Power reception device

Abstract

A power reception device (100) receives first AC power (AC1) and comprises: a power reception circuit (110); a power conversion circuit (120) that converts second AC power (AC2), which is a portion of the first AC power, into first DC power (DC1); a load device (130) that consumes the first DC power; a main power-supply circuit (140) that supplies second DC power (DC2); an auxiliary power-supply circuit (160) that converts third AC power (AC3), which is another portion of the first AC power, and thereby supplies third DC power (DC3); and a control circuit that receives electricity feed from the main power-supply circuit or the auxiliary power-supply circuit. The auxiliary power-supply circuit receives supply of the third AC power through a first location, in the power reception circuit, where the fluctuation of current and voltage due to a short circuit of an input of the power conversion circuit is small. If the control circuit cannot receive electricity feed from the main power-supply circuit, the control circuit receives electricity feed from the auxiliary power-supply circuit.

Description

Powered Device CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from Patent Application No. 2023-220279, filed December 27, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a power receiving device.

[0003] In a power receiving device used in a wireless power transfer system for a vehicle, there is a technology for supplying power to a control unit of a power conversion circuit from multiple power sources, as disclosed in Patent Document 1. In Patent Document 1, a DC-DC converter is provided as a power conversion circuit between a rectifier circuit on the power receiving side and a battery on the load side. When power reception begins, power for the control unit of the DC-DC converter is supplied from a power source connected to the input unit of the DC-DC converter, which is the output unit of the rectifier circuit. In a steady state after power reception begins, power for the control unit of the DC-DC converter is supplied from the power source connected to the output unit of the DC-DC converter.

[0004] The output power of the output section of the rectifier circuit fluctuates depending on the magnitude of the received power. However, the DCDC converter outputs stable power after startup. Therefore, the control section of the DCDC converter can operate stably even if the received power changes after starting to receive power.

[0005] JP 2014-138496 A

[0006] The inventors have been studying a power conversion circuit that performs rectification in a power receiving device of a wireless power transfer system for a vehicle. The power conversion circuit under study by the inventors includes a switch that adjusts output power. Power for a control unit of the switch is supplied from an auxiliary battery other than the battery serving as a load device of the wireless power transfer system. The inventors have been studying the application of the technology of Patent Document 1 as a means for supplying power to replace the auxiliary battery in the event of a voltage drop due to an abnormality in the auxiliary battery.

[0007] However, the power conversion circuit studied by the inventors has a fluctuating output power. That is, unlike Patent Document 1, it is not possible to obtain a stable supply of power from the output power of the power conversion circuit. Therefore, there has been a demand for a technology that can substitute the power supply of the control unit of the power conversion circuit when an abnormality occurs in the power supply of the control unit, even when the output power of the power conversion circuit fluctuates.

[0008] The present disclosure can be realized in the following aspects. According to a first aspect of the present disclosure, there is provided a power receiving device that receives first AC power in a contactless manner using a magnetic field. The power receiving device includes: a power receiving circuit including a power receiving coil that receives the first AC power; a power conversion circuit that converts second AC power, which is a portion of the first AC power, into first DC power; a load device that consumes the first DC power; a main power supply circuit that supplies the second DC power; a secondary power supply circuit that converts third AC power, which is another portion of the first AC power, into the third DC power; and a control circuit that controls the power receiving device and receives power from the main power supply circuit or the secondary power supply circuit, and are connected to the power receiving circuit, and the secondary power supply circuit receives the third AC power via a first location in the power receiving circuit, out of a first location where fluctuations in current and voltage due to a short-circuit of an input part of the power conversion circuit are small and a second location where the fluctuations are large, and the control circuit executes control using the power conversion circuit that combines a short-circuit mode in which the input part of the power conversion circuit is short-circuited and a power supply mode in which the input part of the power conversion circuit is not short-circuited, and receives power from the secondary power supply circuit when it is not possible to receive power from the main power supply circuit.

[0009] In this configuration, the secondary power supply circuit receives third AC power via the first location and supplies third DC power to the control circuit. This allows the control circuit to continue control even when it is unable to receive power from the main power supply circuit. Furthermore, the first location can supply third AC power even when the short-circuit mode is activated because current and voltage fluctuations are small. Note that fluctuations at the first location occur due to the power receiving configuration and filter configuration. Therefore, the power receiving device of the present disclosure allows the control circuit to operate even when it is unable to receive power from the main power supply circuit.

[0010] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which Fig. 1 is an explanatory diagram showing a contactless power transfer system of a first embodiment, Fig. 2 is an explanatory diagram showing a secondary power supply circuit, Fig. 3 is an explanatory diagram showing operation of a power receiving device in a power transfer mode, Fig. 4 is an explanatory diagram showing operation of a power receiving device in a short-circuit mode, Fig. 5 is an explanatory diagram showing operation of a power receiving device in a power transfer mode, Fig. 6 is an explanatory diagram showing operation of a power receiving device in a short-circuit mode, Fig. 7 is a flowchart showing processing by a control circuit of a second embodiment, Fig. 8 is an explanatory diagram showing a contactless power transfer system of a third embodiment, Fig. 9 is an explanatory diagram showing a contactless power transfer system of a fourth embodiment, and Fig. 10 is an explanatory diagram showing operation of a contactless power transfer system of a fifth embodiment. FIG. 11 is an explanatory diagram showing a contactless power transfer system of a sixth embodiment, FIG. 12 is an explanatory diagram showing a secondary power supply circuit of a seventh embodiment, FIG. 13 is an explanatory diagram showing a power receiving device of an eighth embodiment, FIG. 14 is an explanatory diagram showing a vehicle of a ninth embodiment, FIG. 15 is an explanatory diagram showing a modified example of an immittance filter, FIG. 16 is an explanatory diagram showing a modified example of a band-pass filter, FIG. 17 is an explanatory diagram showing a modified example of a band-pass filter, FIG. 18 is an explanatory diagram showing a modified example of a band-pass filter, FIG. 19 is an explanatory diagram showing a modified example of a secondary power supply circuit, and FIG. 20 is an explanatory diagram showing a modified example of a secondary power supply circuit.

[0011] A. First Embodiment: A-1. Device Configuration: A contactless power transfer system 10 shown in Fig. 1 supplies power to a load device 130 in a contactless manner using a magnetic field. The contactless power transfer system 10 includes a power transmission device 200 and a power receiving device 100. That is, the contactless power transfer system 10 supplies power from the power transmission device 200 to the power receiving device 100 in a contactless manner. The contactless power transfer system 10 supplies power to a load device 130 mounted on a vehicle V, for example, in a contactless manner.

[0012] The power transmitting device 200 uses a magnetic field to contactlessly supply AC power to the power receiving device 100. The power transmitting device 200 includes an AC power supply device 210 and a power transmitting resonant circuit 220.

[0013] The AC power supply device 210 supplies AC power of a predetermined operating frequency to the power transmission resonant circuit 220. The AC power supply device 210 includes a power supply circuit and a power transmission circuit. The power supply circuit is, for example, an AC / DC converter circuit, and converts AC power supplied from a power grid into DC power. The power transmission circuit is an inverter that converts DC power supplied from the power supply circuit into AC power at the operating frequency. The operating frequency is, for example, 85 kHz, and is set using a predetermined power transmission frequency stipulated by the Radio Law and the like. Note that the operating frequency is also a frequency corresponding to the resonant frequency of the power transmission resonant circuit 220, which will be described later.

[0014] The power transmitting resonant circuit 220 transmits power to the power receiving circuit 110. The power transmitting resonant circuit 220 includes a power transmitting coil 222 and a power transmitting resonant capacitor 221 connected in series to the power transmitting coil 222. In other words, the power transmitting resonant circuit 220 is a series resonant circuit.

