Non-contact power supply system and control method thereof

Abstract

To estimate mutual inductance and self-inductance of a power reception coil without affecting a power supply operation to a battery in a non-contact power supply system.SOLUTION: In a non-contact power supply system with a power transmission device, a power reception device and a control unit, the power transmission device comprises an inverter and a power transmission unit, and the power reception device comprises: a power reception unit comprising a power reception coil; and a bidirectional converter having a charge mode and a discharge mode. The control unit short-circuits the inverter, operates the bidirectional converter in the discharge mode, calculates equivalent resistance when the battery is observed from input of the bidirectional converter on the basis of battery voltage and battery current, and calculates mutual inductance on the basis of a resonance frequency, power transmission voltage and power reception voltage. The control unit further calculates power transmission current on the basis of the resonance frequency, the mutual inductance, the equivalent resistance, and inductance of the power reception coil.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a contactless power supply system that supplies power contactlessly using a plurality of coils coupled to each other by electromagnetic induction, and a control method that estimates the mutual inductance between the plurality of coils and the inductance of a power receiving coil. [Background technology]

[0002] For example, in a contactless power supply system that supplies power contactlessly using multiple coils coupled to each other by electromagnetic induction, in order to estimate the mutual inductance between the multiple coils and the inductance of the receiving coil, Patent Document 1 discloses an estimation method according to Prior Art 1, in which a short-circuit field effect transistor (hereinafter referred to as FET) is inserted into the circuit of the transmitting coil, and by opening the FET, the circuit of the transmitting coil is opened and the mutual inductance between the multiple coils and the inductance of the receiving coil are estimated.

[0003] Furthermore, in a contactless power transfer system that uses multiple coreless coils to transfer power contactlessly, an estimation method according to Prior Art 2 for estimating the mutual inductance between multiple coils and the inductance of a power receiving coil is disclosed in Patent Documents 2 and 3. Patent Document 3 is the Japanese publication corresponding to Patent Document 2. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Chinese Patent Application Publication No. 201910172598 [Patent Document 2] U.S. Patent Application Publication No. 2015 / 0236526 [Patent Document 3] Special Publication No. 2017-511102 Summary of the Invention [Problem to be solved by the invention]

[0005] The estimation method according to Conventional Example 1 adds the FET to estimate the value of mutual inductance, which affects the power supply operation to the battery, specifically increasing loss. Furthermore, although the value of mutual inductance is estimated, no method for estimating the sign is mentioned. This estimation method has the problem of increasing the size of the power transmission device due to the additional components and reduced efficiency.

[0006] Furthermore, the estimation method according to Conventional Example 2 requires the use of a coreless contactless power supply system, and no mention is made of a method for estimating self-inductance.

[0007] An object of the present invention is to provide a contactless power transfer system and a control method thereof that can estimate mutual inductance and self-inductance of a power receiving coil without affecting the power transfer operation to a battery. [Means for solving the problem]

[0008] A contactless power supply system according to one aspect of the present invention includes: A contactless power supply system including a power transmitting device, a power receiving device, and a control unit that controls the power transmitting device and the power receiving device, The power transmission device is an inverter including a plurality of switching elements for converting an input DC voltage into a predetermined AC voltage; a power transmitting resonant circuit including an inductor and a capacitor and having a predetermined resonant frequency; a power transmitting coil connected to the power transmitting resonant circuit; a first voltage sensor that measures a first voltage of the power transmitting coil; the power transmitting resonant circuit is inserted and connected between the inverter and the power transmitting coil, The power receiving device is a receiving coil electromagnetically coupled to the transmitting coil by mutual inductance; a bidirectional converter having a charging mode in which the AC voltage received by the receiving coil is converted into a predetermined DC voltage and output to a battery, and a discharging mode in which the DC voltage from the battery is converted into a predetermined AC voltage and output to a transmitting coil; a second voltage sensor that measures a second voltage of the receiving coil; a first current sensor that measures a first current in the receiving coil; a third voltage sensor for measuring a battery voltage of the battery; a second current sensor that measures a battery current of the battery; The control unit short-circuiting the inverter by controlling on / off of the plurality of switching elements, operating the bidirectional converter in a discharge mode, and calculating an equivalent resistance when the battery is viewed from the input of the bidirectional converter based on the battery voltage and the battery current; The mutual inductance is calculated based on the resonant frequency, the first voltage, and the first current. [Effects of the Invention]

[0009] Therefore, in a contactless power supply system according to one aspect of the present invention, by turning on the switching element of the inverter, the input side of the power transmission unit downstream of the inverter is short-circuited and the mutual inductance and the self-inductance of the receiving coil are estimated, so that these parameters can be estimated without affecting the power supply operation to the battery. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing an example of the configuration of a contactless power supply system according to a first embodiment. [Figure 2] 10 is a timing chart of gate signals SG1 to SG4 of switching elements Q1 to Q4, illustrating a first control example of the DC / AC inverter 11 of FIG. [Figure 3] 10 is a timing chart of gate signals SG1 to SG4 of switching elements Q1 to Q4, illustrating a second control example of the DC / AC inverter 11 of FIG. [Figure 4A] 1. FIG. 4 is a timing chart of gate signals SG1 to SG4 of switching elements Q1 to Q4 and maximum output voltage vinv of DC / AC inverter 11, illustrating an example of controlling the transmission current from power transmitting unit 12 of FIG. 1 by a phase shift control method. [Figure 4B] 1. FIG. 4 is a timing chart of gate signals SG1 to SG4 of switching elements Q1 to Q4 and output voltage vinv of DC / AC inverter 11 during a drop, illustrating an example of controlling the transmission current from power transmitting unit 12 of FIG. 1 by a phase shift control method. [Figure 5] 2 is a flowchart showing a power transmission process executed by the control unit 10 of FIG. [Figure 6] 2 is a flowchart showing a power receiving process executed by the control unit 20 of FIG. [Figure 7] FIG. 10 is a block diagram showing an example of the configuration of a contactless power supply system according to a second embodiment. [Figure 8] 8 is a block diagram showing an example of the configuration of a phase difference detection circuit 17 in FIG. 7. [Figure 9] 9 is a timing chart showing the operation of the phase difference detection circuit 17 of FIG. 8. [Figure 10] 8 is a flowchart showing a power transmission process executed by a control unit 10A of FIG. 7. [Figure 11] 8 is a flowchart showing a power receiving process executed by a control unit 20A of FIG. 7. [Figure 12A] 1 is a circuit diagram of an equivalent circuit showing an example of the configuration of a contactless power supply system including a plurality of n power transmitting coils and one power receiving coil. [Figure 12B] 12B is a schematic diagram showing the direction of each current in the contactless power supply system of FIG. 12A. FIG. [Figure 13A] 12B is a schematic diagram showing a case where the signs of mutual inductances M1 to M3 are all positive in the contactless power supply system of FIG. 12A. FIG. [Figure 13B] 12B is a schematic diagram showing a case where two mutual inductances M2 and M3 out of the mutual inductances in the contactless power supply system of FIG. 12A are negative. FIG. [Figure 14]FIG. 10 is a block diagram showing a configuration example of a contactless power supply system according to a first modification. [Figure 15] 15 is a circuit diagram showing an example of the configuration of each of the additional resonant circuits 18 and 28 in FIG. 14. [Figure 16A] FIG. 10 is a block diagram showing an example of the configuration of a power receiving device 102BA according to a second modification. [Figure 16B] 16B is a graph showing the characteristics of transmission efficiency with respect to equivalent resistance Req in power receiving device 102BA of FIG. 16A. [Figure 17] FIG. 11 is a block diagram showing an example of the configuration of a power transmitting device 101BA according to a third modification. [Figure 18] FIG. 10 is a block diagram showing an example of the configuration of a power receiving device 102BB according to a fourth modification. [Figure 19] FIG. 13 is a block diagram showing an example of the configuration of a power receiving device 102BC according to a fifth modification. [Figure 20] FIG. 13 is a block diagram showing an example of the configuration of a power receiving device 102BD according to a sixth modification. [Figure 21] FIG. 13 is a block diagram showing an example of the configuration of a power transmitting device 101BB according to a seventh modification. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments and modifications of the present invention will be described with reference to the drawings, in which the same or similar components are designated by the same reference numerals.

