Power receiving device

Abstract

A power receiving device (100) that receives alternating-current electric power in a noncontact manner includes a resonance circuit (110) that receives alternating-current electric power, a rectification circuit (120), a load device (130), a regulation circuit (140) that includes a switch (Sw) that shorts the terminals of the input of the rectification circuit and regulates supplied electric power (Pa), a power receiving sensor (160), and a control circuit (150) that includes a shorting mode and a power feeding mode, performs control that sets a power feeding ratio (D) that is a ratio of a power feeding period to the entire period of power reception to a ratio smaller than a minimum target ratio (Dm) that is the minimum value of a target ratio (Dt) corresponding to a state of resonance or coupling that enables supplied electric power to be a predetermined target electric power (Pt) before power reception of alternating-current electric power starts in accordance with the power receiving sensor, and performs control that increases the power feeding ratio to below the target ratio after power reception is detected by the power receiving sensor.

Description

[0001] Cross-reference of related applications

[0002] This application is based on and claims the priority of Japanese Patent Application No. 2023-216380, filed on December 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] This disclosure relates to power receiving devices. Background Technology

[0004] In the receiving device of a contactless power supply system, such as in Patent Document 1, a switching element is sometimes used in the rectifier circuit that rectifies the received AC power. In the following description, the switching element will be referred to as a switch. In Patent Document 1, a resonant circuit receiving AC power is connected to the load via a rectifier circuit. The technology of Patent Document 1 controls the rectifier circuit by switching, thereby controlling the period during which DC power is supplied to the load and the period during which AC power circulates between the resonant circuit and the rectifier circuit. That is, the receiving device in Patent Document 1 controls the DC power supplied to the load.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 6240503 Summary of the Invention

[0008] When the load is a battery, the control of the DC power supplied to the load is performed, for example, to prevent overcharging. More specifically, when there is excess power received, the control of the DC power supplied to the load is achieved by suppressing the received power, thereby supplying only the power required for charging the battery.

[0009] In contactless power supply systems, the received power depends on the resonance or coupling state of the resonant circuit, which is related to the positional relationship between the receiving and transmitting devices. That is, the receiving device cannot predict the received power in advance. Therefore, the receiving device needs to confirm the received power before the control of the DC power supplied to the load begins. When the load is a battery, the receiving device within the range of the transmitting device begins receiving power under the condition that the battery's remaining charge is insufficient. However, due to the confirmation of the received power, the control of the DC power supplied to the load is delayed. As a result, the DC power supplied to the load is temporarily excessive as a surge power exceeding the power required to charge the battery. Surge power can, for example, cause degradation of the battery as a load and EMC deterioration. Therefore, surge power prevention technology is required in the receiving device of a contactless power supply system.

[0010] This disclosure can be implemented in the following ways.

[0011] According to one aspect of this disclosure, a power receiving device is provided that receives alternating current (AC) power in a non-contact manner via a magnetic field. The power receiving device includes: a resonant circuit comprising a receiving coil for receiving the AC power, the magnitude of which varies depending on the state of resonance or coupling; a rectifier circuit that converts the AC power into direct current (DC) power; a load device that consumes the DC power; a regulating circuit comprising a switch that short-circuits the terminals of the input of the rectifier circuit and regulates the supply power of the AC power to the load device between the receiving coil and the load device; a power receiving sensor that detects the receiving of either the AC power or the DC power; and a control circuit that controls the power receiving device, the control circuit including: a short-circuit mode, which in one cycle of the AC power... Within each half-cycle, the terminals are short-circuited during a pre-defined short-circuit period; and in a power supply mode, the terminals are open during power supply periods other than the short-circuit period within the half-cycle. Based on the power receiving sensor, before the start of AC power reception, control is performed to set the power supply ratio to a ratio less than a minimum target ratio, where the power supply ratio is the ratio of the power supply period within the half-cycle, and the minimum target ratio is the minimum value of a target ratio corresponding to the state of resonance or coupling that enables the supplied power to reach a pre-defined target power. After power reception is detected by the power receiving sensor, control is performed to increase the power supply ratio to below the target ratio.

