JP2018085913A - Wireless power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce strength of a radiation magnetic field at an arbitrary point in the distance with simple structure even when there is a difference in coupling coefficients between a plurality of resonator pairs.SOLUTION: A wireless power transmission system according to an embodiment of the present invention comprises a power transmission device and a power reception device. The power transmission device comprises: an AC power generation circuit that generates AC power; a plurality of first circuits; and a plurality of power transmission resonators that generate magnetic fields according to the AC power received through the plurality of first circuits. The power reception device comprises: a plurality of power reception resonators that receives the AC power through magnetic field coupling to the plurality of power transmission resonators; a plurality of second circuits; and a rectifier circuit that converts the voltages of the AC power received through the plurality of second circuits to DC voltage. An absolute value of an open-circuit output reverse voltage gain in an F matrix of each of the plurality of first circuits is less than 1, and an absolute value of a short-circuit output reverse current gain in an F matrix of each of the plurality of second circuits is less than 1.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a wireless power transmission system.

  In a wireless power transmission system, power is transmitted wirelessly from a power transmission device to a power reception device. The power transmission device includes a commercial AC power source, an AC / DC converter that converts AC power into DC power, a DC / DC converter that converts an output voltage of the AC / DC converter into an arbitrary voltage, and output power of the DC / DC converter. An inverter that generates high-frequency power and a resonator (power transmission resonator) that generates a magnetic field according to the high-frequency power are provided. The power transmission resonator includes a coil and a capacitor. The high frequency power includes the resonance frequency of the power transmission resonator. This realizes efficient transmission. The power receiving device is a resonator that receives power using a magnetic field transmitted from the power transmitting resonator (power receiving resonator), a rectifier that converts AC power obtained by the power receiving resonator into DC power, and an output voltage of the rectifier that matches the battery. DC / DC converter for converting the voltage into a voltage. A pair of a power transmission resonator and a power reception resonator is referred to as a resonator pair. The power receiving device is connected to the battery, and the output voltage of the DC / DC converter is supplied to the battery. In the wireless power transmission system, power is propagated by a magnetic field radiated from the power transmission resonator toward the power reception resonator. The intensity of the radiated magnetic field (leakage magnetic field) needs to be less than or equal to a value compliant with laws and regulations typified by the Radio Law.

  As a technology for satisfying this requirement, a plurality of power transmission systems and a plurality of power receiving systems are used, and the currents of the respective power transmission systems are adjusted so that magnetic fields radiated from the plurality of power transmission systems cancel each other at an arbitrary point in the distance. One that adjusts the phase relationship is known. However, if there is a difference in the coupling coefficient between each resonator pair, the amplitude of the current of each power transmission resonator is different, and the radiated magnetic field cannot be canceled. In order to improve this, it is necessary to change the output voltage in the DC / DC converter of each transmission system and the output voltage of the rectifier in each power reception system according to each coupling coefficient. However, this complicates the process and lowers the convergence of the control.

International Publication No.2015 / 097806

  The embodiment of the present invention provides a wireless power transmission system capable of reducing the intensity of a radiated magnetic field at a distant arbitrary point as a simple configuration even if there is a difference in the coupling coefficient between the plurality of resonator pairs.

  A wireless power transmission system as an embodiment of the present invention includes an AC power generation circuit that generates AC power, a plurality of first circuits connected to the AC power generation circuit, and each of the plurality of first circuits. A power transmission device including a plurality of power transmission resonators that are connected to different ones and generate a magnetic field according to the AC power received via the plurality of first circuits, and magnetic field coupling between the plurality of power transmission resonators A plurality of power receiving resonators that receive the AC power via the plurality of power receiving resonators, a plurality of second circuits connected to different ones of the plurality of power receiving resonators, respectively, and a plurality of second circuits, And a rectifier circuit that converts the voltage of the AC power received via the plurality of second circuits into a DC voltage. The absolute value of the output open reverse voltage gain in each F matrix of the plurality of first circuits is less than 1, and the absolute value of the output short circuit reverse current gain in each F matrix of the plurality of second circuits is Is less than 1.

