JP2017093180A - Noncontact power transmission system, and power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a noncontact power transmission system which enables the simplification of the structure of a drive circuit.SOLUTION: A noncontact power transmission system C transmits an electric power from a power transmission device A to a power-receiving device B1 in a noncontact manner. The power transmission device A includes: a high-frequency power supply device 1 operable to output a constant high-frequency current; and a power transmission unit 2. The power-receiving device B1 includes a power-receiving unit 3. The high-frequency power supply device 1 includes: a DC power supply 11 operable to output a DC voltage; a switching element Qs operable to perform a switching action based on a high-frequency control signal S2; an inductor L1 connected in series between the DC power supply 11 and the switching element Qs; a first resonance circuit LC3 connected in series between the power transmission unit 2 and a node of the switching element Qs and the inductor L1, of which the resonance frequency is coincident with a frequency of the high frequency control signal S2; and a second resonance circuit LC2 connected in parallel with the switching element Qs, of which the resonance frequency is double the frequency of the high frequency control signal S2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a non-contact power transmission system that performs non-contact power transmission and a power transmission device.

  A technique has been developed in which power output from a power source is transmitted to the load in a contactless manner without directly connecting the load and the power source. This technique is generally called non-contact power transmission or wireless power feeding. This technology is applied to power transmission to mobile phones, home appliances, electric vehicles, automated guided vehicles (AGV), and the like.

  In non-contact power transmission, power is transmitted in a non-contact manner from a power transmission device connected to a high-frequency power supply device to a power reception device connected to a load. The power transmission device includes a power transmission coil, and the power reception device includes a power reception coil. Contactless power transmission is performed by magnetically coupling the power transmission coil and the power reception coil.

  A high frequency power supply device used in non-contact power transmission outputs high frequency power of several MHz to several hundred MHz. Such a high-frequency power supply device generally includes a half-bridge type inverter circuit using two switching elements and a full-bridge type inverter circuit using four switching elements (for example, Patent Document 1). reference).

Patent No. 5447509

  However, when a half-bridge type or full-bridge type inverter circuit is used, a drive circuit that drives the inverter circuit needs to be provided with a dead time, so that the circuit configuration becomes complicated.

  The present invention has been conceived under the circumstances described above, and an object of the present invention is to provide a non-contact power transmission system and a power transmission device in which a drive circuit can have a simple configuration.

  In order to solve the above problems, the present invention takes the following technical means.

  A non-contact power transmission system provided by the first aspect of the present invention is a non-contact power transmission system that non-contactly transmits power from a power transmission device to a power reception device, and the power transmission device transmits a constant high-frequency current. A high-frequency power supply device to output, a power transmission coil, and a power transmission unit including a resonance capacitor connected in series to the power transmission coil, the power reception device is a power reception coil magnetically coupled to the power transmission coil, And a power receiving unit including a resonance capacitor connected to the power receiving coil, wherein the high frequency power supply device performs a switching operation based on a DC power supply device that outputs a DC voltage and an input high frequency control signal. An element, an inductor connected in series between the DC power supply device and the switching element, and the switching element A first resonance circuit that is connected in series between a connection point with the inductor and the power transmission unit and that has a frequency of the high-frequency control signal as a resonance frequency, and is connected in parallel to the switching element, and the frequency of the high-frequency control signal And a second resonance circuit having a resonance frequency of twice as high as the resonance frequency, and a power transmission method from the power transmission unit to the power reception unit is a magnetic field resonance method.

  In a preferred embodiment of the present invention, in the power reception unit, the power reception coil and the resonance capacitor on the power reception side are connected in parallel.

  In a preferred embodiment of the present invention, the power receiving unit is configured such that the power receiving coil and the resonance capacitor on the power receiving side are connected in series, and the power receiving device is connected to the power receiving unit at a subsequent stage from the power receiving unit. A voltage-current conversion circuit for converting the voltage output into the current output is further provided.

  In a preferred embodiment of the present invention, the voltage-current conversion circuit includes an inductor and a capacitor that are designed so that the magnitude of each impedance is equal at the frequency of the high-frequency current output from the high-frequency power supply device. A circuit arranged in a T-type or a π-type.

  In a preferred embodiment of the present invention, the voltage-current conversion circuit is a transmission line connected in series to the power receiving unit, and the length of the transmission line is the frequency of the frequency output from the high-frequency power supply device. The length is approximately one quarter of the transmission wavelength in the transmission line.

  In a preferred embodiment of the present invention, the transmission line is a coaxial cable.

  In a preferred embodiment of the present invention, the power receiving device further includes a rectifier circuit that rectifies an output current from the power receiving unit.

  In a preferred embodiment of the present invention, the power reception device has a smoothing circuit connected to the output side of the rectifier circuit.

  In a preferred embodiment of the present invention, the high frequency power supply device includes two switching elements, two inductors, two first resonance circuits, and two second resonance circuits. And is configured as a push-pull circuit.

  In a preferred embodiment of the present invention, the power receiving device is disposed in a vehicle, and the power transmitting device is disposed on a floor surface.

  A power transmission device provided by the second aspect of the present invention is a power transmission device that transmits power to a power reception device in a contactless manner, a high-frequency power supply device that outputs a constant high-frequency current, a power transmission coil, and the power transmission device A power transmission unit including a resonance capacitor connected in series to a coil, wherein the high-frequency power device includes a DC power device that outputs a DC voltage, and a switching element that performs a switching operation based on an input high-frequency control signal. Inductor connected in series between the DC power supply device and the switching element, and connected in series between the connection point of the switching element and the inductor and the power transmission unit, and resonates the frequency of the high frequency control signal A first resonant circuit having a frequency and a parallel connection to the switching element, and a frequency twice the frequency of the high-frequency control signal And a second resonant circuit that the number and the resonance frequency, the power transmission system to the power receiving device is characterized in that a magnetic field resonance method.