[0012] (Inventor's Knowledge) To solve the above-mentioned problems, the present invention focuses on the fact that the power transmission circuit used in a wireless power transfer system is an LC circuit with an L-shaped structure consisting of an inductor L and a capacitor C, and by causing this LC circuit to resonate in parallel, it is possible to estimate the value and sign of the mutual inductance and the self-inductance of the receiving coil without using an additional FET. This makes it possible to estimate the value and sign of the self-inductance and mutual inductance without affecting the power supply operation to the battery, i.e., without additional loss. This enables high efficiency and a reduced number of components, thereby making the power transmission device smaller and lighter.

[0013] The following describes the principle of estimating the values and signs of self-inductance and mutual inductance in a contactless power transfer system including n power transmitting coils and one power receiving coil.

[0014] Fig. 12A is a circuit diagram of an equivalent circuit showing an example of the configuration of a contactless power transfer system including n power transmitting coils and one power receiving coil, and Fig. 12B is a schematic diagram showing the direction of each current in the contactless power transfer system of Fig. 12A.

[0015] 12A, the contactless power supply system includes a plurality of n power transmission units 82-1 to 82-n and one power reception unit 91. Each of the power transmission units 82-1 to 82-n has a capacitance C s and inductance L s The power receiving section 91 is configured as a series circuit of the capacitance C r and inductance L r and equivalent resistance r r and the load resistance R L Here, the inductance Ls of the power transmitting unit 82-1 is equal to the inductance L r The mutual inductance M1 electromagnetically couples the power transmitting section 82-n to the inductance L s is the inductance L of the power receiving part 91 r and the mutual inductance M n The transmission current i tx1 ~i txn When each of the power transmitting units 82-1 to 82-n flows, the power receiving unit 91 receives a receiving current i rx Here, n transmission currents i txi (i=1,2,…,n) and receiving current i rx The relationship is expressed by the following equation:

[0016]

number

[0017] To obtain the desired power supply,

number

[0018]

number

[0019] where the parameter m i is expressed by the following equation:

[0020]

number

[0021] where M i ,L r ,R L are unknown parameters. That is, the transmission current i txm To determine (m=1,2,…,n), we use the parameter M i ,L r ,R L It is necessary to estimate this, and the contactless power supply system according to the embodiment estimates it.

[0022] Fig. 13A is a schematic diagram showing the contactless power supply system of Fig. 12A when all of the mutual inductances M1 to M3 have positive signs, and Fig. 13B is a schematic diagram showing the contactless power supply system of Fig. 12A when two of the mutual inductances M1 to M3, namely, mutual inductances M2 and M3, have negative signs.

[0023] As is clear from FIG. 13A, the transmission voltage v generated in the transmission coil based on the magnetic flux generated from the receiving coil tx1 ~v tx3 In addition, in Figure 13B, the direction of the transmission voltage v tx1 The direction of the transmission voltage v tx2 ,v tx3Here, the mutual inductance M1 is defined as the reference and the signs of the mutual inductances M2 and M3 are defined as negative. The above definitions are i Considering the sign of the transmission current i txm If the current is not supplied, the power supplied will be cancelled out at the power receiving section.

[0024] (Embodiment 1) Fig. 1 is a block diagram showing an example of the configuration of a contactless power supply system 100 according to embodiment 1. In Fig. 1, the contactless power supply system 100 is configured to include a power transmitting device 101 and a power receiving device 102. The power transmitting device 101 includes a DC / AC inverter 11, a power transmitting unit 12, a control unit 10, and a communication unit 19. The power receiving device 102 includes a power receiving unit 21, a bidirectional AC / DC converter 25, a control unit 20, and a communication unit 29.

[0025] 1, the DC / AC inverter 11 is configured by connecting four switching elements Q1 to Q4, which are, for example, N-channel FETs, in series in a bridge configuration, and is controlled on / off by applying gate signals SG1 to SG4 from a control unit 10 to the gates of the switching elements Q1 to Q4, respectively, as will be described later with reference to FIGS. in By switching at a predetermined cycle, the output voltage v inv The power is converted into an AC voltage and output to the power transmission unit 12.

[0026] The power transmission unit 12 has an inductance L tx The transmitting coil 15 and capacitance C L a parallel circuit with the capacitor 14 and an inductance L L The power transmission coil 15 has a transmission voltage v txis measured by a voltage sensor 16 and output to the control unit 10. Here, the capacitor 14 and the inductor 13 form a power transmitting resonant circuit 50 having an L-shaped structure. Here, the inductor 13 and the capacitor 14 are reactance elements. When the power receiving device 102 is located at a predetermined stop position of the power transmitting device 101, the power transmitting coil 15 is electromagnetically inductively coupled to the power receiving coil 22 of the power receiving unit 21 by mutual inductance M. At this time, the control unit 20 of the power receiving device 102 transmits a stop signal to the control unit 10 of the power transmitting device 101 via the communication units 29 and 19.

[0027] The control unit 10 transmits and receives various communication signals to and from the control unit 20 of the power receiving device 102 via the communication units 19 and 29, and executes the power transmission process shown in Fig. 5. As a result, the unknown parameters are calculated, the switching elements Q1 to Q4 of the DC / AC inverter 11 are on / off controlled using the on / off patterns shown in Fig. 2 or 3, and the DC / AC inverter 11 is subjected to phase shift control as shown in Fig. 4A and 4B, thereby adjusting the output voltage of the DC / AC inverter 11 to achieve a desired transmission current. Note that although the communication unit 19 is connected to the communication unit 29 via a wireless communication line, the present invention is not limited to this, and the connection may also be via a wired communication line.