[0015] When the power transmitting coil 222 and the power receiving coil 111RL are magnetically coupled, the power transmitting resonant capacitor 221 resonates the power transmitting resonant circuit 220 with AC power at the operating frequency of the AC power supply device 210. In other words, the capacitance of the power transmitting resonant capacitor 221 is set so that when the power transmitting coil 222 and the power receiving coil 111RL are magnetically coupled, the operating frequency of the AC power supply device 210 and the resonant frequency of the power transmitting resonant circuit 220 approximately match.

[0016] The power transmitting coil 222 generates a magnetic field corresponding to the operating frequency of the AC power supply device 210. Furthermore, the power transmitting coil 222 transmits AC power to the power receiving coil 111RL by magnetically coupling with the power receiving coil 111RL. In other words, the power transmitting coil 222 transmits power contactlessly by utilizing the electromagnetic induction phenomenon.

[0017] The power receiving device 100 receives AC power from the power transmitting device 200 in a contactless manner using a magnetic field. The power receiving device 100 includes a power receiving circuit 110, a power conversion circuit 120, a load device 130, a main power supply circuit 140, a secondary power supply circuit 160, a control circuit 150, a smoothing capacitor 170, and a first power transformer 180.

[0018] The power receiving circuit 110 includes a power receiving resonant circuit 110R and a filter circuit 110F.

[0019] The power receiving resonant circuit 110R includes a power receiving coil 111RL and a power receiving resonant capacitor 111RC connected in series to the power receiving coil 111RL. The power receiving resonant circuit 110R has a resonant frequency that corresponds to the frequency of the first AC power AC1. In other words, the power receiving resonant circuit 110R is a series resonant circuit. In this specification, the "power receiving resonant circuit" is also simply referred to as the "resonant circuit."

[0020] The receiving coil 111RL receives first AC power AC1. The first AC power AC1 is the AC power received by the receiving coil 111RL. In FIG. 1 , the direction in which the first AC power AC1 is supplied is indicated by an arrow AC1. The receiving coil 111RL is magnetically coupled to the transmitting coil 222 by receiving a magnetic field emitted by the transmitting coil 222. As a result, the receiving coil 111RL receives the first AC power AC1. When the receiving coil 111RL is used in a state in which it faces the transmitting coil 222, it receives the magnetic field emitted by the transmitting coil 222. As a result, the receiving coil 111RL receives the first AC power AC1 in a wireless manner.

[0021] The power receiving resonant capacitor 111RC resonates the power receiving resonant circuit 110R with the first AC power AC1 in a state where the power receiving coil 111RL and the power transmitting coil 222 are magnetically coupled. That is, the capacitance of the power receiving resonant capacitor 111RC is set so that the frequency of the first AC power AC1 and the resonant frequency of the power receiving resonant circuit 110R substantially match in a state where the power transmitting coil 222 and the power receiving coil 111RL are magnetically coupled.

[0022] In this embodiment, the power receiving resonant capacitor 111RC includes a positive-side resonant capacitor 111RCp arranged on the positive-side line Lacp of the power receiving circuit 110 and a negative-side resonant capacitor 111RCn arranged on the negative-side line Lacn of the power receiving circuit 110. By arranging the power receiving resonant capacitor 111RC on both the positive-side line Lacp and the negative-side line Lacn, common-mode noise can be suppressed. In this specification, the "power receiving resonant capacitor" is also simply referred to as the "resonant capacitor."

[0023] When the power transmitting resonant circuit 220 is a series resonant circuit and the power receiving resonant circuit 110R is a series resonant circuit, the output section 110Ro of the power receiving resonant circuit 110R has constant current characteristics. A filter circuit 110F is connected to the output section 110Ro of the power receiving resonant circuit 110R. That is, a constant current is input to the filter circuit 110F.

[0024] The filter circuit 110F suppresses harmonic components of the first AC power AC1. The filter circuit 110F is connected between the output 110Ro of the power receiving resonant circuit 110R and the input 120i of the power conversion circuit 120. More specifically, the filter circuit 110F has two first coils 111FL and two first capacitors 111FC connected in series to the power receiving coil 111RL and the input 120i of the power conversion circuit 120. In FIG. 1 , the two first coils 111FL are composed of a positive-side first coil 111FLp on the positive line Lacp and a negative-side first coil 111FLn on the negative line Lacn. The two first capacitors 111FC are composed of a positive-side first capacitor 111FCp on the positive line Lacp and a negative-side first capacitor 111FCn on the negative line Lacn. Furthermore, the filter circuit 110F has a configuration in which a second capacitor 112FC and a second coil 112FL are connected in parallel to the power receiving resonant circuit 110R.

[0025] With this configuration, the filter circuit 110F functions as a bandpass filter. When the input section of a bandpass filter has a constant current characteristic, the output section also has a constant current characteristic. As a result, the portion connected in series to the input section 120i of the power conversion circuit 120, which is also the output section 110Ro of the filter circuit 110F, has a constant current characteristic. The "portion connected in series to the input section 120i of the power conversion circuit 120" is referred to as the "first portion." In the first embodiment, the first portion includes the positive-side first coil 111FLp, the negative-side first coil 111FLn, the positive-side first capacitor 111FCp, the negative-side first capacitor 111FCn, the positive-side resonant capacitor 111RCp, the negative-side resonant capacitor 111RCn, and the receiving coil 111RL. In FIG. 1 , the first portion is depicted with a thicker line than the other portions.

[0026] In this specification, the constant current characteristic refers to the property that the current and voltage fluctuate little when the output section of the circuit is short-circuited. Specifically, the property of the current and voltage fluctuating little is the property that the current and voltage do not reach 0 V when the output section of the circuit is short-circuited. In this specification, the point where the current and voltage fluctuate little is referred to as the first point. In other words, the first point has the property that the current and voltage do not reach 0 V even when the input section 120i of the power conversion circuit 120 is short-circuited.

[0027] In this specification, the "location where the current and voltage fluctuations are large" is referred to as the "second location" in contrast to the first location. The second location is a location connected in parallel between the power transmitting coil 222 and the input section 120i of the power conversion circuit 120. In the first embodiment, the second location is the second capacitor 112FC and the second coil 112FL.

[0028] In the filter circuit 110F, the negative side first coil 111FLn supplies third AC power AC3 to the secondary power supply circuit 160. The third AC power AC3 is a portion of the first AC power AC1. In FIG. 1 , the direction in which the third AC power AC3 is supplied is indicated by an arrow AC3. The negative side first coil 111FLn also serves as the primary side of a first power supply transformer 180, which will be described later. The first power supply transformer 180 is composed of a negative side first coil 111FLn on the primary side and a first secondary power supply coil 161 on the secondary side. When the first AC power AC1 is supplied to the power receiving circuit 110, an electromotive force is generated in the negative side first coil 111FLn. As a result, third AC power AC3, which is a portion of the first AC power AC1, is output from the first secondary power supply coil 161 via the negative side first coil 111FLn. The third AC power AC3 is supplied to the secondary power supply circuit 160 to which the first secondary power supply coil 161 is connected.

[0029] The power conversion circuit 120 converts the second AC power AC2 into the first DC power DC1. The second AC power AC2 is a portion of the first AC power AC1. More specifically, the second AC power AC2 is the first AC power AC1 minus the third AC power AC3. That is, the second AC power AC2 is a portion of the first AC power AC1, and the third AC power AC3 is another portion of the first AC power AC1. In FIG. 1 , the direction in which the second AC power AC2 is supplied is indicated by the arrow AC2.

[0030] The power conversion circuit 120 is a full-bridge circuit that uses four MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) as switching elements. The power conversion circuit 120 includes two leg circuits: a first leg circuit 121 and a second leg circuit 122. The switch Sw is driven by receiving at its gate a voltage according to a command from the control circuit 150. The "power conversion circuit" in the first embodiment is also referred to as a "synchronous rectification circuit."

