonious, most efficiently receiving side capacitor C ₂ is charged by the transmitted power. That is, power is transmitted from the primary circuit 2 to the secondary circuit 3 most efficiently. The magnetic field generated around the power receiving side coil L ₂ by a current flowing in the power receiving side coil L ₂ is an electromotive force generated in L1. 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 sawtooth wave characteristic with a bump that rises while rising like a bump just a little past the lowest voltage portion of the sawtooth voltage.

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 a parameter represented by a relationship similar to Expression (4) described below. However, the inductance of the power transmission coil L _1, it is necessary to consider the mutual inductance M = M of the power receiving coil L ₂ Noto is a value that depends on the time t (t).

At t = t ₂ , the voltage of the primary-side capacitor again reaches the maximum peak, and at this time, the voltage of the secondary-side capacitor has a value close to the minimum. When the primary-side drive switch SW1 is turned on again in accordance with this peak, the terminal voltage E of the DC power supply 5 is step-inputted again. As before, initially flows the charging current to the capacitor C _1, the value that value to the minus the voltage of the capacitor C ₁ from the terminal voltage E definitive t = t ₂ of the DC power source 5 is divided by r ₁ It is. Since generating a counter electromotive force to block the current flowing the coil L ₁ when this, the current to the L ₁ is zero. The voltage of C1 gradually increases, and as the current decreases, the back electromotive force of L1 decreases and the current starts flowing to L1. Whereby the voltage across C ₁ is decreased slightly. At this point close the SW1 (t = t _3). Time t ₃ when closing the switch, when current to the coil starts to flow, and SW1 is a time so as not to destroy the voltage applied to the SW ₁ by back electromotive force generated transmission coil L ₁ by cutting it . 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. Electrical energy stored in the power transmitting side capacitor C ₁ tries to move to the power transmission coil L _1. The magnetic field generated around the L ₁ by the current flowing to the power transmission coil L ₁ at this time, electromotive force current to flow occurs in the power receiving side coil L ₂ bound in mutual inductance M. As described later, if it was characteristic of when the primary-side circuit 2 the secondary side circuit 3 is harmonious, most efficiently receiving side capacitor C ₂ is charged by the transmitted power. That is, power is transmitted from the primary circuit 2 to the secondary circuit 3 most efficiently. The magnetic field generated around the power receiving side coil L ₂ by a current flowing in the power receiving side coil L ₂ is an electromotive force generated in L1. 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 sawtooth wave characteristic with a bump that rises while rising like a bump just a little past the lowest voltage portion of the sawtooth voltage.

As a result, t = t ₃ or later, as shown on the right side of FIG. 1 (b), the terminal voltage VC ₁ of the power transmission capacitor C ₁ decreases, 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) the terminal voltage VC ₁ of the power transmission capacitor C ₁ starts to increase by circulating electric current, a positive value, further increases. The time up to this point is determined by a 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), by blocking a step input terminal voltage E of the DC power source 5 by the primary-side drive switch SW1, the change of terminal voltage VC ₁ is not a sine wave of the waveform at the normal AC Theory 4 shows a transient response of a repetitive waveform having rising and falling characteristics in which a sawtooth wave with a bump is blunted.

When the time constant inherent in the circuit characteristics of the primary circuit 2 and the time constant inherent in the circuit characteristics of the secondary circuit 3 are in harmony, the electric energy of the primary circuit 2 is transmitted to the secondary circuit 3 most efficiently. As a result, characteristic harmonic transmission occurs between the primary circuit 2 and the secondary circuit 3. 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 This is shown in FIG. In FIG. 2 (a), similarly to FIG. 1 (b), the blockade and step input terminal voltage E of the DC power source 5 by the primary-side drive switch SW1, the voltage between the terminals VC ₁ is sawtooth wave is rounded with aneurysm 9 shows a repetitive transient response waveform of rising and falling characteristics. The transient response waveform shown by the solid line in FIG. 2 (a), the terminal voltage VC ₁ of the power transmission capacitor C ₁ starts to increase from a negative value, a positive value, and further increases, t = t _{The state i} indicates that the primary-side drive switch SW1 is turned on.

At this time, as shown by the broken line on the left side of FIG. 2A, the characteristic harmonic 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 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 started to decrease. When the primary-side drive switch SW1 is turned on at t = t _i , the terminal voltage E of the DC power supply 5 is 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 It is charged transmission side capacitor C ₁ at constant tau ₁ primary circuit 2 when the inter-terminal voltage VC ₁ is increased. As shown in FIG. 2 (a), the inter-terminal voltage VC ₁ of the primary-side circuit 2 after reaching the peak value, starts decreasing. 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 to move to the side coil L _1. Terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3 is a negative value between at t = t i _{+ 1} from t = t _i as indicated by a broken line.

t = t i + ₁ and later, as indicated by a solid line in the vicinity of the center of FIG. 2 (a), the capacitance C ₁ of the power transmission _capacitor, the inductance L ₁ of the power transmission coil, constant tau ₂ when 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 electric energy stored in the power transmission side coil L ₁ is transferred to the secondary circuit 3 by the characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3 between the primary circuit 2 and the secondary circuit 3. It is wirelessly transmitted to the power receiving coil L _2. The electric energy wirelessly transmitted to the power receiving coil L ₂ of the secondary circuit 3 is stored in the power receiving capacitor C ₂ of the secondary circuit 3.

As a result, in t = t i + ₁ and later, as indicated by a broken line in the vicinity of the center of FIG. 2 (a), the terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3 starts to increase. After terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3 having reached the peak value, it starts decreasing, a negative value as shown by a broken line on the right side of FIG. 2 (a). As a condition of the present embodiment, the value in the initial state of the charge voltage VC _S load elements 6 (closer to the full charge) near the charge completion voltage, high because the value, the terminal voltage of the power-receiving-side capacitor C ₂ since VC ₂ exceeds the charge voltage VC _S load element 6 around which peaked value, a current flows through the load element 6, electric energy stored in the power receiving side capacitor C2 is moved to the load device 6, a load element The rechargeable battery No. 6 is charged.

t = t i + ₁ and later, when the terminal voltage VC ₁ of the power transmission capacitor C ₁ as shown by the solid line in the middle in FIG. 2 (a) reaches a minimum value of the negative value, the power transmission coil L ₁ 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. Right side as shown by the broken line in FIG. 2 (a), the inter-terminal voltage VC ₁ is a positive value, the voltage between the terminals VC ₂ of the power receiving side capacitor C ₂ is 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 You. 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. 2A, and the terminal voltage VC ₁ increases. As shown in solid line in FIG. 2 (a), the terminal voltage VC ₁ is after reaching the peak value E _0, starts decreasing again. t = t i + ₃ in the turning off state of the primary-side drive switch SW1, the power-transmitting-side capacitor C ₁ starts discharging again, electrical energy stored in the power transmitting side capacitor C ₁ is moved to the power transmission coil L ₁ . Terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3 is a negative value between at t = t i _{+ 3} from t = t i _{+ 2} as indicated by a broken line.

The electric energy stored in the power transmission side coil L ₁ is transferred to the secondary circuit 3 by the characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3 between the primary circuit 2 and the secondary circuit 3. It is wirelessly transmitted to the power receiving coil L _2. The electric energy wirelessly transmitted to the power receiving coil L ₂ of the secondary circuit 3 is stored in the power receiving capacitor C ₂ of the secondary circuit 3. As shown in FIG. 2 (a), by interrupting the step input terminal voltage E by the primary-side drive switch SW1, a sinusoidal waveform change in the voltage VC ₁ between the primary circuit second terminal is in the normal AC theory In other words, it shows a transient response of a repetitive waveform having rising and falling characteristics in which a sawtooth wave with a bump is blunted. On the other hand, the change of terminal voltage VC ₂ of the secondary side circuit 3 shows the transient response of the repetitive waveform such as a triangular wave decimated, not a sinusoidal waveform at regular AC theory. As can be seen from FIG. 2A, the “thinned-out 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 circuit 2 and the vibration waveform of the secondary circuit 3 are not symmetrical vibration waveforms.

2 (b) is 2 terminal voltage E of the further DC power supply 5 to the terminal voltage VC ₁ and transient response waveform of terminal voltage VC ₂ shown in (a), the inter-terminal voltage VC _S and load element 6 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 Harmonic transmission between the primary circuit 2 and the secondary circuit 3 to the secondary 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 shows the change to be superimposed between the voltage VC _1.

A description will be given focusing on the transient response after t = t _{i + 1 in} FIG. Near the center, as shown by the solid line in FIG. 2 (b), the terminal voltage VC ₁ of the power transmission capacitor C ₁ decreases at t = t i + ₁ after 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 electric energy stored in the power transmission side coil L ₁ is transferred to the secondary circuit 3 by the characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3 between the primary circuit 2 and the secondary circuit 3. It is transmitted to the power receiving 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} .

Terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3, a negative value is between t = t _i in t = t i _{+ 1} as indicated by broken lines of the center of the left . Terminal voltage VC ₂ of the power receiving side capacitor C ₂ is increased from a negative value of t = t i + _1, increased positive addition to the value, after reaching the peak value, the right shown in FIG. 2 (b) As shown by the broken line in FIG. 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 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 in Vcs according to Ic is caused by the existence of a series-parallel circuit of a resistor and a capacitor as shown in FIG.

In t = t i + ₁ and later, when the terminal voltage VC ₁ of the power transmission capacitor C ₁ as shown by the solid line in the middle of FIG. 2 (b) reaches a minimum value of the negative value, the power transmission coil L ₁ 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. Right side as shown by the broken line in FIG. 2 (b), when the inter-terminal voltage VC ₁ is a positive value, the voltage between the terminals VC ₂ of the power receiving side capacitor C ₂ is 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 You. 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. 2B, 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 to be superimposed between the voltage VC _1. As shown by the solid line superimposed on the voltage E between the right end of the terminal in FIG. 2 (b), the terminal voltage VC ₁ after reaching the peak value, starts decreasing again. t = t i + ₃ in the turning off state of the primary-side drive switch SW1, the power-transmitting-side capacitor C ₁ starts discharging again, electrical energy stored in the power transmitting side capacitor C ₁ is moved to the power transmission coil L ₁ . Terminal voltage VC ₂ of the power receiving side capacitor C ₂ of the secondary side circuit 3 is a negative value between at t = t i _{+ 3} from t = t i _{+ 2} as indicated by a 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) Then, 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 in Vcs according to Ic is caused by the existence of a series-parallel circuit of a resistor and a capacitor as shown in FIG.

