Power supply system

Abstract

To enable highly efficient power feeding through a transformer while suppressing the generation of leakage flux as much as possible.SOLUTION: A power feeding system 10 includes a transformer 11, a primary side circuit 12, a secondary side circuit 13, a secondary battery 14, a first relay 15 disposed between the secondary side circuit 13 and the secondary battery 14, a second relay 16 disposed between the secondary side circuit 13 and the first relay 15, a voltage measurement unit 17 for measuring voltage of the secondary side circuit 13, and a control unit 18. The control unit 18 turns off the first relay 15 and turns on the second relay 16 to evaluate a positional relation between a primary side coil 20 and a secondary side coil 21 on the basis of changes over time in the voltage of the secondary side circuit 13 as measured by the voltage measurement unit 17 when a predetermined current is fed from the primary side circuit 12.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power feeding system, and particularly relates to a technology for performing power feeding via a transformer. [Background Art]

[0002] For example, as a non-contact charger that charges a secondary battery such as a lithium ion battery in a non-contact manner, a power feeding system of a type that transmits electric power from a power transmission side to a power reception side via a transformer is known (see, for example, Patent Document 1 and Patent Document 2). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2011-205829 [Patent Document 2] Japanese Unexamined Patent Publication No. 2016-152687 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] By the way, in this type of power feeding system, the positional relationship between the power transmission-side coil and the power reception-side coil that constitute the transformer is important for improving power feeding efficiency. In addition, depending on the positional relationship between the power transmission-side coil and the power reception-side coil, leakage magnetic flux may occur, which may adversely affect surrounding electronic devices such as causing malfunction. Therefore, it is necessary to appropriately manage the positional relationship between the two coils. This type of problem becomes more prominent when the core around which each coil is wound has a split configuration. That is, as described in Patent Document 1, when a device provided with a power transmission-side coil (for example, a charging station) and a device provided with a power reception-side coil (for example, a vehicle) are movable relative to each other, the positional relationship between the two coils changes each time. Therefore, it is important to suppress magnetic flux leakage caused by positional displacement as much as possible.

[0005] For example, Patent Document 2 discloses a means for detecting leakage flux that fluctuates according to the relative positions of the transmitting coil and the receiving coil, and notifying the driver or other person based on the detection result, thereby enabling the driver or other person to suitably determine the position of the receiving coil mounted on the vehicle. However, with this means, if there is a problem with the positional relationship between the coils, an unacceptable level of leakage flux will be generated.

[0006] In view of the above circumstances, this specification aims to solve the technical problem of enabling highly efficient power supply via a transformer while suppressing the generation of leakage magnetic flux as much as possible. [Means for solving the problem]

[0007] The aforementioned problems are solved by the power supply system according to the present invention. Specifically, this power supply system comprises a transformer having a primary coil and a secondary coil, a primary circuit for controlling the current flowing through the primary coil, a secondary circuit for controlling the current flowing through the secondary coil, a secondary battery connected to the secondary circuit, a first relay disposed between the secondary circuit and the secondary battery, a second relay disposed between the secondary circuit and the first relay, a voltage measuring unit for measuring the voltage of the secondary circuit, and a control unit, wherein the control unit is characterized by turning off the first relay and turning on the second relay to supply a predetermined current from the primary circuit, and evaluating the positional relationship between the primary coil and the secondary coil based on the change in the voltage of the secondary circuit measured by the voltage measuring unit over time.

[0008] The inventor focused on the time-dependent change in voltage generated in the secondary circuit when power supply to the secondary battery is interrupted, and found that there is a predetermined relationship between this time-dependent change and the positional relationship of each coil of the transformer. The present invention is based on the above finding and connects a second relay between the secondary circuit and the first relay, separate from the primary relay that switches the connection between the secondary circuit and the secondary battery. The positional relationship between the primary coil and the secondary coil is evaluated based on the time-dependent change in voltage of the secondary circuit when power is supplied with the second relay turned on and the first relay turned off. In this way, power supply for evaluating the positional relationship of the coils can be performed under less stringent conditions (e.g., short time, low current) than the power supply conditions when power is supplied (charged) to the secondary battery, so even if the relative position of the coils deviates from the normal position, the leakage of magnetic flux that occurs at that time can be reduced. Therefore, according to the present invention, it is possible to perform power supply via a transformer with high efficiency while suppressing leakage magnetic flux.