  According to the present invention, the high-frequency power supply device can output a high-frequency current of a certain magnitude from the output line by inputting a high-frequency control signal to the switching element. Since it is not necessary to provide a dead time for the high-frequency control signal, a drive circuit for outputting the high-frequency control signal to the switching element can have a simple configuration.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

It is a figure which shows the outline | summary of the whole structure of the non-contact electric power transmission system which concerns on 1st Embodiment. (A) is a circuit diagram which shows the whole structure of the non-contact electric power transmission system which concerns on 1st Embodiment, (b) is a circuit diagram which shows the detail of the internal structure of a high frequency power supply device. It is a figure for demonstrating the circuit of the principal part of the non-contact electric power transmission system which concerns on 1st Embodiment with an equivalent circuit. It is a figure which shows each waveform when a simulation is performed based on the non-contact electric power transmission system which concerns on 1st Embodiment. It is a circuit diagram which shows the whole structure of the non-contact electric power transmission system which concerns on 2nd Embodiment. It is a figure for demonstrating the circuit of the principal part of the non-contact electric power transmission system which concerns on 2nd Embodiment with an equivalent circuit. It is a figure which shows each waveform when a simulation is performed based on the non-contact electric power transmission system which concerns on 2nd Embodiment. It is a figure which shows each waveform when a simulation is performed based on the non-contact electric power transmission system which concerns on 2nd Embodiment. It is a circuit diagram which shows the whole structure of the non-contact electric power transmission system which concerns on 3rd Embodiment. It is a figure which shows the circuit of the principal part of the non-contact electric power transmission system which concerns on 3rd Embodiment. It is a figure which shows each waveform when a simulation is performed based on the non-contact electric power transmission system which concerns on 3rd Embodiment. It is a figure which shows the modification of a high frequency power supply device. It is a figure which shows the other Example of the non-contact electric power feeding system which concerns on 1st-3rd embodiment.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings, taking as an example a case where the non-contact power transmission system according to the present invention is applied to a charging system of an electric vehicle.

  1 and 2 are diagrams for explaining the non-contact power transmission system C according to the first embodiment. FIG. 1 shows an overview of the overall configuration of the non-contact power transmission system C. FIG. 2A is a circuit diagram showing the overall configuration of the non-contact power transmission system C, and FIG. 2B is a circuit diagram showing details of the internal configuration of the high-frequency power supply device 1.

  As shown in FIG. 1, the non-contact power transmission system C includes a power receiving device B1 provided in a vehicle body such as an electric vehicle, and a power transmitting device A embedded in a floor surface such as a parking lot. The power transmission device A includes a power transmission coil disposed on the floor surface, and the power reception device B1 includes a power reception coil disposed on the bottom surface of the vehicle body. The power receiving device B1 receives high-frequency power transmitted from the power transmitting device A by magnetically coupling the power transmitting coil and the power receiving coil. In other words, the magnetic flux changes as a high-frequency current flows through the power transmission coil, and the high-frequency current flows through the power receiving coil interlinked with the magnetic flux. Thereby, electric power can be transmitted from the power transmission device A to the power reception device B1 in a non-contact manner. The power receiving device B1 rectifies the high-frequency current with a rectifying / smoothing circuit and supplies the rectified current to the battery D.

  The power transmission coil and the power reception coil are planar coils wound in a spiral shape, and are arranged such that the coil surfaces are substantially parallel to the floor surface. When power is supplied, as shown in FIG. 1, the vehicle body is arranged such that the power receiving device B1 is directly above the power transmitting device A and the power receiving coil overlaps the power transmitting coil when viewed from above. FIG. 2A shows a state where the power receiving coil is magnetically coupled to the power transmitting coil.

  As illustrated in FIG. 2A, the power transmission device A includes a high frequency power supply device 1 and a power transmission unit 2.

  The high frequency power supply device 1 supplies high frequency power to the power transmission unit 2. The high-frequency power supply device 1 is a so-called constant current source, and outputs a high-frequency current having a certain magnitude. As shown in FIG. 2B, the high frequency power supply device 1 includes a DC power supply device 11, a control device 12, a switching element Qs, a diode D1, inductors L1, L2, L3, and capacitors C1, C2, C3, C4. C10 is provided. The high frequency power supply device 1 converts the DC power generated by the DC power supply device 11 into high frequency power by the switching operation of the switching element Qs.

  The DC power supply device 11 generates and outputs DC power. The DC power supply device 11 rectifies an AC voltage (for example, a commercial voltage 200 [V]) input from a commercial power source by a rectifier circuit (not shown) and smoothes it by a smoothing circuit (not shown), thereby converting it into a DC voltage. And it converts into the DC voltage of a predetermined level (target voltage) with the DC-DC converter which is not illustrated. The DC power supply device 11 converts the DC voltage after rectification and smoothing into a DC voltage of a predetermined level by controlling the conversion operation of the DC-DC converter according to the voltage control signal S1 input from the control device 12. Note that the configuration of the DC power supply device 11 is not limited as long as it outputs a predetermined high-frequency voltage.

  Switching element Qs, diode D1, inductors L1 and L3, and capacitors C1, C3, C4, and C10 constitute a so-called class E amplifier. The class E amplifier receives DC power from the DC power supply 11 and generates and outputs high-frequency power.

  The capacitor C10 is connected in parallel to the DC power supply device 11, and smoothes the DC voltage input from the DC power supply device 11.

  The inductor L1 is connected in series between the output terminal on the high potential side of the DC power supply device 11 and the switching element Qs. When the DC power supply device 11 outputs a constant DC voltage, the inductor L1 supplies a constant DC current to the switching element Qs.

The switching element Qs switches between an on state and an off state in accordance with the high frequency control signal S2 input from the control device 12. In the present embodiment, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) is used as the switching element Qs. The switching element Qs is not limited to a MOSFET, but may be a bipolar transistor, an IGBT (Insulated Gate Bipolar Transistor), or the like. The drain terminal of the switching element Qs is connected to one terminal of the inductor L1 (the terminal different from the terminal connected to the output terminal of the DC power supply device 11). The source terminal of the switching element Qs is connected to the output terminal on the low potential side of the DC power supply device 11. A high frequency control signal S2 is input from the control device 12 to the gate terminal of the switching element Qs. The high frequency control signal S2 is a pulse signal that repeats a high level and a low level at a predetermined frequency f ₀ (for example, 85 [kHz], 13.56 [MHz], etc.). Since the frequency f ₀ is a frequency for switching the switching element Qs, it may be described as “switching frequency f ₀ ” below. The switching element Qs is turned off when the high-frequency control signal S2 is at a low level, and turned on when the high-frequency control signal S2 is at a high level.

  The diode D1 is a so-called flywheel diode, and is connected in antiparallel between the drain terminal and the source terminal of the switching element Qs. That is, the anode terminal of the diode D1 is connected to the source terminal of the switching element Qs, and the cathode terminal of the diode D1 is connected to the drain terminal of the switching element Qs. The diode D1 is for preventing a high reverse voltage due to the counter electromotive force generated by switching the switching element Qs from being applied to the switching element Qs. When the switching element Qs has a function of operating as a diode inside, the diode D1 may not be provided.

  The capacitor C1 is connected in parallel to the switching element Qs. When the switching element Qs is in an off state, a current flows and accumulates electric energy. And after the both-ends voltage of the capacitor | condenser C1 becomes a peak, it discharges and discharge | releases electrical energy. Then, at the timing when the voltage across the capacitor C1 becomes zero, the switching element Qs is switched from the off state to the on state.