The figure which shows the whole structure of the wireless power transmission system which concerns on 1st Embodiment. The figure explaining parameters A-D of F matrix. The figure which shows the structural example of a 1st circuit and a 2nd circuit. The figure which shows the structural example of a power transmission resonator and a power receiving resonator. The block diagram of the power transmission resonator and power receiving apparatus in a basic wireless power transmission system. FIG. 6 is a schematic diagram of a wireless power transmission system in which a first circuit and a second circuit are inserted into the system of FIG. 5. The figure which shows the simulation result explaining the effect of 1st Embodiment. The figure which shows the whole structure of the wireless power transmission system which concerns on 2nd Embodiment. The figure which shows the other example of the whole structure of the wireless power transmission system which concerns on 2nd Embodiment. The figure which shows the whole structure of the wireless power transmission system which concerns on 3rd Embodiment. The figure which shows the other example of the whole structure of the wireless power transmission system which concerns on 3rd Embodiment. The figure which shows the whole structure of the wireless power transmission system which concerns on 4th Embodiment. The figure which shows the other example of the whole structure of the wireless power transmission system which concerns on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an overall configuration of a wireless power transmission system according to the present embodiment. The system includes a power transmission device that wirelessly transmits high-frequency power, a power reception device that receives high-frequency power from the power transmission device, and a battery, and charges the battery with the power transmitted from the power transmission device to the power reception device.

  The power transmission device includes an AC power source 101, an AC / DC converter (AC / DC voltage converter) 102, and a plurality of power transmission systems (two systems in the example in the figure). One power transmission system (referred to as power transmission system A) includes a DC / DC converter (DC / DC voltage converter) 103A, an inverter 104A, a first circuit 105A, and a power transmission resonator 106A. The other power transmission system (referred to as power transmission system B) includes a DC / DC converter (DC / DC voltage converter) 103B, an inverter 104B, a first circuit 105B, and a power transmission resonator 106B. A set of the AC / DC converter 102, the DC / DC converters 103A and 103B, and the inverters 104A and 104B corresponds to the AC power generation circuit 107. The input side of the AC power generation circuit 107 is connected to the AC power source 101, and the output side is connected to the first circuits 105A and 105B.

  The AC power supply 101 supplies AC power (AC voltage and AC current) having a constant frequency. An example of the AC power supply 101 is a commercial power supply. The commercial power source is a device that outputs, for example, a single-phase 100V or three-phase 200V AC voltage at a frequency of 50 Hz or 60 Hz. The AC power supply 101 may be an arbitrary power supply.

  The AC / DC converter 102 is connected to the AC power source 101 via a wiring (cable or the like), and is a circuit that converts the voltage of AC power supplied from the AC power source 101 into a DC voltage.

  The DC / DC converters 103A and 103B are connected to the AC / DC converter 102 via wiring, and are circuits that convert (step up or step down) the DC voltage supplied from the AC / DC converter 102 into different DC voltages. is there. The DC / DC converters 103A and 103B include switching elements such as semiconductor switches, and perform DC / DC conversion by operating the switching elements at a constant operating frequency. The step-up ratio or step-down ratio (hereinafter referred to as the step-up / step-down ratio) of the DC / DC converters 103A and 103B may be individually controllable. Here, it is assumed that the DC / DC converters 103A and 103B have the same step-up / step-down ratio. The same step-up / step-down ratio means that voltages having the same or substantially the same amplitude are output from the DC / DC converters 103A and 103B.

  Inverters 104A and 104B are connected to DC / DC converters 103A and 103B via wiring, and generate AC power (AC current and AC voltage) based on the DC voltage supplied from DC / DC converters 103A and 103B. Circuit. Here, high frequency power is generated as AC power. The inverters 104A and 104B are configured to generate currents having a phase difference of 180 degrees (reverse phase). That is, inverters 104A and 104B are driven in reverse phase. The reason why the phases are reversed is to eliminate or reduce the leakage magnetic field by canceling out the magnetic fields radiated from the power transmission resonators 106A and 106B at a distance. In order to obtain a magnetic field canceling effect, it is not always necessary to have a phase difference of 180 degrees. For example, by providing a phase difference in the range of plus or minus α with respect to 180 degrees, a desired degree of reduction effect is obtained. You may do it.

  The first circuits 105A and 105B are connected to the AC power generation circuit 107. More specifically, the first circuit 105A is connected to the inverter 104A via a wiring, and the first circuit 105B is connected to the inverter 104B via a wiring. That is, the first circuits 105A and 105B are respectively connected to different ones of the inverters 104A and 104B via the wiring. Each of the first circuits 105A and 105B is a circuit in which the absolute value of the output open reverse voltage gain A in the F matrix is less than 1. The first circuits 105A and 105B are composed of a plurality of elements (coils, capacitors, etc.), and the constants (inductance, capacitance, etc.) of these elements satisfy the condition that the output open reverse voltage gain A is less than 1. Is set. In this example, it is assumed that A is set to 0. The reason for setting the value of A in this way will be described later. The configuration of the first circuits 105A and 105B is not limited to a specific configuration and may be arbitrary.