[0009] Furthermore, in the power supply system according to the present invention, if the control unit determines that the positional relationship between the primary coil and the secondary coil is in an acceptable state, it may turn off the second relay and turn on the first relay to start charging the secondary battery.

[0010] By starting the charging of the secondary battery only when it is determined that the positional relationship between the primary and secondary coils is acceptable, charging can always be started with the coils properly aligned, thus enabling stable and highly efficient charging.

[0011] Furthermore, in the power supply system according to the present invention, the predetermined current may be smaller than the current supplied from the primary circuit when the secondary battery is being charged.

[0012] The predetermined current in this invention is set during power supply to evaluate the positional relationship between the primary and secondary coils, and therefore does not need to be set to a large value like during charging. In other words, even with a smaller current than during charging, the positional relationship between the two coils can be properly evaluated by understanding the change in voltage applied to the secondary circuit over time. A smaller current is preferable because it also reduces the amount of magnetic flux leakage that occurs when the relative positions of the coils are misaligned.

[0013] Furthermore, in the power supply system according to the present invention, the primary coil may be provided in a charging station, and the secondary coil may be mounted on a vehicle. In that case, if the control unit determines that the positional relationship between the primary coil and the secondary coil is not acceptable, it may move the secondary coil to a position where the positional relationship becomes acceptable.

[0014] When considering applying the power supply system according to the present invention to a vehicle charging system, if the control unit determines that the positional relationship between the primary coil and the secondary coil is not acceptable, it can move the secondary coil to a position where the positional relationship becomes acceptable. This allows for the rapid and proper correction of the misalignment between the coils, enabling highly efficient charging. In this case, the movement of the secondary coil can be easily and quickly carried out by moving the vehicle on which the secondary coil is mounted. [Effects of the Invention]

[0015] As described above, the power supply system according to the present invention enables highly efficient power supply via a transformer while suppressing the generation of leakage magnetic flux as much as possible. Therefore, when the power source is a secondary battery, highly efficient charging becomes possible. [Brief explanation of the drawing]

[0016] [Figure 1] This figure shows the overall configuration of a power supply system according to one embodiment of the present invention. [Figure 2]Figure 1 shows a flowchart illustrating an example of a method for supplying power to a secondary battery using the power supply system shown. [Modes for carrying out the invention]

[0017] The following describes a power supply system according to one embodiment of the present invention, and a method for supplying power to a secondary battery using this power supply system, based on the drawings.

[0018] Figure 1 shows the overall configuration of a power supply system 10 according to one embodiment of the present invention. In this embodiment, the power supply system 10 is for charging a vehicle and comprises a transformer 11, a primary circuit 12 located on the primary side of the transformer 11, a secondary circuit 13 located on the secondary side of the transformer 11, a secondary battery 14 connected to the secondary circuit 13, a first relay 15 disposed between the secondary circuit 13 and the secondary battery 14, a second relay 16 connected between the secondary circuit 13 and the first relay 15, a voltage measuring unit 17 for measuring the voltage of the secondary circuit 13, and a BMU 18. Here, the BMU 18 corresponds to the control unit according to the present invention. After describing the details of each element below, an example of how to use the power supply system 10 (i.e., a power supply method) will be described.

[0019] The transformer 11 has a primary coil 20 and a secondary coil 21 wound around a core 19. In this embodiment, the core 19 is composed of a pair of divided cores 22 and 23 called a UU core, with the primary coil 20 wound around the primary divided core (first divided core 22) and the secondary coil 21 wound around the secondary divided core (second divided core 23). The primary coil 20 is connected to the primary circuit 12, and the secondary coil 21 is connected to the secondary circuit 13.