[0028] The power receiving section 21 has an inductance L rx The power receiving coil 22 is configured to have a receiving voltage V rx is measured by the voltage sensor 23 and transmitted to the control unit 20, and the receiving current I rx is measured by a current sensor 24 and transmitted to the control unit 20. The bidirectional AC / DC converter 25 is configured by connecting four switching elements Q11 to Q14, which are, for example, N-channel FETs, in series in a bridge configuration, and is on / off controlled by applying gate signals SG11 to SG14 from the control unit 20 to the gates of the switching elements Q11 to Q14, respectively. As a result, the bidirectional AC / DC converter 25 switches the AC voltage from the power receiving coil 22 at a predetermined cycle, thereby generating a predetermined output voltage V batand outputs it to the battery 112, thereby charging the battery 112 as a load. bat is switched at a predetermined cycle, the output voltage is converted to a predetermined value, and the output voltage is output to the power receiving coil 22. bat and a voltage sensor 26 measuring the battery current I bat and a current sensor 27 for measuring the

[0029] The control unit 20 transmits and receives various communication signals to and from the control unit 10 of the power transmitting device 101 via the communication units 29 and 19, and executes the power receiving process of Fig. 6, thereby supporting the power transmitting process of Fig. 5. As a result, the control unit 10 of the power transmitting device 101 calculates the unknown parameters (mutual inductance M and inductance Lrx of the power receiving coil 22), and controls the phase shift of the DC / AC inverter 11 by the phase shift amount D, thereby determining the output voltage v of the DC / AC inverter 11. inv Adjust the desired transmission current I tx The control is performed so that

[0030] Fig. 2 is a timing chart of gate signals SG1 to SG4 of switching elements Q1 to Q4, illustrating a first control example of the DC / AC inverter 11 of Fig. 1. In the DC / AC inverter 11, when H-level gate signals SG1 to SG4 are input to the gates of the switching elements Q1 to Q4, the switching elements Q1 to Q4 are turned on, and when L-level gate signals SG1 to SG4 are input, the switching elements Q1 to Q4 are turned off. This is also true for the bidirectional AC / DC converter 25.

[0031] 2, during the "period for estimating self-inductance and mutual inductance" (measurement mode), the switching elements Q1 and Q4 are turned off and the switching elements Q2 and Q3 are turned on. Next, during the "period for feeding power to the load of the power receiving device" (operation mode), the switching elements Q1 to Q4 are controlled by phase shift control, thereby controlling the transmission current.

[0032] FIG. 3 is a timing chart of gate signals SG1 to SG4 of switching elements Q1 to Q4 showing a second control example of DC / AC inverter 11 of FIG.

[0033] 3, during the "period for estimating self-inductance and mutual inductance" (measurement mode), the switching elements Q1 and Q4 are turned on and the switching elements Q2 and Q3 are turned off. Next, during the "period for feeding power to the load of the power receiving device" (operation mode), the switching elements Q1 to Q4 are controlled by phase shift control, thereby controlling the transmission current.

[0034] FIG. 4A shows an example of controlling the transmission current from the power transmission unit 12 of FIG. 1 by the phase shift control method. inv 4B is a timing chart showing an example of controlling the transmission current from the power transmission unit 12 of FIG. 1 by the phase shift control method, in which the gate signals SG1 to SG4 of the switching elements Q1 to Q4 and the output voltage v of the DC / AC inverter 11 during a drop are inv Specifically, by increasing or decreasing the hatched period in FIG. 4B, the phase difference Dπ between the leg 1 circuit of the switching elements Q1 and Q2 and the leg 2 circuit of the switching elements Q3 and Q4 in the following equation can be controlled, thereby controlling the transmission current i tx Control.

[0035]

number

[0036]

number

[0037] FIG. 5 is a flowchart showing the power transmission process executed by the control unit 10 of FIG.

[0038] In step S1 of Fig. 5, a communication signal is received from the control unit 20 via the communication units 29 and 19. Next, in step S2, it is determined whether or not a stop signal has been received from the received communication signals. If YES, the process proceeds to step S3, whereas if NO, the process returns to step S1. In step S3, the DC / AC inverter 11 is short-circuited. Specifically, as shown in Fig. 2, the switching elements Q1 and Q4 are turned off and the switching elements Q2 and Q3 are turned on, or as shown in Fig. 3, the switching elements Q1 and Q4 are turned on and the switching elements Q2 and Q3 are turned off. Furthermore, in step S4, a short-circuit notification signal is transmitted to the control unit 20 via the communication units 19 and 29. In step S5, a communication signal is received from the control unit 20 via the communication units 29 and 19. In step S6, the equivalent resistance R calculated by the control unit 20 is calculated. eq and the self-inductance L of the receiving coil 22 rx and the received current I measured by the current sensor 24 rx If the answer is YES, the process proceeds to step S7, whereas if the answer is NO, the process returns to step S5.

[0039] In step S7, the voltage sensor 16 detects the transmission voltage V tx Next, in step S8, the mutual inductance M1 is estimated and calculated using the following equation:

[0040] M=V tx / (2πf r I rx ) (1)

[0041] In step S9, the transmission current i tx is estimated and calculated using the following formula:

[0042] i tx =1 / m (2)

[0043]

number

[0044] Next, in step S10, the desired transmission current i tx The inverter output voltage V required to inv is estimated and calculated using the following formula:

[0045] v inv =2πf r L L i tx (4)

[0046] In step S11, the desired inverter output voltage v inv The phase shift amount D of the DC / AC inverter 11 for outputting is calculated using the following equation.

[0047]

number

[0048] In step S12, gate signals SG1 to SG4 are generated and input to the gates of the switching elements Q1 to Q4, with the phases shifted by the phase shift amount D, and the power transmission process is terminated.

[0049] FIG. 6 is a flowchart showing the power receiving process executed by the control unit 20 of FIG.

[0050] 6, it is confirmed that the power receiving device 102 has stopped at a predetermined stop position, and a stop signal indicating the stopped state is transmitted to the control unit 10 via the communication units 29, 19. In step S22, a communication signal is received from the control unit 10 via the communication units 19, 29. In step S23, it is determined whether a short-circuit notification signal for the DC / AC inverter 11 has been received in the received communication signal. If YES, the process proceeds to step S24, whereas if NO, the process returns to step S22.

[0051] In step S24, the bidirectional AC / DC converter 25 is connected to the inductance L L and capacitance C L The resonant frequency fr (See the following formula) and the output voltage V bat Power is transmitted from the power receiving unit 21 to the power transmitting unit 12 using the above.

[0052]

number

[0053] In step S25, the voltage sensors 23 and 26 and the current sensors 24 and 27 are used to measure the received voltage V rx , battery voltage V bat , receiving current I rx and battery current I bat Next, in step S26, the equivalent resistance R when looking at the battery 122 from the input terminal of the bidirectional AC / DC converter 25 is measured. eq is calculated using the following formula:

[0054]

number

[0055] Next, in step S27, the inductance L of the power receiving unit 21 is rx is calculated using the following formula:

[0056]

number

[0057] In step S28, the calculated equivalent resistance R eq and inductance L rx , and the measured battery current I rx The information signal including the above is transmitted to the control unit 10 via the communication units 29 and 19, and the power transmission in step S24 is ended, thereby terminating the power receiving process.

[0058] In the power transmission process of Fig. 5, the period from steps S1 to S11 is the measurement mode period, and the period from step S12 is the operation mode period. In the power reception process of Fig. 6, the period from steps S21 to S28 is the measurement mode period (the bidirectional AC / DC converter 25 is in the discharge mode of the battery 112), and the period thereafter is the operation mode period (the bidirectional AC / DC converter 25 is in the charge mode of the battery 112).