[0012] In this manner, the received power in the power receiving device of this disclosure varies depending on the state of resonance or magnetic coupling of the resonant circuit. Therefore, the power supply ratio that enables the supplied power to reach the target power also varies depending on the state of resonance or coupling. Furthermore, in this manner, there is a possibility that the load device begins to consume DC power while the power receiving device of this disclosure is in a energized state. Therefore, the power receiving device of this disclosure begins to receive power after the power supply ratio is lower than the minimum target ratio, thereby preventing surge power exceeding the target power even when the load device begins to consume DC power. Moreover, after the consumption of DC power begins, the power receiving device of this disclosure can suppress surge power and efficiently supply power to the load device by increasing the power supply ratio. Attached Figure Description

[0013] The above-mentioned objects, other objects, features, and advantages of this disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. The drawings are described below.

[0014] Figure 1 This is an explanatory diagram showing the structure of the contactless power supply system according to the first embodiment.

[0015] Figure 2This is an explanatory diagram showing the power supply mode.

[0016] Figure 3 This is an explanatory diagram illustrating the short-circuit mode.

[0017] Figure 4 This is an explanatory diagram showing the power supply mode.

[0018] Figure 5 This is an explanatory diagram illustrating the short-circuit mode.

[0019] Figure 6 This is an explanatory diagram showing the electrical power received.

[0020] Figure 7 This is an explanatory diagram showing the power supply at the start of power reception.

[0021] Figure 8 This is a flowchart illustrating the control process performed by the control circuit.

[0022] Figure 9 This is a block diagram illustrating the structure of the control system according to the second embodiment.

[0023] Figure 10 This is an explanatory diagram showing the power receiving device according to the fourth embodiment.

[0024] Figure 11 This is an explanatory diagram showing a modified example of the filter circuit.

[0025] Figure 12 This is an explanatory diagram showing a modified example of the filter circuit.

[0026] Figure 13 This is an explanatory diagram showing the electrical power received in a modified example. Detailed Implementation

[0027] A. First implementation method: A-1. Structure of the device: Figure 1 The contactless power supply system 10 shown supplies power to the load device 130 in a contactless manner via a magnetic field. For example... Figure 1 As shown, the contactless power supply system 10 includes a power supply device 200 and a power receiving device 100. The contactless power supply system 10 supplies power from the power supply device 200 to the power receiving device 100 in a contactless manner. For example, the contactless power supply system 10 supplies power to the power receiving device 100 installed in a vehicle in a contactless manner.

[0028] The power transmission device 200 supplies AC power to the power receiving device 100 in a non-contact manner via a magnetic field. The power transmission device 200 includes an AC power supply device 210 and a power transmission resonant circuit 220.

[0029] The AC power supply device 210 supplies AC power at 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 that converts AC power supplied from the mains power supply into DC power. The power transmission circuit is an inverter that converts the DC power supplied from the power supply circuit into AC power at the operating frequency. The operating frequency is set according to the resonant frequency described later. In this embodiment, the operating frequency of the AC power supply device 210 is, for example, 85 kHz, set using a predetermined power transmission frequency defined by the radio wave law or similar methods.

[0030] The power transmission resonant circuit 220 is magnetically coupled to the receiving coil 111, thereby resonating. The power transmission resonant circuit 220 includes a power transmission coil 222 and a power transmission resonant capacitor 221 connected in parallel to the power transmission coil 222. That is, the power transmission resonant circuit 220 is a parallel resonant circuit.