[0020] Although FIG. 1 exemplifies a form in which coils 20 and 21 are wound around the bottom portions 22a and 23a of the respective U-shaped divided cores 22 and 23, the winding positions of the coils 20 and 21 are not limited to the bottom portions 22a and 23a. For example, although not shown in the drawings, the coils 20 and 21 may be wound around a pair of abutting portions 22b and 23b that are bent from both ends of the bottom portions 22a and 23a and extend in the same direction.

[0021] Of course, the form of the core 19 is not limited to a UU core. Any form of divided core is applicable as long as it is constituted by a pair of divided cores.

[0022] The primary-side circuit 12 is connected to a DC power supply 24, and is configured to be able to control the current supplied from the DC power supply 24 in a predetermined manner. Specifically, it is configured to be able to convert direct current into alternating current of a predetermined voltage. In this case, the transformer 11, the primary-side circuit 12, and the secondary-side circuit 13 constitute a DC-DC power converter.

[0023] In the present embodiment, the primary-side circuit 12 is a so-called bridge circuit, and includes four switching elements 12a and antiparallel diodes 12b connected to each of the switching elements 12a. This primary-side circuit 12 is configured to be able to convert a DC voltage input from the DC power supply 24 into a high-frequency square-wave AC voltage. This inverter operation is performed based on a command from a controller 25 (see FIG. 1). In other words, the AC conversion condition by the primary-side circuit 12, such as the magnitude of the AC voltage, can be controlled by the controller 25.

[0024] The secondary-side circuit 13 is configured to be able to control the current supplied from the primary-side circuit 12 via the transformer 11 in a predetermined manner. Specifically, it is configured to be able to convert alternating current into direct current of a predetermined voltage.

[0025] In this embodiment, the secondary circuit 13 is a so-called rectifier circuit and has four diodes 13a and smoothing capacitors 13b connected in parallel to each diode 13a. This secondary circuit 13 is configured to convert the square wave AC voltage input from the primary circuit 12 via the transformer 11 into a DC voltage.

[0026] Capacitors 12c and 13c are connected in parallel to the primary circuit 12 and the secondary circuit 13, respectively.

[0027] The first relay 15 is positioned between the secondary circuit 13 and the secondary battery 14, and is configured to switch between energized and disconnected states between the secondary circuit 13 and the secondary battery 14. That is, when the first relay 15 is ON, power is supplied from the secondary circuit 13 to the secondary battery 14, and when the first relay 15 is OFF, no power is supplied from the secondary circuit 13 to the secondary battery 14.

[0028] The second relay 16 is positioned between the secondary circuit 13 and the first relay 15. In other words, the second relay 16 is connected in parallel with the secondary circuit 13 on the side closer to the secondary circuit 13 than the first relay 15. This allows the second relay 16 to switch between energized and disconnected states with the secondary circuit 13 through its own switching operation, regardless of the on / off state of the first relay 15. That is, when the second relay 16 is ON, the circuit including the second relay 16 connected in parallel with the secondary circuit 13 is energized, and when the second relay 16 is OFF, the circuit including the second relay 16 is electrically disconnected.

[0029] The voltage measuring unit 17 is, for example, a voltmeter, and in this embodiment, it is connected in series with the second relay 16. By connecting in this way, the voltage measuring unit 17 can measure the voltage of the circuit including the second relay 16 when the second relay 16 is ON. In this case, since the circuit including the second relay 16 is connected in parallel with the secondary circuit 13, the voltage measured by the voltage measuring unit 17 can be obtained as the voltage of the secondary circuit 13, or more precisely, the voltage of the capacitor 13c connected in parallel with the secondary circuit 13.

[0030] The BMU 18, acting as the control unit, monitors the state of the secondary battery 14 (various parameters such as voltage) and controls the power supply from the secondary circuit 13 to the secondary battery 14. The BMU 18 also acquires information regarding the voltage values ​​obtained by the voltage measurement unit 17 and can perform processing to evaluate the quality of the junctions of the divided cores 22 and 23, specifically the positional relationship between the primary coil 20 and the secondary coil 21, based on this information.