Here, the F matrix is a matrix in which four parameters A, B, C, and D are stored in corresponding elements as follows.
A is the output open reverse voltage gain.
B is the output short-circuit transfer impedance.
C is an output open transmission admittance.
D is the output short-circuit reverse current gain.

FIG. 2 is a diagram illustrating the parameters A to D. The input current and input voltage to the circuit are I ₁ and V ₁ , and the output current and output voltage are I ₂ and V ₂ . At this time, the parameters A to D are expressed as follows.
Moreover, the following formula | equation is materialized.

  In both of the first circuits 105A and 105B, B, C, and D in the F matrix are not limited to specific values or specific ranges. The absolute value of A is preferably 0.5 or less, more preferably 0.1 or less, and most preferably 0. The value of A is assumed to be the same between the first circuits 105A and 105B. However, the present invention is not necessarily limited to this, and the value of A may be different between the first circuit 105A and the first circuit 105B.

  FIG. 3A illustrates a configuration example of the first circuits 105A and 105B. FIG. 3B illustrates another configuration example of the first circuits 105A and 105B. Here, it is assumed that both the first circuits 105A and 105B have the same configuration, but the first circuits 105A and 105B do not have to be the same as long as the above-described condition regarding the value of the parameter A is satisfied.

  In the configuration of FIG. 3A, a plurality of coils 11, 12,... That are inductive elements are connected in series to the positive terminal. One end of each of capacitors 21, 22,..., Which are capacitive elements, is connected between adjacent coils. The other ends of the capacitors 21, 22,... Are connected to the negative terminal. That is, the configuration in FIG. 3A is a ladder circuit and corresponds to the configuration of a low-pass filter.

  In the configuration of FIG. 3B, a plurality of capacitors 31, 32,... That are capacitive elements are connected in series to the positive terminal. One end of each of coils 41, 42,... That is an inductive element is connected between adjacent capacitors. The other ends of the coils 41, 42,... Are connected to the negative terminal. That is, the configuration in FIG. 3B is a ladder circuit and corresponds to the configuration of a high-pass filter.

  The power transmission resonators 106A and 106B are respectively connected to different ones of the first circuits 105A and 105B via wiring. Specifically, the power transmission resonator 106A is connected to the first circuit 105A, and the power transmission resonator 106B is connected to the first circuit 105B. Each of power transmission resonators 106A and 106B includes a coil and a capacitor. The power transmission resonators 106A and 106B receive high frequency power (high frequency current) from the inverters 104A and 105B via the first circuits 105A and 105B, and generate a magnetic field corresponding to the high frequency power. Wireless power transmission is performed by coupling the magnetic field to the power receiving resonators 106A and 106B of the power receiving apparatus. As an example, the frequency of the electric power transmitted wirelessly matches or approximates the resonance frequency of the power transmission resonators 106A and 106B. Thereby, power transmission efficiency can be improved.

  4A to 4C show configuration examples of the power transmission resonators 106A and 106B. Here, the power transmission resonators 106A and 106B have the same configuration, but they may have different configurations. In the configuration of FIG. 4A, a capacitor (capacitance) 282 is connected in series to one end side of a coil (inductor) 292. The capacitor 282 may be connected in series to the opposite side of FIG. 4A, that is, the other end side of the coil 292. Capacitors 282a and 282b may be connected to both sides of the coil 292 as shown in FIG. 4B, or a plurality of coils 292a and 292b and a capacitor 282a are connected in series as shown in FIG. You may connect. The coils 292, 292a, and 292b may be wound around the magnetic core. As the coil shape, a coil having an arbitrary winding method such as spiral winding or solenoid winding may be used. Configurations other than those shown in FIGS. 4A to 4C are possible.

The power receiving apparatus includes a plurality of reception systems (two systems in the example in the figure). The outputs of the two receiving systems are connected to the battery 205. One receiving system (referred to as power receiving system A) includes a power receiving resonator 201A, a second circuit 202A, a rectifier 203A, and a DC / DC converter 204A. The other receiving system (referred to as power receiving system B) includes a power receiving resonator 201B, a second circuit 202B, a rectifier 203B, and a DC / DC converter 204B. A set of the rectifiers 203A and 203B and the DC / DC converter 204A constitutes a rectifier circuit 206.
The input side of the rectifier circuit 206 is connected to the second circuits 202A and 202B, and the output side is connected to the battery 205.

  The power receiving resonator 201A is coupled to the power transmitting resonator 106A via a magnetic field to receive AC power (AC voltage and AC current). Here, high-frequency power is received as AC power. A coupling coefficient between the power receiving resonator 201A and the power transmitting resonator 106A is k1. Power receiving resonator 201B is coupled to power transmitting resonator 106B via a magnetic field, and receives AC power (AC voltage and AC current). A coupling coefficient between the power receiving resonator 201B and the power transmitting resonator 106B is k2.

