JP2020174453A - Non-contact power supply system - Google Patents

Abstract

To provide a technique for enhancing power transmission efficiency from a power transmission side to a power reception side without performing communication between the power transmission side and the power reception side in a non-contact power supply system.SOLUTION: Non-contact power supply systems 300, 300b, 300c comprise: AC conversion circuits 122 which convert DC power to be input from a power source 130 into AC power to be output; power transmission apparatuses 100, 100b, 100c having power transmission coils 112 which transmit the AC power to be output from the AC conversion circuits; and power reception apparatuses 205 having power reception coils 212 which receive the AC power by non-contact from the power transmission coils. The power transmission apparatuses may comprise power transmission controllers 150, 150c which acquire current values flowing in the power transmission apparatuses, calculate voltage values at which transmission efficiency of the AC power from the power transmission coils to the power reception coils become higher by using the acquired current values, and control the AC conversion circuits to output the AC power at the calculated voltage values.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a contactless power supply system.

In a non-contact power supply system, the power transmission efficiency between the power transmission side and the power reception side is improved by transmitting the current value detected on the power reception side to the power transmission side and adjusting the input voltage to the resonant circuit from the received current value on the power transmission side. Techniques for enhancing are known (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2014-155328

In the conventional technology, since the information on the power receiving side is transmitted to the power transmission side, for example, there is a problem that the power transmission efficiency is lowered due to the deterioration of the communication state between the power transmission side and the power reception side or the communication lag between the power transmission side and the power reception side. There is. Such a problem becomes more remarkable when the power receiving side is a moving body such as a vehicle because the environment on the power receiving side can change from moment to moment.

The present disclosure can be realized in the following forms.

(1) According to one embodiment of the present disclosure, a non-contact power feeding system (300, 300b, 300c) is provided. This non-contact power supply system includes an AC conversion circuit (122) that converts DC power input from a power source (130) into AC power and outputs it, and a power transmission coil (12) that transmits AC power output from the AC conversion circuit. It includes a power transmission device (100, 100b, 100c) having a power transmission device (112), and a power reception device (205) having a power reception coil (212) that receives AC power from the power transmission coil in a non-contact manner. The power transmission device acquires a current value flowing through the power transmission device, and uses the acquired current value to calculate a voltage value at which the transmission efficiency of AC power from the power transmission coil to the power reception coil is high, and the calculation is performed. A power transmission control device (150, 150c) that controls the AC conversion circuit so as to output AC power of a voltage value may be provided.

According to this form of non-contact power supply system, the voltage value that the power transmission control device of the power transmission equipment outputs to the AC conversion circuit using the current value flowing through the power transmission equipment without communicating between the power transmission side and the power reception side. Can be calculated. Since the power transmission control device controls the AC conversion circuit so as to output a voltage value that increases the transmission efficiency, the power transmission efficiency from the power transmission side to the power reception side is high without communication between the power transmission side and the power reception side. can do.

A block diagram showing the overall configuration of a contactless power supply system. A block diagram showing a non-contact power transmission device and a non-contact power receiving device. Explanatory drawing which shows the equivalent circuit of FIG. The block diagram which shows the non-contact power transmission apparatus in 2nd Embodiment. The block diagram which shows the non-contact power transmission apparatus in 3rd Embodiment.

A. First Embodiment:
As shown in FIG. 1, the non-contact power supply system 300 of the present embodiment is a system capable of supplying electric power while the vehicle 200 is traveling. The vehicle 200 is composed of a vehicle equipped with a drive motor such as an electric vehicle or a hybrid vehicle, for example. The non-contact power feeding system 300 includes a non-contact power transmitting device 100 installed on the road RS and functioning as a power transmitting device, and a non-contact power receiving device 205 mounted on a vehicle 200 traveling on the road RS and functioning as a power receiving device.

The non-contact power transmission device 100 includes a plurality of power transmission resonance circuits 110, a plurality of power transmission circuits 120 that supply AC voltage to the plurality of power transmission resonance circuits 110, and a power supply circuit 130 that supplies DC voltage to the plurality of power transmission circuits 120. It includes a power receiving coil position detection unit 140 and a power transmission control device 150.