[0031] Furthermore, in this embodiment, the BMU 18 controls the switching operation of the first relay 15 and the second relay 16, and can also transmit information acquired by the BMU 18 (for example, information regarding the voltage measurement value of the secondary battery 14) to the controller 25.

[0032] In this case, the first split core 22 of the transformer 11, the primary coil 20, the primary circuit 12, the DC power supply 24, and the controller 25 are provided on the charging station 26 side. The second split core 23 of the transformer 11, the secondary coil 21, the secondary circuit 13, the secondary battery 14, the first relay 15, the second relay 16, the voltage measuring unit 17, and the BMU 18 are provided on the vehicle 27 side.

[0033] Next, an example of a method for supplying power to a secondary battery 14 using the power supply system 10 configured as described above (a charging method) will be explained based on the flowchart shown in Figure 2.

[0034] Herein, the power supply method according to this embodiment comprises an evaluation relay switching step S1, a voltage adjustment step S3 of the primary circuit 12, a power transmission step S4, a voltage measurement step S5 of the secondary circuit 13, a core coupling state evaluation step S6, a charging relay switching step S9, and a charging start step S10. It is assumed that the first divided core 22 and the second divided core 23 of the transformer 11 are aligned with each other in a predetermined positional relationship. Steps S1 to S10 will be described below in chronological order.

[0035] (S1) Evaluation relay switching step In step S1, relays 15 and 16 are switched to evaluate the core coupling state of the transformer 11. Specifically, by turning off the first relay 15 and turning on the second relay 16, the secondary circuit 13 and the secondary battery 14 are electrically disconnected, and the secondary circuit 13 and the voltage measuring unit 17 are energized. The on-off operation of the first relay 15 and the second relay 16 is performed (controlled) by the BMU 18.

[0036] (S2) Voltage information transmission step (S3) Voltage adjustment step In this embodiment, first, the BMU 18 transmits information regarding the voltage of the secondary battery 14 acquired by the BMU to the controller 25 of the primary circuit 12. Based on the received voltage information, the controller 25 sends a command to the primary circuit 12 to convert the DC input from the DC power supply 24 into AC with a predetermined voltage, specifically, an AC voltage equal in magnitude to the voltage of the secondary battery 14. As a result, the primary circuit 12 generates AC with the predetermined voltage.

[0037] Furthermore, it is preferable to set the AC current value generated by the primary circuit 12 to be smaller than the AC current value generated by the primary circuit 12 when charging the secondary battery 14. For example, the AC current value generated by the primary circuit 12 for core coupling state checking (the magnitude of the core coupling check current) can be set to a current value that is 10¹ to 10² orders of magnitude smaller than the charging current (for example, 0.1 to 0.5 A).

[0038] (S4) Power transmission step In step S4, the alternating current of a predetermined voltage and current generated in step S3 is transmitted to the secondary circuit 13 via the transformer 11. When the aforementioned alternating current is generated in the primary circuit 12, the first divided core 22 and the second divided core 23 of the transformer 11 are in a predetermined positional relationship and are facing each other (see Figure 1). Therefore, by generating the aforementioned alternating current in the primary circuit 12, electromagnetic induction and mutual induction occur between the first divided core 22 and the second divided core 23, which are in a predetermined positional relationship, and between the primary coil 20 and the secondary coil 21, and the alternating current of a predetermined voltage and current (in this case, a square wave alternating current) generated in the primary circuit 12 is supplied to the secondary circuit 13. The secondary circuit 13 converts the supplied alternating current into a predetermined direct current through its rectification action. The converted direct current power is stored in the capacitor 13c connected in parallel with the secondary circuit 13.

[0039] (S5) Voltage measurement step In step S5, the voltage of the secondary circuit 13 is measured by the voltage measuring unit 17. That is, by turning on the second relay 16 in the previous step S1, the circuit including the second relay 16 and the voltage measuring unit 17 is electrically connected to the secondary circuit 13. This circuit is also connected in parallel with the secondary circuit 13. Therefore, a voltage of the same magnitude as the voltage generated in the secondary circuit 13 (capacitor 13c) is applied to the voltage measuring unit 17. Thus, by measuring the voltage with this voltage measuring unit 17, the voltage of the secondary circuit 13 is measured. This voltage measurement is performed for a predetermined period of time after power transmission from the primary circuit 12 has started.