[0031] In the leg circuit, two switches Sw are connected in series. Furthermore, the leg circuit connects the positive line Ldcp and negative line Ldcn of the DC power. One terminal of the output unit 110Ro of the power receiving circuit 110 is connected between the two switches Sw of the leg circuit. The input unit 120i of the power conversion circuit 120 is located between the two switches Sw of the leg circuit. In other words, the output unit 110Ro of the power receiving circuit 110 and the input unit 120i of the power conversion circuit 120 are connected.

[0032] As described above, the power conversion circuit 120 converts the second AC power AC2, which is a part of the first AC power AC1, into the first DC power DC1. The conversion by the power conversion circuit 120 will be described in detail later.

[0033] The smoothing capacitor 170 is connected in parallel between the output of the power conversion circuit 120 and the load device 130. The smoothing capacitor 170 smoothes the DC current and DC voltage supplied to the load device 130.

[0034] The load device 130 consumes the first DC power DC1 supplied via the power conversion circuit 120. For example, the load device 130 is a battery and a battery protection circuit. In this case, the first DC power DC1 is used to charge the battery and to run the vehicle.

[0035] The main power supply circuit 140 supplies second DC power DC2 to the control circuit 150. The second DC power DC2 is power supplied via a power source different from the first AC power AC1. For example, the second DC power DC2 is power sourced from an auxiliary battery in the vehicle V. The main power supply circuit 140 includes, for example, an auxiliary battery and a DC / DC converter. That is, by connecting the DC / DC converter to the control circuit 150, the main power supply circuit 140 supplies the second DC power DC2 required for operation of the control circuit 150 to the control circuit 150 via the DC / DC converter.

[0036] The secondary power supply circuit 160 converts third AC power AC3, which is a part of the first AC power AC1, into third DC power DC3 and supplies the third DC power DC3 to the control circuit 150. As shown in FIG. 2 , the secondary power supply circuit 160 includes a first secondary power supply coil 161, a rectifier circuit 162, and a protection circuit that protects the control circuit 150 from overvoltage, noise, and the like. The secondary power supply circuit 160 receives the third AC power AC3 from the first secondary power supply coil 161. The secondary power supply circuit 160 converts the third AC power AC3 into third DC power DC3 via the rectifier circuit 162 and the protection circuit. Thus, the secondary power supply circuit 160 supplies the third DC power DC3 to the control circuit 150. The voltage of the third AC power AC3 is transformed by a first power transformer 180 based on the rated voltage of the secondary power supply circuit 160.

[0037] Although the first secondary power supply coil 161 is included in the secondary power supply circuit 160, in the drawings other than FIG. 2, the first secondary power supply coil 161 is shown separated from the secondary power supply circuit 160 to facilitate understanding of the technology.

[0038] The secondary power supply circuit 160 supplies power to the control circuit 150 when the main power supply circuit 140 is unable to supply power to the control circuit 150. Switching between the main power supply circuit 140 and the secondary power supply circuit 160 will be described in detail later.

[0039] As shown in FIG. 1 , the first power transformer 180 has a primary side formed by the negative side first coil 111FLn and a secondary side formed by the first secondary power supply coil 161. That is, the first power supply transformer 180 supplies third AC power AC3, which is part of the first AC power AC1, to the secondary power supply circuit 160 via the negative side first coil 111FLn and the first secondary power supply coil 161. The first power supply transformer 180 is a compound-wound transformer, and the primary side and secondary side are electrically insulated. The turns ratio of the first power supply transformer 180 is designed based on the rated voltage of the secondary power supply circuit 160. Therefore, the voltage of the third AC power AC3 is transformed based on the rated voltage of the secondary power supply circuit 160.

[0040] The control circuit 150 controls the power receiving device 100. The control circuit 150 receives power from the main power supply circuit 140 or the secondary power supply circuit 160. The control circuit 150 includes a control unit 151, a drive circuit 152, and a switching circuit (not shown). The switching circuit will be described in detail later.

[0041] The drive circuit 152 drives the switches Sw of the power conversion circuit 120. More specifically, the drive circuit 152 outputs the power required to drive the switches Sw in response to a command from the control unit 151. The drive circuit 152 is connected to the gates of all the switches Sw of the power conversion circuit 120. That is, the drive circuit 152 drives the switches Sw by applying a gate voltage required for turning the switches Sw on and off to the gates of the switches Sw. Note that in FIG. 1 , the connection between the drive circuit 152 and the gates is omitted to facilitate understanding of the technology.

[0042] The control unit 151 executes the power supply mode or the short-circuit mode using the power conversion circuit 120. More specifically, the control unit 151 generates a signal that controls the on / off operation of the switch Sw. The control unit 151 is mainly configured, for example, by a microcomputer, and includes a CPU, ROM, RAM, etc. (not shown).

[0043] A-2. Power Supply Mode and Short-Circuit Mode: The control unit 151 executes a control combining a short-circuit mode in which the input section 120i of the power conversion circuit 120 is short-circuited and a power supply mode in which the input section 120i of the power conversion circuit 120 is not short-circuited, using the power conversion circuit 120. The operation of the power receiving device 100 in each of the power supply mode and the short-circuit mode will be described below.

[0044] In FIG. 3 , the direction of current flowing through the power receiving device 100 in the power supply mode during the positive half cycle of the second AC power AC2 is indicated by an arrow Aia. To facilitate understanding of the technology, the power transmitting device 200, the control circuit 150, and the like are omitted from FIGS. 3 to 6 , which are used to explain the control modes. In the power supply mode, current flows through the switch Sw of the positive electrode line Ldcp in one of the two leg circuits and the switch Sw of the negative electrode line Ldcn in the other leg circuit. As a result, the current in the power supply mode during the positive half cycle of the second AC power AC2 is rectified by the power conversion circuit 120 and flows to the load device 130. In other words, the first DC power DC1 is supplied to the load device 130.

[0045] 4 , the direction of current flowing through the power receiving device 100 in short-circuit mode during the positive half cycle of the second AC power AC2 is indicated by an arrow Aib. In short-circuit mode, current flows through the switches Sw of the negative lines Ldcn in the two leg circuits. That is, the control unit 151 shorts the input unit 120i of the power conversion circuit 120 by controlling the switches Sw of the negative lines Ldcn in the two leg circuits to the on state. As a result, current in short-circuit mode during the positive half cycle of the second AC power AC2 does not flow to the load device 130 via the power conversion circuit 120. That is, the first DC power DC1 is not supplied to the load device 130.

[0046] 5 , the direction of current flowing through the power receiving device 100 in the power supply mode during the negative half cycle of the second AC power AC2 is indicated by an arrow Aic. The current in the power supply mode during the negative half cycle of the second AC power AC2 is rectified by the power conversion circuit 120 and flows to the load device 130, similar to the current in the power supply mode during the positive half cycle. That is, the first DC power DC1 is supplied to the load device 130.

[0047] 6 , the direction of current flowing through the power receiving device 100 in the short circuit mode during the negative half cycle of the second AC power AC2 is indicated by an arrow Aid. Similar to the short circuit mode during the negative half cycle of the second AC power AC2, the current during the short circuit mode does not flow to the load device 130 via the power conversion circuit 120. In other words, the first DC power DC1 is not supplied to the load device 130.

[0048] The control unit 151 executes control combining a short circuit mode and a power supply mode to control the first DC power DC1 using the power conversion circuit 120, for example. The control unit 151 executes the short circuit mode and the power supply mode during one half cycle of the second AC power AC2. That is, the first DC power DC1 is controlled by the ratio of the short circuit mode period to the power supply mode period during the half cycle. For example, the control unit 151 sets the ratio of the short circuit mode period to the power supply mode period during the half cycle to a predetermined ratio so that the first DC power DC1 does not exceed the rated power of the load device 130. Thus, the first DC power DC1 is controlled.