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) Start decreasing towards the value. In this manner, the electric energy stored in the power transmission side coil L ₁ is regenerated by the characteristic harmonic 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. is wirelessly transmitted to the power receiving coil L ₂ follows side circuit 3. The electric energy wirelessly transmitted to the power receiving coil L ₂ of the secondary circuit 3 is stored in the power receiving capacitor C ₂ of the secondary circuit 3. As shown in FIG. 2 (b), by blocking a step input terminal voltage E by the primary-side drive switch SW1, a sinusoidal waveform change in the voltage VC ₁ between the primary circuit second terminal is in the normal AC theory without represents a repeating transient response waveform rise and fall characteristics with aneurysms sawtooth wave is rounded, inter-terminal voltage VC ₂ of the secondary side circuit 3 shows the transient response of the repetitive waveform such as a triangular wave thinned out.

FIG. 3A is a circuit diagram illustrating a step response of the primary circuit 2 as a single circuit in a state where there is no electromagnetic coupling between the primary circuit 2 and the secondary circuit 3. In FIG. 3 (a), E terminal voltage of the DC power source, the voltage between the terminals of the transmitting-side capacitor C ₁ VC _1, the current flowing through the power transmission coil L ₁ to the power transmission coil current I _L1. When the primary-side drive switch SW1 is turned on at t = 0 ms, the terminal voltage E of the DC power supply 5 is step-input. By the step input of t = 0 ms, as shown in FIG. 3B, the time constant determined by the capacitance C _{1 of} the power transmission side capacitor and the inductance L ₁ of the power transmission side coil is such that the power transmission side capacitor C ₁ has a rising waveform V _{rise of} charging. It defines a terminal voltage VC ₁ increases at a rising waveform V _rise. At the same time, the power transmission side coil current _IL1 also starts increasing as shown in FIG.

As shown in FIG. 3 (b), the inter-terminal voltage VC ₁ is after reaching the peak value at t = 0.075ms increased by rising waveform V _rise, starts decreasing. Even after the terminal voltage VC ₁ starts to decrease, the power transmission coil current I _L1 continues to increase, it can be seen that electrical energy of the power transmission capacitor C ₁ continues to move to the power transmission 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 to move to the coil L _1.

As a result, t = 0.15 ms later, as shown in FIG. 3 (b), the capacitance C ₁ of the power transmission _capacitor, the power transmission coil of the inductance L constant at the transmission side capacitor C ₁ of the terminal voltage when determined by ₁ VC ₁ decreases, when it reaches the peak value of the power transmission coil current _{I L1} at t = 0.17ms, terminal voltage VC ₁ is zero. Then, t = 0.17ms later, the inter-terminal voltage VC ₁ of the power transmission 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 coil current I _L1 becomes zero at t = 0.29ms, terminal voltage VC ₁ of the power transmission capacitor C ₁ is increased by circulating electric current Start. The value of the power transmission coil current I _L1 is, t = time became minimum value of zero negative value in 0.4 ms, the inter-terminal voltage VC ₁ is zero, after which the inter-terminal voltage VC ₁ is a positive value And further increase.

The circuit shown in FIG. 3A does not turn the primary-side drive switch SW1 on again after the primary-side drive switch SW1 is turned off at t = 0.15 ms. In other words, in the case of the circuit shown in FIG. 3A, free oscillation occurs in the shaded area on the right side of FIG. However, in the circuit shown in FIG. 1A, since the primary-side drive switch SW1 drives a forcible step response that repeats on / off periodically, the area of free vibration indicated by the oblique lines in FIG. Are out of the scope of the power transmission device according to the first embodiment. For forced step response, as shown in FIG. 1 (b) ~ FIG 2 (b), the inter-terminal voltage VC ₁ of the primary-side circuit 2 repeats the rise and fall characteristics sawtooth wave with aneurysm dull 3 shows a transient response of a waveform. Further, the voltage between the terminals VC ₂ of the secondary side circuit 3 shows the transient response of the repetitive waveform such as a triangular wave thinned out.

That is, in the power transmission device according to the first embodiment, not the resonance based on the sine wave in the ordinary AC theory, but the time constant inherent in the circuit characteristics of the primary circuit 2 and the circuit of the secondary circuit 3 When the time constant inherent in the characteristic is harmonized, the electric energy of the primary circuit 2 is efficiently transmitted to the secondary circuit 3 by characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3. . In order to harmonize 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, the product of the power transmitting side capacitor C1 and the power transmitting side coil L1, and the power receiving side capacitor Basically, the product of C2 and the power receiving side coil L2 should be the same, and the respective time constants considering the parasitic resistance and the stray capacitance of the power transmitting side and the power receiving side must be matched or harmonized with each other by an integral multiple. The simplest way, the power transmission side capacitor C1 a capacitance of the power receiving side capacitor C2, and equally, including the parasitic resistance of the capacitor, the inductance of the power transmission coil L ₁ and the power receiving side coil L ₂ including the parasitic resistance of the coil It is to make them equal. It should be noted that, when a parasitic resistance exists in the coil and the capacitor, the transmission efficiency becomes maximum when the inductance L of the coil and the capacitance C of the capacitor satisfy Expression (19), as described later. is there.

と し て 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. As the power semiconductor switching element, thyristors such as a gate turn-off thyristor (GTO) and an electrostatic induction thyristor (SI thyristor) in addition to a field effect transistor (FET), an electrostatic induction transistor (SIT), and a bipolar transistor (BJT) are available. It is suitable. In particular, voltage-driven switching elements such as an insulated gate field effect transistor (MISFET), an insulated gate electrostatic induction transistor (MISSIT), an insulated gate bipolar transistor (IGBT), and a MOS control SI thyristor consume less power. It is suitable. Based on the availability on the market and the evaluation of the internal resistance of the power semiconductor switching element, at present, a MOS field effect transistor (MOSFET), which is a type of MISFET, is employed as shown in the circuit of FIG. It is possible to

In a power transmission device in which a rechargeable battery mounted on an EV is used as the load element 6, a large current flows to generate large Joule heat, which generates heat of several hundred watts or more. 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, the power semiconductor switching element is covered with a heat sink such as a copper block to increase thermal conductivity, and the element is destroyed by heat generation. Can be designed easily, and the occurrence 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 way to suppress the generation of Joule heat in the high power power transmission device such as for automotive the EV increases the voltage of the primary-side circuit 2, the two in transmitting coil L ₁ and the turns ratio of the power receiving coil L ₂ That is, the voltage of the secondary circuit 3 is set to the optimum voltage of the load element 6. When a power semiconductor switching element is used as the primary side drive switch SW1, only a simple control for turning on / off the power semiconductor switching element is required, so that a circuit design for increasing the voltage of the primary side circuit 2 is easy. is there.

As described above, according to the power transmission device of the first embodiment, since the primary drive switch SW1 has a simple design of only one, the voltage of the primary circuit 2 is increased and the joule on the primary circuit 2 side is increased. It is easy to design to minimize power loss due to heat generation. Since the energy loss due to the generation of Joule heat can be reduced, the power transmission device according to the first embodiment includes the loss of the power supply circuit (zero-order circuit) in the case of high-power power transmission such as for EVs mounted on vehicles. The overall power transmission efficiency is increased, which can contribute to solving the energy problem of humanity.

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 -It is connected in parallel as a protection element between the drains. Further, 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 a DC power source 5 and the first semiconductor switching element Q1. In the mounting circuit shown in FIG. 4A, the equivalent impedance X _Leq of the load element 6 is expressed by approximating the charging 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 = K _AC (L ₁ · L ₂ ) ^1/2 (1)

It can be shown. And the power transmission side capacitor C ₁ and the series circuit of the power transmission coil L _1, the mutual induction between the power receiver side capacitor C ₂ and series circuit of the power receiving coil L ₂ is the use of mutual inductance M, the following binding equation
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 the 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 using a coil having a mutual inductance M according to an AC theory based on a normal sine wave in a steady state.

However, since the power transmission device according to the first embodiment is a transmission technology of a transient response that does not depend on the sine wave AC theory, the expression of the equivalent circuit in FIG. It is only a schematic diagram in. Maxwell's equation with time changes can be solved analytically if the time change relies on a sine wave. However, when there is a sawtooth-like temporal change as shown in FIGS. 1B and 2B, it is extremely difficult to analytically solve Maxwell's equations. Therefore, in the present invention, the mutual inductance M used in the AC theory is a time-dependent parameter expressed by a function M (t) where t is time, and is expressed by the equivalent circuit shown in FIG. Need attention.

FIG. 5 shows a large-signal equivalent circuit of an 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, in a general nMOSFET, an n ⁺ -type source region 72 and an n ⁺ -type drain region 73 are opposed to a p-type substrate 71 with a surface of the p-type substrate 71 serving as a channel region interposed therebetween. Let me. A gate electrode 84 is provided on the channel region of the source region 72 and the drain region 73 via a gate oxide film 81 having a thickness T _OX . A source electrode 82 is in ohmic contact with the source region 72, and a drain electrode 83 is in ohmic contact with the drain region 73.

As shown in FIG. 5A, in a general nMOSFET, a gate-source capacitance C _GS is provided between the gate electrode 84 and the source region 72, and a gate-drain connection is provided between the gate electrode 84 and the drain region 73. A capacitance C _GD exists between the gate electrode 84 and the substrate 71 and a gate-substrate capacitance C _GB exists. Further, a source-substrate capacitance C _BS exists between the source region 72 and the substrate 71, and a drain-substrate capacitance C _BD exists between the drain region 73 and the substrate 71. In the equivalent circuit shown in FIG. 5B, the drain resistance R _D connected in series between the drain electrode and the channel region and the source resistance R _S connected in series between the source electrode and the channel region are connected to the channel region. 2 shows a configuration connected in series to a constant current source of a current I _DS provided in the first embodiment.

In the power transmission device according to the first embodiment shown in FIG. 4, the drain resistance _RD and the source resistance _{RS of} the MOSFET shown in FIG. 5, which are the ON resistance of the first semiconductor switching element Q1, are important. It is necessary to select an element having a small on-resistance as the first semiconductor switching element Q1. Therefore, in the mounting circuit shown in FIG. 4A, the equivalent internal resistance r ₁ of the DC power supply 5 includes the ON resistance of the first semiconductor switching element Q 1, and the time constant inherent in the circuit characteristics of the primary circuit 2. Need to decide.

When the primary-side drive switch SW1 in the OFF state in FIG. 1 t = t ₁ of (b), the primary circuit 2 becomes RLC series circuit. According to the AC theory, assuming that the parasitic resistance of the power 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, the inductance of the power transmission coil L ₁ is actually it is necessary to consider the mutual inductance M = M (t) shown in FIG. 4 (b), the mutual inductance M = M (t) of analytically It is difficult to explain.