The plurality of power transmission resonance circuits 110 are embedded inside the road RS along the traveling direction of the vehicle 200, which is the extending direction of the road RS. Each power transmission resonant circuit 110 includes a power transmission coil and a resonant capacitor as described below. In the power transmission resonance circuit 110, it is not necessary to install both the power transmission coil and the resonance capacitor along the extending direction of the road RS, and a plurality of power transmission coils may be installed along the extending direction of the road RS.

The plurality of power transmission circuits 120 are circuits that convert DC power supplied from the power supply circuit 130 into high-frequency AC power and supply it to the power transmission coil of the power transmission resonance circuit 110. A specific configuration example of the power transmission circuit 120 will be described later. The power supply circuit 130 is a circuit that supplies DC power to the power transmission circuit 120.

The power receiving coil position detection unit 140 detects the position of the power receiving coil installed at the bottom of the vehicle 200 of the power receiving resonance circuit 210, which will be described later. The plurality of power transmission circuits 120 execute power transmission using one or more power transmission resonance circuits 110 close to the power reception resonance circuit 210 according to the position of the power reception coil of the power reception resonance circuit 210 detected by the power reception coil position detection unit 140. To do.

The vehicle 200 includes a non-contact power receiving device 205, a main battery 230, a motor generator 240, a power receiving side inverter circuit 250, a DC / DC converter circuit 260, an auxiliary battery 270, an auxiliary machine 280, and a power receiving control device. It is equipped with 290. The non-contact power receiving device 205 has a power receiving resonance circuit 210 and a power receiving circuit 220.

The power receiving resonance circuit 210 includes a power receiving coil and a resonance capacitor, which will be described later, and is a device that receives AC power induced in the power receiving coil by an electromagnetic induction phenomenon with the power transmission resonance circuit 110. The power receiving circuit 220 is a circuit that converts AC power output from the power receiving resonance circuit 210 into DC power. A specific configuration example of the power receiving circuit 220 will be described later. The DC power output from the power receiving circuit 220 can be used to charge the main battery 230 as a load, and also for charging the auxiliary battery 270, driving the motor generator 240, and driving the auxiliary machine 280. Is also available.

The main battery 230 is a secondary battery that outputs DC power for driving the motor generator 240. The motor generator 240 operates as a three-phase AC motor and generates a driving force for traveling the vehicle 200. The motor generator 240 operates as a generator when the vehicle 200 is decelerated, and generates three-phase AC power. When the motor generator 240 operates as a motor, the power receiving side inverter circuit 250 converts the DC power of the main battery 230 into three-phase AC power to drive the motor generator 240. When the motor generator 240 operates as a generator, the power receiving side inverter circuit 250 converts the three-phase AC power output by the motor generator 240 into DC power and supplies it to the main battery 230.

The DC / DC converter circuit 260 converts the DC voltage of the main battery 230 into a lower DC voltage and supplies it to the auxiliary battery 270 and the auxiliary 280. The auxiliary battery 270 is a secondary battery that outputs DC power for driving the auxiliary battery 280. The auxiliary machine 280 is a peripheral device such as an air conditioner or an electric power steering device.

The power receiving control device 290 includes a CPU and a memory, and controls each part in the vehicle 200. The power receiving control device 290 controls the power receiving circuit 220 to receive power when receiving non-contact power supply during traveling.

One power transmission circuit 120 and power transmission resonance circuit 110 of the non-contact power transmission device 100, and the power reception resonance circuit 210 and power reception circuit 220 of the non-contact power reception device 205 of the vehicle 200 are composed of the circuits shown in FIG.

In the present embodiment, the power transmission resonance circuit 110 has a power transmission coil 112 and a resonance capacitor 116 connected in series. The power receiving resonance circuit 210 has a power receiving coil 212 and a resonance capacitor 216 connected in series. In the present embodiment, the magnetic resonance method by the primary series secondary series capacitor method (also referred to as “SS method”) is applied to the power transmission resonance circuit 110 and the power reception resonance circuit 210.