[0049] A-3. Switching of power supply circuits: When the main power supply circuit 140 is in a normal state, the control circuit 150 receives power from the main power supply circuit 140. However, when an abnormality in the main power supply circuit 140 prevents the control circuit 150 from receiving power, the control circuit 150 receives power from the secondary power supply circuit 160. An abnormality in the main power supply circuit 140 occurs, for example, when the auxiliary battery serving as the power source for the main power supply circuit 140 fails and is unable to output power.

[0050] As described above, the control circuit 150 includes a switching circuit (not shown). The switching circuit switches between the main power supply circuit 140 and the secondary power supply circuit 160. The switching circuit is, for example, a diode OR circuit. In the switching circuit, the output sections of the main power supply circuit 140 and the secondary power supply circuit 160 are connected to the control circuit 150 via rectifier diodes. When the switching circuit receives a supply of second DC power DC2, it causes the control circuit 150 to supply the second DC power DC2. When the switching circuit does not receive a supply of second DC power DC2, it causes the control circuit 150 to supply third DC power DC3.

[0051] The control circuit 150 executes control that combines the short circuit mode and the power supply mode, even when receiving power from the secondary power supply circuit 160. In the short circuit mode, the input section 120i of the power conversion circuit 120 is short-circuited. However, the secondary power supply circuit 160 receives a supply of third AC power AC3 via the first location in the power receiving circuit 110. Therefore, the control circuit 150 can receive power from the secondary power supply circuit 160 even when the short circuit mode is being executed.

[0052] In this configuration, the secondary power supply circuit 160 receives third AC power AC3 via the first location and supplies third DC power DC3 to the control circuit 150. This allows the control circuit 150 to continue control even when it is unable to receive power from the main power supply circuit 140. Furthermore, even when the short-circuit mode is executed, the first location can supply third AC power AC3 because the fluctuations in current and voltage are small. Therefore, the power receiving device 100 of the present disclosure can operate the control circuit 150 even when it is unable to receive power from the main power supply circuit 140.

[0053] Furthermore, with this configuration, the secondary power supply circuit 160 is supplied with power via the first coil 111FL that constitutes the filter circuit 110F. Unlike the filter circuit 110F, the resonant circuit 110R resonates based on the frequency of the received AC power. For this reason, the voltage of the elements in the resonant circuit 110R tends to be higher than the voltage of the elements in the filter circuit 110F. Therefore, the power receiving device 100 of the present disclosure supplies power to the secondary power supply circuit 160 from the filter circuit 110F, thereby reducing the voltage applied to the secondary power supply circuit 160 and thereby reducing losses occurring in the secondary power supply circuit 160.

[0054] Furthermore, with this configuration, the secondary power supply circuit 160 receives a supply of third AC power AC3 via the first power transformer 180. As a result, the voltage applied to the secondary power supply circuit 160 can be easily reduced by the turns ratio of the first power transformer 180. Therefore, the power receiving device 100 of the present disclosure can reduce losses in the secondary power supply circuit 160 compared to a configuration in which the secondary power supply circuit 160 is directly connected to the first location. Furthermore, because the secondary power supply circuit 160 is insulated from the power receiving circuit 110 by the first power transformer 180, it is less susceptible to noise from the power receiving circuit 110.

[0055] B. Second Embodiment: In the above embodiment, the control unit 151 executes a control combining the short circuit mode and the power supply mode to control the first DC power DC1. However, the control unit 151 may also execute a control combining the short circuit mode and the power supply mode to protect the load device 130. More specifically, the control unit 151 of the second embodiment executes the short circuit mode when receiving power from the secondary power supply circuit 160. That is, the control unit 151 of the second embodiment executes the short circuit mode when power cannot be received from the main power supply circuit 140 due to an abnormality in the main power supply circuit 140. By executing the short circuit mode, the supply of the first DC power DC1 to the load device 130 is stopped. This allows the power receiving device 100 of the second embodiment to prevent an abnormality in the main power supply circuit 140 from affecting the load device 130. The configuration of the second embodiment is the same as the configuration of the first embodiment.

[0056] 7, a specific process performed by the control unit 151 will be described. The control unit 151 starts a process when power cannot be supplied from the main power supply circuit 140.

[0057] 7, the control circuit 150 receives power from the secondary power supply circuit 160. That is, the control circuit 150 operates using the third DC power DC3 due to switching of the power supply circuit.

[0058] 7, the control unit 151 determines the control mode. If the control unit 151 determines that the short circuit mode is being executed, the process proceeds to step S120. If the control unit 151 determines that the power supply mode is being executed, the process proceeds to step S130.

[0059] 7, the control circuit 150 continues the short-circuit mode. That is, the control circuit 150 switches from the control that combines the short-circuit mode and the power supply mode to the control that executes only the short-circuit mode. The control circuit 150 ends the process after the process of step S120.

[0060] In step S130 of Fig. 7, the control circuit 150 executes the short-circuit mode. That is, the control circuit 150 switches from the power supply mode to the short-circuit mode. For example, even when the power supply mode is executed periodically, the control circuit 150 executes the short-circuit mode regardless of the cycle of the power supply mode. The control circuit 150 ends the process after processing step S130.

[0061] In this configuration, when the main power supply circuit 140 cannot supply power to the control circuit 150, the control circuit 150 executes the short-circuit mode by receiving power from the secondary power supply circuit 160. This allows the power receiving device 100 of the present disclosure to prevent an abnormality in the main power supply circuit 140 from affecting the load device 130.

[0062] C. Third Embodiment: In the above embodiments, the filter circuit 110F includes multiple capacitors and multiple coils. However, as shown in FIG. 8 , the filter circuit 110F may be configured with a single first coil 111FL. That is, the first portion includes a negative-side first coil 111FLn, a negative-side resonant capacitor 111RCn, a positive-side resonant capacitor 111RCp, and a power transmitting coil 222. Note that the filter circuit 110Fa of the third embodiment functions as a low-pass filter. When the input section 110Ro of the low-pass filter has constant current characteristics, the output section 110o of the low-pass filter also has constant current characteristics. The other configurations of the third embodiment are the same as those of the first embodiment. In FIG. 8 , components different from those of the first embodiment are indicated by the symbol "a" appended to the reference numerals of the first embodiment.

[0063] This configuration simplifies the configuration of the power receiving circuit 110a of the present disclosure compared to a configuration in which the filter circuit 110F is configured with multiple first coils 111FL or a configuration in which the filter circuit 110F includes a first capacitor 111FC. More specifically, the power receiving circuit 110a of the present disclosure can reduce the number of components and the wiring length compared to a configuration in which a bandpass filter or an immittance filter is included. Therefore, the power receiving device 100a of the present disclosure can prevent malfunctions due to the influence of noise transmitted through the filter or wiring, for example.

[0064] D. Fourth Embodiment: As shown in Fig. 9 , in a contactless power supply system 10b of the fourth embodiment, a power transmission device 200b includes a power transmission resonant circuit 220b that is a parallel resonant circuit. More specifically, the power transmission resonant circuit 220b includes a power transmission coil 222 and a power transmission resonant capacitor 221b connected in parallel to the power transmission coil 222. That is, in the contactless power supply system 10b of the fourth embodiment, the power transmission resonant circuit 220b is a parallel resonant circuit and the power receiving resonant circuit 110R is a series resonant circuit. As a result, the output section 110Ro of the power receiving resonant circuit 110R has constant voltage characteristics.