  The power receiving resonators 201A and 201B include a coil and a capacitor. As an example, the resonance frequencies of the power receiving resonators 201A and 201B match or approximate the frequency of the AC power to be received. As a configuration example of the power receiving resonators 201A and 201B, the configurations shown in FIGS. 4A to 4C can be used, similarly to the power transmitting resonators 106A and 106B.

  Any arrangement relationship between the power transmission resonator 106A and the power reception resonator 201A, the arrangement relationship between the power transmission resonator 106B and the power reception resonator 201B, and magnetic coupling through the space may be used.

  The second circuits 202A and 202B are respectively connected to different ones of the power receiving resonators 201A and 201B via wiring. Specifically, the second circuit 202A is connected to the power receiving resonator 201A, and the second circuit 202B is connected to the power receiving resonator 201B. The second circuits 202A and 202B are circuits in which the absolute value of the output short-circuit reverse current gain D in the F matrix shown in the above formula (A) is less than 1. The second circuits 202A and 202B are composed of a plurality of elements (coils, capacitors, etc.), and the constants of the elements (inductance, capacitance, etc.) are set so as to satisfy the condition that the output open reverse voltage gain D is less than 1. Yes. In this example, the value of D is 0. The reason for setting the value of D in this way will be described later. The configurations of the second circuits 202A and 202B may be arbitrary. As a configuration example of the second circuits 202A and 202B, the configurations shown in FIGS. 3A and 3B can be used as in the first circuits 105A and 105B on the power transmission side.

  In both the second circuits 202A and 202B, A, B, and C in the F matrix are not limited to specific values or specific ranges. The absolute value of D is preferably 0.5 or less, more preferably 0.1 or less, and most preferably 0. The value D of the second circuit 202A may be different from the value D of the second circuit 202B. Here, it is assumed that the value of D is 0 in both the second circuits 202A and 202B.

  The rectifiers 203A and 203B are connected to the second circuits 202A and 202B via wiring. The rectifiers 203A and 203B are circuits that receive AC power from the power receiving resonators 201A and 201B via the second circuits 202A and 202B, and convert the voltage of the AC power into DC voltage.

  The DC / DC converters 204A and 204B are connected to the rectifiers 203A and 203B via wiring, and a constant DC voltage output from the rectifier 203 is converted to a voltage that can be used by the battery 205 (more than the constant DC voltage). This is a circuit that converts the voltage into a high voltage, the same voltage, or a low voltage and outputs it. A battery 205 is connected to the subsequent stage of the DC / DC converter 204 via wiring. The step-up / step-down ratios of the DC / DC converters 204A and 204B may be individually controllable.

  The battery 205 is a device that stores electric power input from the DC / DC converters 204A and 204B. Instead of the battery 205, a resistor (such as a motor) that consumes power may be used. The resistor and the battery may be collectively referred to as a load device.

  As described above, the absolute value of the value A of the F matrix of each of the first circuits 105A and 105B is less than 1, and is 0 in this example. Further, the absolute value of D in each F matrix of the second circuits 202A and 202B is less than 1, and is 0 in this example. When the condition that A and D are 0 is satisfied, the absolute values of the currents of the power transmission resonator 106A and the power reception resonator 201A do not depend on the coupling coefficient k1 between the power transmission resonator 106A and the power reception resonator 201A. The absolute values of the currents of the resonator 106B and the power receiving resonator 201B do not depend on the coupling coefficient k1 between the power transmitting resonator 106A and the power receiving resonator 201A (details will be described later). Therefore, if the step-up / step-down ratios of the inverters 104A and 104B of the two power transmission systems are set to the same value (the output voltages of the inverters 104A and 104B are set to the same value), the step-up / step-down ratios of the rectifiers 203A and 203B of the two power receiving systems The current flowing through the power transmission resonator and the power reception resonator in the system A (the power transmission system A and the power reception system A) can be made equal to the current flowing through the power transmission resonator and the power reception resonator in the system B (power transmission system B and the power reception system B). This greatly simplifies charging control.

