Contactless power receiving device

Abstract

This suppresses the application of high voltage between the drain and source of the switching element. [Solution] The contactless power receiving device includes one or more position detection coils for the contactless power transmitting device to detect the position of the contactless power receiving device, one or more first switching elements, each having one end electrically connected to one end of the one or more position detection coils and the other end electrically connected to the other end of the one or more position detection coils, and a control unit that controls each of the one or more first switching elements to an off state when it starts receiving power transmitted from the contactless power transmitting device, and controls each of the one or more first switching elements to an on state when it interrupts or stops receiving power transmitted from the contactless power transmitting device.

Description

Technical Field

[0001] This disclosure relates to a contactless power receiving device.

Background Art

[0002] Patent Document 1 describes a contactless power receiving device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A contactless charging system (for example, a contactless charging system for an electric vehicle) is required to have (1) a foreign object detection (FOD) function, (2) a position detection (PD) function, and (3) a protection function for instant output stop.

[0005] (1) The FOD function is such that a contactless power transmission device (for example, installed on the ground or the floor of a building) transmits radio waves for foreign object detection, and a contactless power receiving device (for example, mounted on an electric vehicle) or the radio waves reflected by a foreign object receives the radio waves, and based on the amount of change between the transmitted radio waves and the received radio waves, determines the presence or absence of a foreign object.

[0006] (2) The PD function is such that the contactless power receiving device turns on and off a PB coil for position detection at a constant period, and the contactless power transmission device detects the position of the contactless power receiving device based on the impedance of the PB coil.

[0007] (3) The instantaneous output stop protection function is implemented as follows: The contactless power transmission device cannot instantly stop power transmission if any abnormality occurs in the contactless power receiving device. Therefore, the contactless power receiving device instantly stops battery charging by turning on the switching element of the power conversion circuit (for example, the power conversion circuit) that converts the received AC current to DC current and short-circuiting the output terminal of the resonant circuit connected to the resonator coil for power reception.

[0008] The following issues arise in relation to (1) the foreign object detection function, (2) the position detection function, and (3) the instantaneous output stop protection function.

[0009] (A) When the switching element that turns the PB coil on and off is off, if the output momentary stop protection function is activated, a high voltage is applied between the drain and source of the switching element, and this phenomenon actually occurred, causing the voltage to exceed the rated voltage. This could potentially damage the switching element.

[0010] (B) To avoid the above (A), it is conceivable to leave the switching element turned on. However, if the switching element is left on, the FOD function of the contactless power transmission device will incorrectly detect the presence of a foreign object when no foreign object is present at the start of charging.

[0011] This disclosure aims to suppress the application of a high voltage between the drain and source of a switching element when the output instantaneous shutdown protection function is activated. [Means for solving the problem]

[0012] A contactless power receiving device in one aspect of this disclosure is: A contactless power receiving device that receives power transmitted from a contactless power transmission device, The contactless power transmission device includes one or more position detection coils for detecting the position of the contactless power receiving device, One or more first switching elements, each having one end electrically connected to one end of the one or more position detection coils and the other end electrically connected to the other end of the one or more position detection coils, A control unit controls each of the one or more first switching elements to the off state when it starts receiving power transmitted from the contactless power transmission device, and controls each of the one or more first switching elements to the on state when it interrupts or stops receiving power transmitted from the contactless power transmission device. including, It is characterized by the following:

[0013] In the aforementioned non-contact power receiving device, One or more first resonant circuits are electrically connected between the one or more position detection coils and the one or more first switching elements, respectively. This also includes, It is characterized by the following:

[0014] In the aforementioned non-contact power receiving device, A resonator coil for receiving power transmitted from the aforementioned non-contact power transmission device, A second resonant circuit having a first terminal electrically connected to one end of the resonator coil, a second terminal electrically connected to the other end of the resonator coil, and outputting AC voltages from the third and fourth terminals, The fifth and sixth terminals are electrically connected to the third and fourth terminals of the second resonant circuit, respectively, and a power conversion circuit converts the AC voltage output from the third and fourth terminals of the second resonant circuit into a DC voltage and outputs it from the seventh and eighth terminals. It further includes, The control unit, When interrupting or stopping the reception of power transmitted from the contactless power transmission device, the power conversion circuit is controlled to turn on one or more of the first switching elements and to short-circuit the fifth terminal and the sixth terminal. It is characterized by the following:

[0015] In the aforementioned non-contact power receiving device, The power conversion circuit is, a first diode having an anode electrically connected to the fifth terminal and a cathode electrically connected to the seventh terminal; a second diode having an anode electrically connected to the sixth terminal and a cathode electrically connected to the seventh terminal; a second switching element having one end electrically connected to the fifth terminal and the other end electrically connected to the eighth terminal; a third switching element having one end electrically connected to the sixth terminal and the other end electrically connected to the eighth terminal; and includes The control unit is When starting to receive power transmitted from the non-contact power transmission device, it outputs a first signal for controlling the one or more first switching elements to an off state, and when interrupting or terminating the reception of power transmitted from the non-contact power transmission device, it outputs a second signal for controlling the second switching element and the third switching element to an on state, a control circuit; a logical sum circuit for outputting a logical sum signal of the first signal and the second signal to a control terminal of the one or more switching elements; and includes characterized in that.

[0016] In the non-contact power reception device, The control unit is when the non-contact power transmission device detects the position of the non-contact power reception device, it outputs the first signal which is a pulse signal for turning on and off the one or more first switching elements, characterized in that.

Advantages of the Invention

[0017] According to the present disclosure, when the output instantaneous stop protection function operates, it is possible to suppress a high voltage from being applied between the drain and source of the switching element.

Brief Description of the Drawings

[0018] [Figure 1] Figure 1 is a diagram illustrating the principle of the FOD function. [Figure 2] Figure 2 is a diagram illustrating the principle of the PD function. [Figure 3] Figure 3 illustrates the principle of the output instantaneous shutdown protection function. [Figure 4] Figure 4 shows the configuration of a comparative example of a contactless power receiving device. [Figure 5] Figure 5 shows the waveforms of each part of the comparative example non-contact power receiving device when the output instantaneous stop protection function is activated. [Figure 6] Figure 6 shows the impedance change rate detected by the FOD function of the comparative example non-contact power transmission device. [Figure 7] Figure 7 shows the configuration of the contactless power receiving device according to the embodiment. [Figure 8] Figure 8 shows the waveforms of each part when the protection function for instantaneous output shutdown of the contactless power receiving device of the embodiment is activated. [Figure 9] Figure 9 shows the impedance change rate detected by the FOD function of the contactless power transmission device in the embodiment. [Modes for carrying out the invention]

[0019] The embodiments of this disclosure will be described in detail below with reference to the attached drawings. However, this embodiment does not limit the disclosure, and in the following embodiments, the same parts are denoted by the same reference numerals to avoid redundant explanations.

[0020] <Explanation of the principle of Foreign Object Detection (FOD) function> Figure 1 is a diagram illustrating the principle of the FOD function.

[0021] The antenna 100 of the contactless power transmission device 101 outputs a transmission wave 111. The frequency of the transmission wave is exemplified to be around several MHz, but this disclosure is not limited thereto.

[0022] If a foreign object 120 is present, the transmitted wave 111 is reflected by the foreign object 120 and becomes a reflected wave 112.

[0023] The non-contact power transmission device 101 can determine the presence or absence of foreign matter 120 based on the amount of change in the reflected wave 112 relative to the transmitted wave 111.

[0024] <Explanation of the principle of position detection (PD) function> Figure 2 is a diagram illustrating the principle of the PD function.

[0025] The non-contact power receiving device 200 has one or more PB (Passive Beacon) coils 201 that resonate with the FOD's transmitted wave.

[0026] One or more FOD sensors (impedance measuring coils) of the non-contact power transmission device 300 detect the resonance signal of the PB coil 201 of the non-contact power receiving device 200 as a reflected wave due to foreign matter.

[0027] Here, the contactless power receiving device 200 switches the PB coil 201 on and off at a constant frequency during the operation period of the position detection function. The constant frequency is exemplified by several kHz, but is not limited to this disclosure. The contactless power transmitting device 300 can detect the constant periodic on / off switching of the PB coil 201 and distinguish the PB coil 201 from other foreign objects.

[0028] The contactless power transmission device 300 calculates the position of the contactless power receiving device 200 based on the impedance of the PB coil 201 and transmits it to, for example, the vehicle's ECU (Electronic Control Unit).