[0065] In the wireless power transfer system 10b of the fourth embodiment, the power receiving circuit 110b includes a filter circuit 110Fb that functions as an immittance filter. In the filter circuit 110Fb, four first coils 111FLb are connected in series between the power receiving coil 111RL and the input section 120i of the power conversion circuit 120. The four first coils 111FLb include two positive-side first coils 111FLp and two negative-side first coils FLn. Furthermore, a second capacitor 112FCb is connected to the filter circuit 110Fb, connecting the two positive-side first coils 111FLp and the two negative-side first coils FLn.

[0066] With this configuration, the filter circuit 110Fb functions as an immittance filter. The output section 110o of the immittance filter has constant current characteristics when the input section 110Ro of the immittance filter has constant voltage characteristics. In the fourth embodiment, the power transmitting resonant circuit 220b is configured as a parallel resonant circuit, and the power receiving resonant circuit 110R is configured as a series resonant circuit, so that the output section 110Ro of the power receiving resonant circuit 110R has constant voltage characteristics. Therefore, since the filter circuit 110Fb is connected to the output section 110Ro of the power receiving resonant circuit 110R, the output section 110R of the filter circuit 110Fb has constant current characteristics. That is, the portion connected in series with the input section 120i of the power conversion circuit 120, which is also the output section of the filter circuit 110Fb, has constant current characteristics. Therefore, in the fourth embodiment, the first portion includes the two positive-side first coils 111FLp, the two negative-side first coils 111FLn, the positive-side resonant capacitor 111RCp, the negative-side resonant capacitor 111RCn, and the power receiving coil 111RL. The remaining configuration of the fourth embodiment is the same as that of the first embodiment. In Fig. 11, components different from those of the first embodiment are indicated by the symbol "b" appended to the reference numerals of the first embodiment.

[0067] With this configuration, the filter circuit 110Fb has constant current characteristics. Therefore, even if the resonant circuit 110R has constant voltage characteristics, the power receiving device 100b according to the present disclosure can have a first portion where fluctuations in voltage and current are small.

[0068] E. Fifth Embodiment A power receiving device 100 c of a fifth embodiment includes the same configuration as the power receiving device 100 of the first embodiment, and further includes a first voltage sensor 190 that acquires the voltage of the secondary power supply circuit 160 .

[0069] The first voltage sensor 190 is connected in parallel to the first secondary power supply coil 161. Specifically, the first voltage sensor 190 is an integrating circuit. The first voltage sensor 190 obtains the value of the current flowing through the first secondary power supply coil 161 by integrating the value of the voltage applied to the first secondary power supply coil 161. The value of the current flowing through the first secondary power supply coil 161 is based on the turns ratio of the first power supply transformer 180 and the value of the current flowing through the negative side first coil 111FLn. Therefore, the first voltage sensor 190 transmits information related to the current flowing through the negative side first coil 111FLn and the input current of the power conversion circuit 120 to the control unit 151.

[0070] The control unit 151c of the fifth embodiment controls the ratio of the short-circuit mode period to the power supply mode period in the cycle of the first AC power AC1 in accordance with the value obtained by integrating the voltage measured by the first voltage sensor 190. That is, the control unit 151c controls the first DC power DC1. For example, when an abnormality in the power receiving device 100 causes excessive current to flow through the negative-side first coil 111FLn, the control unit 151c increases the ratio of the short-circuit mode period in the cycle of the first AC power AC1. This allows the load device 130 to be protected by reducing or stopping the supply of the first DC power DC1. Additionally, the control unit 151c can control the ratio of the short-circuit mode period to the power supply mode period based on the current flowing through the negative-side first coil 111FLn so as to satisfy the first DC power DC1 required by the load device 130. Other configurations of the fifth embodiment are the same as those of the first embodiment. In FIG. 10 , components different from those of the first embodiment are denoted by the symbols of the first embodiment with the letter c added.

[0071] That is, in this configuration, the value obtained by integrating the voltage becomes information based on the current flowing through the first coil 111FL. The control circuit 150c can, for example, control the power adjustment of the load device 130 and the protection operation from overcurrent without requiring a current sensor that detects the input current of the power conversion circuit 120. Because voltage sensors are generally cheaper than current sensors, the power receiving device 100c of the present disclosure can reduce the cost of the device.

[0072] F. Sixth Embodiment: In the first embodiment, the first power transformer 180 supplies third AC power AC3 to the secondary power supply circuit 160 via the first coil 111FL of the filter circuit 110F. However, as shown in FIG. 11 , the first power transformer 180 in the sixth embodiment has a primary side formed by the power transmission coil 222 and a secondary side formed by the second secondary power supply coil 161d. The first power transformer 180 in the sixth embodiment, which corresponds to the first power supply transformer 180 in the first embodiment, is referred to as the second power supply transformer 180d. The second secondary power supply coil 161d corresponds to the first secondary power supply coil 161 in the first embodiment.

[0073] That is, the second power supply transformer 180d supplies third AC power AC3, which is part of the first AC power AC1, to the secondary power supply circuit 160d via the power receiving coil 111RL and the second secondary power supply coil 161d. The second power supply transformer 180d is a compound-wound transformer, and its primary side and secondary side are electrically insulated. The turns ratio of the second power supply transformer 180d is designed based on the rated voltage of the secondary power supply circuit 160d. Other configurations of the sixth embodiment are the same as those of the first embodiment. In FIG. 11 , components different from those of the first embodiment are indicated by the symbol 'd' added to the reference numerals of the first embodiment. However, to facilitate understanding of the technology, the filter circuit 110F is not shown.

[0074] With this configuration, the secondary power supply circuit 160d can normally supply the third DC power DC3 to the control unit 151 via the elements of the resonant circuit 110R even if an abnormality occurs in the first coil 111FL or the first capacitor 111FC.

[0075] Furthermore, by adopting such a configuration, the turns ratio of the second power transformer 180d can easily reduce the voltage applied to the secondary power supply circuit 160. Therefore, the power receiving device 100d of the present disclosure can reduce losses in the secondary power supply circuit 160d compared to a configuration in which the secondary power supply circuit 160d is directly connected to the power receiving coil 111RL. Furthermore, because the secondary power supply circuit 160d is insulated from the power receiving circuit 110 by the second power transformer 180d, it is less susceptible to noise from the power receiving circuit 110.

[0076] G. Seventh Embodiment: In the first embodiment, the third AC power AC3 is supplied to the secondary power supply circuit 160 via the first power transformer 180. However, the third AC power AC3 may be supplied to the secondary power supply circuit 160 by other methods. The power receiving device 100 of the seventh embodiment does not include the first power transformer 180. FIG. 12 illustrates a portion corresponding to the first coil 111FL of the first embodiment. As shown in FIG. 12, the input section 160ei of the secondary power supply circuit 160e of the seventh embodiment is connected to both ends of the negative side first coil 111FLn. The secondary power supply circuit 160e includes an isolation capacitor 161e connected in series to both ends of the input section 160ei, and a rectifier circuit 162e including a Zener diode.

[0077] The secondary power supply circuit 160e is supplied with third AC power AC3 via an isolation capacitor 161e. In other words, the secondary power supply circuit 160e is electrically insulated from the power receiving circuit 110. The secondary power supply circuit 160e rectifies the third AC power AC3 using a rectifier circuit 162e. The secondary power supply circuit 160e supplies third DC power DC3 to the control circuit 150 at a constant voltage using a Zener diode set based on the rated voltage of the control circuit 150. Other configurations of the seventh embodiment are the same as those of the first embodiment. In FIG. 11 , components different from those of the secondary power supply circuit 160 of the first embodiment are indicated by the symbols of the first embodiment followed by an "e".

[0078] This configuration allows the secondary power supply circuit 160e to be more compact than a configuration in which the secondary power supply circuit 160e receives power while being insulated from the power receiving circuit 110 by a transformer. Furthermore, because the secondary power supply circuit 160e is insulated from the power receiving circuit 110, it is less susceptible to noise from the power receiving circuit 110. Furthermore, because the secondary power supply circuit 160e does not include a resistor, losses are reduced, allowing it to operate with high efficiency.