If the load-side diode D2 on the load side of the secondary circuit 3 and the load element 6 at this time are ignored, the circuit can be regarded as an RLC series circuit. By employing the alternating current theories ignore the load element 6 such as a load-side diode D2, the parasitic resistance of the power receiving coil L ₂ as R _str (L _2), the damping coefficient zeta ₂ of the secondary side circuit 3,

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

It is expressed as Also in equation (5), the inductance of the power receiving coil L _2, it is necessary to consider the mutual inductance M = M (t) shown in Figure 4 (b).

According to the AC theory, the resonance frequency of the RLC series circuit in which the primary side drive switch SW1 is turned off at t = t ₁ in FIG.

f _o1 = (1 / 2π) (C ₁ · L ₁ ) − ^1/2 (6)

Can be approximated. As described above, in (6), in fact, as the inductance of the power receiving coil L _1, must have noted that it is necessary to take into account the mutual inductance M = M (t) that shown in FIG. 4 (b) It is. Similarly, the resonance frequency of the RLC series circuit when the load-side diode D2 on the load side of the secondary circuit 3 and the load element 6 and the like are ignored, according to the AC theory,

_{f o2 = (1 / 2π)} (C 2 · L 2) - 1/2 ...... (7)

Can be approximated. (7) Also in formula, the inductance of the power receiving coil L _2, it is necessary to consider the mutual inductance M = M (t) shown in Figure 4 (b).

Transmitting coil L ₁ and the power receiving coil L ₂ of the power transmission device according to the first embodiment, for example, was as shown FIG. 6 (a) ~ FIG 7 (c), it is a spiral planar coil it can. Primary circuit 2 and the secondary-side circuit 3, in a steady state AC theory holds, as shown in FIG. 4 (b), the equivalent coefficient K between the power transmission coil L ₁ and the power receiving coil L ₂ , Can be approximated by a circuit magnetically coupled with the mutual inductance M. Here, the “equivalent coupling coefficient K” is a pseudo coupling coefficient in an unsteady state defined at the time of a transient response, which is equivalent to the coupling coefficient K _AC derived from AC theory, and is strictly a time-dependent parameter. Therefore, even in the characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3 between the time constant inherent in the circuit characteristic of the primary circuit 2 and the time constant inherent in the circuit characteristic of the secondary circuit 3, It can be evaluated by the “magnetic coupling degree” similar to the theoretical coupling coefficient K _AC .

FIG 6 (a) ~ FIG. 7 (c) is a schematic view showing an embodiment the power transmission coil L ₁ the structure of the power receiving coil L ₂ in FIG. 4 (a). In the power transmission device according to the first embodiment, for example, nine windings of a wiring cable having a conductor cross-sectional area of 16 mm ² are formed into a spiral planar coil having a diameter of about 30 Cm. The two spiral planar coils having a diameter of about 30 Cm are arranged in parallel with each other in a non-contact manner with a gap of a distance d. The efficiency of the characteristic harmonic 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 depends on the magnetic coupling degree similar to the coupling coefficient K _AC defined by AC theory. Depends on the value. The degree of magnetic coupling depends on the distance d between the two spiral planar coils, and it is necessary to control the distance d between the two spiral planar coils.

The degree of magnetic coupling is to mechanically adjust the positional relationship between the two spiral planar coils, insert a magnetic material between the two spiral planar coils, or place a magnetic material around the two spiral planar coils. It can be adjusted by attaching to a pre-formed coupling utilizing the attraction or repulsion acting between the two spiral planar coils to be arranged.

Described in the fourth embodiment and the like, but when the correlation between the power transmission coil L ₁ of the equivalent coefficient K which can be substantially approximated to the coupling coefficient K _{AC =} 0.6 AC theory receiver coil L _2, It is suitable for characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3. In the case of a spiral flat coil in which nine wiring cables each having a conductor cross-sectional area of 16 mm ² are wound, in order to realize an equivalent coupling coefficient K = 0.6, the interval d needs to be about 0 Cm to 2.0 Cm. . On the other hand, in order to realize the mutual relationship between the power transmitting coil L ₁ and the power receiving coil L _{2 under} the condition that the equivalent coupling coefficient K can be approximately approximated to the coupling coefficient K _AC = 0.1 of the _AC theory, the distance d is 10 Cm. It is about. The power transmission coil L ₁ and the power receiving coil L ₂ exaggerated (enlarged) and, as shown schematically in FIG. 6 (b), the load element 6 is a rechargeable battery for vehicle of EV first embodiment the power transmission device according to the used for charging controls the spacing d of the power transmission coil L ₁ and the power receiving side coil L ₂ with a bollard 33 of the rear wheel as a magnetic coupling degree control mechanism to approximately 10 cm, Efficient non-contact power supply can be performed.

As magnetic coupling degree control mechanism for controlling the distance d of the power transmission coil L ₁ and the power receiving side coil L _2, as shown in FIG. 7 (a), the thickness between the power transmission coil L ₁ and the power receiving coil L ₂ By sandwiching the spacer 32 of d ₀ , the distance d = d ₀ between the power transmitting coil L ₁ and the power receiving coil L ₂ can be controlled. Incidentally, the power transmission coil L ₁ corresponding to the value of the critical magnetic coupling of the efficiency characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3 from the primary 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) Is also good. Insertion position in the vertical direction of the magnetic plates 31C, or by the insertion area of the magnetic material plate 31C, the value of the magnetic coupling degree between the power transmission coil L ₁ and the power receiving coil L ₂ can be controlled. Magnetic plate 31C is not between the power transmission coil L ₁ and the power receiving side coil L _2, as shown in FIG. 7 (c), may be inserted magnetic plate 31b on the back side of the power transmission coil L ₁ Absent. 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 Is, of course.

To control the vertical insertion position of the magnetic plate 31C shown in FIG. 7B and the vertical insertion position of the magnetic plate 31b shown in FIG. an optical ranging unit 41 as shown in), the power transmission coil L ₁ may be provided in the power feeding device side is provided. The distance measuring unit 41 may be provided with a magnetic coupling degree control mechanism including a light emitting unit 411 and a light receiving unit 412. If the light receiving section 412 is an optical time-of-flight (TOF type) distance measuring element d, the light emitting section 411 emits pulse light. For pulse emission, for example, a near-infrared LD (laser diode) or near-infrared LED is used. Pulsed light reflected from the rear of the power receiving coil L ₂ and EV is irradiated to the light receiving portion 412, such as through a lens and a BPF (band-pass filter). The distance measuring unit 41 may be configured as a laser interferometer or the like.

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

Data of the distance between the distance calculation unit 421 has calculated the power transmission coil L ₁ receiver coil L ₂ is transmitted to the coupling coefficient calculation unit 422 of the logical operation control unit 42. The coupling coefficient calculation unit 422 calculates the current magnetic force between the power transmission coil L ₁ and the power reception coil L ₂ from the data on the distance between the power transmission coil L ₁ and the power reception coil L ₂ calculated by the distance calculation unit 421. Find the value of the degree of static 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 necessary to realize the desired equivalent coupling coefficient, stored in the data storage device 45. Then, the output is outputted to the coupling coefficient adjustment driving device 43. The coupling coefficient adjustment driving device 43 of the magnetic coupling degree control mechanism shown in FIG. 8A uses the magnetic plate moving distance data transmitted from the coupling coefficient calculation unit 422 as shown in FIG. The drive control is performed such that the vertical insertion position of the body plate 31C and the vertical insertion position of the magnetic plate 31b shown in FIG. A well-known position control mechanism such as a step motor can be adopted as the coupling coefficient adjustment driving device 43. In this way, from the output of the distance measuring unit 41, it is possible to perform feedback control so that the insertion positions of the magnetic plate 31C and the magnetic plate 31b in the vertical direction become desired positions.

In the computer system of the magnetic coupling degree control mechanism including the logical operation control unit 42 illustrated 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 an arbitrary 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 using a microprocessor (MPU) or the like mounted as a microchip. Also, as a logical operation control unit 42 constituting a computer system of the magnetic coupling degree control mechanism, a digital signal processor (DSP) specializing in signal processing with an enhanced arithmetic operation function and a memory or a peripheral circuit are mounted on an embedded device. A microcontroller (microcomputer) for 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. 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 _on1 of the first semiconductor switching element Q1 at this time is shown. 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. The electric energy of the power transmission side coil L ₁ is transmitted to the power reception side coil L ₂ of the secondary circuit 3, though it is small. 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 electric energy stored in the power transmission side coil L ₁ is transferred to the secondary circuit 3 by the characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3 between the primary circuit 2 and the secondary circuit 3. It is wirelessly transmitted to the power receiving 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. Terminal voltage VC ₂ of the power receiving side capacitor C ₂ is a timing shown in FIG. 9 (b) is a positive value. Terminal voltage VC ₂ of the power receiving side capacitor C ₂ after reaching the peak value, starts decreasing.

When the terminal voltage VC ₂ is reduced, the electric energy stored in the power receiving side capacitor C _2, as shown in FIG. 9 (b), into the load element 6 as the charging current I _CS, the load device 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 refluxed as electrical energy is stored in the power receiving coil L _2. Electrical energy stored in the power receiving side coil L _2, as shown in FIG. 9 (c), between the primary-side circuit 2 and the secondary-side circuit 3 between the secondary-side circuit 3 and the primary-side circuit 2 ring flows to the power transmission coil L ₁ of the primary-side circuit 2 by characteristic harmonic 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 provided in the circuit 2, the magnitude of the electric energy circulated from the secondary circuit 3 can be measured. That is, the current is transmitted from the primary circuit 2 to the secondary circuit 3 by the characteristic metering transmission between the primary circuit 2 and the secondary circuit 3 by the ammeter 461 and the voltmeter 462 provided in the primary circuit 2. The efficiency of wireless transmission can be measured.

For this reason, a magnetic coupling degree control mechanism for controlling the vertical insertion position of the magnetic plate 31C shown in FIG. 7B and the vertical insertion position of the magnetic plate 31b shown in FIG. to configure the transmission efficiency measuring unit 46 as shown in FIG. 8 (b), the power transmission coil L ₁ may be provided in the power feeding device side is provided. The transmission efficiency measuring unit 46 is an ammeter 461 and a voltmeter 462 provided in the primary circuit 2 as shown in FIG.