[0059] As described above, according to this embodiment, by turning on two predetermined switching elements (Q1 and Q4 or Q2 and Q3) among the switching elements Q1 to Q4 of the DC / AC inverter 11 and turning off the other two switching elements (Q2 and Q3 or Q1 and Q4), the output side of the DC / AC inverter 11 is short-circuited, that is, the input side of the power transmitting unit 12 is short-circuited, and the mutual inductance M and the self-inductance L of the power receiving coil 22 are rx Therefore, these parameters can be estimated without affecting the power supply operation to the battery 112.

[0060] (Embodiment 2) Fig. 7 is a block diagram showing an example of the configuration of a contactless power supply system 100A according to embodiment 2. The contactless power supply system 100A in Fig. 7 differs from the contactless power supply system 100 in Fig. 1 in the following points. (1) Instead of the power transmitting device 101, a power transmitting device 101A is provided. (2) The power supply 10 further includes a DC / AC inverter 11A and a power transmission unit 12A. (3) A phase difference detection circuit 17 is further provided. (4) DC / AC inverter 11 inverter output voltage v inv Change the sign to v inv1 was changed to. (5) Inductance L of the inductor 13 of the power transmission unit 12 L Change the sign to L L1 was changed to. (6) Capacitance C of the capacitor 14 of the power transmission unit 12 L Change the sign to C L1 was changed to. (7) Inductance L of the transmitting coil 15tx Change the sign to L tx1 was changed to. (8) The sign of the mutual inductance M between the power transmitting coil 15 and the power receiving coil 22 is changed to M1. (9) The control unit 10 executes the power transmission process of FIG. 10 instead of the power transmission process of FIG. (10) The control unit 20 executes the power receiving process of FIG. 11 instead of the power receiving process of FIG. The differences will be explained below.

[0061] 7, a contactless power supply system 100A is configured to include a power transmitting device 101A and a power receiving device 102. The power transmitting device 101A includes two DC / AC inverters 11, 11A, a power transmitting unit 12, a control unit 10, and a communication unit 19. The power receiving device 102 includes a power receiving unit 21, a bidirectional AC / DC converter 25, a control unit 20, and a communication unit 29.

[0062] 7, the DC / AC inverter 11A is configured by connecting four switching elements Q21 to Q24, which are, for example, N-channel FETs, in series in a bridge configuration, similar to the DC / AC inverter 11, and is controlled on / off as described later by applying gate signals SG1 to SG4 from the control unit 10 to the gates of the switching elements Q21 to Q24, respectively. in By switching at a predetermined cycle, the output voltage v inv2 The power is converted into an AC voltage and output to the power transmission unit 12A.

[0063] The power transmission unit 12A has an inductance L tx2 The transmitting coil 15 and capacitance C L2 a parallel circuit with the capacitor 14 and an inductance L L The power transmission coil 15 has a transmission voltage v tx2is measured by a voltage sensor 16A and output to the control unit 10. Here, the inductor 13 and the capacitor 14 form a power transmitting resonant circuit 50A. When the power receiving device 102 is located at a predetermined stop position of the power transmitting device 101, the power transmitting coil 15A is electromagnetically inductively coupled to the power receiving coil 22 of the power receiving unit 21 by a mutual inductance M2. At this time, the control unit 20 of the power receiving device 102 transmits a stop signal to the control unit 10 of the power transmitting device 101 via the communication units 29 and 19.

[0064] The control unit 10 transmits and receives various communication signals to and from the control unit 20 of the power receiving device 102 via the communication units 19 and 29, and executes the power transmission process shown in Fig. 10. As a result, the unknown parameters are calculated, and the switching elements Q1 to Q4, Q21 to Q24 of the DC / AC inverters 11, 11A are on / off controlled in accordance with the on / off patterns shown in Fig. 2 or 3, and the DC / AC inverters 11, 11A are phase-shift-controlled with the phase shift amounts D1 and D2 as shown in Figs. 4A and 4B, thereby controlling the output voltage v of the DC / AC inverters 11, 11A. inv1 ,v inv2 Adjust the desired transmission current I tx1 ,I tx2 The control is performed so that

[0065] Fig. 8 is a block diagram showing an example of the configuration of the phase difference detection circuit 17 of Fig. 7. Fig. 9 is a timing chart showing the operation of the phase difference detection circuit 17 of Fig. 8.

[0066] 8 and 9, the phase difference detection circuit 17 is configured to include two comparators 171 and 172, a phase comparator 173, and a low-pass filter (LPF) 174. Each of the comparators 171 and 172 detects the input power transmission voltage V tx1 ,V tx2 is compared with the ground voltage (0V), and the comparison result signal V comp1 ,V comp2 and outputs it to the phase comparator 173. The phase comparator 173 receives two comparison result signals V comp1 ,V comp2 The phase comparison voltage signal V indicates the phase comparison result. pfdis generated and output through a low-pass filter 174, a phase difference voltage Vφ tx12 and outputs it to the control unit 10.

[0067] Fig. 10 is a flowchart showing the power transmission process executed by the control unit 10A of Fig. 7. The power transmission process of Fig. 10 differs from the power transmission process of Fig. 5 in the following points. (1) Instead of the processes of steps S3 and S7 to S12, the processes of steps S3A and S7A to S12A are executed, respectively. (2) Steps S13 to S15 are further executed.

[0068] In step S1 of FIG. 10, a communication signal is received from control unit 20 via communication units 29 and 19. Next, in step S2, it is determined whether a stop signal has been received from the received communication signals. If the determination is YES, the process proceeds to step S3A. If the determination is NO, the process returns to step S1. In step S3A, DC / AC inverters 11 and 11A are short-circuited. Specifically, as shown in FIG. 2, switching elements Q1 and Q4 of DC / AC inverter 11 are turned off and switching elements Q2 and Q3 are turned on, or as shown in FIG. 3, switching elements Q1 and Q4 are turned on and switching elements Q2 and Q3 are turned off. Furthermore, switching elements Q21 and Q24 of DC / AC inverter 11A are turned off and switching elements Q22 and Q23 are turned on, or switching elements Q21 and Q24 are turned on and switching elements Q22 and Q23 are turned off. Furthermore, in step S4, a short-circuit notification signal is transmitted to control unit 20 via communication units 19 and 29. In step S5, a communication signal is received from the control unit 20 via the communication units 29 and 19, and in step S6, the equivalent resistance R calculated by the control unit 20 is eq and the self-inductance L of the receiving coil 22 rx and the received current I measured by the current sensor 24 rx If the answer is YES, the process proceeds to step S7, whereas if the answer is NO, the process returns to step S5.

[0069] In step S7A, the voltage sensors 16 and 16A detect the power transmission voltage V tx1 ,V tx2 The phase difference voltage Vφ from the phase difference detection circuit 17 is measured. tx12 Next, in step S8A, the mutual inductance M1 is estimated and calculated using the following equation:

[0070]

number

[0071] Next, in step S13, the phase difference voltage Vφ tx12 If it is a voltage corresponding to a phase difference of 0 degrees, the process proceeds to step S14, and if it is a voltage corresponding to a phase difference of 180 degrees, the process proceeds to step S15. In step S14, the mutual inductance M2 is estimated and calculated using the following equation, and then the process proceeds to step S9A.

[0072]

number

[0073] On the other hand, in step S15, the mutual inductance M2 is estimated and calculated using the following equation, and then the process proceeds to step S9A.