[0031] When the power supply resonant capacitor 221 is magnetically coupled to the power supply coil 222 and the power receiving coil 111, it causes the power supply resonant circuit 220 to resonate through AC power at the operating frequency. That is, the capacitance of the power supply resonant capacitor 221 is set such that, when the power supply coil 222 and the power receiving coil 111 are magnetically coupled, the operating frequency is approximately the same as the resonant frequency of the power supply resonant circuit 220.

[0032] The transmitting coil 222 generates a magnetic field corresponding to the operating frequency of the AC power supply device 210. Furthermore, the transmitting coil 222 transmits AC power to the receiving coil 111 via magnetic coupling. In other words, the transmitting coil 222 transmits power non-contactly by utilizing electromagnetic induction.

[0033] The power supply coil 222 is laid on the ground for use. More specifically, the power supply coil 222 is laid on the ground in an orientation that is opposite to the power receiving coil 111 installed on the vehicle. The positional relationship between the power supply coil 222 and the power receiving coil 111 will be explained in detail later.

[0034] The power receiving device 100 receives AC power from the power transmitting device 200 in a non-contact manner via a magnetic field. The power receiving device 100 includes a power receiving resonant circuit 110, a synchronous rectifier circuit 120, a load device 130, a regulating circuit 140, a power receiving sensor 160, a control circuit 150, and a smoothing capacitor 170. The power receiving device 100 is installed in a vehicle.

[0035] The receiving resonant circuit 110 is magnetically coupled to the transmitting coil 222, thereby resonating. It includes a receiving coil 111 and a receiving resonant capacitor 112 connected in series with the receiving coil 111. That is, the receiving resonant circuit 110 is a series resonant circuit.

[0036] The receiving coil 111 receives the magnetic field generated by the transmitting coil 222, thereby magnetically coupling with the transmitting coil 222. The receiving coil 111 is installed on the vehicle with its orientation facing away from the ground. The receiving coil 111 is opposite to the transmitting coil 222 laid on the ground, thereby receiving the magnetic field generated by the transmitting coil 222. Thus, the receiving coil 111 receives the AC power from the receiving device 100 in a non-contact manner. In this specification, the AC power received by the receiving coil 111 is referred to as the received power Pr.

[0037] When the receiving coil 111 and the transmitting coil 222 are magnetically coupled, the receiving resonant capacitor 112 causes the receiving resonant circuit 110 to resonate with AC power at the operating frequency. That is, the capacitance of the receiving resonant capacitor 112 is set such that, when the transmitting coil 222 and the receiving coil 111 are magnetically coupled, the operating frequency is approximately the same as the resonant frequency of the receiving resonant circuit 110.

[0038] Furthermore, the received power Pr varies depending on the magnetic coupling state between the receiving coil 111 and the transmitting coil 222, as well as the resonance state of the receiving resonant circuit 110. That is, the received power Pr also varies depending on the relationship between the operating frequency and the resonant frequency. However, for ease of understanding, this specification will describe the situation where the operating frequency and the resonant frequency coincide. The relationship between the magnetic coupling state between the receiving coil 111 and the transmitting coil 222 and the received power Pr will be explained later.

[0039] In this embodiment, the powered resonant capacitor 112 includes a first capacitor 112P on the positive side and a second capacitor 112N on the negative side. By arranging resonant capacitors on both the positive and negative sides, common-mode noise can be suppressed. Furthermore, in this specification, the powered resonant circuit 110 will also be simply referred to as a resonant circuit.

[0040] The synchronous rectifier circuit 120 converts the received AC power into DC power. In this embodiment, the synchronous rectifier circuit 120 is a single-phase rectifier circuit using four MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) as rectifier elements. The synchronous rectifier circuit 120 includes two bridge arm circuits: a first bridge arm circuit 121 and a second bridge arm circuit 122. Alternatively, the synchronous rectifier circuit 120 may be simply referred to as rectifier circuit 120.