The transmission meter 461 of the logical operation controller 47 constituting the magnetic coupling degree control mechanism shown in FIG. 8B is connected to the ammeter 461 and the voltmeter 462 shown in FIG. 9C. . The output of the ammeter 461 and the voltmeter 462 is inputted to the transmission efficiency calculating unit 471 via the output buffer or interface, not shown, in the transmission efficiency calculating section 471, of the power transmission coil L ₁ and the power receiving coil L ₂ Arithmetic processing required for transmission efficiency measurement between the two is performed. The logical operation control unit 47 stores data necessary for logical operation such as transmission efficiency operation in the logical operation control unit 47 and data of an insertion position in a vertical direction of the magnetic plate required to realize a desired transmission efficiency. Connected 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 for instructing the operation of the logical operation control unit 47.

Data transmission efficiency between the transmission efficiency calculation unit 471 has calculated the power transmission coil L ₁ receiver coil L ₂ is transmitted to the coupling coefficient calculation unit 472 of the logical operation control unit 47 constituting the magnetic coupling of the control mechanism Is done. Coupling coefficient calculation unit 472, the transmission efficiency of data between the transmission efficiency calculation unit 471 and the power transmitting coil L ₁ calculated power receiving coil L _2, between the power receiving side coil L ₂ and the current of the power transmission coil L ₁ Of the degree of magnetic coupling of 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 necessary to achieve the desired transmission efficiency, stored in the data storage device 45. Are output to the coupling coefficient adjustment driving device 43. The coupling coefficient adjustment driving device 43 uses the data of the change in the transmission efficiency due to the movement of the magnetic plate sent from the coupling coefficient calculation unit 472 to determine the insertion position in the vertical direction of the magnetic plate 31C shown in FIG. The drive control is performed such that the vertical insertion position of the magnetic plate 31b shown in FIG. A well-known position control mechanism such as a step motor can be adopted as the coupling coefficient adjustment driving device 43. In this way, the magnetic coupling degree control mechanism shown in FIG. 8B sets the insertion position of the magnetic plate 31C or the magnetic plate 31b in the vertical direction from the output of the transmission efficiency measurement unit 46 to the desired position. Feedback control.

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

The conventionally known “resonance” means that the sine wave vibration of the primary circuit 2 is transmitted to the freely vibrating secondary circuit 3, and the secondary circuit 3 has the same frequency as the primary circuit 2. This 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 free oscillation 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 non-sinusoidal sawtooth-like transient response characteristic to the secondary circuit 3 by the concept of “characteristic harmonic transmission” first proposed by the present inventors. By using a sawtooth-like transient response characteristic that is a non-sinusoidal wave, a complicated and expensive AC power supply circuit that generates a sinusoidal vibration on the primary circuit 2 side as in the related art becomes unnecessary.

As described above, in the power transmission device according to the first embodiment, the time constant inherent in the primary circuit 2 and the time constant inherent in the secondary circuit 3 are harmonized and the electric energy of the primary circuit 2 is adjusted. Is transmitted to the secondary circuit 3. Characteristics harmony transmission between the primary-side circuit 2 and the secondary-side circuit 3, for example, the capacity of the power transmission capacitor C ₁ and the power receiving side capacitor C _2, and equal, including the parasitic resistance of the capacitor, the power transmission coil L ₁ and inductance of the power receiving coil L ₂ and may be equal, including the parasitic resistance of the coil. Therefore, for example, if the repetition cycle of ON / OFF of the primary side drive switch SW1 is set to 500 to 600 μs, the capacitances of the power transmission side capacitor C ₁ and the power reception side capacitor C ₂ are made equal to each other within a 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, for example, in the range of 5 μH to 20 μH.

A plurality of bumps are included in one cycle in the sawtooth-like transient response waveform as shown in FIG. 1B and FIG. It is extremely difficult to analytically solve the transient response waveform of the power transmission device according to the first embodiment. Therefore, although approximate, the circuit shown in FIG. 28 is simulated by AC theory. In FIG. 28, the capacitance of the capacitor of the primary circuit 2 and the inductance of the coil of the secondary 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. At this time, the resonance frequency f _o1 of the RLC series circuit given by the equation (6) is 2.25 kHz, and the resonance frequency f _o2 of the RLC series circuit given by the equation (7) is 2.25 kHz. 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. Transmitting coil L ₁ has a property that prevents the inflow of originally rapid current. Gradually the voltage of the power transmission side capacitor C ₁ is increased, current starts flowing gradually to the power transmission coil L _1. In time, the charge is also to flow out to the power transmission coil L ₁ side that has accumulated in the power transmission side capacitor C _1. When this happens, the voltage of the power transmission side capacitor C1 drops. Time to turn off the primary-side drive switch SW1 is ideal that the sum of the electrostatic energy (1/2) CV ² and magnetic energy (1/2) LI ² is set to be 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.

Voltage of the counter electromotive force generated in the power transmission coil L ₁ is, care must be taken so as not to exceed the withstand voltage of the first semiconductor switching element Q1 to be used for primary drive switch SW1 shown in FIG. The repetition cycle of ON / OFF of the primary-side drive switch SW1 is set slightly earlier than the timing at which the voltage VC1 of the power transmission capacitor C1 reaches the peak in consideration of the time until the voltage VC1 rises again and reaches the 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. With reference to FIG. 30, aneurysm sawtooth illustrates that occur to the current of the power receiving coil L ₂ primary circuit 2 by the magnetic flux due to current induced in is reduced. The voltage of the secondary side circuit 3 is the same as in the case of the mode using 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 as described later in the fourth embodiment. Corresponds to the phenomenon that the voltage of the primary side circuit 2 becomes zero when the maximum value becomes maximum, and the middle peak 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. An approximate simulation using the circuit shown in FIG. 31 which is a simplified circuit diagram in which the parasitic capacitance and the parasitic resistance and the like are omitted from the circuit of FIG. 28 shows that the shape of the W as shown in FIG. 32 is obtained. A transient response waveform in which the voltage of the valley on the right side of FIG. The middle peaks of the W-shaped transient response waveforms respectively surrounded by the dashed circles A ₁ and A ₂ in FIG. 32 are shown in FIGS. 1B and ₂ due to the influence of parasitic capacitance and parasitic resistance. It can be seen that such a saw wave appears as a bump.

In the case of the mode of the first embodiment in which only the primary-side drive switch SW1 is used, as shown in FIGS. 30A to 30D, if the repetition cycle of ON / OFF of the primary-side drive switch SW1 is increased, a transient response waveform is obtained. The aneurysm becomes small, and gradually approaches the response waveform of the sawtooth wave as shown in FIGS. FIG. 29 is an enlarged view of the transient response waveform in the case of the repetition period of 575 μs shown in FIG. 30C, which corresponds to the transient response waveforms shown in FIG. 1B and FIG. .

In the case where the ON / OFF repetition cycle of the primary-side drive switch SW1 is 565 μs, the waveform is a W-shaped transient response waveform surrounded by _a dashed circle Aa in FIG. Since the repetition period obtained from the resonance frequency of the RLC series circuit defined by the expressions (6) and (7) is 444 μs, the repetition period in FIG. However, it is longer than the repetition period required by AC theory. That is, in the power transmission device according to the first embodiment, it can be seen that the power transmission device oscillates at a repetition cycle 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 electric energy from the primary circuit 2 to the secondary circuit 3 by characteristic harmonic 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. Further, as shown in FIG. 1B and FIG. 2, swelling starts to occur on the upper side of the sawtooth wave.

By further transmitting electric energy from the primary side circuit 2 to the secondary side circuit 3 by characteristic harmonic 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 a shoulder, and the shape of W disappears from the transient response waveform. Then, as shown in FIG. 1B and FIG. 2, a bump appears on the upper side of the sawtooth wave.

In the case where the electric energy is further transmitted to the secondary circuit 3 by the characteristic harmonic transmission, the amplitude is further reduced, and the repetition period is further increased to 580 μs in FIG. 30 (d). _As indicated by _d , the bulge-shaped shoulder showing the transient response waveform further rises. Then, as shown in FIGS. 1B and 2, the bump on the upper side of the sawtooth wave is also remarkable, and a two-stage bump is shown. As described above, in the shape of W showing the transient response waveform, the amplitude gradually decreases, and when the repetition period is lengthened, the voltage of the right valley does not gradually decrease, the right valley of the W shape rises, and the two-stage bump , A sawtooth-like transient response waveform having

When the ON / OFF repetition cycle of the primary-side drive switch SW1 is lengthened, the voltage at the right valley of the W shape rises because the electric energy received by the secondary-side circuit 3 has moved 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 different from the parasitic inductance of the electric wire 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, it is estimated that the parasitic inductance is about 1 mH to 3 μH. That is, the sawtooth-like transient response waveform having a plurality of bumps shown in FIGS. 1B and 2 is generated by a time constant peculiar to a circuit relying on parasitic resistance, parasitic capacitance, and parasitic inductance. I understand.

Next, using the resonance frequency f _o1 of the RLC series circuit given by Expression (6), which is a conventional AC theory, ω ₀ = 2πf _o1 and ω1 = ω ₀ / (1-k) ^1/2, and FIG. As shown, as an energy transfer function f1, a sigmoid function that attenuates stepwise after 2π / ω1 second which is a 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 a coupling coefficient K _AC of the _AC theory used for the definition of Equation (1) (k = K _AC ).

Further, as an arbitrary attenuation function f2, a function for reducing the number 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 is initially the voltage charged in the capacitor C ₁ of the primary side, V2 is, can correspond to the remaining voltage in the capacitor C ₁ of the primary side of the after being transferred to the electrical energy to the secondary side circuit 3. 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 ω ₀ = 2πf _o1 and ω ₂ = ω ₀ / (1 + k) ^1/2 , the mutual induction function φ (k) is

φ (k) = cos (ω1t) + cos (ω2t) (10)

35, the function (V1 / 2) φ (k) shows a change as shown by a thin broken line curve after the transfer timing of 2π / ω1 seconds in FIG. 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 K _{AC of 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 / ω1 second can be considered as a 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. This corresponds to a 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. Function shown by the solid line f1 · f2 · φ (k) is the voltage VC1 across the capacitor C _1, it is seen that 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 circuit 3 by the characteristic harmonic transmission. That is, as shown in FIG. 32, the valley on the right side of the W-type transient response waveform becomes smaller, gradually rises upward, and does not become hollow. As a result, the RC time constant becomes a sawtooth wave and is attenuated by the dissipation of electric energy by the parasitic resistance. The approximate simulation by the AC theory for the circuit shown in FIG. 28 is only an approximation to the last, and there is a limit of the AC theory, but it should be able to understand a sawtooth-like transient response waveform having approximately two steps of bumps. . Actually, 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, the power transmission side capacitor C ₁ and the power receiving side capacitor C ₂ to employ the same capacitor, by employing a power transmitting coil L ₁ and the power receiving side the same coil to the inductance of the coil L _2, a parasitic resistance in coil and capacitor In addition, the time constant inherent in the primary circuit 2 and the time constant inherent in the secondary circuit 3 can be harmonized.