[0074]

number

[0075] In step S9A, the transmission current i tx1 ,i tx2 is calculated using the following formula:

[0076] i tx1 =m1 / (m1 2 + m2 2 ) (12) itx2 =m2 / (m1 2 + m2 2 ) (13)

[0077]

number

[0078]

number

[0079] Next, in step S10A, the desired transmission current i tx1 ,i tx2 The inverter output voltage V required to inv1 ,v inv2 is calculated using the following formula:

[0080] v inv1 =2πf r L L1 i tx1 (16) v inv2 =2πf r L L2 i tx2 (17)

[0081] In step S11A, the desired inverter output voltage v inv1 ,v inv2 The phase shift amounts D1 and D2 of the DC / AC inverters 11 and 11A for outputting the above are calculated using the following equations.

[0082]

number

[0083]

number

[0084] In step S12A, gate signals SG1 to SG4 are generated with a phase shift of D1 and input to the gates of the switching elements Q1 to Q4, and gate signals SG21 to SG24 are generated with a phase shift of D2 and input to the gates of the switching elements Q21 to Q24, thereby driving and controlling the DC / AC inverter 11 and terminating the power transmission process.

[0085] Fig. 11 is a flowchart showing the power receiving process executed by the control unit 20 in Fig. 7. The power receiving process in Fig. 11 differs from the power receiving process in Fig. 6 in the following points. (1) Instead of the processes of steps S23 and S24, the processes of steps S23A and S24A are executed, respectively. The differences will be explained below.

[0086] In step S23A of FIG. 11, it is determined whether or not a short circuit notification signal for the DC / AC inverters 11, 11A has been received in the received communication signal. If YES, the process proceeds to step S24A, whereas if NO, the process returns to step S22.

[0087] In step S24A, the bidirectional AC / DC converter 25 is connected to the inductance L L and capacitance C L The resonant frequency f r (See the following formula) and the output voltage V bat The power is transmitted wirelessly from the power receiving unit 21 to the power transmitting unit 12 using the above.

[0088]

number

[0089] 11, the processes of steps S21 to S22 and S25 to S28 are executed in the same manner as the processes of FIG. 6. In step S28, the calculated equivalent resistance R eq and inductance L rx , and the measured battery current I rxThe information signal including the above is transmitted to the control unit 10 via the communication units 29 and 19, and the power transmission in step S24A is ended, thereby terminating the power receiving process.

[0090] In the power transmission process of Fig. 10, the period from steps S1 to S11A is the measurement mode period, and the period from step S12 is the operation mode period. In the power reception process of Fig. 11, the period from steps S21 to S28 is the measurement mode period (bidirectional AC / DC converter 25 is in power transmission mode), and the period thereafter is the operation mode period (bidirectional AC / DC converter 25 is in charge mode).

[0091] As described above, according to this embodiment, among the switching elements (Q1 to Q4; Q21 to Q24) of the DC / AC inverters 11 and 11A, predetermined two switching elements (Q1 and Q4 or Q2 and Q3; Q21 and Q24 or Q22 and Q23) are turned on, while the other two switching elements (Q2 and Q3 or Q1 and Q4; Q22 and Q23 or Q21 and Q24) are turned off, thereby short-circuiting the output side of the DC / AC inverter 11, that is, short-circuiting the input side of the power transmitting units 12 and 12A, and thereby reducing the mutual inductance M and the self-inductance L of the power receiving coil 22. rx This allows these parameters to be estimated without affecting the power supply operation to the battery 112.

[0092] According to the second embodiment, compared to the first embodiment, in particular, by transmitting power using a plurality of power transmission coils 15, 15A, the estimation accuracy of the mutual inductances M1, M2 is improved, thereby increasing the power supply efficiency and significantly increasing the robustness against positional misalignment.

[0093] In the second embodiment described above, the case where there are two power transmitting coils 15, 15A has been described, but as described above with reference to FIG. 12B, the estimation method can be applied to the case where there are a plurality of n power transmitting coils.

[0094] (Variation 1) Fig. 14 is a block diagram showing an example of the configuration of a contactless power supply system 100B according to Modification 1. The contactless power supply system 100B in Fig. 14 differs from the contactless power supply system 100 in Fig. 1 in the following points. (1) Instead of the power transmitting unit 12, a power transmitting unit 12B further including an additional resonant circuit 18 is provided. (2) Instead of the power receiving unit 21, a power receiving unit 21B further including an additional resonant circuit 28 is provided. The differences will be explained below.

[0095] 14, the additional resonant circuit 18 has four terminals T1 to T4 and is inserted between the capacitor 14 and the power transmitting coil 15. The additional resonant circuit 28 has four terminals T11 to T14 and is inserted between the power receiving coil 22 and the bidirectional AC / DC converter 25.

[0096] Fig. 15 is a circuit diagram showing an example of the configuration of each of the additional resonant circuits 18 and 28 in Fig. 14. In Fig. 15, the additional resonant circuit 18 may be any of the following circuits 18A to 18C. Furthermore, the additional resonant circuit 28 may be any of the following circuits 28A to 28E.

[0097] In configuration example 1 of Fig. 15, the additional resonant circuit 18 includes an L circuit 18A including an inductor L1 inserted between terminals T1 and T3, and terminals T2 and T4 are directly connected. In configuration example 2 of Fig. 15, the additional resonant circuit 18 includes a C circuit 18B including a capacitor C1 inserted between terminals T1 and T3, and terminals T2 and T4 are directly connected. In configuration example 3 of Fig. 15, the additional resonant circuit 18 includes an LC circuit 18C including a series circuit of inductor L1 and capacitor C1 inserted between terminals T1 and T3, and terminals T2 and T4 are directly connected.

[0098] In configuration example 4 of Fig. 15, the additional resonant circuit 28 includes a C circuit 28A including a capacitor C11 inserted between terminals T11 and T13, and terminals T12 and T14 are directly connected. In configuration example 5 of Fig. 15, the additional resonant circuit 28 includes a C circuit 28B including a capacitor C12 inserted between terminals T11 and T12, and terminals T11 and T13 are directly connected, and terminals T12 and T14 are directly connected. In configuration example 6 of Fig. 15, the additional resonant circuit 28 includes an inductor L11 inserted between terminals T11 and T13, and a CL circuit 28C including a capacitor C12 inserted between terminals T11 and T12, and terminals T12 and T14 are directly connected. 15, the additional resonant circuit 28 includes a CLC circuit 28D including a series circuit of a capacitor C11 and an inductor L11 inserted between the terminals T1 and T3, and a capacitor C12 inserted between the connection point of the capacitor C11 and the inductor L11 and the terminals T12 and T14. In configuration example 8 of FIG. 15, the additional resonant circuit 28 includes a CLC circuit 28E including a series circuit of a capacitor C11 and a capacitor C13 inserted between the terminals T1 and T3, and an inductor L12 inserted between the connection point of the capacitor C11 and the capacitor C13 and the terminals T12 and T14.

[0099] As described above, according to the first modification, since the first modification further includes additional resonant circuits 18 and 28 compared to the first embodiment, the power transmitting unit 12 and the power receiving unit 21 can be brought into a resonant state at a predetermined resonant frequency, thereby increasing the transmission efficiency.