The inductor L3 and the capacitor C3 are connected in series to form a resonance circuit LC3. Inductor L3 and the capacitor C3, the resonance frequency is designed to match the switching frequency f _0. The resonance circuit LC3 is connected in series between the connection point between the drain terminal of the switching element Qs and one terminal of the inductor L1 and the power transmission unit 2. Due to the resonance characteristics of the resonance circuit LC3, the output current becomes a sine wave having a resonance frequency (switching frequency f ₀ ). The resonance circuit LC3 corresponds to the “first resonance circuit” of the present invention.

  The capacitor C4 is connected to the output side of the resonance circuit LC3 so as to be in parallel with the DC power supply device 11. The capacitor C4, the inductor L3, and the capacitor C3 function as an impedance matching circuit. The capacitor C3 cuts a direct current component from the high frequency current output from the high frequency power supply device 1.

With the configuration described above, the class E amplifier including the switching element Qs, the diode D1, the inductors L1 and L3, and the capacitors C1, C3, C4, and C10 is switched according to the high frequency control signal S2 input from the control device 12. By switching the element Qs, a high-frequency current having a switching frequency f ₀ is generated and output.

In the present embodiment, the high frequency power supply device 1 has a resonance circuit LC2 in which an inductor L2 and a capacitor C2 are connected in series, connected in parallel to the switching element Qs. Inductor L2 and capacitor C2, the resonance frequency is designed to match the frequency twice the switching frequency f _0. Resonant circuit LC2, to the double frequency component of the switching frequency f ₀ (2-order harmonic component) becomes a low impedance, the components of the switching frequency f ₀ (fundamental wave component) and 3 times the frequency component (3 It becomes high impedance to the second harmonic component). The resonance circuit LC2 corresponds to the “second resonance circuit” of the present invention.

In addition, the filter LC1 including the inductor L1 and the capacitor C1 also has an impedance combined with the resonance circuit LC2 with respect to the component (fundamental wave component) of the switching frequency f ₀ and the frequency component (third harmonic component) three times that of the component. It is designed to have a high impedance and a low impedance with respect to a frequency component (second harmonic component) twice the switching frequency f ₀ . The capacitance of the capacitor C1 is designed in consideration of the capacitance component inside the switching element Qs.

  From the above configuration, the second harmonic component of the generated high-frequency current flows to the resonance circuit LC2, and the generated voltage due to the second harmonic component current between the drain and source of the switching element Qs can be suppressed.

  The control device 12 controls the high-frequency power supply device 1 and is a microcomputer or FPGA (Field-Programmable Gate Array) equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). Composed.

  The control device 12 controls the level of the DC voltage output from the DC power supply device 11 by feedback control. Specifically, the control device 12 generates a control pulse signal for making the deviation between the output voltage of the DC power supply device 11 and the set target voltage zero. Then, the control pulse signal is amplified to a level at which the DC-DC converter can be driven by a drive circuit (not shown), and is output to the DC power supply device 1 as the voltage control signal S1. Accordingly, the control device 12 can control the DC voltage output from the DC power supply device 11 to the target voltage and output a constant DC voltage from the DC power supply device 11. Further, the control device 12 changes the level of the output voltage of the DC power supply device 11 by changing the target voltage.

Further, the control device 12 generates a pulse signal (which may be a sine wave signal or the like) having a switching frequency f ₀ based on the reference clock, and a level at which the switching element Qs can be driven by a drive circuit (not shown). And output as a high frequency control signal S2 to the gate terminal of the switching element Qs.

  The power transmission unit 2 includes a power transmission coil Lt and a resonance capacitor Ct. The power transmission coil Lt transmits the high frequency power supplied from the high frequency power supply device 1 to the power receiving device B. The resonance capacitor Ct is connected in series to the power transmission coil Lt to form a series resonance circuit.

The power transmission coil Lt and the resonance capacitor Ct are designed so that the resonance frequency matches the frequency f ₀ (switching frequency f ₀ ) of the high frequency power supplied from the high frequency power supply device 1. That is, the self-inductance L _R of the power transmission coil Lt and the capacitance C _R of the resonance capacitor Ct are designed so as to have a relationship of the following expression (1). If the switching frequency f ₀ is high, the stray capacitance between the windings of the power transmission coil Lt may be used as the resonance capacitor Ct.

  Further, as shown in FIG. 2A, the power receiving device B <b> 1 includes a power receiving unit 3 and a rectifying / smoothing circuit 4.

  The power receiving unit 3 includes a power receiving coil Lr and a resonance capacitor Cr. The power receiving coil Lr is magnetically coupled to the power transmitting coil Lt and receives power in a non-contact manner. The resonance capacitor Cr is connected in parallel to the power receiving coil Lr to form a parallel resonance circuit.

Similarly to the power transmission coil Lt and the resonance capacitor Ct, the power reception coil Lr and the resonance capacitor Cr are designed such that the resonance frequency matches the frequency f ₀ (switching frequency f ₀ ) of the high frequency power supplied from the high frequency power supply device 1. The If the switching frequency f ₀ is high, the stray capacitance between the windings of the power receiving coil Lr may be used as the resonance capacitor Cr.

  The power transmission unit 2 and the power reception unit 3 are both resonant circuits and are coupled in resonance. That is, power transmission is performed from the power transmission unit 2 to the power reception unit 3 in a non-contact manner by a magnetic field resonance method. The power received by the power receiving unit 3 is output to the rectifying and smoothing circuit 4.

  The rectifying / smoothing circuit 4 rectifies the high-frequency current output from the power receiving unit 3 and converts it into a direct current. The rectifying / smoothing circuit 4 includes a full-wave rectifying circuit in which four diodes are bridge-connected. The rectifying / smoothing circuit 4 also includes a smoothing circuit for smoothing the rectified output. The configuration of the rectifying / smoothing circuit 4 is not limited as long as it converts a high-frequency current into a direct current. The direct current output from the rectifying / smoothing circuit 4 is supplied to the battery D.

  The battery D is a secondary battery such as a lithium ion battery. The battery D is charged by DC power output from the rectifying and smoothing circuit 4 and supplies power to a motor (not shown). A constant current is input to the battery D regardless of the state of charge of the battery D. In addition, the kind of secondary battery is not limited, A lead storage battery etc. may be sufficient. Further, instead of the battery D, an electric double layer capacitor or a lithium ion capacitor may be used.

  Next, with reference to FIG. 3, it will be described that the current supplied to the battery D is constant regardless of the state of charge of the battery D.

  FIG. 3A shows the main part of the non-contact power transmission system C shown in FIG.

The output voltage of the high-frequency power supply device 1 is V ₁ and the output current is I ₁ . Further, the voltage applied to the rectifying / smoothing circuit 4 is V ₂ , and the current input to the rectifying / smoothing circuit 4 is I ₂ . The voltages V ₁ and V ₂ and the currents I ₁ and I ₂ are all vectors.