  If the value of A in the F matrix of each of the first circuits 105A and 105B is less than 1 and the value of D in the F matrix of each of the second circuits 202A and 202B is less than 1, the power transmission resonator 106A and The dependency of the absolute value of the current of the power receiving resonator 201A on the coupling coefficient k1 can be reduced, and the dependency of the absolute value of the current of the power transmission resonator 106B and the power receiving resonator 201B on the coupling coefficient k2 can be reduced. The closer the values of A and D are to 0, the greater this effect. Therefore, the current flowing through the power transmission resonator and the power reception resonator in the system A (the power transmission system A and the power reception system A) is changed to the system B (the power transmission system B and the power reception system) with a simple configuration regardless of the difference between the coupling coefficients k1 and k2. The currents flowing in the power transmission resonator and the power reception resonator in the system B) can be the same or close. Since the dependence on the coupling coefficients k1 and k2 can be reduced, the control for individually controlling the step-up / step-down ratio of the DC / DC converters 103A and 103B and the DC / DC converters 204A and 204B is also simplified.

  Hereinafter, the absolute value of the A value of the F matrix of each of the first circuits 105A and 105B is less than 1 or 0, and the absolute value of D of the F matrix of each of the second circuits 202A and 202B is less than 1 or 0. The reason why the above-described effect can be obtained will be described.

As described above, the wireless power transmission system according to the present embodiment cancels the magnetic field at any distant point by driving the inverters of the two power transmission systems in opposite phases. Here, in order to cancel a far magnetic field, i is the sum of the power transmission resonator current i _tx1 of one power transmission system and the power reception resonator current i _{rx1 of} one power reception system corresponding to the one power transmission system. _trx1 is a power transmitting resonator current i _tx2 of the other grid, it is required equal to i _TRX2 is the sum of the power-receiving resonator current i _rx2 of the other power receiving system corresponding to the other grid. This relationship is expressed as follows.

FIG. 5A is a block diagram of a power transmission resonator and a power receiving device in a basic wireless power transmission system. This system is a system of one system (one power transmission system and one power reception system).
Here, on the power transmission side (primary side)
And form a power transmission resonator. The resonance frequency f ₀ of this resonator is assumed to be equal to the frequency of the input AC voltage. Also, the power receiving side (secondary side)
Is a power receiving resonator that resonates at a resonance frequency f ₀ . V _B indicates a battery (storage battery) charged by the present system. Z _rec is the input impedance of the rectifier 301, and v _rec is the input AC voltage to the rectifier 301. further,
Are magnetically coupled by a coupling coefficient k. Here, the mutual inductance M is expressed by the following equation.

FIG. 5B is obtained by replacing the circuit of FIG. 5A with a T-type circuit using mutual inductance. The F matrix F _reso from the input terminal of the power transmission resonator to the output terminal of the power reception resonator is expressed as _follows .
Here, ω ₀ is the resonance angular frequency and is expressed as ω ₀ = 2πf ₀ . From FIG. 5B and equation (5), i _tx and i _rx are expressed as follows.
In addition, the inverse transfer function
Is shown below.
Therefore, from the equation (8), Z _rec is expressed as follows.

Here, when the voltage conversion ratio of the rectifier 301 is 1, the absolute value of v _rec is shown as follows.
Therefore, | i _tx | and | i _rx | are derived from equations (7), (9), and (10) as follows.

From equations (11) and (12), it can be confirmed that the absolute value | i _tx | of the input current of the power transmission resonator and the output current | i _rx | of the power reception resonator depend on the coupling coefficient k. Here, a large displacement tolerance is required for a system that charges a moving body such as a vehicle. However, when an installation error occurs between the power transmission resonator and the power reception resonator, the coupling coefficient k ₁ between the power transmission / reception resonators of one system and the coupling coefficient k ₂ between the power transmission / reception resonators of the other system shown in FIG. The difference increases as the positional deviation increases. For this reason, Δi _trx increases and the magnetic field canceling effect decreases.

Here, even when a positional deviation occurs due to an installation error, a ladder circuit (corresponding to the first circuit) is inserted between the inverter and the power transmission resonator in order to reduce Δi _trx , and power reception Consider inserting a ladder circuit (corresponding to the second circuit) between the resonator and the rectifier.

  FIG. 6 is a schematic diagram of a wireless power transmission system in which a first circuit is inserted between the inverter and the power transmission resonator and a second circuit is inserted between the power reception resonator and the rectifier in the system of FIG. .

F _TLC represents the F matrix of the first circuit 311, F _RLC represents the F matrix of the second circuit 312, and F _all represents the F matrix from the inverter output terminal to the input terminal of the rectifier 301. _Place F _TLC , F _RLC and F _all as follows:

From FIG. 6 and equations (5) and (14), i _tx and i _rx are expressed as follows.
Furthermore, the input current i _rec of the rectifier 301 is expressed as follows:
From equations (14) and (18), v _rx is expressed as follows.
Plus reverse voltage gain
As shown below,
From equation (20), Z _rec is
It is shown.
Further, from the formulas (10), (13) and (14), F _all is
It is shown.
Therefore, from equations (16), (17), (18), (19), (21) and (22), i _tx and i _rx are expressed as follows.
Where β is the rectifier input voltage to inverter output voltage ratio,
Given in.