[0079] H. Eighth Embodiment: In the above-described embodiments, in the short-circuit mode, the switches Sw of the negative lines Ldcn in the two leg circuits are controlled to the on state, thereby short-circuiting the input section 120i of the power conversion circuit 120. However, the short-circuit mode may be realized by other methods. As shown in FIG. 13 , the power conversion circuit 120f of the eighth embodiment includes a protection circuit 123 that short-circuits the input section 120i. The power conversion circuit 120 executes the power supply mode and the short-circuit mode by the protection circuit 123.

[0080] More specifically, the protection circuit 123 is a switch that connects the negative line Lacn and the positive line Lacp in the input section 120i of the power conversion circuit 120. The protection circuit 123 switches on and off in response to a command from the control circuit 150f. That is, the protection circuit 123 is turned on when the short circuit mode is executed by the control circuit 150f. The protection circuit 123 is turned off when the power supply mode is executed by the control circuit 150f. Therefore, in the short circuit mode, the protection circuit 123 shorts the input section 120i of the power conversion circuit 120f.

[0081] Furthermore, the control circuit 150f of the seventh embodiment includes an inverting output unit 153. Specifically, the inverting output unit 153 is a NOT gate. The inverting output unit 153 inverts the command of the control unit 151f and sends it to the drive circuit 152f.

[0082] The control unit 151f issues a command to the protection circuit 123f to execute the power supply mode and the short-circuit mode using a pulse signal. The protection circuit 121f operates in the short-circuit mode when the pulse signal is turned on. The protection circuit 121f operates in the power supply mode when the pulse signal is turned off. Therefore, the pulse signal turned on by the control unit 151f is inverted by the inverting output unit 153 to cause the protection circuit 121f to execute the power supply mode. The pulse signal turned off by the control unit 151f is inverted by the inverting output unit 153 to cause the protection circuit 121f to execute the short-circuit mode.

[0083] For example, if the control circuit 150f cannot receive power supply, the pulse signal of the control unit 151f is turned off. That is, the protection circuit 123 executes the short-circuit mode. Therefore, by stopping the supply of the first DC power DC1, the load device 130 is protected in the event of such an abnormality in the power receiving device 100f.

[0084] Other configurations of the sixth embodiment are the same as those of the first embodiment. In Fig. 13, configurations different from those of the first embodiment are indicated by the symbols of the first embodiment followed by an f. Note that the leg circuits in the power conversion circuit 120f perform rectification under the control of another control circuit 150 (not shown).

[0085] With this configuration, the secondary power supply circuit 160f supplies only the power necessary to control the protection circuit 123. Therefore, the power receiving device 100f of the present disclosure can reduce the rated power of the secondary power supply circuit 160f compared to a configuration in which circuits other than the protection circuit 123 of the power conversion circuit 120f are also controlled. In other words, the power receiving device 100f of the present disclosure can reduce the size of the secondary power supply circuit 160f.

[0086] Furthermore, since the control circuit 150f controls only the switches of the protection circuit 123, control of the power receiving device 100f of the present disclosure can be achieved more easily than when controlling the other switches Sw of the power conversion circuit 120f.

[0087] Furthermore, in this configuration, the power receiving device 100 of the present disclosure outputs an OFF pulse signal when the control circuit 150f cannot receive power. An ON pulse signal is input to the protection circuit 123 by the inverting output unit 153, and the short-circuit mode is implemented. Therefore, the power receiving device 100f of the present disclosure can protect the load device 130 by operating the protection circuit 123 in the short-circuit mode when an abnormality occurs in the control circuit 150f.

[0088] I. Ninth Embodiment In the above embodiments, the power receiving device 100 is mounted on a vehicle V, for example. When the power receiving device 100 is mounted on a vehicle V and the vehicle V includes a vehicle control unit 20 that controls the vehicle V, the control circuit 150 may notify the vehicle control unit 20. Note that, as shown in FIG. 14 , the power transmitting device 200 transmits power to the power receiving device 100 mounted on the vehicle V while laid on the ground G. The power receiving device 100 of the eighth embodiment includes a second voltage sensor that detects the voltage of the first secondary power supply coil 161, instead of the first voltage sensor 190 of the fifth embodiment. The second voltage sensor is not an integrating circuit, but sends an instantaneous voltage value to the control unit 151 of the ninth embodiment. The other configurations of the ninth embodiment are the same as those of the fifth embodiment.

[0089] The control circuit 150 of the ninth embodiment executes the short-circuit mode or notifies the vehicle control unit 20 of information based on the input voltage of the secondary power supply circuit 160 based on the detection result of the second voltage sensor when the voltage of the secondary power supply circuit 160 is lower than a predetermined reference voltage. The control circuit 150 of the ninth embodiment executes the power supply mode when the input voltage of the secondary power supply circuit 160 is equal to or higher than the predetermined reference voltage. The reference voltage is, for example, the maximum voltage of the secondary power supply circuit 160 under normal conditions.

[0090] By adopting this configuration, when an abnormal state occurs, for example, in which the input voltage of the secondary power supply circuit 160 is lower than the reference voltage, the power receiving device 100 can protect the power receiving device 100 by executing short-circuit mode, or can notify the vehicle V of the abnormality so that the driver of the vehicle V can consider countermeasures.

[0091] J. Modification 1: In the eighth embodiment, the protection circuit 123 is configured with a switch Sw that connects the negative line Lacn and the positive line Lacp. However, the protection circuit 123 may also be configured with a switch Sw on the negative line Ldcn side of the two leg circuits in the power conversion circuit 120. That is, the control circuit 150f controls only the switch Sw on the negative line Ldcn side of the two leg circuits. Because the short-circuit mode is realized only by the switch Sw on the negative line Ldcn side, control of the switch Sw on the positive line Ldcp side is not required. However, the switch Sw on the positive line Ldcp side is controlled by another control circuit.

[0092] With this configuration, the secondary power supply circuit 160 supplies only the power required by some of the switches Sw of the power conversion circuit 120. Therefore, the power receiving device 100f of the present disclosure can reduce the rated power of the secondary power supply circuit 160 compared to a configuration in which all of the switches Sw of the power conversion circuit 120f are controlled. In other words, the power receiving device 100f of the present disclosure can reduce the size of the secondary power supply circuit 160.

[0093] Furthermore, since the protection circuit 123 is configured by the switch Sw of the power conversion circuit 120f, the power conversion circuit 120f does not need to include an additional switch Sw for the protection circuit 123. This reduces the size of the power receiving device 100f according to the present disclosure.

[0094] K. Modification 2: The filter circuit 110Fb of the fourth embodiment may function as an immittance filter using other configurations. For example, the immittance filter can also be realized by the configuration of the filter circuit 110Fb1 shown in FIG. 15. In FIG. 15, the filter circuit 110Fb of FIG. 9 is replaced with the filter circuit 110Fb1. Note that in FIG. 15, the illustration of the power transmitting device 200b and the control circuit 150 is omitted to facilitate understanding of the technology. In the filter circuit 110Fb1 of FIG. 15, the positive side first coil 111FLp and the negative side first coil 111FLn are connected in series to the power receiving coil 111RL and the input section 120i of the power conversion circuit 120. Furthermore, in the filter circuit 110Fb1 of FIG. 15, a second capacitor 112FCb is connected to the output section 110Ro of the power receiving resonant circuit 110R. The filter circuit 110Fb1 configured as above also serves as an immittance filter.

[0095] L. Modification 3: The filter circuit 110F in the first embodiment may be configured differently to function as a bandpass filter. For example, the bandpass filter may be realized by the filter circuits 110F1 to 110F3 shown in FIGS. 16 to 18. In FIGS. 16 to 18, the filter circuit 110F in FIG. 1 is replaced with the filter circuits 110F1 to 110F3. Note that in FIGS. 16 to 18, the power transmitting device 200, the control circuit 150, and the like are omitted from illustration to facilitate understanding of the technology.