In general, an equivalent circuit of a non-contact power transmission system can be represented by replacing a magnetically coupled power transmission coil and power reception coil with a T-type circuit composed of three coils. When the circuit shown in FIG. 3A is converted into an equivalent circuit expressed using a T-type circuit, the circuit shown in FIG. 3B is obtained. In FIG. 3B, as shown in the figure, the impedance of the capacitor or coil is expressed as Z1 to Z4. Each impedance Z1 to Z4 is a vector. Among the coils of the T-type circuit, the inductance of the coil on the power transmission unit side (the coil included in the impedance Z1) is the mutual inductance due to the magnetic coupling between the power transmission coil Lt and the power reception coil Lr from the self-inductance of the power transmission coil Lt. It will be reduced. Among the coils of the T-type circuit, the inductance of the coil on the power receiving unit side (the coil included in the impedance Z3) is the mutual inductance due to the magnetic coupling between the power transmitting coil Lt and the power receiving coil Lr from the self-inductance of the power receiving coil Lr. It will be reduced. In addition, the inductance of the coils connected in parallel among the coils of the T-type circuit (the coil included in the impedance Z2) is a mutual inductance due to magnetic coupling between the power transmission coil Lt and the power reception coil Lr. Therefore, each impedance Z1-Z4 can be represented by the following formulas (2)-(5). Note that the inductances of the power transmission coil Lt and the power reception coil Lr are L _t and L _r , respectively, and the capacitances of the resonance capacitor Ct and the resonance capacitor Cr are C _t and C _r , respectively. The coupling coefficient between the power transmission coil Lt and the power reception coil Lr is k.

FIG. 3C is a diagram showing an equivalent circuit in which the circuit shown in FIG. 3B is expressed using the F parameter. The elements A, B, C, and D of the F parameter are all vectors, and the F parameter is expressed by the following equation (6).

Substituting Z1 + Z2 = Z2 + Z3 + Z4 = 0, which is a conditional expression of magnetic resonance, into the above equation (6), the following equation (7) is obtained. From this, the following formula (9) is obtained from the following formula (8) and the above formulas (3) and (4).

If the distance between the power transmission coil Lt and the power reception coil Lr does not change, the coupling coefficient k does not change. Therefore, from the above equation (9), the magnitude of the current I ₂ output from the power receiving unit 3 is proportional to the magnitude of the current I ₁ input to the power transmission unit 2. Further, the current I ₁ is input to the power transmission unit 2, an output current I ₁ of the high-frequency power supply device 1. When the DC voltage output from the DC power supply device 11 is constant, the magnitude of the output current I ₁ of the high frequency power supply device 1 is constant. Therefore, when the DC voltage output from the DC power supply device 11 is constant, the magnitude of the output current I ₂ of the power receiving unit 3 is constant regardless of the impedance of the connected load. That is, the output of the power receiving unit 3 can be considered as a constant current source that outputs a constant current I ₂ . Since the magnitude of the output current I ₂ of the power receiving unit 3 is constant, the current rectified and smoothed by the rectifying and smoothing circuit 4 is constant. Therefore, the current supplied to the battery D is constant regardless of the state of charge of the battery D.

FIG. 4 shows each waveform when the rectifying / smoothing circuit 4 and the battery D are replaced with load resistors in the circuit shown in FIG. The DC voltage V _dc output from the DC power supply 11 is 200 [V], the high-frequency control signal S2 is a rectangular wave signal having a frequency f = 13.56 [MHz] and a duty ratio of 40%, and the power transmission coil Lt and the power reception coil Lr. The coupling coefficient of k is 0.5, and the resistance value of the load resistance is changed to 5 [Ω], 10 [Ω], 15 [Ω], 20 [Ω], 25 [Ω], and 30 [Ω]. A simulation was performed. 4A shows the waveform of the drain-source voltage V _ds of the switching element Qs, and FIG. 4B shows the output voltage (that is, the voltage applied to the load resistor) V of the power receiving unit 3. ₂ shows the waveform. FIG. 4C shows the waveform of the output current (that is, the current flowing through the load resistor) I ₂ of the power receiving unit 3.

As shown in FIG. 4A, the drain-source voltage V _ds of the switching element Qs is less than 500 [V], which is 2 with respect to the DC voltage V _dc (200 [V]). It is about 5 times. On the other hand, when the simulation is performed by deleting the resonance circuit LC2 including the inductor L2 and the capacitor C2 shown in FIG. 2B, the drain-source voltage V _ds of the switching element Qs becomes 700 V or more. (Not shown), 3.5 times or more of the DC voltage V _dc . That is, it was confirmed that the voltage generated in the switching element Qs can be suppressed by the resonance circuit LC2 including the inductor L2 and the capacitor C2.

Further, as shown in FIG. 4B, the waveform of the output voltage V ₂ of the power receiving unit 3 varies depending on the resistance value of the load resistance, whereas it is shown in FIG. Thus, it was confirmed that the waveform of the output current I ₂ of the power receiving unit 3 did not change depending on the resistance value of the load resistance.

  Next, the effect of the non-contact power transmission system C according to the first embodiment will be described.

  According to the present embodiment, the high frequency power supply device 1 can output a high frequency current of a certain magnitude to the power transmission unit 2 by inputting the high frequency control signal S2 to one switching element Qs. Since there is no need to provide a dead time for the high-frequency control signal S2, a drive circuit for outputting the high-frequency control signal S2 to the switching element can have a simple configuration.

Further, according to the present embodiment, the resonance circuit LC2 including the inductor L2 and the capacitor C2 is connected in parallel to the switching element Qs of the high frequency power supply device 1. The resonant circuit LC2, to the double frequency component of the switching frequency f ₀ (2-order harmonic component) becomes a low impedance, the components of the switching frequency f ₀ (fundamental wave component) and 3 times the frequency components ( It becomes a high impedance to the third harmonic component). Accordingly, the second harmonic component of the high frequency current generated in the high frequency power supply device 1 flows into the resonance circuit LC2, and the generated voltage due to the second harmonic component current between the drain and source of the switching element Qs is suppressed. it can. Therefore, it is not necessary for the switching element Qs to have a high breakdown voltage.

  According to this embodiment, the power transmission unit 2 is a series resonance circuit, and the power reception unit 3 is a parallel resonance circuit. The high frequency power supply device 1 outputs a high frequency current of a certain magnitude to the power transmission unit 2 and transmits power from the power transmission unit 2 to the power reception unit 3 by a magnetic field resonance method. Therefore, the output of the power receiving unit 3 is equivalent to the output of the constant current source. Therefore, the current output to the battery D is constant regardless of the state of charge of the battery D. That is, the battery D can be charged with a constant current.

  In the first embodiment, the case where the power receiving unit 3 is a parallel resonant circuit has been described. However, the present invention is not limited to this. A case where the power receiving unit 3 is a series resonance circuit will be described below.