Here, when the first circuit 311 and the second circuit 312 are composed of passive elements
It is.
Therefore, from equations (23), (24) and (25), i _tx and i _rx are
It is derived. Here, when A _TLC and D _RLC are 0, the coefficient of M is 0, so from equations (10), (26), and (27),
Is guided.

From equations (28) and (29), it is understood that the absolute values | i _tx | and | i _rx | of the transmitting and receiving resonator currents do not depend on the coupling coefficient k.

Therefore, in the configuration of FIG. 1, A of the F matrix of each of the first circuits 105A and 105B is 0 (corresponding to the case where A _TLC is 0 in the example of FIG. 6), and the F matrix of each of the second circuits 202A and 202B. If the condition of D of 0 is satisfied (corresponding to the case where A _RLC is 0 in the example of FIG. 6), the step-up / step-down ratios of the inverters 104A and 104B of the two power transmission systems are set to the same value, and the rectifiers 203A of the two power receiving systems , 203B can be equalized between the two systems by simply setting the step-up / step-down ratio of 203B to the same value. This greatly simplifies charging control.

In the example described above, the case where A _TLC and D _RLC are 0 in Equations (26) and (27) has been described. However, if A _TLC and D _RLC are less than 1, the transmitting resonator current and the receiving resonator current are The dependence of the absolute values | i _tx | and | i _rx | on the coupling coefficient k can be reduced. The closer to 0, the lower the dependency on the coupling coefficient k.

That is, in the example of FIG. 6, a state in which the first circuit 311 and the second circuit 312 are omitted, the power transmission resonator is directly connected to the input terminal by wiring, and the power receiving resonator is directly connected to the rectifier 301 by wiring. That is, consider a system in which the first circuit and the second circuit do not exist. At this time, the following holds.

Therefore, by providing a first circuit with A _TLC smaller than 1 on the power transmission side and a second circuit with D _RLC smaller than 1 on the power receiving side, compared to a wireless power transmission system in which the first circuit and the second circuit do not exist The effect of the present embodiment (dependence on the coupling coefficient k can be reduced) can be obtained.

  The effect of this embodiment will be described in comparison with related technology. FIG. 7 shows a simulation result for explaining the effect of the present embodiment. As a related technique, a configuration in which the first circuits 105A, 105B, 202A, and 202B are omitted from the configuration in FIG. 1 is used. The step-up / step-down ratios of the DC / DC converters 103A and 103B on the power transmission side are the same (the output voltages are the same or substantially the same), and the step-up / step-down ratios of the power-receiving side DC / DC converters 204A and 204B are the same. In addition, the value of the parameter A in the F matrix of the first circuits 105A and 105B is 0, and the value of the parameter D in the F matrix of the second circuits 202A and 202B is 0.

  Between the coupling coefficient k1 of the resonator pair A (the pair of the power transmitting resonator 106A and the power receiving resonator 201A) and the coupling coefficient k2 of the resonator pair B (the pair of the power transmitting resonator 106B and the power receiving resonator 201B) − FIG. 7 shows the result of calculating the current difference between the two power transmission resonators 106A and 106B and the current difference between the power reception resonators 201A and 201B when there is a difference of 0.2 to 0.2. . For the calculation, simulation software SPICE (Simulation Program with Integrated Circuit Emphasis) is used.

  From FIG. 7, in the wireless power transmission system in which the first circuits 105A, 105B, 202A, 202B according to the present embodiment are inserted, even if a coupling coefficient difference occurs between the resonator pair A and the resonator pair B, The currents of the resonators 106A and 106B are substantially constant, and the currents of the power receiving resonators 201A and 201B are also substantially constant. For this reason, the step-up / step-down ratio of the DC / DC converters 103A and 103B on the power transmission side can be made common, and the step-up / step-down ratio of the DC / DC converters 204A and 204B on the power receiving side can be made common. Therefore, the control variable can be reduced, and the leakage magnetic field can be reduced with a simple configuration.

(Second Embodiment)
FIG. 8 shows the overall configuration of the wireless power transmission system according to the present embodiment. Elements that are the same as or correspond to those in FIG. 1 are given the same reference numerals, and redundant descriptions are omitted.

  In the first embodiment, each of the two power transmission systems is provided with a DC / DC converter and an inverter. However, in this embodiment, the DC / DC converter 103 and the inverter 104 are common to the two power transmission systems. Is provided. One of the two power transmission systems corresponds to the set of the first circuit 105A and the power transmission resonator 106A, and the other power transmission system corresponds to the set of the first circuit 105B and the power transmission resonator 106B.