As described above, the power transmission device according to the first embodiment of the present invention is a technology that does not rely on an AC theory using a novel concept of characteristic harmonic transmission, so that an inexpensive DC power supply 5 can be used. it 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 power loss on the control circuit side. In particular, when a power semiconductor switching element is used as the primary-side drive switch SW1, only simple control for turning on / off the power semiconductor switching element is required, so that power loss on the control circuit side is reduced, and the power supply circuit is reduced. The overall power transmission efficiency including the (zero-order circuit) loss can be improved. In particular, since the circuit configuration is simplified, it is not easily broken, and the circuit design becomes easy. Further, the limit power of the power transmission can be increased to a value exceeding the limit power in the conventional AC theory. Although the limit power of power transmission can be pushed up to infinity in principle, 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 suppressed to a minimum, and a reduction in weight, size, and efficiency is achieved. This makes it possible to manufacture a wireless power transmission device with improved overall power transmission efficiency due to power saving at low cost. In addition, since the characteristic harmonic transmission can be realized with a repetition period longer than the repetition period obtained by the conventional AC theory, the frequency may be lower than the case of the heavy resonance in the conventional AC theory. Since a low-frequency circuit design is sufficient, the voltage on the primary circuit 2 side can be easily increased, and the energy loss due to the generation of Joule heat can be reduced, so that the power transmission device according to the first embodiment has a comprehensive power transmission. A power transmission device with high efficiency can be manufactured at low cost. By lowering the parasitic resistance, it is possible in principle to manufacture a power transmission device whose 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 a power transmission side switch SW2 to the circuit configuration of the power transmission device according to the first embodiment shown in FIG. The configuration is as follows. Similarly to the primary drive switch SW1, the “power transmission switch SW2” is a circuit element that limits free oscillation of the primary circuit 2 and realizes a transient current-voltage change in the primary circuit 2.

As the primary side drive switch SW1 and the power transmission side switch SW2 shown in FIG. 10A, thyristors such as a GTO thyristor and an SI thyristor other than the same FET, SIT, and BJT as the power transmission device according to the first embodiment are used. A power semiconductor switching element is used. In particular, when a voltage-driven switching element such as a MISFET, a MISIT, an IGBT, or a MOS-controlled SI thyristor is used, power consumption is reduced. Therefore, it is suitable for the primary drive switch SW1 and the power transmission switch SW2. From the availability on the market and the evaluation of the internal resistance of the power semiconductor switching element, it is currently possible to employ MOSFETs as the primary side drive switch SW1 and the power transmission side switch SW2 of the circuit shown in FIG. It is possible.

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

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 Two return diodes FWD ₂ are connected in parallel as protection elements between the source and the 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 Are connected in series. In the mounting circuit shown in FIG. 10B, the equivalent impedance X _Leq of the load element 6 is expressed by approximating the charging capacity C _s .

The wireless power transmission method according to the first embodiment will be described with reference to the timing chart of FIG. 11 and the time-series schematic diagrams 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. . When the power transmission switch SW2 is turned off, the primary circuit 2 has not yet been formed. As shown in FIG. 12A, depending on the ON state of the primary drive switch SW1, the DC power supply 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 indicated by a thin broken line in FIG. 11, the inter-terminal voltage VC ₁ of the power transmission capacitor C ₁ is charged at a constant voltage while ringing. Although not shown in FIG. 11, but terminal voltage VC ₂ of the power receiving side capacitor C at this timing is shown in FIG. 12 (a) as a negative value. 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 switch SW2 at the timing of FIG. 12B, the ON state of the power transmission switch SW2 is indicated by the on-resistance r _on2 of the second semiconductor switching element Q2. . 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 power feeding side circuit 1 consisting of circuit and transmission-side capacitor C ₁ is eliminated.

When the electrical energy stored in the power transmitting side capacitor C ₁ is moved to the power transmission coil L _1, terminal voltage VC ₁ shown in thin broken lines in FIG. 11, after taking a negative maximum value, becomes 0V. 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 the charging of the power receiving side capacitor C ₂ is started, the terminal voltage VC ₂ of the power receiving side capacitor C, as shown by the thick broken line in FIG. 11, after taking a negative maximum value, in FIG. 12 (c) It becomes a positive value as shown. Terminal voltage VC ₁ takes the maximum value when it becomes 0V. As can be seen from the thick broken line in changes in FIG. 11, when the inter-terminal voltage VC ₂ is that after taking the negative maximum value, a positive value, the inter-terminal voltage VC ₁ shown in thin broken line becomes 0V To take the maximum value.

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, 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 electrical energy stored in the power receiving side capacitor C flows back to the power receiving coil L _2, resulting characteristics harmonize transmission between the primary-side circuit 2 and the secondary-side circuit 3, a part of the electrical energy to the primary side circuit 2 Return. When the electrical energy stored in the power receiving side capacitor C is moved to the load device 6 and the receiver coil L _2, the power receiving side capacitor C ₂ is discharged. When the power-receiving-side capacitor C ₂ is discharged, the voltage between the terminals VC ₂ indicated by thick broken line on the right side of FIG. 11, after taking a negative maximum value, it becomes 0V. At this time, the inter-terminal voltage VC ₁ indicated by a thin broken line on the right side of FIG. 11 takes a negative local maximum value, then increases to a positive value, and increases when the power transmission side switch SW2 is turned off. Is maintained. As described in FIG. 9D, by measuring the terminal voltage VC ₁ , the transmission efficiency of the characteristic harmonic transmission between the primary side circuit 2 and the secondary side circuit 3 and the rechargeable type as the load element 6 are measured. It can be seen that the state of charge of the battery can be monitored. Not mutually symmetry is the vibration waveform and the vibration waveform and the vibration waveform of the terminal voltage VC ₂ of the secondary side circuit 3 between the primary circuit second terminal voltage VC ₁ As can be seen from Figure 11.

共振 As mentioned above, “resonance” is a concept applied to a system that is freely vibrating. 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 oscillation of the primary side circuit 2 and realizes the transient current-voltage change in the primary side circuit 2 SW1 and a primary-side drive switch SW1 are provided. For this reason, in the power transmission device according to the second embodiment, it is possible to transmit the non-sinusoidal transient response characteristic to the secondary circuit 3 by a new concept “characteristic harmonic transmission”. . Since a non-sinusoidal transient response characteristic based on an inexpensive DC power supply 5 having a simple configuration of the control circuit can be used, a sine wave vibration higher than the commercial frequency is generated in the primary circuit 2 as in the related art. Since an expensive AC power supply circuit is not required, the circuit is hardly broken and circuit design becomes easy.

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. It has two switches, a switch SW1 and a power transmission side switch SW2. 33A to 33C, the capacitances of the capacitors and the inductances of the coils 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. 33 (a) shows a rechargeable battery employed as a load circuit 36 by transmitting electric energy of the primary circuit 2 to the secondary circuit 3 by characteristically harmful transmission at a voltage E ₀ of the DC power supply 5 = 36 V. 5 is a circuit of the power transmission device according to the second embodiment when the charging voltage V _cs = 24V. 33B uses the same voltage E ₀ = 36 V of the DC power supply 5 as in FIG. 33A, and transmits the electric energy of the primary circuit 2 to the secondary circuit 3 by characteristic harmony transmission. This is a circuit in which the charging voltage _Vcs of the rechargeable battery adopted as 36 is set to 100 V and the current is not set to flow through the load circuit 36. FIG. 33B shows a case where the charging voltage V _cs of the rechargeable battery employed as the load circuit 36 is set to 100 V and the current is not set to flow through the load circuit 36 as in FIG. However, there is a case where the voltage transmitted to the secondary circuit 3 is subtracted in advance and the voltage E ₀ of the DC power supply 5 is set to 26V.

FIG. 34 shows a change in the voltage of the power transmission side capacitor C1 as an approximate simulation result. As shown in FIG. 32, in the approximate simulation based on the AC theory of the power transmission device according to the second embodiment, the change in the voltage of the power transmitting side capacitor C1 is the same as that of the W type shown in FIG. 3. 3 shows a transient response waveform. The solid line in FIG. 34 is the result of the approximate simulation for the circuit shown in FIG. 33A, the broken line in FIG. 34 is the result of the approximate simulation for the circuit shown in FIG. 33B, and the dashed line in FIG. 33 is a result of an approximate simulation of the circuit shown in FIG.

At first, an attempt is made to supply current to the load circuit 36 as shown by the broken line in FIG. 34. However, since the charging voltage _Vcs of the rechargeable battery is set to be as high as 100 V, no current flows to the load circuit 36, and It changes like the curve shown by the chain line. The timing at which the current is caused to flow through the load circuit 36 is estimated to be around the center of the peak of the W-shaped transient response waveform in FIG.

As described above, according to the power transmission device according to the second embodiment, as in the power transmission device according to the first embodiment, the control circuit and peripheral circuits use the inexpensive DC power supply 5. This eliminates the need for an expensive switching power supply. 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 and hardly broken, and the circuit design becomes easy. As a result, the overall configuration of the power transmission device is simplified, the weight and size of the power transmission device can be reduced, and the efficiency can be improved. The transmission device can be manufactured at low cost. In the same manner as described in the power transmission device according to the first embodiment, the power limit 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. Can in principle be extended to infinity. Further, it is possible in principle to increase the power transmission efficiency to a value close to 100%.

(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 a power receiving switch SW3 is added to the power transmission device according to the second embodiment. Like the power transmission switch SW2 and the primary drive switch SW1, the "power receiving switch SW3" also limits the free oscillation of the secondary circuit 3 and realizes a transient current-voltage change in the secondary circuit 3. Circuit element.

As the primary side drive switch SW1, the power transmission side switch SW2, and the power reception side switch SW3 shown in FIG. 13 (a), in addition to the FET, SIT, BJT similar to the power transmission device according to the first and second embodiments, GTO A power semiconductor switching element including a thyristor such as a thyristor or an SI thyristor is used. In view of the requirement for low internal resistance and availability in the market, it is industrially necessary to employ MOSFETs as the primary drive switch SW1, the power transmission switch SW2, and the power reception switch SW3, respectively, of the mounting circuit shown in FIG. It is considered superior.

