Power reception device used for non-contact power supply, and electric leakage detection system

Abstract

A power reception device (100, 100b, 100c, 100d, 100e, 100g, 100h) used for non-contact power supply comprises: a resonance circuit (RC) that has a coil (10) and capacitors (21, 22); a rectification circuit (REC) that is provided closer to the output side than the resonance circuit and converts AC into DC; an X phase and a Y phase that connect the resonance circuit and the rectification circuit; a sensor (210, 210f, 210g, 210h) that is provided between the resonance circuit and the rectification circuit and detects parameters related to a differential current value of currents flowing through the X phase and the Y phase; and an electric leakage detection unit (SC) that detects electric leakage using the detected parameters.

Description

Power receiving device and leakage detection system used for non-contact power supply Cross-reference to related applications

[0001] This application is based on Japanese Application No. 2024-190941 filed on October 30, 2024, the content of which is incorporated herein by reference.

[0002] This disclosure relates to a power receiving device and a leakage detection system used for non-contact power supply.

[0003] Various technologies related to non-contact power supply have been proposed. For example, Patent Document 1 discloses a device for diagnosing leakage current in a power receiving device used for non-contact power supply. This device detects leakage current by detecting the difference in alternating current flowing through both ends of a coil in the resonant circuit of the power receiving device.

[0004] Japanese Unexamined Patent Application Publication No. 2013-252040

[0005] Generally, since both ends of the coil used in the power receiving device of a non-contact power supply system are at a high voltage, when applying the technology disclosed in Patent Document 1, a device capable of handling high voltage is required. Therefore, there is room for improvement in the device for detecting leakage current in the power receiving device.

[0006] This disclosure can be realized in the following forms.

[0007] According to a first aspect of this disclosure, a power receiving device used for non-contact power supply is provided. This power receiving device includes a resonant circuit having a coil and a capacitor, a rectifier circuit provided on the output side of the resonant circuit for converting alternating current to direct current, an X phase and a Y phase connecting the resonant circuit and the rectifier circuit, a sensor provided between the resonant circuit and the rectifier circuit, the sensor detecting a parameter related to the differential current value of the currents flowing through the X phase and the Y phase, and a leakage detection unit detecting leakage current using the detected parameter.

[0008] According to this embodiment of the power receiving device, the sensor that detects parameters related to the difference current value of the currents flowing between the X phase and the Y phase is installed between the resonant circuit and the rectifier circuit, where the voltage is lower than the voltage generated in the resonant circuit. Therefore, leakage current can be detected with a relatively simple configuration without requiring a device that can handle high voltages.

[0009] According to another aspect of the present disclosure, a leakage current detection system is provided. This leakage current detection system comprises a plurality of power receiving devices, each having a resonant circuit, a rectifier circuit provided on the output side of the resonant circuit and converting alternating current to direct current, and an X phase and a Y phase connecting the resonant circuit and the rectifier circuit; a single sensor provided between the resonant circuit and the rectifier circuit in the plurality of power receiving devices, which detects a parameter related to the difference current value of the currents flowing between the X phase and the Y phase; and a leakage current detection unit that detects leakage current based on the detected parameter.

[0010] According to this embodiment of the leakage current detection system, a single sensor is provided between the resonant circuit and the rectifier circuit in multiple power receiving devices, which detects parameters related to the difference current value of the currents flowing between the X phase and the Y phase. Therefore, leakage current occurring in either the X phase or the Y phase of multiple power receiving devices can be detected using a single sensor. As a result, the entire power receiving device system, which consists of multiple power receiving devices, can be configured more compactly compared to a configuration that uses one sensor for each power receiving device.

[0011] The above-mentioned and other purposes, features and advantages of this disclosure will become clearer from the following detailed description with reference to the attached drawings. The drawings are as follows: Figure 1 is a schematic diagram showing the schematic configuration of a power receiving device in one embodiment of this disclosure; Figure 2 is a schematic diagram showing the schematic configuration of a power receiving device in a second embodiment; Figure 3 is a schematic diagram showing the schematic configuration of a power receiving device in a third embodiment; Figure 4 is a schematic diagram showing the schematic configuration of a power receiving device in a fourth embodiment; Figure 5 is a schematic diagram showing the schematic configuration of a power receiving device in a fifth embodiment; Figure 6 is a diagram illustrating a sensor composed of a ring-shaped member; Figure 7 is a plan view showing the schematic configuration of a power receiving device in a seventh embodiment; Figure 8 is a cross-sectional view along line VIII-VIII in Figure 7; Figure 9 is a schematic diagram showing the schematic configuration of a power receiving device in an eighth embodiment; Figure 10 is a diagram illustrating a sensor in an eighth embodiment; and Figure 11 is a diagram illustrating the schematic configuration of a leakage detection system in a ninth embodiment.