[0100] (Variation 2) 16A is a block diagram showing a configuration example of a power receiving device 102BA according to Modification 2. Also, FIG. 16B shows an equivalent resistance R eq 16A is a graph showing the characteristics of the transmission efficiency versus the power receiving coil 22. Compared to the power receiving device 102 in FIG. 1, the power receiving device 102BA in FIG. 16A is characterized in that a DC / DC converter 31 is inserted between the bidirectional AC / DC converter 25 and the battery 112. The equivalent resistance R eqBy inserting the DC / DC converter 31, the duty ratio D of the DC / DC converter 31 changes as shown in FIG. 16B and the following equation. DCDC By changing the equivalent resistance R eq Adjust the power supply efficiency to the maximum value η max can be raised to.

[0101]

number

[0102] As described above, according to the second modification, by inserting the DC / DC converter 31 in the power receiving device, the equivalent resistance R eq By adjusting the impedance between the bidirectional AC / DC converter 25 and the battery 112, the efficiency of power supply to the battery 112 can be increased.

[0103] (Variation 3) 17 is a block diagram showing a configuration example of a power transmission device 101BA according to Modification 3. The power transmission device 101BA in FIG. 17 has a capacitance C add By connecting an additional capacitor 32 for reducing harmonics having a composite impedance circuit 33 (composite impedance X L ) is inserted.

[0104] The operating frequency of the power transmission unit 12 is f r Then, the composite impedance X of the composite impedance circuit 33 of the inductor 13 and the additional capacitor 32 is L is expressed by the following equation:

[0105]

number

[0106] Here, the operating frequency f r In this case, the required impedance XL The magnitude of is determined at the design stage, and the circuit operates as an impedance X L As long as the magnitude of is the desired value, the inductance L L and the capacitance C of the additional capacitor 32 add The magnitude of is arbitrary. From equation (22), if there is no additional capacitor 32, r L L The magnitude of the desired impedance X L Inductance L L If there is an additional capacitor 32, the inductance L L Even if the additional capacitance C add Adjust the magnitude of to obtain the desired impedance X L When comparing the case with and without the additional capacitor 32, the operating frequency f r In the case of impedance X L Even if the magnitude of is the same, there will be a difference in the impedance for the harmonic components. For example, the impedance X for the third harmonic 3L is expressed by the following equation:

[0107]

number

[0108] From equation (23), the inductance L L The larger the magnitude of the impedance X 3L However, during the deformation process, the following equation is substituted using the relationship in equation (22):

[0109]

number

[0110] Here, the inductance L L Since the magnitude of the impedance X for harmonics can be made larger when the additional capacitor 32 is present, by inserting the additional capacitor 32,L Therefore, once you have determined how much you want to reduce the harmonics, you can increase the inductance L L The magnitude of the additional capacitance C add The magnitude of can also be calculated using equation (22).

[0111] As described above, according to the third modification, by inserting the additional capacitor 32, the impedance X L can be increased, and the harmonic charging current can be reduced.

[0112] In the third modification of FIG. 17, the additional resonant circuit 18 may be omitted.

[0113] (Variation 4) Fig. 18 is a block diagram showing an example configuration of a power receiving device 102BB according to Modification 4. The power receiving device 102BB in Fig. 18 is characterized in that two switches SW1 and SW2 and a DC / DC converter 34 are inserted between the bidirectional AC / DC converter 25 and the battery 112. When the control unit 20 turns on the switch SW1 and turns off the switch SW2, power is supplied from the battery 112 to the power receiving coil 22 (charge mode). On the other hand, when the control unit 20 turns off the switch SW1 and turns on the switch SW2, power is supplied to the power receiving coil 22 by a DC voltage from the DC / DC converter 34, which converts a predetermined DC voltage from the battery 112 into a predetermined DC voltage (discharge mode).

[0114] As described above, according to the fourth modification, the power receiving device further includes the DC / DC converter 34, so that power can be supplied from the DC / DC converter 34 during parameter estimation, thereby reducing power consumption compared to the first embodiment.

[0115] (Variation 5) Fig. 19 is a block diagram showing a configuration example of a power receiving device 102BC according to Modification 5. The power receiving device 102BC in Fig. 19 is characterized in that, compared to the power receiving device 102 in Fig. 1, a low-pass filter (LPF) 35 is inserted between the bidirectional AC / DC converter 25 and the battery 112. The low-pass filter 35 is configured to pass frequency components lower than a predetermined cutoff frequency so as to reduce ripples of harmonic components in the output voltage or output current to the battery 112.

[0116] As described above, according to the fifth modification, by inserting the low-pass filter 35, the ripple in the output voltage or output current to the battery 112 can be reduced.

[0117] (Variation 6) Fig. 20 is a block diagram showing a configuration example of a power receiving device 102BD according to Modification 6. The power receiving device 102BD in Fig. 21 is characterized in that a low-pass filter (LPF) 35 and a DC / DC converter 31 are inserted between the bidirectional AC / DC converter 25 and the battery 112. Thus, by inserting the low-pass filter 35, it is possible to reduce ripples in the output voltage or output current to the battery 112, and further, by inserting the DC / DC converter 31, it is possible to match the impedance between the bidirectional AC / DC converter 25 and the battery 112 and increase the efficiency of power supply to the battery 112.

[0118] As described above, according to the sixth modification, the effects of the second and fifth modifications can be achieved.

[0119] (Variation 7) Fig. 21 is a block diagram showing a configuration example of a power transmitting device 101BB according to Modification 7. The power transmitting device 101BB in Fig. 22 is characterized in that the insertion positions of inductors 13, 13A, 13-1 to 13-n and capacitors 14, 14A, 14-1 to 14-n in power transmitting sections 12, 12A are swapped in power transmitting device 101 in Fig. 1 or power transmitting device 101A in Fig. 7. This makes it possible to obtain the same power supply efficiency before and after swapping the insertion positions.

[0120] (Other variations) In the above embodiments, the control units 10, 20 short-circuit the inverter 11 by controlling the on / off of the multiple switching elements Q1 to Q4, operate the bidirectional converter 25 in discharge mode, calculate the equivalent resistance when viewing the battery 112 from the input of the bidirectional converter 25 based on the battery voltage and battery current, calculate the inductance of the receiving coil 22 based on the resonant frequency, the receiving voltage, and the receiving current, calculate the mutual inductance based on the resonant frequency and the transmitting voltage, and calculate the transmitting current based on the resonant frequency, the mutual inductance, the equivalent resistance, and the inductance of the receiving coil 22. However, it is not always necessary to calculate all of the mutual inductance, the inductance of the receiving coil 22, and the equivalent resistance; for example, in the case of a coreless system, the self-inductance of the receiving coil 22 is known, so it is also possible to calculate only the mutual inductance and the equivalent resistance.

[0121] In the above embodiment, for example, the calculation processes of steps S26 and S27 in Figures 7 and 11 are executed by the control unit 20, but the present invention is not limited to this, and parameters necessary for the calculation processes may be transmitted to the control unit 10 and calculated by the control unit 10.

[0122] In the above embodiment, the DC / AC inverter 11 is configured with four switching elements Q1 to Q4, but the present invention is not limited to this. The DC / AC inverter 11 may be configured to have at least a plurality of switching elements that are controlled to be on / off to bring the inverter into a short-circuit state.