説明 As described in the power transmission devices according to the first and second embodiments, the large power transmission device generates a large amount of Joule heat. In the power transmission device according to the third embodiment, since only three power semiconductor switching elements are required to be used as the primary side drive switch SW1, the power transmission side switch SW2, and the power reception side switch SW3, the elements are prevented from being damaged due to 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 only simple control for turning on / off the primary-side drive switch SW1 and the power transmission-side switch SW2 is required, the design of increasing the voltage of the primary-side circuit 2 and suppressing the generation of Joule heat can be simplified.

In mounting the circuit shown in FIG. 13 (b), the first reflux diode FWD ₁ is between MOSFET source and drain of the first semiconductor switching element Q1, a second reflux diode FWD ₂ is the second semiconductor switching between the source and drain of the MOSFET as an element Q2, the third wheeling diode FWD ₃ of between the source and the drain of the MOSFET as a third semiconductor switching element Q3, are connected in parallel as respective protective elements. As shown in FIG. 13 (b), third wheeling diode FWD ₃ of, since it is provided in the direction of flow a circulating electric current from the power receiving side coil L _2, second, and the second is freewheeling diode FWD ₂ in the opposite direction 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 one semiconductor switching element Q1. Also in the mounting circuit shown in FIG. 13B, the equivalent impedance X _Leq of the load element 6 is expressed by approximating the charging capacity C _s .

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 chart shown in FIG. However, as in the first and second embodiments, and assuming the characteristics harmonize transmission in conditions corresponding to the coupling coefficient K _{AC =} 0.6 by the AC theory, the value in the initial state of the charge voltage VC _S is fully It is assumed that the voltage is sufficiently high close to charging.

First, in step S31 of the flowchart in FIG. 14, the power transmission switch SW2 and the power reception switch SW3 are turned off, and only the primary drive switch SW1 is turned on. As indicated by a thin broken line in FIG. 15, the inter-terminal voltage VC ₁ of the power transmission capacitor C ₁ is charged at a constant voltage while ringing. Although not shown in FIG. 15, but terminal voltage VC ₂ of the power receiving side capacitor C is at this timing is a negative value. 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, the charging voltage VC _S at this point is assumed to high.

As shown in FIG. 15, after the primary drive switch SW1 is turned off, after a certain time, in step S32, the power transmission switch SW2 and the power reception switch SW3 are simultaneously turned on. 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 A characteristic harmonic transmission between three occurs. When the electrical energy stored in the power transmitting side capacitor C ₁ is moved to the power transmission coil L _1, terminal voltage VC ₁ shown in thin broken lines in FIG. 15, after taking a negative maximum value, becomes 0V. 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 is the power-receiving-side switch SW3 is so turned on, the power-receiving-side capacitor C ₂ by the receiver coil current Charge. When the charging of the power receiving side capacitor C ₂ is started, the terminal voltage VC ₂ of the power receiving side capacitor C, as shown by the thick broken line in FIG. 15, begins to increase from a negative maximum value, central left of Figure 15 It becomes a positive value as shown in the position indicated by the arrow. While the inter-terminal voltage VC ₂ has a negative value, the charging current _ICS does not flow. However, when the inter-terminal voltage VC ₂ has a positive value, the charging current ICS is as shown by a dashed line in the center of FIG. I _CS begins to rise.

At the timing when the charging current I _CS starts to rise, in step S33, the power transmission switch SW2 and the power reception switch SW3 are turned off. Off state of the power transmission switch SW2 and the power receiving side switch SW3, depending on the characteristics conditioner transmission between the primary-side circuit 2 and the secondary-side circuit 3, the voltage between the terminals VC ₂ is maximized as shown by a thick broken line in FIG. 15, and terminal voltage VC ₁ shown by a thin broken line is a point which becomes 0V. The charging current I _CS indicated by a dashed line in the center of FIG. 15 increases even after the power transmitting switch SW2 and the power receiving switch SW3 are turned off, reaches a peak value, and then decreases, and reaches 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 ( Shoulder) shaped waveform. 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 Is small, and the influence on the characteristic harmonic 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 inter-terminal voltage VC ₁ shown in thin broken lines on the right side of Figure 15 also starts to decrease, then taking the negative maximum value, increasing a positive value.

Next, in step S36, the inter-terminal voltage VC ₁ is maximized, the terminal voltage VC ₂ to turn off the power-transmission-side switch SW2 and the power receiving side switch SW3 at the time becomes 0V. Figure 15 terminal voltage VC ₁ shown in thin broken lines in step S36 the time as shown in is the same value as the terminal voltage VC ₂ shown by a thick broken line at step S34, the power-transmission-side switch SW2 and the power receiving side It is maintained at a constant value after the switch SW3 is turned off. You. Although not shown, the voltage between the terminals of the terminal voltage VC ₁ and the load device 6 at step S36 the time are the same value. Therefore, in the same manner as described in FIG. 9 (d), the by measuring the terminal voltage VC _1, the transmission efficiency and the load device characteristics harmony transmission between the primary-side circuit 2 and the secondary-side circuit 3 6 It can be seen that the state of charge 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 with the timing diagram of the power transmission device according to the third embodiment shown in FIG. 15, the number of power receiving side switches SW3 is increased by one. also, it is a waveform illustrating the primary circuit 2 and the terminal voltage VC ₁ and terminal voltage VC ₂ temporal change such as in the characteristic harmonic transmissions between the secondary-side circuit 3 (transient response), it is almost identical I understand.

“Resonance” is a concept used in an AC circuit that is freely vibrating. However, in the power transmission device according to the third embodiment, the free vibration of the primary circuit 2 and the secondary circuit 3 is limited, A primary side drive switch SW1, a power transmission side switch SW2, and a power reception side switch SW3 for realizing a transient current-voltage change in the primary side circuit 2 and the secondary side circuit 3 are provided. For this reason, in the power transmission device according to the third embodiment, the transient response characteristic of the primary circuit 2 can be transmitted to the secondary circuit 3 by a new concept “characteristic harmony transmission”. is there. Since the control circuit can transmit electric energy using the non-sinusoidal transient response characteristic based on the inexpensive DC power supply 5 having a simple configuration, the sine wave higher than the commercial frequency is applied to the primary circuit 2. An expensive AC power supply circuit for generating vibration is not required.

Therefore, according to the power transmission device according to the third embodiment of the present invention, similarly to the power transmission devices according to the first and second embodiments, the inexpensive DC power supply 5 whose control circuit and peripheral circuits are simple is used. Since it can be used, an expensive switching power supply is not required, the circuit configuration is simplified, and 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 is simplified, and the power transmission device can be reduced in weight, size, and efficiency, and the loss of the power supply circuit (zero-order circuit) can be reduced. Thus, a wireless power transmission device with improved overall power transmission efficiency including the above can be manufactured at low cost. According to the power transmission device according to the third embodiment, as described in the power transmission devices according to the first and second embodiments, the circuit configuration is simplified, so that the circuit is not easily broken 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. It 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 a load control switch SW4 is added to the power transmission device according to the third embodiment. The “load control switch SW4” is a circuit element that limits the free oscillation of the secondary circuit 3 and realizes a transient current-voltage change in the secondary circuit 3, similarly to the power receiving switch SW3.

As the primary drive switch SW1, the power transmission switch SW2, the power reception switch SW3, and the load control switch SW4 shown in FIG. 16A, similarly to the power transmission devices according to the first to third embodiments, FET, SIT , BJT, and a power semiconductor switching element including a thyristor such as a GTO thyristor and an SI thyristor can be used. Considering the requirement of a low internal resistance, the MOSFET is connected to the primary drive switch SW1, the power transmission switch SW2, the power reception switch SW3, and the load of the mounting circuit shown in FIG. It is preferable to adopt each as the control switch SW4.

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

In mounting the circuit shown in FIG. 16 (b), the first reflux diode FWD ₁ is between the source and drain of the MOSFET as a first semiconductor switching element Q1, a second reflux diode FWD ₂ is the second semiconductor switching between MOSFET source and drain of the elements Q2, third wheeling diode FWD ₃ of between MOSFET source and drain of the third semiconductor switching element Q3, a fourth freewheeling diode FWD ₄ of the fourth semiconductor switching Each element is connected in parallel as a protection element between the source and the drain of the MOSFET as the element Q4. As shown in FIG. 16B, the third return diode FWD ₃ is provided in the direction in which the circulating current flows from the power receiving side coil L ₂ , so that the second return diode FWD ₂ faces in the opposite direction. This is provided in the same manner as in FIG. 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 Are 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 expressed by approximating the charging capacity C _s .

As already described, comparing the timing diagram of the power transmission device according to the second embodiment shown in FIG. 11 with the timing diagram of the power transmission device according to the third embodiment shown in FIG. There is also increasing one, the waveform indicating the primary circuit 2 and the secondary-side circuit terminal voltage VC ₁ and terminal voltage VC ₂ temporal change such as in the characteristic harmonic transmissions between 3 (transient response), most Is the same. As shown in FIG. 16A, even when the power transmission device according to the third embodiment has a configuration in which a load control switch SW4 is added, the essence of characteristic harmonic transmission does not change, and its basic operation and waveform indicating the temporal change in such voltage VC ₁ and terminal voltage VC ₂ between the terminals in the characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3 (transient response) is almost the same.

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

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 of the primary drive switch SW1, the power transmission switch SW2, the power reception switch SW3, and the load control switch SW4. Therefore, it cannot be described by the combination 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 turned off and the power transmission-side switch SW2 and the power reception-side switch SW3 are turned on, the LCR resonance circuit of the primary circuit 2 and the secondary circuit 3 It is necessary to consider a circuit in which the LCR resonance circuit is coupled by the mutual inductance M.

In addition, 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 turned on, the power transmission device according to the fourth embodiment of the present invention is required. Not all can be interpreted by conventional AC theory. That is, in the free vibration region as already shown by the diagonal line in FIG. 3B, the conventional sine wave AC theory can be used, but the primary side drive switch SW1, the power transmission side switch SW2, the power reception side switch SW3, and the load. In the operating environment of the power transmission device according to the fourth embodiment in which the boundary condition of the circuit is changed every moment using the four switches of the control switch SW4, a sawtooth rising as illustrated in FIG. It is necessary to analyze including the transient response such as characteristics.