[0012] A. First Embodiment: <Outline Configuration of Power Receiving Device 100> The power receiving device 100 shown in Figure 1 is used in a contactless power supply system. Specifically, the contactless power supply system consists of the power receiving device 100 and a power transmitting device (not shown). Power is supplied from the power transmitting device to the power receiving device 100 in a contactless manner by the resonance of the resonant circuit of the power transmitting device and the resonant circuit RC of the power receiving device 100. The power receiving device 100 is installed, for example, on the underside of a vehicle. The power transmitting device is buried, for example, in the road. The power receiving device 100 includes a resonant circuit RC, a filter circuit FL, a rectifier circuit REC, a load L, and a sensor circuit 200.

[0013] <Configuration of the resonant circuit RC> The resonant circuit RC resonates with the resonant circuit of the power transmission device. The resonant circuit RC has a power receiving coil 10 and power receiving capacitors 21 and 22. The power receiving coil 10 is magnetically coupled to the power transmitting coil of the resonant circuit in the power transmission device and receives alternating current from the power transmission device. The power receiving capacitors 21 and 22 are connected to each end of the power receiving coil 10. The power receiving capacitors 21 and 22 cause the resonant circuit RC to resonate. The resonant frequency of the resonant circuit RC of the power receiving device 100 and the resonant frequency of the resonant circuit of the power transmission device are configured to be approximately the same.

[0014] In this disclosure, of the pair of lines connected to both ends of the receiving coil 10, the line from connection point CP11 on one end of the receiving coil 10 to connection point CP12 of the rectifier circuit REC (described later) is called the "X phase". The line from connection point CP21 on the other end of the receiving coil 10 to connection point CP22 of the rectifier circuit REC is called the "Y phase". Therefore, the X phase and the Y phase can be said to connect the resonant circuit RC and the rectifier circuit REC. Currents flow in opposite directions through the X phase and the Y phase.

[0015] <Configuration of Filter Circuit FL> The filter circuit FL is located on the output side (load L side) of the resonant circuit RC. The filter circuit FL reduces the noise of the AC current received by the resonant circuit RC. The filter circuit FL has a parallel filter PF and a series filter SF. The parallel filter PF has a parallel capacitor PC1 and a parallel reactor PL1. The parallel capacitor PC1 and the parallel reactor PL1 are connected in parallel to the X phase and the Y phase. The series filter SF has series capacitors SC1 and SC2 and series reactors SL1 and SL2. The series capacitor SC1 and the series reactor SL1 are connected in series with each other and are located in the X phase. The series capacitor SC2 and the series reactor SL2 are connected in series with each other and are located in the Y phase.

[0016] <Configuration of the rectifier circuit REC> The rectifier circuit REC is located on the output side of the filter circuit FL. The rectifier circuit REC converts AC current to DC current. The rectifier circuit REC has four switching elements Q1, Q2, Q3, and Q4. The switching elements Q1, Q2, Q3, and Q4 are, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors).

[0017] <Configuration of Load L> Load L is any device that utilizes the DC current converted by the rectifier circuit REC. Load L is, for example, a battery that stores the power source of a vehicle.

[0018] <Configuration of Sensor Circuit 200> The sensor circuit 200 detects leakage current in the power receiving device 100. The sensor circuit 200 includes a sensor 210, a leakage current detection line 220, an amplifier AMP, and a leakage current detection unit SC. The sensor 210 detects parameters related to the difference in current value between the X phase and the Y phase. "Parameters related to the difference in current value between the X phase and the Y phase" refers to physical quantities that can change when there is a difference in the current values ​​flowing through the X phase and the Y phase. Such physical quantities include, for example, current value, voltage value, magnetic flux, and magnetic flux density. It can also be said that the sensor 210 detects changes that occur when there is a difference in the current values ​​flowing through the X phase and the Y phase. Parameter detection will be described later. In this embodiment, the sensor 210 is provided between the filter circuit FL and the rectifier circuit REC. The sensor 210 is, for example, a magnetic material with through holes. The X phase and the Y phase are arranged so that they pass through these through holes. A leakage detection wire 220 is attached to the sensor 210. The leakage detection wire 220 is, for example, a copper wire, an enameled wire, or an aluminum wire. The amplifier AMP is connected to the leakage detection wire 220 and increases the current flowing through the leakage detection wire 220.