  FIG. 5 is a circuit diagram showing an overall configuration of a non-contact power transmission system C ′ according to the second embodiment. In FIG. 5, the same or similar elements as those in the non-contact power transmission system C (see FIG. 2) according to the first embodiment are denoted by the same reference numerals. In the non-contact power transmission system C ′, the power receiving unit 3 ′ is a series resonance circuit, and the voltage-current conversion circuit 5 is provided between the power receiving unit 3 ′ and the rectifying / smoothing circuit 4. Different from the non-contact power transmission system C according to the first embodiment.

In the power reception unit 3 ′, a resonance capacitor Cr is connected in series to the power reception coil Lr, and a series resonance circuit is configured. Similarly to the power transmission coil Lt and the resonance capacitor Ct, the power reception coil Lr and the resonance capacitor Cr are designed such that the resonance frequency matches the frequency f ₀ (switching frequency f ₀ ) of the high frequency power supplied from the high frequency power supply device 1. The Note that when the frequency of the high-frequency current output from the high-frequency power supply device 1 is high, the floating capacitance between the windings of the power receiving coil Lr may be used as the resonance capacitor Cr.

The voltage-current conversion circuit 5 converts a voltage output into a current output. The voltage-current conversion circuit 5 is a circuit in which two inductors L11 and L12 and a capacitor C11 are arranged in a T shape. The inductor L11 and the inductor L12 are connected in series, and are connected in series between the power receiving unit 3 ′ and the rectifying / smoothing circuit 4. A capacitor C11 is connected in parallel at a connection point between the inductor L11 and the inductor L12. Each inductance and capacitance is determined so that the magnitudes of the impedances of the inductors L11 and L12 and the capacitor C11 at the switching frequency f ₀ are equal.

  FIG. 6A shows a main part of the non-contact power transmission system C ′ shown in FIG.

The output voltage of the high-frequency power supply device 1 is V ₁ and the output current is I ₁ . The output voltage of the power receiving unit 3 ′ is V ₂ and the output current is I ₂ . The output voltage of the voltage-current conversion circuit 5 is V ₃ and the output current is I ₃ . That is, the voltage applied to the rectifying / smoothing circuit 4 is V ₃ , and the current input to the rectifying / smoothing circuit 4 is I ₃ . The voltages V ₁ , V ₂ , V ₃ and the currents I ₁ , I ₂ , I ₃ are all vectors.

When the circuit shown in FIG. 6A is converted into an equivalent circuit expressed using a T-type circuit, the circuit shown in FIG. 6B is obtained. In FIG. 6B, as shown in the drawing, the impedance of the capacitor or coil is represented as Z1 to Z3. The impedances Z1 to Z3 are all vectors and can be expressed by the following equations (10) to (12). Note that the inductances of the power transmission coil Lt and the power reception coil Lr are L _t and L _r , respectively, and the capacitances of the resonance capacitor Ct and the resonance capacitor Cr are C _t and C _r , respectively. The coupling coefficient between the power transmission coil Lt and the power reception coil Lr is k.

When the circuit shown in FIG. 6B is expressed by using the F parameter, the F parameter is expressed by the following equation (13). Note that each of the elements A, B, C, and D of the F parameter is a vector.

Substituting Z1 + Z2 = Z2 + Z3 = 0, which is a conditional expression of magnetic resonance, into the above equation (13), the following equation (14) is obtained. From this, the following equation (16) is obtained from the following equation (15) and the above equation (11).

If the distance between the power transmission coil Lt and the power reception coil Lr does not change, the coupling coefficient k does not change. Therefore, from the above equation (16), the magnitude of the voltage V ₂ output from the power receiving unit 3 ′ is proportional to the magnitude of the current I ₁ input to the power transmission unit 2. Further, the current I ₁ is input to the power transmission unit 2, an output current I ₁ of the high-frequency power supply device 1. When the DC voltage output from the DC power supply device 11 is constant, the magnitude of the output current I ₁ of the high frequency power supply device 1 is constant. Therefore, when the DC voltage output from the DC power supply 11 is constant, the magnitude of the output voltage V ₂ of the power receiving unit 3 ′ is constant regardless of the impedance of the connected load. That is, the output of the power receiving unit 3 ′ can be considered as a constant voltage source that outputs a voltage V ₂ having a constant magnitude.

FIG. 6C shows a circuit of the voltage-current conversion circuit 5. In FIG. 6C, as shown in the drawing, the impedance of the capacitor or coil is represented as Z4 to Z6. The impedances Z4 to Z6 are all vectors and can be expressed by the following equations (17) to (19). Note that the inductance of the inductor L11 and inductor L12, respectively, and L ₁₁ and L _12, has a capacitance of the capacitor C11 and C _11.

When the circuit shown in FIG. 6C is expressed using F parameters, the F parameters are expressed by the following equation (20). Note that each of the elements A, B, C, and D of the F parameter is a vector.

The inductances and capacitances are determined so that the magnitudes of the impedances of the inductors L11 and L12 and the capacitor C11 at the frequency f ₀ (switching frequency f ₀ ) of the high-frequency power supplied from the high-frequency power supply device 1 are equal. Z4 + Z5 = Z5 + Z6 = 0. Substituting this into the above equation (20) yields the following equation (21). From this, the following equation (23) is obtained from the following equation (22) and the above equation (18).

Since the capacitance C ₁₁ is a fixed value, from the above equation (23), the magnitude of the output current I ₃ of the voltage-current conversion circuit 5 is the voltage output from the power receiving unit 3 ′ and input to the voltage-current conversion circuit 5. proportional to the magnitude of V _2. Further, when the DC voltage output from the DC power supply device 11 is constant, the magnitude of the output voltage V ₂ of the power receiving unit 3 ′ is constant. Therefore, when the DC voltage output from the DC power supply 11 is constant, the magnitude of the output current I ₃ of the voltage-current conversion circuit 5 is constant regardless of the impedance of the connected load. That is, the output of the voltage-current conversion circuit 5 can be considered as a constant current source that outputs a constant current I ₃ . Since the magnitude of the output current I ₃ of the voltage-current conversion circuit 5 is constant, the current rectified and smoothed by the rectifying and smoothing circuit 4 is constant. Therefore, the current supplied to the battery D is constant regardless of the state of charge of the battery D.

FIG. 7 and FIG. 8 show waveforms when the rectifying / smoothing circuit 4 and the battery D are replaced with load resistors in the circuit shown in FIG. 5 and simulation is performed. The DC voltage V _dc output from the DC power supply 11 is 200 [V], the high frequency control signal S2 is a rectangular wave signal having a frequency f = 13.56 [MHz] and a duty ratio of 40%, and the resistance value of the load resistance is 5 The simulation was performed by changing [Ω], 10 [Ω], 15 [Ω], 20 [Ω], 25 [Ω], and 30 [Ω].