[0040] (S6) Core coupling state evaluation step When the voltage of the secondary circuit 13 is measured during power transmission via the transformer 11 as described above, the coupling state of the divided cores 22 and 23 constituting the transformer 11, in other words, the positional relationship between the primary coil 20 and the secondary coil 21 attached to predetermined positions on each divided core 22 and 23, is evaluated based on the information regarding the measured voltage. In this embodiment, the positional relationship between the primary coil 20 and the secondary coil 21 is evaluated based on the change in voltage of the secondary circuit 13 over time obtained by the voltage measurement unit 17. At this time, data is acquired in advance regarding the relationship between the amount of voltage change in the secondary circuit 13 (for example, how much the voltage increased in a predetermined time) and the positional relationship between the primary coil 20 and the secondary coil 21, for example, the amount of misalignment in the direction perpendicular to the abutting direction of the divided cores 22 and 23, when AC of a predetermined voltage and current is transmitted from the primary circuit 12 to the secondary circuit 13 via the transformer 11. Then, using the data acquired in step S5, the positional relationship between the primary coil 20 and the secondary coil 21 is evaluated based on the voltage change in the secondary circuit 13. In this case, for example, if the voltage measurement taken after a predetermined time (e.g., 2 seconds) from the start of measurement is equal to or greater than a preset voltage measurement threshold (e.g., 80V), it can be considered that power is being transmitted through the transformer 11 at an efficiency of a predetermined level or higher. Therefore, the positional misalignment between coils 20 and 21, and consequently between the divided cores 22 and 23, is determined to be small enough to be acceptable, and the process proceeds to step S7. This determination process is performed by the BMU 18.

[0041] (S8) Secondary coil movement step Alternatively, if the voltage measurement value after a predetermined time has elapsed from the start of measurement is less than a preset threshold for voltage measurement value, it can be assumed that power is being transmitted through the transformer 11 at an efficiency lower than the required efficiency. In this case, it is determined that the misalignment between coils 20 and 21, and consequently the misalignment between divided cores 22 and 23, is unacceptably large, and the process proceeds to step S8. Step S8 will be explained first. In step S8, the secondary coil 21 is moved by an amount and direction that resolves the misalignment. In this embodiment, the secondary coil 21 is located on the vehicle 27 side, so the misalignment is resolved by moving the vehicle 27 by a predetermined amount and direction. After that, the process returns to step S4, and steps S4 to S6 are performed. Steps S4 to S6 and S8 are repeated until the misalignment becomes small enough to be acceptable.

[0042] While it is possible to actually detect the direction of the misalignment using sensors, etc., a structure that restricts the direction of misalignment during the coupling operation of the divided cores 22 and 23 due to the movement of the vehicle 27 may be provided on at least one of the primary side (charging station 26 side) and the secondary side (vehicle 27 side).

[0043] (S7) Voltage evaluation step If it is determined that the misalignment between coils 20 and 21, and consequently between divided cores 22 and 23, is small enough to be acceptable, the process in step S7 is performed. Specifically, in step S7, it is determined whether the voltage of the secondary circuit 13 has reached a magnitude equal to the voltage of the secondary battery 14 as a result of the power transmission step S4. This determination process is performed by the BMU 18. The voltage of the secondary battery 14 referred to here may be the voltage value related to the information transmitted to the controller 25 in step S2. If it is determined that the voltage of the secondary circuit 13 has reached the voltage of the secondary battery 14, for example, the BMU 18 sends a command to the controller 25 to stop power transmission, and the process proceeds to step S9. This process is also performed by the BMU 18.