  In order to reverse the currents of the power transmission resonators 106A and 106B, the connection of the two input terminals (plus terminal and minus terminal) of the power transmission resonator 106B to the first circuit 105B is opposite to that in FIG.

  In the first embodiment, each of the two power receiving systems is provided with a rectifier and a DC / DC converter. However, in this embodiment, the rectifier 203 and the DC / DC converter are common to the two power receiving systems. 204 is provided. One of the two power receiving systems corresponds to a set of the power receiving resonator 201A and the second circuit 202A, and the other power receiving system corresponds to a set of the power receiving resonator 201B and the second circuit 202B. In order to make the phases of the currents input from the two power receiving systems to the rectifier 203 in phase, the connection of the two output terminals (plus terminal and minus terminal) of the power receiving resonator 201B to the second circuit 202B is opposite to FIG. It has become.

In the first circuits 105A and 105B, as in the first embodiment, the constants of the plurality of elements are set so that the absolute value of the output open reverse voltage gain A in the F matrix of the first circuits 105A and 105B is less than 1. Has been. As an example, the value of A is 0 in both circuits. In the second circuits 202A and 202B, as in the first embodiment, the constants of the plurality of elements are set so that the absolute value of the output short circuit reverse current gain D in the F matrix of the second circuits 202A and 202B is less than 1. Has been.
As an example, the value of D is 0 in both circuits.

  With the above configuration, the amplitude of the transmission currents of the two power transmission systems is the same or close and the amplitude of the power reception currents of the two power reception systems is the same with a simple configuration regardless of the difference in the coupling coefficient between each resonator pair. Or you can be close. Thereby, the strength of the leakage magnetic field can be reduced.

  FIG. 9 shows another example of the overall configuration of the wireless power transmission system according to the present embodiment. Differences from FIG. 8 will be described. The positive terminal on the input side of the first circuit 105B on the power transmission side is electrically connected to the negative terminal on the output side of the inverter 104, and the negative terminal on the input side of the first circuit 105B on the power transmission side is connected to the output side of the inverter 104. Is electrically connected to the positive terminal. As a result, the current input to the first circuit 105B is out of phase with the current input to the first circuit 105A.

  Further, the positive terminal on the output side of the second circuit 202B on the power receiving side is electrically connected to the negative terminal on the input side of the rectifier 203, and the negative terminal on the output side of the second circuit 202B is connected to the input side of the rectifier 203. Electrically connected to the positive terminal. As a result, the current output from the second circuit 202B is in phase with the current output from the second circuit 202A. The effect of this configuration is the same as in FIG.

(Third embodiment)
FIG. 10 shows the overall configuration of the wireless power transmission system according to the present embodiment. The configuration of the power transmission device is the same as that in FIG. 1 of the first embodiment. The configuration of the power receiving apparatus is the same as that in FIG. 8 of the second embodiment. The conditions relating to the parameter A of the F matrix of each of the first circuits 105A and 105B on the power transmission side and the conditions relating to the parameter D of the F matrix of each of the second circuits 202A and 202B on the power receiving side are the same.

  With the above configuration, the same effect as that of the first embodiment can be obtained. That is, regardless of the difference in the coupling coefficient between the resonator pairs, the amplitude of the transmission currents of the two transmission systems can be made the same or close with a simple configuration. Therefore, the strength of the leakage magnetic field can be reduced by simple control regardless of the difference in the coupling coefficient between the resonator pairs.

  FIG. 11 shows another example of the overall configuration of the wireless power transmission system according to the present embodiment. The configuration of the power transmission device is the same as that of the first embodiment. The configuration of the power receiving apparatus is the same as that in FIG. 9 of the second embodiment. The effect of this configuration is the same as in FIG.

(Fourth embodiment)
FIG. 12 shows the overall configuration of the wireless power transmission system according to the present embodiment. The configuration of the power transmission device is the same as that in FIG. 8 of the second embodiment. The configuration of the power receiving apparatus is the same as that in FIG. 1 of the first embodiment. The conditions relating to the parameter A of the F matrix of each of the first circuits 105A and 105B on the power transmission side and the conditions relating to the parameter D of the F matrix of each of the second circuits 202A and 202B on the power receiving side are the same.

  With the above configuration, the amplitudes of the received currents of the two power receiving systems can be made the same or close with a simple configuration regardless of the difference in the coupling coefficient between the resonator pairs. Thereby, the strength of the leakage magnetic field can be reduced.