In FIG. 7, the coupling coefficient between the power transmission coil Lt and the power reception coil Lr is set to k = 0.5. FIG. 7A shows the waveform of the drain-source voltage V _ds of the switching element Qs, and FIG. 7B shows the output voltage of the voltage-current conversion circuit 5 (that is, applied to the load resistance). shows the waveform of the voltage) V _3. 7C shows the waveform of the output current of the voltage-current conversion circuit 5 (that is, the current flowing through the load resistor) I ₃ and the current input to the power transmission unit 2 (the output current of the high-frequency power supply device 1). ) The waveform of I ₁ is shown.

As shown in FIG. 7A, the drain-source voltage V _ds of the switching element Qs is less than 500 [V] as in FIG. 4A, and the DC voltage V _dc (200 [V]) is about 2.5 times. Further, as shown in FIG. 7B, the waveform of the output voltage V ₃ of the voltage-current conversion circuit 5 varies depending on the resistance value of the load resistance, whereas FIG. As shown, it has been confirmed that the waveform of the output current I ₃ of the voltage-current conversion circuit 5 does not change depending on the resistance value of the load resistance.

In FIG. 8, the coupling coefficient between the power transmission coil Lt and the power reception coil Lr is k = 0.3. FIG. 8A shows the waveform of the drain-source voltage V _ds of the switching element Qs, and FIG. 8B shows the output voltage of the voltage-current conversion circuit 5 (that is, applied to the load resistance). shows the waveform of the voltage) V _3. 8C shows the waveform of the output current of the voltage-current conversion circuit 5 (that is, the current flowing through the load resistor) I ₃ and the current input to the power transmission unit 2 (the output current of the high-frequency power supply device 1). ) The waveform of I ₁ is shown.

As shown in FIG. 8A, the drain-source voltage V _ds of the switching element Qs is less than 500 [V] as in FIG. 8A, and the DC voltage V _dc (200 [V]) is about 2.5 times. Further, as shown in FIG. 8B, the waveform of the output voltage V ₃ of the voltage-current conversion circuit 5 changes depending on the resistance value of the load resistance, whereas FIG. As shown, it has been confirmed that the waveform of the output current I ₃ of the voltage-current conversion circuit 5 does not change depending on the resistance value of the load resistance.

Further, as shown in FIG. 7C and FIG. 8C, the magnitude of the output current I ₃ of the voltage-current conversion circuit 5 changes as the coupling coefficient k changes. Was confirmed. When the coupling coefficient k decreases (see FIG. 8C), the output current I ₃ decreases. Further, as shown in FIGS. 7B and 8B, when the coupling coefficient k decreases, the output voltage V ₃ also decreases.

  Also in the second embodiment, the high frequency power supply device 1 can output a high frequency current of a certain magnitude to the power transmission unit 2 by inputting the high frequency control signal S2 to one switching element Qs. Since there is no need to provide a dead time for the high-frequency control signal S2, a drive circuit for outputting the high-frequency control signal S2 to the switching element can have a simple configuration.

  Also in the second embodiment, the switching circuit Qs of the high frequency power supply device 1 is connected in parallel with a resonance circuit LC2 including an inductor L2 and a capacitor C2. Accordingly, the second harmonic component of the high frequency current generated in the high frequency power supply device 1 flows into the resonance circuit LC2, and the generated voltage due to the second harmonic component current between the drain and source of the switching element Qs is suppressed. it can.

  According to the second embodiment, the power transmission unit 2 is a series resonance circuit, and the power reception unit 3 ′ is a series resonance circuit. The high-frequency power supply 1 outputs a high-frequency current of a certain magnitude to the power transmission unit 2 and transmits power from the power transmission unit 2 to the power reception unit 3 ′ by magnetic field resonance. Therefore, the output of the power receiving unit 3 'is equivalent to the output of the constant voltage source. Further, a voltage-current conversion circuit 5 is connected to the subsequent stage of the power receiving unit 3 '. Therefore, the output of the voltage-current conversion circuit 5 is equivalent to the output of the constant current source. Therefore, the current output to the battery D is constant regardless of the state of charge of the battery D. That is, the battery D can be charged with a constant current.

  In the second embodiment, the voltage-current conversion circuit 5 is described as a circuit in which the two inductors L11 and L12 and the capacitor C11 are arranged in a T shape. However, the circuit of the voltage-current conversion circuit 5 is described. The configuration is not limited to that described above. For example, a circuit in which one inductor and two capacitors are arranged in a T-type may be used, a circuit in which two inductors and one capacitor are arranged in a π-type, or one inductor and two capacitors may be used. It is good also as a circuit which has arrange | positioned to pi type.

  The voltage-current conversion circuit 5 is not limited to a circuit combining an inductor and a capacitor. The voltage-current conversion circuit 5 may be any circuit that converts the voltage output from the power receiving unit 3 ′ into a current output.

  FIG. 9 is a circuit diagram showing an overall configuration of a non-contact power transmission system C ″ according to the third embodiment. In FIG. 9, a non-contact power transmission system C ′ (see FIG. 5) according to the second embodiment and The same or similar elements are denoted by the same reference numerals. The non-contact power transmission system C ″ has a configuration of the voltage-current conversion circuit 5 ′ according to the second embodiment. This is different from the voltage-current conversion circuit 5 of FIG.

  The voltage-current conversion circuit 5 'converts a voltage output into a current output. The voltage-current conversion circuit 5 includes a transmission line TL. The transmission line TL is connected in series between the power receiving unit 3 ′ and the rectifying / smoothing circuit 4. In the present embodiment, the transmission line TL is a coaxial cable. Note that the transmission line TL is not limited to a coaxial cable, and may be a coaxial tube, a line formed on a substrate, or the like.

The length of the transmission line TL is set to approximately one quarter of the transmission wavelength of the fundamental wave of the high frequency (that is, the high frequency output from the high frequency power supply device 1) input from the power receiving unit 3 ′ in the transmission line TL. The high-frequency wavelength λ output from the high-frequency power supply device 1 is expressed by λ [m] = ν [m / s] / f [Hz] where f is the frequency and ν is the velocity of the radio wave in the transmission line TL. . The speed ν of the radio wave on the coaxial cable (made of polyethylene) is about 66% of the speed of the radio wave in the vacuum (3.0 × 10 ⁸ [m / s]). For example, the switching frequency f ₀ = 13.56 Assuming [MHz], the wavelength λ of the high frequency output from the high frequency power supply device 1 is λ = (3.0 × 10 ⁸ ) × (66/100) / (13.56 × 10 ⁶ ) ≈14.60 [m ]. Since the length of the transmission line TL is approximately ¼ of the wavelength λ, 14.60 × (1/4) ≈3.65 [m]. Note that the radio wave velocity ν on the coaxial cable is about 66% of the radio wave velocity in vacuum, but the radio wave velocity on the coaxial cable depends on the wavelength reduction rate of the coaxial cable used (specifically, the coaxial cable It depends on the insulating material. Therefore, the length of the transmission line TL may be appropriately changed according to the type of the coaxial cable used. Further, as can be seen from the above calculation formula, the wavelength λ becomes longer as the frequency of the high frequency output from the high frequency power supply device 1 is lower. Therefore, when the frequency is low, it is necessary to use a long transmission line TL. In order to accommodate the transmission line TL in the housing of the power receiving device B3, the size of the power receiving device B3 must be increased. Therefore, the high frequency output from the high frequency power supply device 1 is desirably 6.78 MHz or more.