[0019] The detection of parameters related to the differential current value by the sensor 210 in this embodiment will be described. When no leakage current occurs, the current values ​​flowing through the X-phase and Y-phase passing through the sensor 210 are approximately the same. At this time, the magnetic flux generated around the X-phase and Y-phase are approximately the same magnitude and in opposite directions, so they cancel each other out. In contrast, when a leakage current occurs in any part of the power receiving device 100, a difference occurs in the current values ​​flowing through the X-phase and Y-phase. This causes an imbalance in the magnetic flux generated around the X-phase and Y-phase, and a current is generated in the leakage current detection line 220. The current is amplified by the amplifier AMP. Therefore, it can be said that the sensor 210 in this embodiment also detects the change in magnetic flux around the sensor 210 that occurs due to the difference in the currents flowing through the X-phase and Y-phase.

[0020] The leakage detection unit SC detects leakage current in the power receiving device 100 based on parameters detected by the sensor 210. The leakage detection unit SC is, for example, a computer having a processor and memory. Current amplified by the amplifier AMP is transmitted to the leakage detection unit SC. In this embodiment, the leakage detection unit SC determines that leakage current has occurred when the transmitted current is above a predetermined threshold. In other words, the leakage detection unit SC detects the occurrence of leakage current when the transmitted current is above a predetermined threshold. The threshold is pre-recorded in memory.

[0021] After determining that a ground fault has occurred, the leakage detection unit SC may optionally take actions such as notifying the worker or stopping the power supply to the power receiving device 100.

[0022] According to the power receiving device 100 of the first embodiment described above, the sensor 210 that detects parameters related to the difference current value of the currents flowing between the X phase and the Y phase is provided between the resonant circuit RC and the rectifier circuit REC, where the voltage is lower than the voltage generated in the resonant circuit portion. Therefore, leakage current can be detected with a relatively simple configuration without requiring equipment capable of handling high voltages. More specifically, since the power receiving coil 10 and power receiving capacitors 21 and 22 in the resonant circuit RC are resonant, a relatively high voltage of several kV to tens of kV is generally generated. In contrast, on the output side of the resonant circuit RC, the voltage is generally relatively low, around several hundred volts. For this reason, according to the power receiving device 100 of this embodiment, parameters can be detected with a relatively simple configuration without requiring equipment capable of handling high voltages.

[0023] Furthermore, according to the power receiving device 100 of the first embodiment, the leakage detection unit SC determines that a leakage has occurred when the value exceeds a predetermined threshold. Therefore, by setting the threshold according to the environment in which the power receiving device 100 is used, the accuracy of leakage detection can be improved.

[0024] Furthermore, according to the power receiving device 100 of the first embodiment, the sensor 210 is provided between the filter circuit FL and the rectifier circuit REC, so the sensor 210 can be positioned relatively easily.

[0025] B. Second Embodiment: The power receiving device 100b of the second embodiment shown in Figure 2 differs from the power receiving device 100 of the first embodiment in the position where the sensor 210 is provided. The other components of the power receiving device 100b of the second embodiment are the same as those of the power receiving device 100 of the first embodiment, so they are given the same reference numerals and their detailed description is omitted.

[0026] As shown in Figure 2, the sensor 210 in the second embodiment is located within the series filter SF provided in the X phase and the Y phase, respectively. More specifically, it is located between the series reactor SL1 and the series capacitor SC1 in the X phase, and between the series reactor SL2 and the series capacitor SC2 in the Y phase. It can also be said that the sensor 210 in the second embodiment is located on the input side (the side of the power receiving coil 10) than the sensor 210 in the first embodiment.

[0027] Note that the order of the series reactors SL1 and SL2 and the series capacitors SC1 and SC2 in the series filter SF may be reversed. That is, as shown in Figure 2, the series capacitors SC1 and SC2 may be on the input side, or, unlike the series filter SF shown in Figure 2, the series reactors SL1 and SL2 may be on the input side.