[0029] <Explanation of the principle of the output instantaneous suspension protection function> Figure 3 illustrates the principle of the output instantaneous shutdown protection function.

[0030] The non-contact power receiving device 400 receives AC power from a non-contact power transmitting device (not shown), converts it to DC power, and outputs a DC voltage Vout between terminals 1a and 1b.

[0031] The contactless power receiving device 400 includes a resonator coil 11, a resonant circuit 12, a power conversion circuit 13, a control unit 14, and a gate drive circuit 15.

[0032] The resonant circuit 12 corresponds to an example of the "second resonant circuit" in this disclosure. Terminal 12a of the resonant circuit 12 corresponds to an example of the "first terminal" in this disclosure. Terminal 12b of the resonant circuit 12 corresponds to an example of the "second terminal" in this disclosure. Terminal 12c of the resonant circuit 12 corresponds to an example of the "third terminal" in this disclosure. Terminal 12d of the resonant circuit 12 corresponds to an example of the "fourth terminal" in this disclosure.

[0033] The resonator coil 11 includes a winding 11a. One end of the winding 11a is electrically connected to terminal 11b. The other end of the winding 11a is electrically connected to terminal 11c.

[0034] The resonator coil 11 receives AC power transmitted from a contactless power transmission device and outputs AC voltage and AC current between terminals 11b and 11c.

[0035] The resonant circuit 12 has terminals 12a, 12b, 12c, and 12d. Terminal 12a is electrically connected to terminal 11b. Terminal 12b is electrically connected to terminal 11c.

[0036] The resonant circuit 12 resonates due to the AC voltage and AC current input between terminals 12a and 12b, and outputs the AC voltage and AC current from between terminals 12c and 12d.

[0037] Terminal 13e of the power conversion circuit 13 is electrically connected to terminal 12c of the resonant circuit 12. Terminal 13f of the power conversion circuit 13 is electrically connected to terminal 12d of the resonant circuit 12.

[0038] Terminal 13e of the power conversion circuit 13 corresponds to an example of the "fifth terminal" of this disclosure. Terminal 13f of the power conversion circuit 13 corresponds to an example of the "sixth terminal" of this disclosure. Terminal 13g of the power conversion circuit 13 corresponds to an example of the "seventh terminal" of this disclosure. Terminal 13h of the power conversion circuit 13 corresponds to an example of the "eighth terminal" of this disclosure.

[0039] The power conversion circuit 13 includes a diode 13a, a diode 13b, a switching element 13c, and a switching element 13d.

[0040] Diode 13a corresponds to an example of the “first diode” in this disclosure. Diode 13b corresponds to an example of the “second diode” in this disclosure. Switching element 13c corresponds to an example of the “second switching element” in this disclosure. Switching element 13d corresponds to an example of the “third switching element” in this disclosure.

[0041] In this disclosure, each switching element is assumed to be a MOSFET, but this disclosure is not limited to this. Each switching element may be a silicon power device, a GaN power device, a SiC power device (e.g., an IGBT (Insulated Gate Bipolar Transistor)), or the like.

[0042] Each switching element has a parasitic diode (body diode) that can actively conduct current, or a diode connected in antiparallel. A parasitic diode is the pn junction between the back gate and the source and drain of a MOSFET.

[0043] The anode of diode 13a is electrically connected to the drain and terminal 13e of switching element 13c. The cathode of diode 13a is electrically connected to the cathode and terminal 13g of diode 13b. The source of switching element 13c is electrically connected to the source and terminal 13h of switching element 13d.

[0044] The anode of diode 13b is electrically connected to the drain and terminal 13f of switching element 13d. The cathode of diode 13b is electrically connected to the cathode and terminal 13g of diode 13a. The source of switching element 13d is electrically connected to the source and terminal 13h of switching element 13c.

[0045] The power conversion circuit 13 rectifies the AC voltage and AC current input between terminals 13e and 13f, and outputs a DC voltage Vout between terminals 13g and 13h.

[0046] Terminal 13g of the power conversion circuit 13 is electrically connected to terminal 1a of the contactless power receiving device 1. Terminal 13h of the power conversion circuit 13 is electrically connected to terminal 1b of the contactless power receiving device 1.

[0047] Terminal 1a is electrically connected to the high-potential side of load 2 (e.g., a battery). Terminal 1b is electrically connected to the low-potential side of load 2.