(Simulation of characteristic harmonic transmission waveform)
Determined each terminal voltage VC ₁ and terminal voltage VC ₂ waveform of the power transmission capacitor C ₁ and the power receiving side capacitor C ₂ in the configuration illustrated in FIG. 16 (a) by simulation by conventional AC theory, primary circuit The characteristic harmonic transmission waveform between the secondary circuit 2 and the secondary circuit 3 is confirmed. The coupling coefficient K _AC of the primary side circuit 2 and the secondary side circuit 3 is 0.6, the capacities 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 Each of the inductances 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 To store electric charge. Next, when the primary drive switch SW1 is turned off and the power transmission switch SW2 and the power reception switch SW3 are turned on, it can be expected that characteristic harmony transmission between the primary circuit 2 and the secondary circuit 3 will occur. The resulting terminal voltage VC ₁ and terminal voltage VC ₂ of the waveform by simulation shown in FIG. 17 (a). A waveform as either sinusoidal sine wave with small amplitude greater amplitude is the synthesis of terminal voltage VC ₁ of the waveform and the voltage between the terminals VC ₂ waveforms, different from the sine wave in a normal AC Theory .

In FIG. 17A, the power transmission switch SW2 and the power reception switch SW3 are turned on in 0.2 ms. In 0.45 ms, the inter-terminal voltage VC ₁ is to 0V, and the voltage between the terminals VC ₂ becomes 20V. This indicates that all the energy on the power transmission side is transmitted to the power reception side. If the power transmission side switch SW2 and the power reception side switch SW3 are turned off in 0.45 ms, the power by the characteristic harmony transmission is efficiently increased. Transmission can take place.

(Measurement of characteristic harmonic transmission waveform by mounted circuit)
Subsequently, the waveform of the characteristic harmonic transmission between the primary circuit 2 and the secondary circuit 3 is measured by the mounting circuit having the configuration illustrated in FIG. Primary circuit 1 and the secondary side equivalent coupling coefficient K 0.6 of the circuit 2, 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 any inductance 60MyuH, the initial voltage 20V applied to the power transmission side capacitor _{C 1.} 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 there is no symmetry between the terminal voltage VC ₂ waveforms.

Since there is a parasitic resistance in the mounted circuit, the waveform is attenuated with time, unlike the result of the simulation based on the normal AC theory in FIG. In FIG. 17B, transmission starts at 0.2 ms, and the terminal voltage VC ₂ reaches a maximum of 15 V at 0.45 ms. At this time, the inter-terminal voltage VC ₁ is −3 V, and not all of the energy on the power transmission side is transmitted to the power reception side, and part of the energy remains on the power transmission side. It can be confirmed that it is transmitted to the side. As already mentioned, with respect to the power transmission device according to the third embodiment, even if the added constitutes a load control switch SW4, the temporal change of such voltages VC ₁ and terminal voltage VC ₂ between the terminals (transient response ) Are almost the same. That is, a drawing waveform and the waveform of the terminal voltage VC ₂ of terminal voltage VC ₁ shown in FIG. 17 (b) showing a macroscopic change, macro sinusoidal small amplitude sinusoidal large amplitude synthesis Although it looks like a waveform as shown in the figure, when the time axis is lengthened and viewed in detail, it is the same as the waveforms shown in FIGS. 11 and 15, and does not indicate a change in a sine wave.

(Change in equivalent coupling coefficient and change in characteristic harmonic 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 , Characteristic harmonic 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 above-described combination equation (2) and equation (3).

In the conventional AC theory, the voltage VC ₂ between the terminals of the power receiving side capacitor C ₂ generated by the characteristic harmonic 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)

Becomes 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 inter-terminal voltage VC ₁ of the power transmission capacitor is zero formula (11) is the maximum value _{VC 0 × (L 2 / L} 1) (1/2) , and the according to the normal AC theory, in this case the power transmission side All energy has been transmitted to the receiving side.

In the configuration illustrated in FIG. 16A, the change in the waveform of the characteristic harmonic transmission between the primary side circuit 2 and the secondary side circuit 3 when the coupling coefficient K _AC according to the normal AC theory is changed is compared with the normal change. Determined by simulation based on AC theory. Both the capacity of the power transmission capacitor _{C 1} and the power receiving side capacitor _{C 2 500μF,} both the inductance of the power transmission coil L ₁ and the power receiving coil L ₂ 10 .mu.H, and 25V the initial voltage applied to the power transmission side capacitor _{C 1} . In the following description, the coupling coefficient K _AC according to the AC theory is approximated to be equal to the equivalent coupling coefficient, and the equivalent coupling coefficient K is set to 0.00, 0.1, 0.6, 0.8, and 0.88, respectively. A simulation based on AC theory was performed. The normal AC theoretical simulation results obtained terminal voltage VC ₁ and terminal voltage VC ₂ waveforms, illustrated in FIG. 19 (c) from Fig. 18 (a). As shown in FIG. 18A, when the coupling coefficient K is 0.00 according to the ordinary AC theory, the primary circuit 1 and the secondary circuit do not interact with each other, and the primary circuit 2 and the secondary circuit do not interact with each other. No characteristic transmission between the three occurs.

When the equivalent coupling coefficient K is 0.1, 0.6, 0.8, 0.88, characteristic harmonic transmission occurs between the primary circuit 2 and the secondary circuit 3 in all cases. As shown in FIG. 18B, 2.2 ms when the equivalent coupling coefficient K = 0.1, and 0.28 ms when the equivalent coupling coefficient K = 0.6 as shown in FIG. 19A. 19 (c), the terminal voltage VC ₁ of the power transmission capacitor 0.3ms when the equivalent coupling coefficient K = 0.88 is to 0V, and the voltage between the terminals VC ₂ is the power transmission side of the power-receiving-side capacitor has become the same value as the initial voltage VC ₀ between terminals of the capacitor C _1, the energy of the power transmission is transmitted to all the power receiving side. As shown in FIG. 19 (b), when the equivalent coupling coefficient K = 0.8, the maximum value of the inter-terminal voltage VC ₂ of the power receiving side capacitor initial voltage VC ₀ value less than between the transmission side capacitor _{C 1} pin When the equivalent coupling coefficient K = 0.8, power transmission cannot be performed more efficiently than when the equivalent coupling coefficient K = 0.1, 0.6, and 0.88.

Further, as compared with the case of the equivalent coupling coefficient K = 0.6,0.88, time until when the equivalent coupling coefficient K = 0.1, terminal voltage VC ₂ of the power receiving side capacitor takes a maximum value Is long. Equation (11) is represented by the sum of 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 due to the coil parasitic resistance r _L = R _str (L ₁ ) = R _str (L ₂ ) and the capacitor parasitic resistance r _C , so that the equivalent coupling coefficient K = 0.6, 0. 88, power transmission can be performed most efficiently. In addition, when the parasitic resistances r _L and r _C are low, power transmission can be performed efficiently even when the equivalent coupling coefficient K = 0.1. When the distance d is increased, the equivalent coupling coefficient K is decreased. Therefore, if the parasitic resistances r _L and r _C are sufficiently low, it can be said that the signal can be transmitted over a long distance.

Shown in FIG. 19 (a), shows an enlarged view of a terminal voltage VC ₁ and terminal voltage VC ₂ of waveform when the equivalent coupling coefficient K = 0.6 in FIG. 20 (a). Also shows the power transmitting coil L ₁ and the power receiving side waveform of the current _{I 1} and _{I 2} of the coil L ₂ in this case is shown in FIG. 20 (b). In 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 power transmission side capacitor C ₁ , and the currents I ₁ and I ₂ become 0 A. ing. When the power transmission switch SW2 and the power reception switch SW3 are turned off in 0.28 ms, power transmission can be performed with maximum efficiency. Further, at this time, the currents I ₁ and I ₂ are 0 A, and the power transmission coil L ₁ back electromotive force generated in the power receiving side coil L ₂ and from becoming zero, it is possible to prevent the destruction of the power transmission switch SW2 and the power receiving side switch SW3.

(Optimal combination of inductance L and capacitance C)
In the configuration illustrated in FIG. 16A, the transmission efficiency is highest when the energy stored on the power transmission side is transmitted to the power receiving side by the characteristic harmonic transmission between the primary side circuit 2 and the secondary side circuit 3. The combination of the inductance L of the coil and the capacitance C of the capacitor is determined by the following procedure. The transmission efficiency P is defined as P _on Ce _-tr , the energy to be transmitted at one time, and P _on Ce _-loss , the energy lost at one time due to the parasitic resistance r _{L of the} coil and the parasitic resistance r _{C of the} capacitor. 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)

The energy P _on Ce _-tr to be transmitted at one time is _×× CV ₀ ² , and the energy P _on Ce _-loss lost at one time is (r _L + r _C ) / 2 × C / L × V 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 ) Since it is ^1/2 × V,

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

Becomes

K _L (LC) ^1/2 + K _C (LC) ^-1/2 > = 2 (K _L K _C ) ^1/2 (17)

It 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)

At this time
LC = K _C / K _L (19)

Becomes When the inductance L of the coil and the capacitance C of the capacitor satisfy Expression (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 a normal AC theory. It is assumed that V = 36V, coupling coefficient K _L = 600 / H, and coupling coefficient K _C = 3.00 × 10 ⁻⁶ ΩF. FIG. 21 shows the change in the transmission efficiency with respect to the capacitance of the capacitor when the inductance of the coil is 1, 2, 5, 10, 20, and 50 μH, obtained as a result of the simulation based on the ordinary AC theory. As shown in FIG. 21, when the inductance of the coil is 1, 2, 5, 10, 20, and 50 μH, the combination of the inductance L of the coil and the capacitance C of the capacitor that maximizes the transmission efficiency is as follows. 5000, 2500, 1000, 500, 250, and 100 μF, satisfying the expression (19).

(Power transmission when the voltage between the terminals of the load element is low)
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 is described with reference to the flowchart shown in FIG. 23 and the timing chart shown in FIG. Will be explained. However, when the characteristic harmonic transmission between the primary side circuit 2 and the secondary side circuit 3 occurs, such as an equivalent coupling coefficient K equivalent to the coupling coefficient K _AC = 0.6, 0.88 defined by the AC theory. , the maximum value of the inter-terminal voltage VC ₂ is the same value as the initial voltage VC ₀ between terminals of the power transmission capacitor C _1, then the terminal voltage VC ₁ is so to 0V, and the equivalent coefficient K is adjusted It is assumed that

First, in step S11, the power transmission switch SW2, the power reception switch SW3, and the load control switch SW4 are turned off, and the primary 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 switch SW2 and the power reception switch SW3 are turned on, characteristic harmony transmission between the primary circuit 2 and the secondary circuit 3 occurs. Next, in step S13, the power transmission side when the absolute value of terminal voltage VC ₂ by characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3 is maximized, the terminal voltage VC ₁ is 0V The switch SW2 and the power receiving side switch SW3 are turned off.