  FIG. 10 shows the main part of the non-contact power transmission system C ″ shown in FIG.

The output voltage of the high-frequency power supply device 1 is V ₁ and the output current is I ₁ . The output voltage of the power receiving unit 3 ′ is V ₂ and the output current is I ₂ . The output voltage of the voltage-current conversion circuit 5 ′ is V ₃ and the output current is I ₃ . That is, the voltage applied to the rectifying / smoothing circuit 4 is V ₃ , and the current input to the rectifying / smoothing circuit 4 is I ₃ . Since the voltages and currents are alternating currents, V ₁ , I ₁ , V ₂ , I ₂ , V ₃ , and I ₃ are all vectors.

Since the power transmission unit 2 and the power reception unit 3 ′ are common to the second embodiment, the magnitude of the output voltage V ₂ of the power reception unit 3 ′ is connected when the DC voltage output from the DC power supply device 11 is constant. The same is true regardless of the load impedance.

When the circuit of the voltage-current conversion circuit 5 ′ is expressed using the F parameter, the F parameter is expressed by the following equation (24). Note that each of the elements A, B, C, and D of the F parameter is a vector. Z ₀ is a characteristic impedance of the transmission line TL, β is a phase constant (2π / λ) (λ is a transmission wavelength in the transmission line TL), and l is a line length. Since the line length l of the transmission line TL is ¼ of the transmission wavelength λ, β · l = π / 2. Accordingly, the F parameter is expressed by the following equation (25).

From this, the following equation (27) is obtained from the following equation (26).

Since the characteristic impedance Z ₀ is a fixed value, the magnitude of the output current I ₃ of the voltage-current conversion circuit 5 ′ is output from the power receiving unit 3 ′ and input to the voltage-current conversion circuit 5 ′ from the above equation (27). Is proportional to the magnitude of the applied voltage V ₂ . Further, when the DC voltage output from the DC power supply device 11 is constant, the magnitude of the output voltage V ₂ of the power receiving unit 3 ′ is constant. Therefore, when the DC voltage output from the DC power supply 11 is constant, the magnitude of the output current I ₃ of the voltage-current conversion circuit 5 ′ is constant regardless of the impedance of the connected load. That is, the output of the voltage-current conversion circuit 5 ′ can be considered as a constant current source that outputs a current I ₃ having a constant magnitude. Since the output current I ₃ of the voltage-current conversion circuit 5 ′ is constant, the current rectified and smoothed by the rectifying and smoothing circuit 4 is constant. Therefore, the current supplied to the battery D is constant regardless of the state of charge of the battery D.

FIG. 11 shows each waveform when the rectifying / smoothing circuit 4 and the battery D are replaced with load resistors in the circuit shown in FIG. The DC voltage V _dc output from the DC power supply 11 is 200 [V], the high-frequency control signal S2 is a rectangular wave signal having a frequency f = 13.56 [MHz] and a duty ratio of 40%, and the power transmission coil Lt and the power reception coil Lr. The coupling coefficient of k is 0.5, and the resistance value of the load resistance is changed to 5 [Ω], 10 [Ω], 15 [Ω], 20 [Ω], 25 [Ω], and 30 [Ω]. A simulation was performed. 11A shows the waveform of the drain-source voltage V _ds of the switching element Qs, and FIG. 11B shows the output voltage of the voltage-current conversion circuit 5 ′ (that is, applied to the load resistance). Voltage) V ₃ waveform. FIG. 11C shows the waveform of the output current (that is, the current flowing through the load resistor) I ₃ of the voltage-current conversion circuit 5 ′ and the current input to the power transmission unit 2 (the output of the high-frequency power supply device 1). The waveform of (current) I ₁ is shown.

As shown in FIG. 11A, the drain-source voltage V _ds of the switching element Qs is less than 500 [V], which is 2 with respect to the DC voltage V _dc (200 [V]). It is about 5 times. Further, as shown in FIG. 11B, the waveform of the output voltage V ₃ of the voltage-current conversion circuit 5 ′ varies depending on the resistance value of the load resistance, whereas in FIG. As shown, it was confirmed that the waveform of the output current I ₃ of the voltage-current conversion circuit 5 ′ did not change depending on the resistance value of the load resistance.

  Also in the third embodiment, the high frequency power supply device 1 can output a high frequency current of a certain magnitude to the power transmission unit 2 by inputting the high frequency control signal S2 to one switching element Qs. Since there is no need to provide a dead time for the high-frequency control signal S2, a drive circuit for outputting the high-frequency control signal S2 to the switching element can have a simple configuration.

  In the third embodiment, the switching circuit Qs of the high frequency power supply device 1 is also connected in parallel with a resonance circuit LC2 including an inductor L2 and a capacitor C2. Accordingly, the second harmonic component of the high frequency current generated in the high frequency power supply device 1 flows into the resonance circuit LC2, and the generated voltage due to the second harmonic component current between the drain and source of the switching element Qs is suppressed. it can.

  According to the third embodiment, the power transmission unit 2 is a series resonance circuit, and the power reception unit 3 ′ is a series resonance circuit. The high-frequency power supply 1 outputs a high-frequency current of a certain magnitude to the power transmission unit 2 and transmits power from the power transmission unit 2 to the power reception unit 3 ′ by magnetic field resonance. Therefore, the output of the power receiving unit 3 'is equivalent to the output of the constant voltage source. In addition, a voltage-current conversion circuit 5 'is connected to the subsequent stage of the power receiving unit 3'. Therefore, the output of the voltage-current conversion circuit 5 'is equivalent to the output of the constant current source. Therefore, the current output to the battery D is constant regardless of the state of charge of the battery D. That is, the battery D can be charged with a constant current.