[0048] The control unit 14 includes a control circuit 14a. The control circuit 14a is exemplified by, but is not limited to, an MCU (Micro Controller Unit), a DSP (Digital Signal Processor), etc. The control unit 14 is exemplified by, but is not limited to, a control circuit 14a executing a control program.

[0049] When the control circuit 14a controls the switching elements 13c and 13d to the ON state, it outputs a high-level signal S1 to the gate drive circuit 15. When the control circuit 14a controls the switching elements 13c and 13d to the OFF state, it outputs a low-level signal S1 to the gate drive circuit 15.

[0050] The gate drive circuit 15 outputs signal S2, which is obtained by converting the voltage level of signal S1, to the gate of switching element 13c and the gate of switching element 13d.

[0051] If no abnormality 600 (e.g., output disconnection) occurs in the non-contact power receiving device 400, the control unit 14 outputs a low-level signal S1 to the gate drive circuit 15. Specifically, the control circuit 14a outputs a low-level signal S1 to the gate drive circuit 15. The gate drive circuit 15 outputs a signal S2, which is the voltage level of signal S1 converted, to the gate of switching element 13c and the gate of switching element 13d.

[0052] As a result, switching elements 13c and 13d are turned off. At this time, the power conversion circuit 13 becomes equivalent to a bridge diode with diode 13a, diode 13b, the parasitic diode of switching element 13c, and the parasitic diode of switching element 13d. Therefore, the power conversion circuit 13 rectifies the AC voltage and AC current output from terminals 12c and 12d of the resonant circuit 12 and outputs a DC voltage Vout to the load 2.

[0053] The control unit 14 interrupts or stops receiving power from the contactless power transmission device when an abnormality 600 occurs in the contactless power receiving device 400. Specifically, the control circuit 14a outputs a high-level signal S1 to the gate drive circuit 15. The gate drive circuit 15 outputs a signal S2, which is the voltage level of signal S1 converted, to the gate of switching element 13c and the gate of switching element 13d.

[0054] As a result, switching elements 13c and 13d are turned on. At this time, the path from terminal 12c of the resonant circuit 12 ←→ switching element 13c ←→ switching element 13d ←→ terminal 12d of the resonant circuit 12 is short-circuited.

[0055] Therefore, the non-contact power receiving device 400 can instantaneously stop the output of the DC voltage Vout to the load 2.

[0056] <Comparative Example> (composition) Figure 4 shows the configuration of a comparative example of a contactless power receiving device.

[0057] Compared to the contactless power receiving device 400 (see Figure 3), the contactless power receiving device 500 further includes a PB coil 16-1, a PB coil 16-2, a resonant circuit 17-1, a resonant circuit 17-2, a switching element 18-1, a switching element 18-2, and an isolator 19.

[0058] In this disclosure, the number of PB coils 16, resonant circuits 17, and switching elements 18 is set to 2 each, but this disclosure is not limited to this. The number of PB coils 16, resonant circuits 17, and switching elements 18 may be 1 each, or 3 or more each.

[0059] PB coil 16-1 and PB coil 16-2 correspond to examples of “one or more position detection coils” in this disclosure. Resonant circuit 17-1 and resonant circuit 17-2 correspond to examples of “one or more first resonant circuits” in this disclosure. Switching element 18-1 and switching element 18-2 correspond to examples of “one or more first switching elements” in this disclosure.

[0060] The PB coil 16-1 includes winding 16-1a. One end of winding 16-1a is electrically connected to terminal 16-1b. The other end of winding 16-1a is electrically connected to terminal 16-1c.

[0061] The resonant circuit 17-1 includes a capacitor 17-1a and a resistor 17-1b. One end of the capacitor 17-1a is electrically connected to terminal 16-1b of the PB coil 16-1. The other end of the capacitor 17-1a is electrically connected to one end of the resistor 17-1b.

[0062] In this disclosure, the resonant circuit 17-1 is an RC series circuit, but this disclosure is not limited thereto.

[0063] The other end of resistor 17-1b is electrically connected to the drain of switching element 18-1. The source of switching element 18-1 is electrically connected to terminal 16-1c of PB coil 16-1.

[0064] The PB coil 16-2 includes winding 16-2a. One end of winding 16-2a is electrically connected to terminal 16-2b. The other end of winding 16-2a is electrically connected to terminal 16-2c.