[0028] In the power receiving device 100b of the second embodiment described above, the sensor 210 is provided between the series reactors SL1 and SL2 and the series capacitors SC1 and SC2. Compared to a configuration in which the sensor 210 is provided on the output side of the filter circuit FL, the possibility that the sensor 210 is directly affected by a square wave voltage containing a relatively large amount of harmonic components generated at the input portion of the rectifier circuit REC can be reduced. Specifically, as in the power receiving device 100b of this embodiment, the presence of the series reactor SL1 or series capacitor SC1 between the rectifier circuit REC and the sensor 210 can reduce noise, thereby suppressing a decrease in the detection accuracy of the sensor 210 caused by noise.

[0029] C. Third Embodiment: The power receiving device 100c of the third embodiment shown in Figure 3 differs from the power receiving device 100 of the first embodiment in the position where the sensor 210 is provided. The other components of the power receiving device 100c of the third embodiment are the same as those of the power receiving device 100 of the first embodiment, so the same reference numerals are used and their detailed descriptions are omitted.

[0030] As shown in Figure 3, the sensor 210 in the third embodiment is provided between the series filter SF and the parallel filter PF. More specifically, the sensor 210 is provided between the series capacitors SC1 and SC2 and the parallel reactor PL1. It can also be said that the sensor 210 in the third embodiment is provided on the input side compared to the sensor 210 in the second embodiment.

[0031] Note that the order of the parallel filter PF and the series filter SF in the filter circuit FP can be reversed. That is, as shown in Figure 3, the parallel filter PF may be on the input side, or, unlike the filter circuit FL shown in Figure 3, the series filter SF may be on the input side.

[0032] In the power receiving device 100c of the third embodiment described above, the sensor 210 is provided between the series filter SF and the parallel filter PF. Compared to a configuration in which the sensor 210 is provided on the output side of the filter circuit FL, the possibility of the sensor 210 being directly affected by a square wave voltage containing a relatively large amount of harmonic components generated at the input portion of the rectifier circuit REC can be further reduced. Specifically, as in the power receiving device 100c of this embodiment, the presence of a series filter SF or a parallel filter PF between the rectifier circuit REC and the sensor 210 can further reduce noise, and the decrease in detection accuracy of the sensor 210 due to noise can be further suppressed.

[0033] D. Fourth Embodiment: The power receiving device 100d of the fourth embodiment shown in Figure 4 differs from the power receiving device 100 of the first embodiment in the position where the sensor 210 is provided. The other components of the power receiving device 100d of the fourth embodiment are the same as those of the power receiving device 100 of the first embodiment, so they are given the same reference numerals and their detailed description is omitted.

[0034] As shown in Figure 4, the sensor 210 in the fourth embodiment is placed within the parallel filter PF. More specifically, it is provided between the parallel reactor PL1 and the parallel capacitor PC1, spanning the X phase and the Y phase. It can also be said that the sensor 210 in the fourth embodiment is located on the input side compared to the sensor 210 in the third embodiment.

[0035] Note that the order of the parallel capacitor PC1 and the parallel reactor PL1 in the parallel filter PF can be reversed. That is, as shown in Figure 4, the parallel capacitor PC1 may be on the input side, or, unlike the parallel filter PF shown in Figure 4, the parallel reactor PL1 may be on the input side.

[0036] In the power receiving device 100d of the fourth embodiment described above, the sensor 210 is provided between the parallel reactor PL1 and the parallel capacitor PC1. Compared to a configuration in which the sensor 210 is provided on the output side of the filter circuit FL, the possibility of the sensor 210 being directly affected by a square wave voltage containing a relatively large amount of harmonic components generated at the input portion of the rectifier circuit REC can be further reduced. Specifically, as in the power receiving device 100d of this embodiment, the presence of a parallel capacitor PC1 or parallel reactor PL1 between the rectifier circuit REC and the sensor 210 can further reduce noise, and the decrease in detection accuracy of the sensor 210 due to noise can be further suppressed.

[0037] E. Fifth Embodiment: The power receiving device 100e of the fifth embodiment shown in Figure 5 differs from the power receiving device 100 of the first embodiment in the position where the sensor 210 is provided. The other components of the power receiving device 100e of the fifth embodiment are the same as those of the power receiving device 100 of the first embodiment, so they are denoted by the same reference numerals and their detailed description is omitted.