[0044] Alternatively, if it is determined that the voltage of the secondary circuit 13 has not reached the voltage of the secondary battery 14, power supply from the primary circuit 12 is continued, and steps S5 to S7 are repeated at predetermined intervals. This series of steps S5 to S7 is repeated until the voltage of the secondary circuit 13 reaches the voltage of the secondary battery 14.

[0045] (S9) Charging relay switching step In step S9, the relays 15 and 16 are switched to enable charging of the secondary battery 14. Specifically, the first relay 15 is turned on and the second relay 16 is turned off, which electrically disconnects the secondary circuit 13 and the secondary battery 14, while energizing the secondary circuit 13 and the voltage measuring unit 17. The on-off switching operation of the relays 15 and 16 described above is performed by the BMU 18.

[0046] (S10) Charging start step In step S10, a predetermined voltage and current of alternating current is supplied from the primary circuit 12 to the secondary circuit 13 via the transformer 11, and the predetermined voltage of direct current rectified in the secondary circuit 13 is supplied to the secondary battery 14. This charges the secondary battery 14. The charging of the secondary battery 14 is controlled by the BMU 18.

[0047] As described above, in the power supply system 10 according to this embodiment, in addition to the first relay 15 that switches the connection between the secondary circuit 13 of the transformer 11 and the secondary battery 14, a second relay 16 is connected between the secondary circuit 13 and the first relay 15. When the second relay 16 is turned on and the first relay 15 is turned off, the positional relationship between the primary coil 20 and the secondary coil 21 is evaluated based on the change in voltage of the secondary circuit 13 over time. In this way, power supply to evaluate the positional relationship of coils 20 and 21, and consequently the positional relationship of the divided cores 22 and 23, can be performed under less stringent conditions (e.g., short time, low current) than the power supply conditions when supplying (charging) the secondary battery 14. Therefore, even if the relative positions of coils 20 and 21 are deviated from their normal positions, the leakage of magnetic flux that occurs at that time can be reduced. Thus, according to the power supply system 10 according to this embodiment, it is possible to charge the secondary battery 14 with an external power source (in this case, a DC power source 24) via the transformer 11 with high efficiency while suppressing leakage magnetic flux.

[0048] In particular, in this embodiment, the predetermined current supplied from the primary circuit 12 during the core coupling state evaluation step S6 is smaller than the current supplied from the primary circuit 12 during the secondary battery 14 charging start step S10 (here, 10 1 Since the order of magnitude A is achieved, the amount of leakage per hour that occurs when the relative positions of coils 20 and 21 are misaligned can be kept to a minimum. Of course, even with a current smaller than that during charging, the positional relationship between coils 20 and 21 can be properly evaluated based on the change in voltage applied to the secondary circuit 13 over time (in this case, the voltage measurement after a predetermined time has elapsed), so there is no problem in performing the core coupling state evaluation step S6.

[0049] Furthermore, when charging is not performed, it is desirable that the voltage of the secondary circuit 13 be zero or close to zero. With the power supply system 10 according to this embodiment, the charge stored in the capacitor 13c of the secondary circuit 13 can be discharged by turning off the first relay 15 connected to the secondary battery 14 and turning on the second relay 16 connected in parallel with the secondary circuit 13, so there is no need to provide a separate relay for discharge.

[0050] Furthermore, as in this embodiment, in steps S4 to S7, the voltage across capacitor 13c of the secondary circuit 13 is raised to a magnitude equal to the measured voltage of the secondary battery 14. Therefore, in step S9, charging under the desired conditions becomes possible simply by switching relays 15 and 16. Consequently, the pre-charge relay, which conventionally needed to be connected in parallel with the main charging relay (first relay 15 in this embodiment) to protect the secondary battery 14, becomes unnecessary, and the circuit can be simplified.

[0051] Although one embodiment of the present invention has been described above, the power supply system and power supply method according to the present invention may also adopt configurations other than those described above, without departing from the spirit of the invention.