The power transmission resonance circuit 110 and the power reception resonance circuit 210 apply a non-contact power feeding system of a power transmission side single phase to a power reception side single phase, the power transmission side is composed of a single phase power transmission coil 112, and the power reception side is a single phase power reception coil. It is composed of 212. The inductance value of the power transmission coil 112 is represented by Lr1, and the capacitance value of the resonant capacitor 116 is represented by Cr1. The inductance value of the power receiving coil 212 is represented by Lr2, and the capacitance value of the resonant capacitor 216 is represented by Cr2.

The power transmission circuit 120 includes an inverter circuit 122, a current sensor 123 that acquires a current value of AC power output from the inverter circuit 122, and an imittance conversion circuit 124 having two inductances 124L and one capacitor 124C. There is. The imittance conversion circuit 124 is configured as a T-LCL type low-pass filter. The inductance value of the inductance 124L is represented by L1, and the capacitance value of the capacitor 124C is represented by C1. The inverter circuit 122 functions as an AC conversion circuit that converts DC power from the power supply circuit 130 into AC power and outputs it. In the present embodiment, the inverter circuit 122 adjusts the output voltage by switching the switching pulse width (also referred to as duty cycle) by PWM control.

The power receiving circuit 220 includes an imitation conversion circuit 224 having two inductances 224L and one capacitor 224C, a rectifying circuit 226 that converts AC power into DC power, and power conversion that converts AC power into DC power suitable for charging the main battery 230. It has a DC / DC converter circuit 228 as a circuit. The imittance conversion circuit 224 is configured as a T-LCL type low-pass filter. The inductance value of the inductance 224L is represented by L2, and the capacitance value of the capacitor 224C is represented by C2.

In the following description, for convenience of explanation, the inductance and capacitor included in the imitation conversion circuits 124 and 224, and the coil and capacitor included in the power transmission resonance circuit 110 and the power reception resonance circuit 210 are designated by symbols indicating their respective values. It may be shown by using. For example, the inductance 124L of the imittance conversion circuit 124 may be indicated as "inductance L1" by using the inductance value L1.

The configuration from the power supply circuit 130 of the non-contact power transmission device 100 shown in FIG. 2 to the power receiving circuit 220 on the power receiving side is represented by the equivalent circuit shown in FIG. The power supply circuit 130 and the inverter circuit 122 are replaced with an AC power supply SAC. The power transmission resonance circuit 110 and the power reception resonance circuit 210 are replaced with a T-type equivalent circuit TEC using the mutual inductance Lm between the power transmission coil Lr1 and the power reception coil Lr2. The T-type equivalent circuit TEC is also called a power transmission / reception circuit TEC. R1 and R2 are winding resistors. The rectifier circuit 226 and the DC / DC converter circuit 228 are replaced with impedance Z4.

In the following description, the impedance seen from the terminal pair P1-P1 * on the input side of the imittance conversion circuit 124 on the power transmission side to the input side of the imittance conversion circuit 124 is defined as Z1. Impedance Z1 is V1 / I1. V1 is the voltage between the terminals and P1-P1 *, and is the voltage of the AC power output from the inverter circuit 122. I1 is the current of the AC power output from the inverter circuit 122, and is the current flowing through the imittance conversion circuit 124. The characteristic impedance of the imittance conversion circuit 124 is Z01.