[0038] As shown in Figure 5, the sensor 210 in the fifth embodiment is provided between the resonant circuit RC and the filter circuit FL. More specifically, the sensor 210 is provided on the output side of the power receiving capacitors 21 and 22 of the resonant circuit RC, and on the input side of the filter circuit FL. It can also be said that the sensor 210 in the fifth embodiment is provided on the input side of the sensor 210 in the fourth embodiment.

[0039] In the power receiving device 100e of the fifth embodiment described above, the sensor 210 is provided between the power receiving capacitors 21 and 22 and the filter circuit FL. Compared to a configuration in which the sensor 210 is provided on the output side of the filter circuit FL, the possibility of the sensor 210 being directly affected by a square wave voltage containing a relatively large amount of harmonic components generated at the input portion of the rectifier circuit REC can be further reduced. Specifically, as in the power receiving device 100e of this embodiment, the presence of a filter circuit FL including a parallel filter PF and a series filter SF between the rectifier circuit REC and the sensor 210 can further reduce noise, and the decrease in detection accuracy of the sensor 210 due to noise can be further suppressed.

[0040] F. Sixth Embodiment: The sensor 210f of the sixth embodiment shown in Figure 6 differs from the sensor 210 of the first embodiment in that it is composed of a ring-shaped member. The other components of the sixth embodiment are the same as those of the power receiving device 100 of the first embodiment, so the same reference numerals are used and their detailed description is omitted.

[0041] The material of the ring-shaped member is any magnetic material, such as ferrite. The ring-shaped member has an annular external shape. In this disclosure, "ring-shaped" includes not only an annular shape but also a rectangular frame shape, such as the sensor 210f shown in Figure 6. The X phase and Y phase are each wrapped around the sensor 210f in positions symmetrical with respect to the line connecting the midpoint of the upper side US and the midpoint of the lower side DS. The leakage detection wire 220 is wrapped around the lower side DS.

[0042] As described above, the sensor 210f of the sixth embodiment is composed of a ring-shaped member, so that the X-phase and Y-phase can be easily attached to mutually symmetrical positions on the sensor 210f. This allows for more accurate detection of parameters related to the differential current values ​​of the X-phase and Y-phase.

[0043] G. Seventh Embodiment: The power receiving device 100g of the seventh embodiment shown in Figures 7 and 8 differs from the sensor 210 of the first embodiment in that a portion of the X phase and Y phase are provided on the printed circuit board PR, and the sensor 210g is composed of two parts. The other components of the power receiving device 100g of the seventh embodiment are the same as those of the power receiving device 100 of the first embodiment, so the same reference numerals are used and their detailed description is omitted.

[0044] As shown in FIG. 7, the X-phase and Y-phase near the sensor 210g in the power receiving device 100g are provided on the printed circuit board PR. The connection between the X-phase on the printed circuit board PR and the X-phase outside the printed circuit board PR is made by connecting the connection point CX1 provided at the end of the X-phase on the printed circuit board PR and the connection point CX2 provided at the end of the X-layer outside the printed circuit board PR. Similarly, the connection between the Y-phase on the printed circuit board PR and the Y-phase outside the printed circuit board PR is made by connecting the connection point CY1 and the connection point CY2.

[0045] As shown in FIG. 8, the sensor 210g is constituted by a ring-shaped member. Further, the sensor 210g is constituted by a first portion 211g and a second portion 212g. In the present embodiment, the first portion 211g and the second portion 212g have a substantially U-shaped symmetrical shape with respect to each other. The first portion 211g and the second portion 212g are arranged so as to sandwich the X-phase and the Y-phase provided on the printed circuit board PR in the thickness direction of the printed circuit board PR. Also, one of each pair of protruding portions of the first portion 211g and the second portion 212g is arranged to be located in the hole H penetrating in the thickness direction of the printed circuit board PR. The first portion 211g and the second portion 212g are joined by the portions protruding toward the printed circuit board PR side.

[0046] According to the power receiving device 100g of the seventh embodiment described above, a part of the X-phase and the Y-phase is provided on the printed circuit board PR, and the first portion 211g and the second portion 212g of the sensor 210g are arranged so as to sandwich the X-phase and the Y-phase provided on the printed circuit board PR. Therefore, the sensor 210g can be easily assembled.

[0047] Also, since the X-phase and the Y-phase sandwiched between the first portion 211g and the second portion 212g are provided on the printed circuit board PR, it is possible to suppress the displacement of the positions of the X-phase and the Y-phase within the sensor 210g. Thereby, the noise included in the parameter detected by the sensor 210g can be reduced.