Next, in step S14, when the load control switch SW4 in the ON state, and the charging current _{I CS} is generated, terminal voltage VC ₂ is reduced. Next, in step S15, when the charging current _ICS becomes 0, the load control switch SW4 is turned off. Terminal voltage VC ₂ and terminal voltage of the load device 6 at this time is the same value. If at the time of step S11 the load element 6 terminal voltage is sufficiently low, the voltage between the terminals VC ₂ of the power receiving side capacitor at the time of step S15 to 0V, or sufficiently low extent can be regarded as 0V, discharging the power receiving side capacitor C ₂ It is possible to return to step S11 without performing.

(Power transmission method when the voltage between the terminals of the load element is not low)
A second wireless power transmission method according to the fourth embodiment when the voltage between terminals of the load element 6 is not low will be described with reference to a flowchart shown in FIG. 25 and a timing chart shown in FIG. . However, it is assumed that the equivalent coupling coefficient K is adjusted similarly to the case where 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, when the charging current _ICS becomes 0, the load control switch SW4 is turned off. Terminal voltage VC ₂ at this time is equal to the charge voltage VC _S. In the next step S26, the power receiving side capacitor is discharged.

In step S26, when the power transmission side switch SW2 and the power reception side switch SW3 are turned on, characteristic harmony transmission between the primary side circuit 2 and the secondary side circuit 3 occurs again. In step S27, the maximum absolute value of terminal voltage VC ₁ by characteristic harmonic transmissions between the primary-side circuit 2 and the secondary-side circuit 3, the power-transmission-side switch SW2 and at the time when the terminal voltage VC ₂ becomes 0V The power receiving side switch SW3 is turned off. Since the terminal voltage VC ₁ at step S27 the time is equal to the terminal voltage VC ₂ at the time step S25, the charging voltage VC _S and terminal voltage VC ₁ at step S27 the time are the same value. Therefore, in this case, in the inter-terminal voltage VC _1, it is possible to monitor the charging voltage VC _S.

As described above, according to the power transmission device according to the fourth embodiment of the present invention, similarly to the power transmission devices according to the first to third embodiments, the control circuit and the peripheral circuits are simple and inexpensive. Since the DC power supply 5 can be used, an expensive switching power supply is unnecessary, the circuit configuration is simplified, the power loss on the control circuit side is minimized, the circuit is hardly broken, and the circuit design becomes easy. As a result, according to the power transmission device according to the fourth embodiment, the entire configuration of the power transmission device is simplified, and the power transmission device can be reduced in weight, size, and efficiency, and the loss of the power supply circuit (zero-order circuit) can be reduced. Increasing the total power transmission efficiency, including theoretically, to a value close to 100% in principle, pushing the limit power of power transmission to infinity in principle, and extending the limit distance of power transmission to infinity in principle The wireless power transmission device can be manufactured at low cost.

(Fifth embodiment)
Power transmission device according to a fifth embodiment of the present invention, as shown in FIG. 26, a primary circuit 2C and the secondary side circuit 3C comprises a first mutual coupling capacitor C ₂₃ and a second mutual coupling capacitor is bound electrostatically at C _24, the power transmission device according to the first embodiment, the coil to the capacitor, has a configuration obtained by rearranging the capacitor to the coil. From the law of electromagnetic induction and Maxwell's equation, it is possible to exchange such a coil and a capacitor. That is, as shown in FIG. 26, the power transmission device according to the fifth embodiment is similar to the power transmission device according to the first embodiment shown in FIG. 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 A primary circuit 2 is provided.

The power transmission device according to the fifth embodiment, as shown in FIG. 26, first the transmission side capacitor C ₂₁ and the power transmission coil L ₂₁ is connected to one electrode on one of the nodes to be connected 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 This is different from the power transmission device according to the first embodiment shown. The power transmission device according to a fifth embodiment is connected to one electrode to the other electrode of the first mutual coupling capacitor C _23, the other electrode to the other electrode of the second cross coupling 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 _It further comprises a secondary circuit 3 having ₂₂ .

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 one terminal of L ₂₁ and are connected in series between the DC power source 5 comprises a primary drive switch SW1 for inputting step intermittent DC voltage to the power transmission coil L _21. Further, constitute a circuit for connecting the one terminal and the other terminal of the power receiving coil L _22, a power receiving side coil L ₂₂ and the load device 6 that receives the magnetic energy, the anode is one of the power receiving coil L ₂₂ On the terminal side, a load-side diode D2 having a cathode connected to the load element 6 is provided. 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 circuit 2 to the secondary circuit 3 in a non-contact manner. . Seek waveform of the current flowing through the simulation using conventional AC theoretical power transmission coil L ₂₁ to the power receiving coil L _22, to confirm the characteristics harmonize transmission waveform between the primary-side circuit 2 and the secondary-side circuit 3.

Primary circuit 21 and 0 equivalent coupling coefficient of the secondary-side circuit 22, both the power transmission coil L ₂₁ and the inductance of the power receiving coil L ₂₂ 0.1MyuH, the power transmission side capacitor _{C 21} capacitance of the power-receiving-side capacitor _{C 22} the both 400pF, both the first mutual coupling capacitor _{C 23} a capacitance of the second mutual coupling capacitor _{C 24} to 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 transmission coil L ₂₁ to the power receiving coil L ₂₂ shown in FIG. 27 (a). Also shows the respective terminal voltage V21, V22 of waveform of the power transmission capacitor _{C 21} and the power reception side capacitor _{C 22} in FIG. 27 (b). At 0 ns, the currents flowing through the power transmitting coil L ₂₁ and the power receiving coil L ₂₂ are 30 A and 0 A, respectively. At 60 ns, the currents flowing through the power transmitting coil L ₂₁ and the power receiving coil L ₂₂ are 30 A and 0 A, respectively. Characteristic harmonic transmission occurs between the primary circuit 2 and the secondary circuit 3.

As described above, according to the power transmission device according to the fifth embodiment of the present invention, even if the electrostatic coupling is performed, the power transmission device according to the first to fourth embodiments has a magnetic coupling. As in the case of the coupling, the control circuit and the peripheral circuits can use the DC power supply 5 which is simple and inexpensive, so that an expensive switching power supply is unnecessary. Further, even with the electrostatic coupling, the circuit configuration is simplified and hardly broken as in the power transmission devices according to the first to fourth embodiments, the circuit design is facilitated, and the power loss on the control circuit side is reduced. Is also minimized. As a result, according to the power transmission apparatus according to the fifth embodiment of the present invention, the overall configuration of the power transmission apparatus is simplified, and the power transmission apparatus can be reduced in weight, size, and efficiency, and a power supply circuit (zero-order circuit) The total power transmission efficiency, including the power loss, has been increased to a value close to 100%, the limit power for power transmission has been pushed up to infinity in principle, and the limit distance for power transmission has been extended to infinity in principle. A wireless power transmission device can be manufactured at low cost.

(Other embodiments)
As described above, the present invention has been described with reference to the first to fifth embodiments. However, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art. 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. This is merely 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 including the primary side drive switch SW1 and the power transmission side switch SW2 is adopted. It is possible.

Similarly, even in the case of the circuit configuration of the electrostatic coupling method 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 A configuration including the switch SW3 is possible. Further, the configuration may be the same as that of the power transmission device according to the fourth embodiment of the present invention, including the primary drive switch SW1, the power transmission switch SW2, the power reception 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 with each other. You can also. Further, in the power transmission device according to the first embodiment of the present invention, the magnetic coupling degree control mechanism described with reference to FIGS. 6A to 8B according to the second to fourth embodiments will be described. It may be applied to a power transmission device. As described above, the present invention includes various embodiments and the like that are not described in the present specification and the drawings, and the technical scope of the present invention is defined by the invention-specifying matters according to the appropriate claims from the above description. It is only determined.

DESCRIPTION OF SYMBOLS 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: logical operation control unit, 421: distance operation unit, 422, 472: coupling coefficient calculation unit, 43: coupling coefficient adjustment driving 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)

1. 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 between one terminal and the other terminal of the power transmission side capacitor,
   A primary-side drive switch that is connected between the one terminal of the power-transmission-side capacitor and the DC power supply and that step-inputs an intermittent DC voltage to the power-transmission-side capacitor;
   A power receiving side coil facing the power transmitting side coil and receiving the magnetic energy from the power transmitting side coil; a power receiving side capacitor connected in parallel with the power receiving side coil and storing the magnetic energy stored in the power receiving side coil as electrostatic energy A secondary circuit having
   A load element that constitutes a circuit that connects between one terminal and the other terminal of the power receiving side capacitor, and receives the electrostatic energy from the power receiving side capacitor,
   An anode includes a load-side diode connected to the load element, and a cathode is connected to the one terminal of the power-receiving-side capacitor, and transmits electric energy from the primary circuit to the secondary circuit in a non-contact manner. A power transmission device characterized by the above-mentioned.
2. 2. The power transmission device according to claim 1, further comprising: a power supply side diode having an anode connected to the DC power supply and a cathode connected to the one terminal of the power transmission side capacitor.
3. The power transmission device according to claim 1 or 2, wherein the primary-side drive switch is a semiconductor switching element.
4. 4. 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.
5. The power transmission device according to any one of claims 1 to 4, further comprising a magnetic coupling degree control mechanism that controls a magnetic coupling degree between the power transmitting side coil and the power receiving side coil. .
6. 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. .
7. 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.
8. 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.
9. 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 between one terminal and the other terminal of the power transmission side coil,
   A primary-side drive switch that is connected between the one terminal of the power-transmission-side coil and the DC power supply and that step-inputs an intermittent DC voltage to the power-transmission-side coil;
   A first mutual coupling capacitor having one electrode connected to one node connecting the power transmission side capacitor and the power transmission side coil in parallel;
   A second mutual coupling capacitor having one electrode connected to the other node connecting the power transmission side capacitor and the power transmission side coil in parallel;
   A power receiving device that connects one electrode to the other electrode of the first interconnection capacitor, connects the other electrode to the other electrode of the second interconnection capacitor, and receives the electrostatic energy from the primary circuit; A side capacitor, a secondary circuit having a power receiving coil that is connected in parallel to the power receiving capacitor and stores the electrostatic energy stored in the power receiving capacitor as magnetic energy,
   A load element that constitutes a circuit that connects between one terminal and the other terminal of the power receiving coil, and receives the magnetic energy from the power receiving coil,
   An anode has a load-side diode connected to the load element, and a cathode is connected to the one terminal of the power-receiving-side coil. A power transmission device characterized by the above-mentioned.
   

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