[0123] The above-described first to ninth modifications can be applied to the contactless power supply system 100 in FIG. 1 and the contactless power supply system 100A in FIG. 7 (including a plurality of DC / AC inverters and a plurality of power transmission units). [Industrial Applicability]

[0124] As described above in detail, in the contactless power supply system according to one aspect of the present invention, by turning on the switching element of the inverter, the input side of the power transmission unit downstream of the inverter is short-circuited and the mutual inductance and the self-inductance of the receiving coil are estimated, so that these parameters can be estimated without affecting the power supply operation to the battery. [Explanation of symbols]

[0125] 10 Control Unit 11, 11A, 11-1 to 11-n DC / AC inverter 12, 12A, 12B Power transmission section 13, 13A, 13-1 to 13-n inductors 14, 14A, 14-1 to 14-n capacitors 15, 15A, 15-1 to 15-n power transmission coil 16 Voltage Sensor 17 Phase difference detection circuit 18 Additional resonant circuit 18-1~18-n Additional resonant circuit 18A L circuit 18B C circuit 18C LC circuit 19 Communications Department 20 Control Unit 21, 21B Power receiving section 22 receiving coil 23 Voltage sensor 24 Current Sensor 25 Bidirectional AC / DC converter 26 Voltage sensor 27 Current Sensor 28 Additional resonant circuit 28A C circuit 28B C circuit 28C CL circuit 28D CCL circuit 28E CLC circuit 29 Communications Department 31 DC / DC converter 32 additional capacitors 33 Synthetic Impedance Circuit 34 DC / DC converter 35 Low-pass filter (LPF) 50,50A power transmission resonant circuit 82-1~82-n Power transmission section 91 Power receiving unit 100, 100A, 100B contactless power supply system 101,101B,101BA,101BB,101BC Power transmission equipment 102, 102B, 102BA, 102BB, 102BC, 102BD Power receiving device 111 DC power supply 112 Battery 171,172 Comparators 173 Phase comparator 174 Low-pass filter (LPF) C1~C12 capacitors C add Additional Capacitor C s ,C r capacitance L1~L12 inductors L s ,L r Inductance M1~M n Mutual inductance Q1~Q14 switching elements R L Load resistance SG1~SG24 gate signals SW1~SW2 switches T1~T14 terminals i tx ,i tx1 ~i txn Transmission Current i rx Receiving current r2 equivalent resistance v inv ,v inv1 ~v invn Inverter Output Voltage v tx ,v tx1 ~v txn Transmission voltage

Claims

1. A contactless power supply system including a power transmitting device, a power receiving device, and a control unit that controls the power transmitting device and the power receiving device, The power transmission device is an inverter including a plurality of switching elements for converting an input DC voltage into a predetermined AC voltage; a power transmitting resonant circuit including an inductor and a capacitor and having a predetermined resonant frequency; a power transmitting coil connected to the power transmitting resonant circuit; a first voltage sensor that measures a first voltage of the power transmitting coil; the power transmitting resonant circuit is inserted and connected between the inverter and the power transmitting coil, The power receiving device is a receiving coil electromagnetically coupled to the transmitting coil by mutual inductance; a bidirectional converter having a charging mode in which the AC voltage received by the receiving coil is converted into a predetermined DC voltage and output to a battery, and a discharging mode in which the DC voltage from the battery is converted into a predetermined AC voltage and output to a transmitting coil; a second voltage sensor that measures a second voltage of the receiving coil; a first current sensor that measures a first current in the receiving coil; a third voltage sensor for measuring a battery voltage of the battery; a second current sensor that measures a battery current of the battery; The control unit short-circuiting the inverter by controlling the on / off of the plurality of switching elements, operating the bidirectional converter in a discharge mode, and calculating an equivalent resistance when the battery is viewed from the input of the bidirectional converter based on the battery voltage and the battery current; The wireless power transfer system calculates the mutual inductance based on the resonant frequency, the first voltage, and the first current.

2. the control unit further calculates a transmission current of the power transmitting coil based on the resonant frequency, the mutual inductance, the equivalent resistance, and the inductance of the power receiving coil. The contactless power supply system according to claim 1 .

3. the control unit further controls the plurality of switching elements to short-circuit the inverter and, when the bidirectional converter is operated in a discharge mode, calculates an inductance of the power receiving coil based on the resonant frequency, the second voltage, and the first current. The contactless power supply system according to claim 2 .

4. The power transmitting resonant circuit is a first reactance element connected between the inverter and one end of the power transmitting coil; a second reactance element connected between one end of the power transmitting coil and the other end of the power transmitting coil, the power transmitting resonant circuit has an L-shaped structure formed by the first and second reactance elements, (1) the first reactance element is an inductor and the second reactance element is a capacitor; (2) the first reactance element is a capacitor and the second reactance element is an inductor; is one of The contactless power supply system according to claim 1 .

5. The control unit calculating an output voltage of the inverter required to pass a desired transmission current through the power transmitting coil based on the resonant frequency and the inductance of the power transmitting resonant circuit; the inverter is operated as an inverter by controlling the on / off of the plurality of switching elements, the bidirectional converter is operated in a charging mode, and a phase shift amount of the on / off control of the plurality of switching elements of the inverter is controlled based on the output voltage of the inverter and the input DC voltage so as to flow the desired transmission current; The contactless power supply system according to claim 1 .

6. the control unit includes a first control unit and a second control unit, The second control unit short-circuiting the inverter by controlling the on / off of the plurality of switching elements, operating the bidirectional converter in a discharge mode, calculating an equivalent resistance when viewing the battery from an input of the bidirectional converter based on the battery voltage and the battery current, and calculating an inductance of a receiving coil based on the resonant frequency, the second voltage, and the first current; The first control unit calculating the mutual inductance based on the resonant frequency, the first voltage, and the first current, and calculating a transmission current of the power transmitting coil based on the resonant frequency, the mutual inductance, the equivalent resistance, and an inductance of the power receiving coil; The contactless power supply system according to claim 1 .

7. the control unit includes a first control unit and a second control unit, The second control unit short-circuiting the inverter by controlling the on / off of the plurality of switching elements, operating the bidirectional converter in a discharge mode, calculating an equivalent resistance when viewing the battery from an input of the bidirectional converter based on the battery voltage and the battery current, and calculating an inductance of a receiving coil based on the resonant frequency, the second voltage, and the first current; The first control unit calculating the mutual inductance based on the resonant frequency, the first voltage, and the first current; and calculating a transmission current of the power transmitting coil based on the resonant frequency, the mutual inductance, the equivalent resistance, and an inductance of the power receiving coil; calculating an output voltage of the inverter required to pass a desired transmission current through the power transmitting coil based on the resonant frequency and the inductance of the power transmitting resonant circuit; the inverter is operated as an inverter by controlling the on / off of the plurality of switching elements, the bidirectional converter is operated in a charging mode, and a phase shift amount of the on / off control of the plurality of switching elements of the inverter is controlled based on the output voltage of the inverter and the input DC voltage so as to flow the desired transmission current; The contactless power supply system according to claim 1 .

8. the wireless power supply system includes a plurality of the power transmission devices, the wireless power supply system further includes an output voltage detection circuit that detects a phase difference between the first voltages of the plurality of power transmission devices; The control unit calculating a value and a sign of each mutual inductance between each power transmitting coil of the plurality of power transmitting devices and the power receiving coil based on the resonant frequency, the phase difference, and each first voltage of the plurality of power transmitting devices; calculating a transmission current of the power transmitting coil based on the resonant frequency, the value and sign of each mutual inductance, the equivalent resistance, and the inductance of the power receiving coil; The contactless power supply system according to claim 1 .