[0048] H. Eighth Embodiment: The power receiving device 100h of the eighth embodiment shown in Figures 9 and 10 differs from the power receiving device 100 of the first embodiment in the position and configuration of the sensor 210h. The other components of the power receiving device 100h of the eighth embodiment are the same as those of the power receiving device 100 of the first embodiment, so they are given the same reference numerals and their detailed description is omitted.

[0049] In the power receiving device 100h of the eighth embodiment, each of the series reactors SL1 and SL2 has a core. The sensor 210h is shared with the cores of each of the series reactors SL1 and SL2. That is, the sensor 210h and the two cores are integrated. Such a sensor 210h and core are made up of a single figure-eight shaped member, as shown in Figure 9, for example. The material of the figure-eight shaped member is any magnetic material such as ferrite.

[0050] Sensor 210h has an upper side USh, a lower side DSh, a left side LSh, a right side RSh, and a connecting portion 211h. The left side LSh is connected to the left end of both the upper side USh and the lower side DSh, and the right side RSh is connected to the right end of both the upper side USh and the lower side DSh. The connecting portion 211h connects the central portions of the upper side USh and the lower side DSh in the longitudinal direction. The X phase is wound around the left side LSh. The Y phase is wound around the right side RSh. It can also be said that the X phase and the Y phase are wound in positions symmetrical with respect to the connecting portion 211h. The leakage detection wire 220 is wound around the connecting portion 211h. Parameters related to the differential current values ​​of the X phase and the Y phase can also be detected by such a sensor 210h.

[0051] According to the power receiving device 100h of the eighth embodiment described above, the sensor 210h is shared with the cores of the series reactors SL1 and SL2 in the X and Y phases, so a more compact configuration can be achieved compared to a configuration in which the sensor and core are separate.

[0052] Furthermore, since the sensor 210h is composed of an eight-shaped member, the X-phase and Y-phase can be easily attached to the sensor 210h at mutually symmetrical positions. This allows for more accurate detection of parameters related to the differential current values ​​of the X-phase and Y-phase.

[0053] I. Ninth Embodiment: The leakage detection system 300 shown in Figure 11 is used to detect leakage current in multiple power receiving devices 101 and 102. The leakage detection system 300 detects leakage current in multiple power receiving devices 101 and 102 using a single sensor 210i. In this embodiment, there are two power receiving devices 101 and 102. Each of the power receiving devices 101 and 102 has a similar configuration to the others. The detailed configuration of the power receiving devices 101 and 102 other than the sensor 210i is the same as that of the power receiving device 100 in the first embodiment.

[0054] The sensor 210i is provided between the resonant circuits RC1 and RC2 and the rectifier circuits REC1 and REC2 of each power receiving device 101 and 102. In this embodiment, the sensor 210i is provided on the output side of the filter circuits FL1 and FL2 and on the input side of the rectifier circuits REC1 and REC2. The sensor 210i detects parameters related to the difference current value of the current flowing between the X phase and the Y phase in the multiple power receiving devices 101 and 102.

[0055] According to the ninth embodiment of the leakage current detection system 300 described above, the system includes a single sensor 210i that is provided between the resonant circuits RC1, RC2 and the rectifier circuits REC1, REC2 in the multiple power receiving devices 101, 102. This sensor detects parameters related to the difference current value of the current flowing between the X phase and the Y phase. Therefore, leakage current generated in either the X phase or the Y phase of the multiple power receiving devices 101, 102 can be detected using a single sensor 210i. This allows for a more compact overall power receiving device system compared to a configuration using one sensor per power receiving device.

[0056] J. Other Embodiments 1: (J1) In the above embodiments, the leakage detection unit SC determined that a leakage current had occurred when the detected parameter was above a predetermined threshold, but the disclosure is not limited thereto. The leakage detection unit SC may detect a leakage current in any manner using the parameter. For example, the leakage detection unit SC may determine that a leakage current has occurred when the number of times the detected parameter exceeds a predetermined threshold is greater than or equal to a predetermined number. Alternatively, the leakage detection unit SC may determine that a leakage current has occurred when the detected parameter falls outside a predetermined range.

[0057] (J2) In the seventh embodiment described above, the sensor 210g was a ring-shaped member, but the disclosure is not limited thereto. The sensor 210g may be a member of any shape made of a magnetic material.