Let Z2 be the impedance seen from the terminal pair P2-P2 * on the output side of the imittance conversion circuit 124 to the rear stage side. Impedance Z2 is V2 / I2. V2 is the voltage between the terminals and P2-P2 *, and I2 is the current flowing to the rear stage side. The impedance of the input side of the imittance conversion circuit 224 on the power receiving side as seen from the terminal pair P3-P3 * on the input side of the imittance conversion circuit 224 is Z3. Impedance Z3 is V3 / I3. V3 is the voltage between the terminals and P3-P3 *, and I3 is the current flowing through the imittance conversion circuit 224. The characteristic impedance of the imittance conversion circuit 224 is Z03. The impedance seen from the terminal pair P4-P4 * on the output side of the imittance conversion circuit 224 to the rear stage side is Z4. Impedance Z4 is represented by V4 / I4. V4 is the voltage between the terminals and P4-P4 *, and I4 is the current flowing to the rear stage side. This impedance Z4 is an impedance that changes according to the state of the main battery 230. Impedance Z4 is highest when the main battery 230 is fully charged, and impedance Z4 is lowest when the voltage of the main battery 230 is the lowest voltage allowed for use. This is the case when charging is performed with the highest current.

In the imittance conversion circuit 124 on the transmission side of FIG. 3, AC power of voltage V1 and current I1 is input from the AC power supply SAC, and impedance Z2 is connected to the output side (also referred to as “rear stage side”) of the imittance conversion circuit 124. It can be thought of as an equivalent circuit. In the following description, this impedance Z2 is also referred to as "post-stage impedance Z2".

The rear impedance Z2 is represented by the following equation (1).
Z2 = Z02 ² / Z3 = (Z02 ² / Z03 ² ) ・ Z4 ・ ・ ・ (1)
Z02 is the characteristic impedance of the T-type equivalent circuit TEC, and Z03 is the characteristic impedance of the imittance conversion circuit 124 on the power receiving side. The characteristic impedance Z02 of the T-type equivalent circuit TEC is represented by the following equation (2) using the angular frequency of AC power as ω1.
Z02 = ω1 ・ Lm ・ ・ ・ (2)

The transmission efficiency from the power transmission resonance circuit 110 to the power reception resonance circuit 210 via the T-type equivalent circuit TEC is represented by a voltage ratio of V3 / V2. When V2 = Z01 / I1 and V3 = V1 / Z02 / Z01 and the optimum voltage ratio for obtaining the maximum efficiency is a1, the relationship between the transmission efficiency for obtaining the maximum efficiency and the optimum voltage ratio a1 is expressed by the following equation ( It is represented by 3). The voltage V1 between the terminals and P1-P1 * at which the maximum efficiency can be obtained can be expressed by the following equations (4) from the equation (3).

In the present embodiment, as described above, the magnetic resonance method based on the SS method is applied to the power transmission resonance circuit 110 and the power reception resonance circuit 210. Therefore, the optimum voltage ratio a1 can be expressed by the following equation (5).

Next, the details of the power transmission control device 150 will be described with reference to FIG. The power transmission control device 150 includes a mutual inductance estimation unit 152, a correction unit 154, a command voltage calculation unit 156, and a signal generation unit 158. The power transmission control device 150 is composed of a microcomputer including a CPU and a memory, and each part is made to function by reading a program in the memory by the CPU.

The mutual inductance estimation unit 152 acquires an estimated value of the mutual inductance Lm. In the present embodiment, the mutual inductance estimation unit 152 has a correspondence map showing the correspondence between the relative position of the power receiving coil 212 with respect to the power transmission coil 112 and the mutual inductance Lm. A correspondence map showing the correspondence between the relative position of the power receiving coil 212 with respect to the power transmission coil 112 and the mutual inductance Lm is created using theoretical values, and is also created using the results of analysis and actual machine evaluation, and the power transmission control device 150 It is stored in advance in the memory of. The mutual inductance estimation unit 152 determines the estimated value of the mutual inductance Lm from the corresponding map using the relative position of the power receiving coil 212 detected by the power receiving coil position detecting unit 140, and outputs the estimated value to the correction unit 154. The power receiving coil position detection unit 140 may detect the position of the power receiving coil 212 of the power receiving resonance circuit 210 from the magnitudes of the transmitted power and the transmitted current in the plurality of power transmission circuits 120, or detect the position of the vehicle 200. The position of the power receiving coil 212 of the power receiving resonance circuit 210 may be detected by using a position sensor or a distance measuring device.