[0096] In the filter circuit 110F1 of FIG. 16, a negative side first coil 111FLn and a positive side first capacitor 111FCp are connected in series to the power receiving coil 111RL and the input part 120i of the power conversion circuit 120.

[0097] In addition to the filter circuit 110F1 of FIG. 16, the filter circuit 110F2 of FIG. 17 further includes a second capacitor 112FC connected to the output section 110Ro of the power receiving resonant circuit 110R.

[0098] In the filter circuit 110F3 of Figure 18, a positive side first coil 111FLp, a positive side first capacitor 111FCp, a negative side first coil 111FLnn, and a negative side first capacitor 111FCn are connected in series to the receiving coil 111RL and the input section 120i of the power conversion circuit 120.

[0099] The above configuration also realizes a bandpass filter.

[0100] M. Modification 4: The secondary power supply circuit 160e of the seventh embodiment may be realized with other configurations. For example, the rectifier circuit 162e1 in the secondary power supply circuit 160e1 of FIG. 19 has a configuration in which one rectifier diode connected in series with the isolation capacitor 161e is removed from the rectifier circuit 162e of the seventh embodiment of FIG. 12. In addition, the rectifier circuit 162e2 in the secondary power supply circuit 160e2 of FIG. 20 is configured with a bridge circuit of rectifier diodes. The secondary power supply circuit 160e of the seventh embodiment can also be realized with the above configuration.

[0101] N. Modification 5: (1) In the above embodiment, the power receiving device 100 is mounted on a vehicle V. However, the power receiving device 100 may be mounted on another moving body. For example, the power receiving device 100 may be mounted on an airplane. (2) In the above embodiment, a battery is exemplified as the load device 130. However, the load device 130 is not limited to a battery. The load device 130 may be, for example, a lighting device or a power plant. (3) In the first embodiment, the power receiving resonant capacitor 111RC includes a positive-side resonant capacitor 111RCp arranged on the positive-side line Lacp of the power receiving circuit 110 and a negative-side resonant capacitor 111RCn arranged on the negative-side line Lacn of the power receiving circuit 110. However, the power receiving resonant capacitor 111RC may include only the positive-side resonant capacitor 111RCp arranged on the positive-side line Lacp of the power receiving circuit 110. (4) In the third embodiment, the filter circuit 110F is configured with one first coil 111FL. However, the filter circuit 110F may be configured with one or more first coils 111FL. For example, the filter circuit 110F may be configured with two or three first coils 111FL. (5) In the above embodiment, the switch Sw of the synchronous rectifier circuit 120 is a MOSFET. However, the switch Sw of the synchronous rectifier circuit 120 may be another switching element. The switch Sw may be, for example, a BJT (bipolar junction transistor) or an IGBT (insulated gate bipolar transistor). (6) In the above embodiment, a failure of the auxiliary battery is given as an example of a case in which power cannot be supplied from the main power supply circuit 140. However, due to other factors, the control circuit 150 may reach a state where it is unable to receive power from the main power supply circuit 140. For example, the control circuit 150 may reach a state where it is unable to receive power from the main power supply circuit 140 due to a lack of remaining charge in the auxiliary battery or a circuit failure in the load device 130. (7) In the sixth embodiment, the power receiving circuit 110 includes a filter circuit 110F. However, the power receiving circuit 110 does not have to include the filter circuit 110F.(8) In the seventh embodiment, the control circuit 170f includes the inverting output unit 153. However, the control circuit 170f does not have to include the inverting output unit 153. (9) In the above embodiments, the secondary power supply circuit 160 receives the third AC power AC3 via the first coil 111FL or the power receiving coil 111RL. However, the secondary power supply circuit 160 may receive the third AC power AC3 from the first capacitor 111FC or the power receiving resonant capacitor 111RC. (10) In the above embodiments, the secondary power supply circuit 160 receives the third AC power AC3 while being electrically isolated from the power receiving circuit 110 by the first power transformer 180 and the isolation capacitor 161e. However, the secondary power supply circuit 160 may receive the third AC power AC3 while being electrically connected to the power receiving circuit 110. (11) In the above embodiments, the secondary power supply circuit 160 may be configured by combining the first power transformer 180 and the isolation capacitor 161e. That is, the secondary power supply circuit 160 receives the third AC power AC3 via the first power transformer 180 and the insulating capacitor 161e. Therefore, due to the double insulation, the secondary power supply circuit 160 is less susceptible to the effects of noise from the power receiving circuit 110. (12) In the above embodiment, the switching circuit is a diode OR circuit. However, the switching circuit may be configured with a switch. The switch of the switching circuit is driven by the second DC power DC2 to connect the control circuit 150 and the main power supply circuit 140 when the second DC power DC2 is supplied. The switch of the switching circuit connects the control circuit 150 and the secondary power supply circuit 160 when the second DC power DC2 is not supplied.

[0102] The present disclosure is not limited to the above-described embodiments and modifications, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and modifications corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above problems or achieve some or all of the above effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

[0103] O. Other Aspects: The features of the present disclosure are as follows: (Aspect 1) A power receiving device (100, 100a to 100f) that receives first AC power (AC1) in a contactless manner using a magnetic field, comprising: a power receiving circuit (110, 110a, 110b) including a power receiving coil (111RL) that receives the first AC power; a power conversion circuit (v) that converts second AC power (AC2), which is a portion of the first AC power, into first DC power (DC1); a load device (130) that consumes the first DC power; a main power supply circuit (140) that supplies the second DC power (DC2); and secondary power supply circuits (160, 160d, 160f, 160e, 160e1, 160e2) that convert third AC power (AC3), which is another portion of the first AC power, and supply the third DC power (DC3). a control circuit (150, 150c, 150f) that controls the power receiving device (100), the control circuit receiving power from the main power supply circuit or the secondary power supply circuit, wherein an output section (110o) of the power receiving circuit and an input section (120i) of the power conversion circuit are connected, the secondary power supply circuit receiving the third AC power via a first location in the power receiving circuit out of a first location where fluctuations in current and voltage due to a short circuit in the input section of the power conversion circuit are small and a second location where the fluctuations are large, the control circuit executing, by the power conversion circuit, control that combines a short-circuit mode in which the input section of the power conversion circuit is short-circuited and a power supply mode in which the input section of the power conversion circuit is not short-circuited, the power receiving device receiving power from the secondary power supply circuit when it cannot receive power from the main power supply circuit. (Form 2) The power receiving device according to Form 1, wherein the control circuit executes the short-circuit mode when receiving power from the secondary power supply circuit.(Mode 3) A power receiving device according to Mode 2, wherein the power receiving circuit further comprises a resonant circuit (110R) having a resonant frequency corresponding to the frequency of the first AC power, and a filter circuit (110F, 110F1 to 110F3, 110Fb, 110Fb1) that suppresses harmonic components of the first AC power, the resonant circuit comprises the power receiving coil, and in the filter circuit, at least one of one or more first coils (111FL) and one or more first capacitors (111FC) are connected in series to the power receiving coil and an input section of the power conversion circuit, and the first location is at least one of the one or more first capacitors and the one or more first coils. (Mode 4) The power receiving device according to Mode 3, wherein the secondary power supply circuit further includes a first secondary power supply coil (161), and a first coil among the one or more first coils that supplies the third AC power to the secondary power supply circuit, and the first secondary power supply coil together form a first power supply transformer (180) that supplies the third AC power to the secondary power supply circuit. (Mode 5) The power receiving device according to Mode 4, wherein the filter circuit is one of the first coils. (Mode 6) The power receiving device according to Mode 4, wherein the output section of the resonant circuit has a constant voltage characteristic, and the filter circuit is an immittance filter when the output section of the resonant circuit is configured to have the constant voltage characteristic. (Mode 7) The power receiving device according to Mode 4, wherein the filter circuit is a band-pass filter. (Mode 8) The power receiving device according to Mode 4, further comprising: a first voltage sensor (190) that acquires a voltage of the first secondary power supply coil, the first voltage sensor integrating the voltage of the first secondary power supply coil; and the control circuit further controls a ratio of a period of the short circuit mode to a period of the power supply mode in a cycle of the first AC power, according to a value obtained by integrating the voltage by the first voltage sensor.(Mode 9) The power receiving device according to Mode 1, wherein the power receiving circuit further includes a resonant circuit having a resonant frequency corresponding to the frequency of the first AC power, the resonant circuit including the power receiving coil and one or more resonant capacitors (111RC), and the first location is the one or more resonant capacitors and the power receiving coil. (Mode 10) The power receiving device according to Mode 9, wherein the secondary power supply circuit further includes a second secondary power supply coil (161d), and the power receiving coil and the second secondary power supply coil form a second power supply transformer (180d) that supplies the third AC power to the secondary power supply circuit. (Mode 11) The power receiving device according to any one of Modes 1, 2, 3, and 9, wherein the secondary power supply circuit further includes an isolation capacitor (161e) connected in series across both ends of an input section of the secondary power supply circuit. (Mode 12) The power receiving device according to any one of modes 1 to 10, wherein the power conversion circuit further includes a protection circuit (123) that short-circuits an input section of the power conversion circuit, and in the short-circuit mode, the protection circuit short-circuits the input section of the power conversion circuit. (Mode 13) The power receiving device according to mode 12, wherein the control circuit issues a command to the protection circuit to execute the power supply mode and the short-circuit mode by a pulse signal, the protection circuit operates in the short-circuit mode when the pulse signal is in an on state, and operates in the power supply mode when the pulse signal is in an off state, and the control circuit further includes an inverting output section that inverts the pulse signal. (Mode 14) The power receiving device according to Mode 1, mounted on a vehicle (V), the vehicle including a vehicle control unit (20) that controls the vehicle, the power receiving device further including a second voltage sensor that detects the voltage of the secondary power supply circuit, the control circuit, based on the detection result of the second voltage sensor, when the voltage of the secondary power supply circuit is lower than a predetermined reference voltage, executes the short-circuit mode or notifies the vehicle control unit of information based on the input voltage of the secondary power supply circuit, and when the voltage of the secondary power supply circuit is higher than the predetermined reference voltage, executes the power supply mode.