[0058] (J3) In the eighth embodiment described above, the sensor 210h was composed of an eight-shaped member, but the disclosure is not limited thereto. The sensor 210h may be a member of any shape made of a magnetic material.

[0059] K. Other Embodiments 2: (K1) The sensor 210f, which is composed of the ring-shaped member described in the sixth embodiment above, may be used not only with the power receiving device 100 of the first embodiment, but also in combination with a power receiving device of any embodiment. Similarly, the configuration in which a part of the X phase and Y phase described in the seventh embodiment is provided on the printed circuit board PR may be used in combination with a power receiving device of any embodiment.

[0060] (K2) In the seventh embodiment described above, the first portion 211g and the second portion 212g were symmetrical and substantially U-shaped, but the disclosure is not limited thereto. The first portion 211g and the second portion 212g may be any shape. The first portion 211g and the second portion 212g may be, for example, L-shaped.

[0061] (K3) In the leakage detection system 300 described in the ninth embodiment above, the position of the sensor 210i is not limited to being on the output side of the filter circuits FL1, FL2 and on the input side of the rectifier circuits REC1, REC2. The sensor 210i may be provided at any position between the resonant circuits RC1, RC2 and the rectifier circuits REC1, REC2. For example, the sensor 210i may be provided between the resonant circuits RC1, RC2 and the filter circuits FL1, FL2. Alternatively, the sensor 210i may be provided at any position within the filter circuits FL1, FL2. Furthermore, the number of power receiving devices 101, 102 may be any number of three or more.

[0062] (K4) In each of the above embodiments, any filter circuit may be provided between the rectifier circuits REC, REC1, REC2 and the load L.

[0063] (K5) In each of the above embodiments, the configuration of the filter circuit FL may be any configuration as long as it does not interfere with the configuration of each embodiment. For example, in the power receiving device 100 of the first embodiment, the parallel reactor PL1 may be omitted. Also, for example, in the power receiving device 100 of the first embodiment, the filter circuit FL itself may be omitted.

[0064] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in each embodiment corresponding to the technical features in the embodiments described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. This disclosure may be implemented, for example, in the following forms.

[0065] This disclosure may be realized in the following forms: [Form 1] A power receiving device (100, 100b, 100c, 100d, 100e, 100g, 100h) used for contactless power supply, comprising: a resonant circuit (RC) having a coil (10) and capacitors (21, 22); a rectifier circuit (REC) provided on the output side of the resonant circuit and converting alternating current to direct current; an X phase and a Y phase connecting the resonant circuit and the rectifier circuit; a sensor (210, 210f, 210g, 210h) provided between the resonant circuit and the rectifier circuit for detecting parameters related to the difference current value of the currents flowing between the X phase and the Y phase; and a leakage detection unit (SC) that detects leakage current using the detected parameters. [Form 2] A power receiving device according to Form 1, wherein the leakage detection unit determines that a leakage current has occurred when the parameter is above a predetermined threshold. [Form 3] A power receiving device according to Form 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the sensor is provided between the filter circuit and the rectifier circuit. [Form 4] A power receiving device according to Form 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit has series reactors (SL1, SL2) provided in the X phase and the Y phase, respectively, and series capacitors (SC1, SC2) connected in series with the series reactors, wherein the sensor is provided between the series reactors and the series capacitors. [Embodiment 5] A power receiving device according to Embodiment 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit has a series filter (SF) provided in series with each of the X phase and the Y phase, and a parallel filter (PF) provided in parallel with the X phase and the Y phase, and the sensor is provided between the series filter and the parallel filter.[Embodiment 6] A power receiving device according to Embodiment 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit has a parallel reactor (PL1) provided in parallel with the X phase and the Y phase, and a parallel capacitor (PC1) provided in parallel with the X phase and the Y phase, and the sensor is provided between the parallel reactor and the parallel capacitor. [Embodiment 7] A power receiving device according to Embodiment 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, and the sensor is provided between the capacitor of the resonant circuit and the filter circuit. [Embodiment 8] A power receiving device according to any one of Embodiments 1 to 7, wherein the sensor is composed of a ring-shaped member. [Embodiment 9] A power receiving device according to any one of Embodiments 1 to 8, wherein a portion of the X phase and the Y phase is provided on a printed circuit board (PR), the sensor is composed of a first part (211g) and a second part (212g), and the first part and the second part are arranged to sandwich the X phase and the Y phase provided on the printed circuit board in the thickness direction of the printed circuit board. [Embodiment 10] A power receiving device according to Embodiment 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, the filter circuit having series reactors (SL1, SL2) including a core, provided on each of the X phase and the Y phase, and the sensor is shared with the core of the series reactor in the X phase and the Y phase. [Embodiment 11] A power receiving device according to Embodiment 10, wherein the shared sensor, the core of the X phase, and the core of the Y phase are composed of a single figure-eight shaped member.[Embodiment 12] A leakage current detection system (300) comprising: a plurality of power receiving devices (101, 102) each having a resonant circuit (RC1, RC2), a rectifier circuit (REC1, REC2) provided on the output side of the resonant circuit and converting AC to DC, and an X phase and a Y phase connecting the resonant circuit and the rectifier circuit; a single sensor (210i) provided between the resonant circuit and the rectifier circuit in the plurality of power receiving devices, which detects a parameter related to the difference current value of the current flowing between the X phase and the Y phase; and a leakage current detection unit (300) that detects leakage current based on the detected parameter.