The correction unit 154 corrects the characteristic impedance Z02 of the T-type equivalent circuit TEC from the estimated value of the mutual inductance Lm. More specifically, when the correction unit 154 receives the input of the estimated value of the mutual inductance Lm from the mutual inductance estimation unit 152, the correction unit 154 calculates the corrected characteristic impedance Z02 from the above equation (2). The corrected characteristic impedance Z02 is output to the command voltage calculation unit 156.

The command voltage calculation unit 156 outputs the calculated command voltage value V1 to the signal generation unit 158. More specifically, the command voltage calculation unit 156 uses the current value I1 of the output current from the inverter circuit 122 acquired from the current sensor 123 and the corrected characteristic impedance Z02 acquired from the correction unit 154 to describe the above. The command voltage value V1 is calculated from the above equations (4) and (5). The calculated command voltage value V1 is output to the signal generation unit 158. As the mutual inductance Lm of the formula (5), the estimated value of the mutual inductance Lm obtained from the mutual inductance estimation unit 152 may be used, or the mutual inductance Lm of a predetermined set value may be used.

The signal generation unit 158 calculates the duty cycle duty 1 in which the output voltage of the inverter circuit 122 is the command voltage value V1 based on the input command voltage value V1 by using the following equation (6). Let Vin be the input voltage to the inverter circuit 122 output from the power supply circuit 130.

The duty cycle duty 1 may be calculated by using, for example, a map in which the command voltage value V1 and the duty cycle duty 1 are related, without using the above equation (6). A rate limiter may be provided between the signal generation unit 158 and the command voltage calculation unit 156, and the control response may be adjusted by the rate limiter. The inverter circuit 122 modulates the output voltage by PWM control based on the input duty cycle duty 1 and outputs the voltage.

As described above, according to the non-contact power supply system 300 of the present embodiment, the power transmission control device 150 of the non-contact power transmission device 100 uses the current value I1 flowing through the non-contact power transmission device 100 to receive power from the power transmission side. The command voltage value V1 of the inverter circuit 122 can be calculated without communicating with the side. The power transmission control device 150 uses the current value I1 of the output power of the inverter circuit 122 to calculate the command voltage value V1 that increases the transmission efficiency, and controls the inverter circuit 122 so as to output the command voltage value V1. Therefore, it is possible to increase the power transmission efficiency from the power transmission side to the power reception side without communicating between the power transmission side and the power reception side.

According to the non-contact power feeding system 300 of the present embodiment, the power transmission control device 150 controls the inverter circuit 122 so as to output the command voltage value V1 that maximizes the transmission efficiency, thereby causing the non-contact power transmission device 100 to be non-contact. The transmission efficiency to the contact power receiving device 205 can be maximized.

According to the non-contact power supply system 300 of the present embodiment, the command voltage value V1 that maximizes the transmission efficiency is calculated by using the above equations (2), (4) and (5). Therefore, an accurate command voltage value V1 can be calculated based on the theoretical value by using the value that can be acquired by the non-contact power transmission device 100 on the power transmission side.

According to the non-contact power supply system 300 of the present embodiment, the characteristic impedance Z02 is calculated from the above equation (2) by using the estimated value of the mutual inductance Lm acquired by the non-contact power transmission device 100 on the power transmission side. Therefore, the command voltage value V1 corrected for the positional deviation between the power transmission coil 112 and the power reception coil 212 can be calculated on the power transmission side, and the transmission efficiency from the non-contact power transmission device 100 to the non-contact power reception device 205 can be further increased.

B. Second embodiment:
The non-contact power feeding system 300b of the second embodiment will be described with reference to FIG. The non-contact power feeding system 300b of the second embodiment is different from the non-contact power feeding system 300 of the first embodiment in that the non-contact power transmission device 100b is provided in place of the non-contact power transmission device 100. The non-contact power transmission device 100b includes a power supply circuit 130b that performs PAM control instead of the power supply circuit 130.

The power supply circuit 130b includes a PAM circuit 131 connected to a DC power supply. The PAM circuit is composed of a booster circuit, and adjusts the voltage value of the input voltage Vin input to the inverter circuit 122.