9. the or each power transmitting device further comprises an additional resonant circuit including at least one of an inductor and a capacitor; The contactless power supply system according to any one of claims 1 to 8.

10. the power receiving device further includes a DC / DC converter inserted between the bidirectional converter and the battery and configured to convert an input DC voltage into a predetermined DC voltage; The contactless power supply system according to any one of claims 1 to 8.

11. the or each power transmitting device further comprises an additional capacitance connected in series with the inductor of the power transmitting resonant circuit; The contactless power supply system according to any one of claims 1 to 8.

12. the power receiving device further includes another first DC / DC converter inserted between the bidirectional converter and the battery in the discharge mode, and converting a battery voltage from the battery into a predetermined DC voltage; The contactless power supply system according to any one of claims 1 to 8.

13. the power receiving device further includes a low-pass filter inserted between the bidirectional converter and the battery, the low-pass filter reducing ripples in the output voltage or the output current from the bidirectional converter. The contactless power supply system according to any one of claims 1 to 8.

14. the power receiving device further includes a second DC / DC converter inserted between the bidirectional converter and the battery in the discharging mode, and configured to convert an output voltage from the bidirectional converter into a predetermined DC voltage. The contactless power supply system according to any one of claims 1 to 8.

15. the power receiving device further includes a low-pass filter and a second DC / DC converter inserted between the bidirectional converter and the battery, the low-pass filter reduces ripples in an output voltage or an output current from the bidirectional converter and outputs the output voltage or the output current to the separate second DC / DC converter; the second DC / DC converter converts the output voltage from the low-pass filter into a predetermined DC voltage; The contactless power supply system according to any one of claims 1 to 8.

16. A control method for a contactless power supply system including a power transmitting device, a power receiving device, and a control unit that controls the power transmitting device and the power receiving device, The power transmission device is an inverter including a plurality of switching elements for converting an input DC voltage into a predetermined AC voltage; a power transmitting resonant circuit including an inductor and a capacitor and having a predetermined resonant frequency; a power transmitting coil connected to the power transmitting resonant circuit; a first voltage sensor that measures a first voltage of the power transmitting coil; the power transmitting resonant circuit is inserted and connected between the inverter and the power transmitting coil, The power receiving device is a receiving coil electromagnetically coupled to the transmitting coil by mutual inductance; a bidirectional converter having a charging mode in which the AC voltage received by the receiving coil is converted into a predetermined DC voltage and output to a battery, and a discharging mode in which the DC voltage from the battery is converted into a predetermined AC voltage and output to a transmitting coil; a second voltage sensor that measures a second voltage of the receiving coil; a first current sensor that measures a first current in the receiving coil; a third voltage sensor for measuring a battery voltage of the battery; a second current sensor that measures a battery current of the battery; The control method includes: the control unit short-circuits the inverter by controlling on / off of the plurality of switching elements, operates the bidirectional converter in a discharge mode, and calculates an equivalent resistance when the battery is viewed from the input of the bidirectional converter based on the battery voltage and the battery current; the control unit calculating the mutual inductance based on the resonant frequency, the first voltage, and the first current; A control method for a contactless power supply system including:

17. The control method further comprises: the control unit calculating a transmission current of the power transmitting coil based on the resonant frequency, the mutual inductance, the equivalent resistance, and an inductance of the power receiving coil, A control method for a contactless power supply system according to claim 16.

18. The control method further comprises: a control unit that short-circuits the inverter by controlling the on / off of the plurality of switching elements to operate the bidirectional converter in a discharge mode, and calculates an inductance of the power receiving coil based on the resonant frequency, the second voltage, and the first current. A control method for a contactless power supply system according to claim 17.

19. The power transmitting resonant circuit is a first reactance element connected between the inverter and one end of the power transmitting coil; a second reactance element connected between one end of the power transmitting coil and the other end of the power transmitting coil, the power transmitting resonant circuit has an L-shaped structure formed by the first and second reactance elements, (1) the first reactance element is an inductor and the second reactance element is a capacitor; (2) the first reactance element is a capacitor and the second reactance element is an inductor; is one of A control method for a contactless power supply system according to claim 16.

20. a step of the control unit calculating an output voltage of the inverter required to pass a desired transmission current through the power transmitting coil based on the resonant frequency and the inductance of the power transmitting resonant circuit; the control unit controls the plurality of switching elements to perform inverter operation, operates the bidirectional converter in a charging mode, and controls a phase shift amount of the on / off control of the plurality of switching elements of the inverter based on the output voltage of the inverter and the input DC voltage so as to flow the desired transmission current; The control method for a contactless power supply system according to any one of claims 16 to 19, further comprising:

21. the control unit includes a first control unit and a second control unit, the second control unit short-circuits the inverter by controlling the on / off of the plurality of switching elements, operates the bidirectional converter in a discharge mode, calculates an equivalent resistance when the battery is viewed from an input of the bidirectional converter based on the battery voltage and the battery current, and calculates an inductance of a receiving coil based on the resonant frequency, the second voltage, and the first current; the first control unit calculating the mutual inductance based on the resonant frequency, the first voltage, and the first current, and calculating a transmission current of the power transmitting coil based on the resonant frequency, the mutual inductance, the equivalent resistance, and an inductance of the power receiving coil; The control method for a contactless power supply system according to any one of claims 16 to 19, further comprising:

22. the control unit includes a first control unit and a second control unit, the second control unit short-circuits the inverter by controlling the on / off of the plurality of switching elements, operates the bidirectional converter in a discharge mode, calculates an equivalent resistance when the battery is viewed from an input of the bidirectional converter based on the battery voltage and the battery current, and calculates an inductance of a receiving coil based on the resonant frequency, the second voltage, and the first current; the first control unit calculating the mutual inductance based on the resonant frequency, the first voltage, and the first current, and calculating a transmission current of the power transmitting coil based on the resonant frequency, the mutual inductance, the equivalent resistance, and an inductance of the power receiving coil; a step in which the first control unit calculates an output voltage of the inverter required to pass a desired power transmission current through the power transmission coil based on the resonant frequency and the inductance of the power transmission resonant circuit; the first control unit controls the plurality of switching elements to perform inverter operation, operates the bidirectional converter in a charging mode, and controls a phase shift amount of the on / off control of the plurality of switching elements of the inverter based on the output voltage of the inverter and the input DC voltage so as to flow the desired transmission current; 20. A control method for a contactless power supply system according to claim 16, comprising:

23. the wireless power supply system includes a plurality of power transmission devices, the wireless power supply system further includes an output voltage detection circuit that detects a phase difference between the first voltages of the plurality of power transmission devices; the control unit calculating a value and a sign of each mutual inductance between each power transmitting coil of the plurality of power transmitting devices and the power receiving coil based on the resonant frequency, the phase difference, each first voltage and each power transmitting current of the plurality of power transmitting devices; a step of the control unit calculating a transmission current of the power transmitting coil based on the resonant frequency, the value and sign of each mutual inductance, the equivalent resistance, and the inductance of the power receiving coil; 20. A control method for a contactless power supply system according to claim 16, comprising:

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