[0052] For example, regarding the change in voltage of the secondary circuit 13 over time in the core coupling state evaluation step S6, this embodiment illustrates a case where the amount of voltage rise from the start of measurement to after a predetermined time has elapsed (for example, 100V 2 seconds after the start of measurement) is used as the criterion for determination. However, other parameters may of course be used as the criterion. For example, the time required to reach a predetermined voltage from the start of measurement may be used as the criterion, or the amount of voltage rise per unit time (rate of rise) may be used as the criterion. In short, as long as data regarding the correlation with the positional relationship between coils 20 and 21 is effectively acquired, the specific criteria for determining the change over time are arbitrary.

[0053] Furthermore, in this embodiment, before the core coupling state evaluation step S6, the BMU 18 transmits information regarding the voltage of the secondary battery 14 acquired by the BMU 18 to the controller 25 of the primary side circuit 12 (voltage information transmission step S2). Based on the received voltage information, the controller 25 sends a command to the primary side circuit 12 to convert the DC input from the DC power supply 24 into AC with a voltage equal to that of the secondary battery 14 (voltage adjustment step S3). However, these steps S2 and S3 may be omitted. In other words, the transmission voltage during core coupling state evaluation may be set arbitrarily, as long as the coupling state of the divided cores 22 and 23 (positional relationship between coils 20 and 21) can be properly evaluated in the core coupling state evaluation step S6.

[0054] Furthermore, in the above embodiment, an example was given in which the voltage of the secondary circuit 13 can be measured by a voltage measuring unit 17 connected in series with the second relay 16, but of course, this is not the only example. For example, the voltage of the secondary circuit 13 may be measured with a BMU 18. This is because the BMU 18 has a configuration for voltage measurement as it has a function to monitor the voltage of the secondary battery 14.

[0055] Furthermore, while the above description has illustrated the application of the present invention to a motor drive battery in a motor-driven vehicle 27 such as an electric vehicle, it is of course not limited to this. For example, the present invention may be applied to an on-board battery that supplies power to a power load other than the drive motor. Alternatively, the power supply system or power supply method according to the present invention may be applied to all battery applications where continuous and stable operation of the battery is required, not limited to on-board applications. [Explanation of Symbols]

[0056] 10 Power supply system 11 transformers 12 Primary circuit 13 Secondary circuit 13c capacitor 14 Secondary battery 15 First Relay 16. Second Relay 17 Voltage Measurement Section 19 cores 20 Primary coil 21 Secondary coil 22,23 split cores 24 DC power supply 25 Controllers 26 Charging Stations 27 vehicles S1 Evaluation relay switching step S5 Voltage measurement step S6 Core coupling state evaluation step S9 Charging Relay Switching Step S10 Charging Start Step

Claims

1. A transformer having a primary coil and a secondary coil, A primary side circuit that controls the current flowing through the primary side coil, A secondary circuit that controls the current flowing through the secondary coil, A secondary battery connected to the secondary circuit, A first relay is disposed between the secondary circuit and the secondary battery, A second relay is disposed between the secondary circuit and the first relay, A voltage measuring unit for measuring the voltage of the secondary circuit, It includes a control unit, The control unit turns off the first relay and turns on the second relay. A power supply system that transmits information regarding the voltage of the secondary battery to a controller provided in the primary circuit, controls the primary circuit so that the controller generates an alternating current with a voltage equal to the voltage of the secondary battery, and evaluates the positional relationship between the primary coil and the secondary coil based on the change in the voltage of the secondary circuit measured by the voltage measuring unit when a predetermined current is supplied from the primary circuit.

2. The power supply system according to claim 1, wherein the control unit determines that the positional relationship between the primary coil and the secondary coil is in an acceptable state, turns off the second relay, turns on the first relay, and starts charging the secondary battery.

3. The power supply system according to claim 1 or 2, wherein the predetermined current is smaller than the current supplied from the primary circuit when the secondary battery is being charged.

4. The primary coil is installed in the charging station, and the secondary coil is mounted on the vehicle. The power supply system according to claim 1, wherein the control unit determines that the positional relationship between the primary coil and the secondary coil is not in an acceptable state, and moves the secondary coil to a position where the positional relationship becomes acceptable.

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