In the present embodiment, the non-contact power transmission device 100b adjusts the voltage value of the input voltage Vin to the inverter circuit 122 by the PAM circuit 131 so that the output voltage from the inverter circuit 122 becomes the command voltage value V1. More specifically, the signal generation unit 158 that receives the input of the command voltage value V1 calculated in the same manner as in the first embodiment sets the input voltage Vin to the inverter circuit 122 using the following equation (7). calculate. The duty 2 is set at the maximum value that the inverter circuit 122 can drive. The inverter circuit 122 in which the calculated input voltage Vin is input from the PAM circuit 131 outputs an AC voltage having a command voltage value of V1.

According to the non-contact power supply system 300b of the present embodiment, the power transmission control device 150 controls the inverter circuit 122 so as to output the command voltage value V1 that maximizes the transmission efficiency by the PAM control of the power supply circuit 130b, and is non-contact. The transmission efficiency from the contact power transmission device 100b to the non-contact power reception device 205 can be maximized.

C. Third Embodiment:
The non-contact power feeding system 300c of the third embodiment will be described with reference to FIG. The non-contact power feeding system 300c of the third embodiment is different from the non-contact power feeding system 300 of the first embodiment in that the non-contact power transmission device 100c is provided in place of the non-contact power transmission device 100. The non-contact power transmission device 100c includes a power transmission control device 150c instead of the power transmission control device 150, and an input current sensor 132 between the power supply circuit 130 and the inverter circuit 122 instead of the current sensor 123. The input current sensor 132 detects the direct current output from the power supply circuit 130, that is, the current value Iin of the input current to the inverter circuit 122.

The power transmission control device 150c is different from the power transmission control device 150 in that it further includes a current correction unit 159. In the present embodiment, the power transmission control device 150c calculates the command voltage value V1 of the inverter circuit 122 by using the input current Iin to the inverter circuit 122 acquired by the input current sensor 132. The current correction unit 159, which receives the input of the input current Iin detected by the input current sensor 132, calculates the current value I1 of the output current from the inverter circuit 122 as an effective value by the following equation (8).

The command voltage calculation unit 156 uses the current value I1 input from the current correction unit 159 and the corrected characteristic impedance Z02 acquired from the correction unit 154 to command from the above equations (4) and (5). The voltage value V1 is calculated.

According to the non-contact power supply system 300c of the present embodiment, the current value Iin of the input current to the inverter circuit 122 is acquired, the current value I1 as the effective value to be output to the inverter circuit 122 is calculated, and the current value Iin is used. Then, the command voltage value V1 of the inverter circuit 122 is calculated. Since the input current Iin is a direct current, it can be easily detected, and the command voltage value V1 can be calculated using a current value with high detection accuracy.

D. Other embodiments:
(D1) In each of the above embodiments, the magnetic resonance method by the SS method is applied to the power transmission resonance circuit 110 and the power reception resonance circuit 210, but the primary parallel secondary parallel capacitor method (also referred to as “PP method”) is used. It may be applied. In such an embodiment, the power transmission coil 112 and the resonance capacitor 116 are connected in parallel in the power transmission resonance circuit 110, and the power reception coil 212 and the resonance capacitor 216 are connected in parallel in the power reception resonance circuit 210. In this case, the optimum voltage ratio a1 is calculated by using the following formula (9) instead of the above formula (5).

(D2) In each of the above embodiments, the command voltage value V1 is calculated from the equations (4) and (5), but instead of this, the following equation (10) may be used for the calculation. In this case, the characteristic impedance Z03 and the impedance Z4 of the imittance conversion circuit 124 are preferably set in advance as set values that maximize the transmission efficiency.