  FIG. 13 shows another example of the overall configuration of the wireless power transmission system according to the present embodiment. The configuration of the power transmission device is the same as that in FIG. 9 of the second embodiment. The configuration of the power receiving apparatus is the same as that in FIG. 1 of the first embodiment. The effect of this configuration is the same as that of FIG.

(Other embodiments)
In each of the embodiments described above, the number of power transmission systems is two. Moreover, the number of power receiving systems was two.
However, in each embodiment, the number of power transmission systems may be three or more. Further, the number of power receiving systems may be three or more. Also in this case, a first circuit is arranged in each power transmission system, and a second circuit is arranged in each power reception system. What is necessary is just to adjust the phase relationship of the transmission current of these power transmission systems according to the number of power transmission systems. For example, when the number of power transmission systems is 3, an alternating current may be generated by an inverter of each power transmission system so that the phases differ between the three power transmission systems by 120 degrees. If the number of transmission systems is N, the number of first circuits is also N, and the AC power current supplied from the AC power generation circuit 107 (FIG. 1) to the plurality of first circuits is 360 degrees / N. The AC current is out of phase.
Thus, also in the case of three or more systems, the same effects as those of the first to fourth embodiments described above can be obtained. Therefore, a wireless power transmission system that cancels out the magnetic field radiated from each power transmission system at a distant point can be realized with a simple configuration.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

11, 12, 31, 32, 292, 292a, 292b: inductor (coil)
21, 22, 41, 42, 282, 282a, 282b: capacitors (capacitance)
101: AC power supply 102: AC / DC converters 103, 103A, 103B, 204, 204A, 204B: DC / DC converters 104, 104A, 104B: Inverters 105A, 105B, 311: First circuit (power transmission side ladder type circuit)
202A, 202B, 312: second circuit (power receiving side ladder type circuit)
106A, 106B: Power transmission resonator 107: AC power generation circuit 201A, 201B: Power reception resonator 203, 203A, 203B, 301: Rectifier 205: Battery (load device)
206: Rectifier circuit

Claims (9)

An AC power generation circuit for generating AC power, a plurality of first circuits connected to the AC power generation circuit, and a plurality of first circuits connected to different ones of the plurality of first circuits, respectively. A plurality of power transmission resonators that generate a magnetic field in accordance with the AC power received via the power transmission device,
A plurality of power receiving resonators that receive the AC power via magnetic field coupling with the plurality of power transmission resonators, a plurality of second circuits that are respectively connected to different ones of the plurality of power receiving resonators, and A rectifier circuit that is connected to a plurality of second circuits and converts the voltage of the AC power received via the plurality of second circuits into a DC voltage, and a power receiving device including:
The absolute value of the output open reverse voltage gain in each F matrix of the plurality of first circuits is less than 1, and the absolute value of the output short circuit reverse current gain in each F matrix of the plurality of second circuits is Wireless power transmission system that is less than one. The AC power generation circuit includes an AC / DC converter that converts an AC voltage supplied from an AC power source into a DC voltage, a plurality of DC / DC converters that convert the DC voltage into different DC voltages, and the DC / DC converters. A plurality of inverters that generate AC power based on the DC voltage converted by the DC converter,
The wireless power transmission system according to claim 1, wherein the step-up ratio or step-down ratio of the plurality of DC / DC converters is the same. The rectifier circuit includes a plurality of rectifiers that convert the voltage of the AC power into the DC voltage, and a plurality of DC / DC converters that convert the voltages converted by the plurality of rectifiers into different DC voltages,
The wireless power transmission system according to claim 1, wherein step-up ratios or step-down ratios of the plurality of DC / DC converters are the same. 4. Each of the plurality of first circuits includes a plurality of inductive elements connected in series and a capacitive element having one end connected between adjacent inductive elements. The wireless power transmission system described in 1. Each of the plurality of second circuits includes a plurality of inductive elements connected in series and a capacitive element having one end connected between adjacent inductive elements. The wireless power transmission system described in 1. 4. Each of the plurality of first circuits includes a plurality of capacitive elements connected in series and an inductive element having one end connected between adjacent capacitive elements. 5. The wireless power transmission system described in 1. 7. Each of the plurality of second circuits includes a plurality of capacitive elements connected in series and an inductive element having one end connected between adjacent capacitive elements. The wireless power transmission system according to one item. The absolute value of the output open reverse voltage gain of each of the plurality of first circuits is 0, and the absolute value of the output short circuit reverse current gain of each of the plurality of second circuits is 0. The wireless power transmission system according to any one of 1 to 7. The number of the plurality of first circuits is N,
9. The radio according to claim 1, wherein currents of AC power supplied from the AC power generation circuit to the plurality of first circuits are AC currents whose phases are shifted by 360 degrees / N, respectively. Power transmission system.