  In the first to third embodiments, the case where the high-frequency power supply 1 uses a so-called single-class class E amplifier has been described. However, the present invention is not limited to this. For example, as shown in FIG. 12, a push-pull circuit may be used. The high-frequency power supply device 1 ′ uses a so-called push-pull type amplifier in which class E amplifiers are connected symmetrically so as to amplify only one polarity signal. Two resonant circuits LC2 are also provided for each polarity. Even in this case, the high-frequency power supply device 1 can output a high-frequency current of a certain magnitude to the power transmission unit 2 by inputting the high-frequency control signal S2 to each switching element Qs. Since there is no need to provide a dead time for the high-frequency control signal S2, a drive circuit for outputting the high-frequency control signal S2 to the switching element can have a simple configuration. Each switching element Qs is connected in parallel with a resonance circuit LC2 including an inductor L2 and a capacitor C2. Therefore, the second harmonic component flows into the resonance circuit LC2, and the voltage generated by the second harmonic component current between the drain and source of the switching element Qs can be suppressed.

  In the said 1st thru | or 3rd Embodiment, although the case where the power transmission apparatus A was embed | buried under the floor surface (refer FIG. 1) was demonstrated, it is not restricted to this. For example, only the power transmission coil may be embedded in the floor surface, or the power transmission coil may be disposed on the floor surface without being embedded in the floor surface. Moreover, it is not limited to when the power transmission coil and the power reception coil are provided so as to be substantially parallel to the floor surface. For example, as shown in FIG. 13A, the power receiving device B is disposed at the rear part of the vehicle body, the power transmitting device A is disposed on the wall surface of the garage, and the power transmitting coil and the power receiving coil are substantially perpendicular to the floor surface. It may be. Moreover, as shown in FIG.13 (b), the power receiving apparatus B is arrange | positioned at the side surface of a vehicle body, the power transmission apparatus A is arrange | positioned at the wall surface of a garage, and a power transmission coil and a power receiving coil become substantially perpendicular | vertical with respect to a floor surface. It may be. In short, the power transmission coil and the power reception coil need only be disposed in the vehicle body and in the garage (parking lot) so that they can be disposed in substantially parallel positions.

  In the first to third embodiments, the case where the non-contact power transmission system according to the present invention is used for charging a battery built in an electric vehicle has been described as an example. However, the present invention is not limited to this. For example, it can also be used for charging an AGV (automatic guided vehicle) battery or an electric double layer capacitor used for transportation in a factory. The present invention can also be applied when charging a battery of an electric product such as an electric tool or a notebook computer. Further, the present invention can also be applied to a case where power is directly supplied to a load such as an electric product connected to the power receiving device instead of charging the battery. In this case, the rectifying and smoothing circuit 4 may not be provided as long as the high frequency power is supplied to the load as it is. Further, the rectified DC power may be converted into suitable AC power by an inverter circuit and used.

  The non-contact power transmission system and the power transmission device according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the non-contact power transmission system and the power transmission device according to the present invention can be varied in design in various ways.

A power transmission device 1,1 ′ high frequency power supply device 11 DC power supply device 12 control device C1, C2, C3, C4, C10 capacitor L1, L2, L3 inductor LC1 filter LC2 resonance circuit (second resonance circuit)
LC3 resonant circuit (first resonant circuit)
Qs switching element D1 diode 2 power transmission unit Lt power transmission coil Ct resonance capacitor B1, B2, B3 power reception device 3, 3 ′ power reception unit Lr power reception coil Cr resonance capacitor 4 rectification smoothing circuit 5, 5 ′ voltage-current conversion circuit L11, L12 inductor C11 Capacitor TL Transmission line C, C ', C "Non-contact power transmission system D1 Battery

Claims (11)

A non-contact power transmission system for transmitting power from a power transmission device to a power reception device in a non-contact manner,
The power transmission device is:
A high frequency power supply device that outputs a constant high frequency current;
A power transmission unit, and a power transmission unit including a resonance capacitor connected in series to the power transmission coil;
With
The power receiving device is:
A power reception coil magnetically coupled to the power transmission coil, and a power reception unit including a resonance capacitor connected to the power reception coil,
The high frequency power supply device
A DC power supply that outputs a DC voltage;
A switching element that performs a switching operation based on an input high-frequency control signal;
An inductor connected in series between the DC power supply device and the switching element;
A first resonance circuit connected in series between a connection point between the switching element and the inductor and the power transmission unit, and having a frequency of the high-frequency control signal as a resonance frequency;
A second resonance circuit connected in parallel to the switching element and having a resonance frequency of twice the frequency of the high-frequency control signal;
With
The power transmission method from the power transmission unit to the power reception unit is a magnetic resonance method.
A non-contact power transmission system characterized by that. In the power receiving unit, the power receiving coil and the resonance capacitor on the power receiving side are connected in parallel.
The contactless power transmission system according to claim 1. In the power receiving unit, the power receiving coil and the resonance capacitor on the power receiving side are connected in series,
The power receiving apparatus further includes a voltage-current conversion circuit that converts a voltage output from the power receiving unit into a current output at a subsequent stage of the power receiving unit.
The contactless power transmission system according to claim 1. The voltage-current conversion circuit includes:
A circuit in which inductors and capacitors designed so that the magnitude of each impedance is equal at the frequency of the high-frequency current output from the high-frequency power supply device is arranged in a T-type or a π-type.
The contactless power transmission system according to claim 3. The voltage-current conversion circuit is a transmission line connected in series to the power receiving unit,
The length of the transmission line is a length of about a quarter of the transmission wavelength in the transmission line of the frequency output by the high-frequency power supply device.
The contactless power transmission system according to claim 3. The transmission line is a coaxial cable.
The contactless power transmission system according to claim 5. The power receiving device further includes a rectifier circuit that rectifies an output current from the power receiving unit.
The contactless power transmission system according to claim 1. A smoothing circuit is connected to the output side of the rectifier circuit,
The contactless power transmission system according to claim 7. The high frequency power supply device
Two switching elements, two inductors, two first resonance circuits, and two second resonance circuits,
Configured as a push-pull circuit,
The non-contact power transmission system according to claim 1. The power receiving device is disposed in a vehicle,
The power transmission device is disposed on a floor surface,
The contactless power transmission system according to claim 1. A power transmission device that transmits power to a power receiving device in a contactless manner,
A high frequency power supply device that outputs a constant high frequency current;
A power transmission unit, and a power transmission unit including a resonance capacitor connected in series to the power transmission coil;
With
The high frequency power supply device
A DC power supply that outputs a DC voltage;
A switching element that performs a switching operation based on an input high-frequency control signal;
An inductor connected in series between the DC power supply device and the switching element;
A first resonance circuit connected in series between a connection point between the switching element and the inductor and the power transmission unit, and having a frequency of the high-frequency control signal as a resonance frequency;
A second resonance circuit connected in parallel to the switching element and having a resonance frequency of twice the frequency of the high-frequency control signal;
With
The power transmission method to the power receiving device is a magnetic resonance method.
A power transmission device characterized by that.