(D3) In each of the above embodiments, the command voltage value V1 is calculated from the equations (4) and (5). On the other hand, in a non-contact power supply system designed to maximize the transmission efficiency at the maximum output, the transmission efficiency is increased by using the output voltage V1 and the output current I1 of the inverter circuit 122 when operated at the maximum output. The maximum output voltage-current ratio (V1 / I1) may be set in advance. In this case, for example, the command voltage value V1 may be derived from the current value I1 of the output current from the inverter circuit 122 acquired by the current sensor 123 and the output voltage-current ratio that maximizes the preset transmission efficiency. .. Further, the input voltage-current ratio (Vin / Iin) that maximizes the transmission efficiency may be set in advance by using the input voltage Vin and the input current Iin of the inverter circuit 122 when operated at the maximum output. In this case, for example, the input voltage Vin to the inverter circuit 122 may be derived by using the current value Iin acquired by the input current sensor 132 and the preset input voltage-current ratio that maximizes the transmission efficiency. According to this form of non-contact power feeding system, the transmission efficiency from the non-contact power transmitting device to the non-contact power receiving device can be maximized without using the estimated value of the mutual inductance Lm.

The present disclosure is not limited to the above-described embodiment, and can be realized by various configurations within a range not deviating from the gist thereof. For example, the technical features of the embodiments corresponding to the technical features in each embodiment described in the column of the outline of the invention are for solving a part or all of the above-mentioned problems, or a part of the above-mentioned effects. Or, in order to achieve all of them, it is possible to replace or combine them as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be appropriately deleted.

100, 100b, 100c non-contact power transmission device, 112 power transmission coil, 122 inverter circuit, 130 power supply circuit, 150, 150c power transmission control device, 205 non-contact power reception device, 212 power reception coil, 300, 300b, 300c non-contact power supply system

Claims (5)

A non-contact power supply system (300, 300b, 300c), an AC conversion circuit (122) that converts DC power input from a power source (130) into AC power and outputs it, and an AC conversion circuit (122) that is output from the AC conversion circuit. A power transmission device (100, 100b, 100c) having a power transmission coil (112) for transmitting AC power, and
A power receiving device (205) having a power receiving coil (212) that receives AC power from the power transmission coil in a non-contact manner is provided.
The power transmission device
The current value flowing through the transmission device is acquired, and the acquired current value is used to calculate the voltage value at which the transmission efficiency of the AC power from the transmission coil to the power receiving coil is high, and the AC power of the calculated voltage value is calculated. A power transmission control device (150, 150c), which controls the AC conversion circuit so as to output
Contactless power supply system. The power transmission control device calculates a voltage value that maximizes the transmission efficiency using the acquired current value, and outputs the AC power of the voltage value that maximizes the calculated transmission efficiency. The non-contact power supply system according to claim 1, wherein the circuit is controlled. The power transmission device includes a filter circuit (124) between the AC conversion circuit and the power transmission coil.
The non-contact power supply system according to claim 2, wherein the voltage value V1 that maximizes the transmission efficiency is obtained by the following formula (1).
V1 = a1, Z01 ² , I1 / Z02 ... Equation (1)
I1: Current value of AC power output by the AC conversion circuit Z01: Characteristic impedance value of the filter circuit Z02: Characteristic impedance value of the power transmission / reception circuit (TEC) represented by the equivalent circuit including the transmission coil and the power reception coil a1: Transmission A set value of the optimum voltage ratio of the AC voltage output by the power receiving coil to the AC voltage applied to the power transmission coil, which is the optimum voltage ratio that changes according to the characteristic impedance value of the power receiving circuit. The power transmission control device obtains the mutual inductance value between the power transmission coil and the power reception coil, and corrects the voltage value V1 that maximizes the power transmission efficiency by using the characteristic impedance Z02 obtained by the following equation (2). Item 3. The non-contact power transmission system according to item 3.
Z02 = ω1 ・ Lm ・ ・ ・ Equation (2)
ω1: Frequency of AC voltage applied to the power transmission coil Lm: Mutual inductance between the power transmission coil and the power reception coil in the power transmission / reception circuit The non-contact power supply system according to any one of claims 1 to 4, wherein the current value flowing through the power transmission device is the current value of the DC power input to the AC conversion circuit.

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