Claims

1. A power receiving device (100, 100a to 100f) that receives first AC power (AC1) non - contactlessly by a magnetic field, comprising: - A power receiving circuit (110, 110a, 110b) including a power receiving coil (111RL) that receives the first AC power; - A power conversion circuit (120, 120f) that converts second AC power (AC2), which is a part of the first AC power, into first DC power (DC1); - A load device (130) that consumes the first DC power; - A main power supply circuit (140) that supplies second DC power (DC2); - A sub - power supply circuit (160, 160d, 160f, 160e, 160e1, 160e2) that converts third AC power (AC3), which is another part of the first AC power, and supplies third DC power (DC3); - A control circuit (150, 150c, 150f) that controls the power receiving device (100), the control circuit being powered by the main power supply circuit or the sub - power supply circuit. - The output part (110o) of the power receiving circuit and the input part (120i) of the power conversion circuit are connected. - The sub - power supply circuit receives the supply of the third AC power through the first location in the power receiving circuit where the fluctuations of current and voltage are small due to a short - circuit of the input part of the power conversion circuit, among the first location and the second location where the fluctuations are large. - The control circuit: - Executes control that combines a short - circuit mode in which the input part of the power conversion circuit is short - circuited by the power conversion circuit and a power - supply mode in which the input part of the power conversion circuit is not short - circuited. - A power receiving device that receives power from the sub - power supply circuit when power supply from the main power supply circuit is not available.

2. The power receiving device according to claim 1, wherein the control circuit executes the short - circuit mode when receiving power from the sub - power supply circuit.

3. The power receiving device according to claim 2, wherein the power receiving circuit further includes a resonance circuit (110R) having a resonance frequency corresponding to the frequency of the first AC power, and a filter circuit (110F, 110F1 to 110F3, 110Fb, 110Fb1) for suppressing harmonic components of the first AC power, the resonance circuit includes the power receiving coil, in the filter circuit, at least one of one or more first coils (111FL) and one or more first capacitors (111FC) is connected in series between the power receiving coil and the input part of the power conversion circuit, and the first location is at least one of the one or more first capacitors and the one or more first coils, the power receiving device.

4. The power receiving device according to claim 3, wherein the secondary power supply circuit further includes a first secondary power supply coil (161), and a first coil that supplies the third AC power to the secondary power supply circuit among the one or more first coils and the first secondary power supply coil constitute a first power transformer (180) that supplies the third AC power to the secondary power supply circuit, the power receiving device.

5. The power receiving device according to claim 4, wherein the filter circuit is one of the one first coils, the power receiving device.

6. The power receiving device according to claim 4, wherein the output part of the resonance circuit has a constant voltage characteristic, and the filter circuit is an impedance filter when the output part of the resonance circuit has the constant voltage characteristic, the power receiving device.

7. The power receiving device according to claim 4, wherein the filter circuit is a band-pass filter, the power receiving device.

8. The power receiving device according to claim 4, further including a first voltage sensor (190) for obtaining the voltage of the first secondary power supply coil, and the first voltage sensor integrates the voltage of the first secondary power supply coil, and the control circuit further controls the ratio of the period of the short-circuit mode and the period of the power supply mode in the period of the first AC power according to the value obtained by integrating the voltage by the first voltage sensor, the power receiving device.

9. The power receiving device according to claim 1, wherein the power receiving circuit further includes a resonance circuit having a resonance frequency corresponding to the frequency of the first AC power, the resonance circuit includes the power receiving coil and one or more resonance capacitors (111RC), and the first location is the one or more resonance capacitors and the power receiving coil, the power receiving device.

10. The power receiving device according to claim 9, wherein the secondary power supply circuit further includes a second secondary power supply coil (161d), and the power receiving coil and the second secondary power supply coil constitute a second power supply transformer (180d) that supplies the third AC power to the secondary power supply circuit.

11. The power receiving device according to any one of claims 1, 2, 3, and 9, wherein the secondary power supply circuit further includes an insulating capacitor (161e) connected in series across both ends of the input portion of the secondary power supply circuit.

12. The power receiving device according to any one of claims 1 to 10, wherein the power conversion circuit further includes a protection circuit (123) that short-circuits the input portion of the power conversion circuit, and in the short-circuit mode, the protection circuit short-circuits the input portion of the power conversion circuit.

13. The power receiving device according to claim 12, wherein the control circuit issues a command to cause the protection circuit to execute the power supply mode and the short-circuit mode by a pulse signal, the protection circuit operates in the short-circuit mode when the pulse signal is in the on state and operates in the power supply mode when the pulse signal is in the off state, and the control circuit further includes an inversion output portion that inverts the pulse signal.

14. The power receiving device according to claim 1, mounted on a vehicle (V), the vehicle including a vehicle control unit (20) that controls the vehicle, the power receiving device further including a second voltage sensor that detects the voltage of the secondary power supply circuit, and the control circuit, based on the detection result of the second voltage sensor, when the voltage of the secondary power supply circuit is lower than a predetermined reference voltage, executes the short-circuit mode or notifies the vehicle control unit of information based on the input voltage of the secondary power supply circuit, and when the voltage of the secondary power supply circuit is higher than the predetermined reference voltage, executes the power supply mode.

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