[0065] The resonant circuit 17-2 includes a capacitor 17-2a and a resistor 17-2b. One end of the capacitor 17-2a is electrically connected to terminal 16-2b of the PB coil 16-2. The other end of the capacitor 17-2a is electrically connected to one end of the resistor 17-2b.

[0066] In this disclosure, the resonant circuit 17-2 is an RC series circuit, but this disclosure is not limited to this.

[0067] The other end of resistor 17-2b is electrically connected to the drain of switching element 18-2. The source of switching element 18-2 is electrically connected to terminal 16-2c of PB coil 16-2.

[0068] When the control circuit 14a performs the position detection function, it outputs a pulse signal (for example, a PWM (Pulse Width Modulation) signal S3) to the gates of switching element 18-1 and switching element 18-2 via the isolator 19. As a result, switching elements 18-1 and 18-2 repeatedly switch on and off.

[0069] As a result, the impedance of PB coil 16-1 and PB coil 16-2 changes, allowing the non-contact power transmission device (not shown) to detect the position of the non-contact power receiving device 500.

[0070] When position detection is complete and contactless power reception begins, the control circuit 14a outputs a low-level signal S3 to the gates of switching element 18-1 and switching element 18-2 via the isolator 19. As a result, switching elements 18-1 and 18-2 turn off.

[0071] In other words, while the contactless power receiving device 500 is receiving power, switching elements 18-1 and 18-2 are in the off state.

[0072] (assignment) [Regarding (A) above] Figure 5 shows the waveforms of each part of the comparative example non-contact power receiving device when the output instantaneous stop protection function is activated.

[0073] In Figure 5, line 701 represents signal S1. Line 702 represents the DC voltage Vout. Line 703 represents the drain-source voltage Vds-1 of switching element 18-1. Line 704 represents the drain-source voltage Vds-2 of switching element 18-2.

[0074] If an abnormality 600 occurs at timing t0, the control unit 14 interrupts or stops receiving power from the contactless power transmission device. Specifically, at timing t1, the control circuit 14a outputs a high-level signal S1 as shown by line 701. As a result, switching elements 13c and 13d are turned on, and the contactless power receiving device 500 instantaneously stops outputting the DC voltage Vout.

[0075] Furthermore, the reason why the drain-source voltage Vds-1, indicated by line 703, and the drain-source voltage Vds-2, indicated by line 704, fluctuate up and down during the period prior to timing t1 is that PB coils 16-1 and 16-2 are being affected by electromagnetic interference from the power transmission of the contactless power transmission device.

[0076] As described above, while the contactless power receiving device 500 is receiving power, switching elements 18-1 and 18-2 are in the off state. That is, at timing t1, switching elements 18-1 and 18-2 are in the off state. At this time, when the output instantaneous stop protection function of the contactless power receiving device 500 is activated, i.e., when switching elements 13c and 13d are turned on, a high voltage is applied between the drain and source of each of the switching elements 18-1 and 18-2, as shown by lines 703 and 704, and the phenomenon of exceeding the rated voltage actually occurred.

[0077] As an example, although the rated voltages of the drain-source voltages Vds-1 and Vds-2 are 60V, a phenomenon actually occurred where the drain-source voltage Vds-1 became 63.7V, as indicated by arrow 705.

[0078] As a result, the non-contact power receiving device 500 may suffer damage to each of its switching elements 18-1 and 18-2.

[0079] [Regarding (B) above] To avoid the above (A), it is conceivable that the control unit 14 keeps switching element 18-1 and switching element 18-2 in the ON state while the non-contact power receiving device 500 is receiving power.

[0080] Figure 6 shows the impedance change rate detected by the FOD function of the comparative example non-contact power transmission device. More specifically, it shows the impedance change rate of PB coil 16-1 and PB coil 16-2 detected by the FOD function of the non-contact power transmission device when switching elements 18-1 and 18-2 are ON while the non-contact power receiving device 500 is receiving power.

[0081] In Figure 6, line 711 shows the impedance change rates of PB coil 16-1 and PB coil 16-2, respectively. Line 712 is the detection threshold for the impedance change rate at which the FOD function of the contactless power transmission device detects foreign objects.