[0066] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

Claims

1. A power receiving device (100, 100b, 100c, 100d, 100e, 100g, 100h) used for contactless power supply, comprising: a resonant circuit (RC) having a coil (10) and capacitors (21, 22); a rectifier circuit (REC) provided on the output side of the resonant circuit and converting alternating current to direct current; an X phase and a Y phase connecting the resonant circuit and the rectifier circuit; sensors (210, 210f, 210g, 210h) provided between the resonant circuit and the rectifier circuit for detecting parameters related to the difference current value of the currents flowing between the X phase and the Y phase; and a leakage detection unit (SC) that detects leakage current using the detected parameters.

2. A power receiving device according to claim 1, wherein the leakage detection unit determines that a leakage has occurred when the parameter is equal to or greater than a predetermined threshold.

3. A power receiving device according to claim 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the sensor is provided between the filter circuit and the rectifier circuit.

4. A power receiving device according to claim 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit has series reactors (SL1, SL2) provided in the X phase and the Y phase, respectively, and series capacitors (SC1, SC2) connected in series with the series reactors, and the sensor is provided between the series reactors and the series capacitors.

5. A power receiving device according to claim 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit has a series filter (SF) provided in series with each of the X phase and the Y phase, and a parallel filter (PF) provided in parallel with the X phase and the Y phase, and the sensor is provided between the series filter and the parallel filter.

6. A power receiving device according to claim 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit has a parallel reactor (PL1) provided in parallel with the X phase and the Y phase, and a parallel capacitor (PC1) provided in parallel with the X phase and the Y phase, and the sensor is provided between the parallel reactor and the parallel capacitor.

7. A power receiving device according to claim 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the sensor is provided between the capacitor of the resonant circuit and the filter circuit.

8. A power receiving device according to any one of claims 1 to 7, wherein the sensor is composed of a ring-shaped member.

9. A power receiving device according to claim 8, wherein a portion of the X phase and the Y phase is provided on a printed circuit board (PR), the sensor is composed of a first portion (211g) and a second portion (212g), and the first portion and the second portion are arranged to sandwich the X phase and the Y phase provided on the printed circuit board in the thickness direction of the printed circuit board.

10. A power receiving device according to claim 2, further comprising a filter circuit (FL) provided between the resonant circuit and the rectifier circuit, wherein the filter circuit is provided in each of the X phase and the Y phase and has series reactors (SL1, SL2) including a core, and the sensor is shared with the core of the series reactor in the X phase and the Y phase.

11. A power receiving device according to claim 10, wherein the shared sensor, the X-phase core, and the Y-phase core are composed of a single figure-eight shaped member.

12. Leakage current detection system (300), comprising: a plurality of power receiving devices (101, 102) each having a resonant circuit (RC1, RC2), a rectifier circuit (REC1, REC2) provided on the output side of the resonant circuit and converting AC to DC, and an X phase and a Y phase connecting the resonant circuit and the rectifier circuit; a single sensor (210i) provided between the resonant circuit and the rectifier circuit in the plurality of power receiving devices, which detects a parameter related to the difference current value of the current flowing between the X phase and the Y phase; and a leakage current detection unit (300) that detects leakage current based on the detected parameter.

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