[0082] timing t 10 At this point, the contactless power receiving device 500 begins receiving power. Then, as shown by line 711, the impedance change rate of PB coil 16-1 and PB coil 16-2 detected by the FOD function of the contactless power transmission device exceeds the detection threshold shown by line 712. In other words, the contactless power transmission device incorrectly detects the presence of a foreign object even though no foreign object is present.

[0083] <Embodiment> [composition] Figure 7 shows the configuration of the contactless power receiving device according to the embodiment.

[0084] Compared to the contactless power receiving device 500 (see Figure 4), the contactless power receiving device 1 includes a control unit 14A instead of the control unit 14.

[0085] Compared to the control unit 14, the control unit 14A further includes a logical OR circuit 14b in addition to the control circuit 14a.

[0086] Signal S1 is input to one input terminal of the OR circuit 14b. Signal S3 is input to the other input terminal of the OR circuit 14b.

[0087] The OR circuit 14b outputs signal S4, which is the OR signal of signal S1 and signal S3, to the gates of switching element 18-1 and switching element 18-2 via the isolator 19.

[0088] Signal S1 is high only when the instantaneous output stop protection function of the non-contact power receiving device 1 is activated; otherwise, it is low.

[0089] Therefore, signal S4 becomes a pulse signal when the position detection function of the contactless power receiving device 1 is operating, and is at a low level while the contactless power receiving device 1 is receiving power. Then, it becomes at a high level when the output instantaneous stop protection function of the contactless power receiving device 1 is activated.

[0090] In other words, the control unit 14A controls switching elements 18-1 and 18-2 to the off state while the contactless power receiving device 1 is receiving power. Then, the control unit 14A controls switching elements 18-1 and 18-2 to the on state at the timing when the output instantaneous stop protection function starts to operate.

[0091] (effect) [Regarding (A) above] When the output instantaneous shutdown protection function is activated, that is, when the control circuit 14a outputs a high-level signal S1, the OR circuit 14b outputs a high-level signal S4 to the gates of switching element 18-1 and switching element 18-2. As a result, switching elements 18-1 and 18-2 turn on.

[0092] Figure 8 shows the waveforms of each part when the protection function for instantaneous output shutdown of the contactless power receiving device of the embodiment is activated.

[0093] In Figure 8, line 801 represents the drain-source voltage Vds-1 of switching element 18-1. Line 802 represents the drain-source voltage Vds-2 of switching element 18-2.

[0094] timing t 20 When an abnormality 600 occurs, the control unit 14A interrupts or stops receiving power from the contactless power transmission device. Specifically, the control circuit 14a controls the timing t 20 At this point, a high-level signal S1 is output. As a result, switching elements 13c and 13d are turned on, and the contactless power receiving device 1 instantaneously stops outputting the DC voltage Vout.

[0095] At this time, the OR circuit 14b outputs a high-level signal S4 to the gates of switching element 18-1 and switching element 18-2. As a result, switching elements 18-1 and 18-2 are turned on. Consequently, as shown by lines 801 and 802, the drain-source voltages Vds of switching elements 18-1 and 18-2 are suppressed.

[0096] As an example, with drain-source voltages Vds-1 and Vds-2 having a rated voltage of 60V, drain-source voltage Vds-1 was suppressed to 9.9V as indicated by arrow 803, and drain-source voltage Vds-2 was suppressed to 9.1V as indicated by arrow 804.

[0097] This makes it possible to suppress the possibility of each of the switching elements 18-1 and 18-2 being damaged in the non-contact power receiving device 1.

[0098] [Regarding (B) above] The control circuit 14a outputs a low-level signal S3 when power is received, and the OR circuit 14b outputs a low-level signal S4 to the gates of switching element 18-1 and switching element 18-2. As a result, switching elements 18-1 and 18-2 are turned off.

[0099] Figure 9 shows the impedance change rate detected by the FOD function of the contactless power transmission device in the embodiment. More specifically, it shows the impedance change rate of PB coil 16-1 and PB coil 16-2 detected by the FOD function of the contactless power transmission device when switching elements 18-1 and 18-2 are in the off state while the contactless power receiving device 1 is receiving power.

[0100] In Figure 9, line 811 shows the impedance change rates of PB coil 16-1 and PB coil 16-2, respectively. Line 812 is the detection threshold for the impedance change rate at which the FOD function of the contactless power transmission device detects foreign objects.

[0101] timing t 30 At this point, the contactless power receiving device 1 begins receiving power. As shown by line 812, the impedance change rate of PB coil 16-1 and PB coil 16-2 detected by the FOD function of the contactless power transmission device does not exceed the detection threshold shown by line 812. In other words, the contactless power transmission device will not falsely detect the presence of foreign objects.

[0102] Therefore, the non-contact power receiving device 1 can suppress the non-contact power transmitting device from falsely detecting the presence of foreign objects.

[0103] Furthermore, the control unit 14A can be implemented simply by adding a logical OR circuit 14b to the existing control circuit 14a. Therefore, the contactless power receiving device 1 does not require any changes to the control program. Changing the control program and verifying its operation is time-consuming. Therefore, the contactless power receiving device 1 has a significant effect in reducing the amount of work required.

[0104] While embodiments of the present disclosure have been described above, the present disclosure is not limited by the content of these embodiments. Furthermore, the aforementioned components include those that are readily conceivable to those skilled in the art, those that are substantially identical, and those that fall within the so-called equivalent range. Moreover, the aforementioned components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the embodiments described above. [Explanation of Symbols]

[0105] 1, 400, 500 Non-contact power receiving device 2 loads 11 Resonator Coil 11a, 16-1a, 16-2a windings 12, 17-1, 17-2 resonant circuit 13 Power Conversion Circuit 13a, 13b diodes 13c, 13d, 18-1, 18-2 switching elements 14, 14A Control Unit 14a Control circuit 14b OR circuit 15 Gate drive circuit 16-1, 16-2 PB coil 17-1a, 17-2a Capacitors 17-1b, 17-2b resistance 19 Isolators

Claims

1. A contactless power receiving device that receives power transmitted from a contactless power transmission device, The contactless power transmission device includes one or more position detection coils for detecting the position of the contactless power receiving device, One or more first switching elements, each having one end electrically connected to one end of the one or more position detection coils and the other end electrically connected to the other end of the one or more position detection coils, A control unit controls each of the one or more first switching elements to the off state when it starts receiving power transmitted from the contactless power transmission device, and controls each of the one or more first switching elements to the on state when it interrupts or stops receiving power transmitted from the contactless power transmission device. including, A non-contact power receiving device characterized by the following features.

2. One or more first resonant circuits are electrically connected between the one or more position detection coils and the one or more first switching elements, respectively. This also includes, A non-contact power receiving device according to claim 1, characterized in that...

3. A resonator coil for receiving power transmitted from the aforementioned non-contact power transmission device, A second resonant circuit having a first terminal electrically connected to one end of the resonator coil, a second terminal electrically connected to the other end of the resonator coil, and outputting AC voltages from the third and fourth terminals, The fifth and sixth terminals are electrically connected to the third and fourth terminals of the second resonant circuit, respectively, and a power conversion circuit converts the AC voltage output from the third and fourth terminals of the second resonant circuit into a DC voltage and outputs it from the seventh and eighth terminals. It further includes, The control unit, When interrupting or stopping the reception of power transmitted from the contactless power transmission device, the power conversion circuit is controlled to turn on one or more of the first switching elements and to short-circuit the fifth terminal and the sixth terminal. A contactless power receiving device according to claim 1 or 2, characterized in that...

4. The aforementioned power conversion circuit is A first diode having its anode electrically connected to the fifth terminal and its cathode electrically connected to the seventh terminal, A second diode having its anode electrically connected to the sixth terminal and its cathode electrically connected to the seventh terminal, A second switching element having one end electrically connected to the fifth terminal and the other end electrically connected to the eighth terminal, A third switching element, one end of which is electrically connected to the sixth terminal and the other end of which is electrically connected to the eighth terminal, Includes, The control unit, A control circuit outputs a first signal to control one or more first switching elements to the off state when it starts receiving power from the contactless power transmission device, and outputs a second signal to control the second and third switching elements to the on state when it interrupts or stops receiving power from the contactless power transmission device. A logical OR circuit for outputting a logical OR signal of the first signal and the second signal to the control terminals of the one or more switching elements, including, A contactless power receiving device according to claim 3, characterized in that...

5. The control unit, When the non-contact power transmission device detects the position of the non-contact power receiving device, it outputs the first signal, which is a pulse signal for turning one or more first switching elements on or off. A non-contact power receiving device according to claim 4, characterized in that...

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