[0041] In the bridge arm circuit, two switches Sw are connected in series. Furthermore, the bridge arm circuit connects the positive line Lp and the negative line Ln of the DC power. One of the output terminals of the resonant circuit 110 is connected between the two switches Sw in the bridge arm circuit. That is, the location between the two switches Sw in the bridge arm circuit is the input terminal of the synchronous rectifier circuit 120. Regarding the input terminals of the synchronous rectifier circuit 120, the bridge arm circuit with terminal P1 is the first bridge arm circuit 121. The bridge arm circuit with terminal P2 is the second bridge arm circuit 122.

[0042] The two switches Sw in the bridge arm circuit consist of a first switch SwH, which serves as the rectifier element on the positive line Lp side, and a second switch SwL, which serves as the rectifier element on the negative line Ln side. That is, the switches Sw constitute all the rectifier elements in the synchronous rectifier circuit 120.

[0043] The bridge arm circuit's switch Sw includes a parallel diode Di, which is connected in parallel with respect to the forward direction of switch Sw in a reverse orientation. The parallel diode Di is, for example, the body diode of a MOSFET. That is, the drain of switch Sw is configured on the positive line Lp side, and the source of switch Sw is configured on the negative line Ln side. The cathode of the parallel diode Di is connected to the drain. The anode of the parallel diode Di is connected to the source. Furthermore, the gate of switch Sw is connected to control circuit 150. Switch Sw is driven by receiving a voltage at its gate corresponding to a command from control circuit 150.

[0044] Furthermore, in this specification, the positive electrode line Lp side is referred to as the high side, and the negative electrode line Ln side is referred to as the low side. Therefore, the first switch SwH is also referred to as the high-side switch SwH, and the second switch SwL is referred to as the low-side switch SwL.

[0045] That is, the synchronous rectifier circuit 120 rectifies the AC power input from the resonant circuit 110 through the switch Sw. The DC power rectified by the synchronous rectifier circuit 120 is output to the load device 130 through the positive line Lp and the negative line Ln.

[0046] The regulating circuit 140 is located between the receiving coil 111 and the load device 130, regulating the supply power Pa from the received power Pr, which is AC power, supplied to the load device 130. The regulating circuit 140 includes a switch Sw that short-circuits the terminals of the input of the synchronous rectifier circuit 120. Additionally, the switch Sw of the regulating circuit 140 is also the low-side switch SwL of the synchronous rectifier circuit 120.

[0047] The regulating circuit 140 short-circuits the input terminals of the synchronous rectifier circuit 120 by turning on both low-side switches SwL. As a result, AC power is not rectified by the synchronous rectifier circuit 120. The regulating circuit 140 also opens the input terminals of the synchronous rectifier circuit 120 by turning off at least one of the two low-side switches SwL. As a result, AC power is rectified by the synchronous rectifier circuit 120 and is output as DC power. In this specification, the state in which the input terminals of the synchronous rectifier circuit 120 are short-circuited by the regulating circuit 140 is referred to as the short-circuit mode. The state in which the input terminals of the synchronous rectifier circuit 120 are open by the regulating circuit 140 is referred to as the power supply mode. Each mode will be described in detail later.

[0048] A smoothing capacitor 170 is connected in parallel between the output of the synchronous rectifier circuit 120 and the load device 130. The smoothing capacitor 170 smooths the DC current and DC voltage supplied to the load device 130.

[0049] The current sensor 160 detects the current received by the DC power supply. More specifically, the current sensor 160 detects the current flowing through the load device 130 due to the received power. That is, the current sensor 160 is a current sensor that measures the current value of the DC power supply. The current sensor 160 is connected in series with the output of the synchronous rectifier circuit 120 and the load device 130.

[0050] The load device 130 consumes DC power. The load device 130 is, for example, a device including a battery and battery protection circuitry. The load device 130 is charged by receiving a power supply Pa from the synchronous rectifier circuit 120. The power supplied to the load device 130 is utilized, for example, by a vehicle equipped with a power receiving device 100.

[0051] The load device 130 begins to consume DC power based on a pre-defined reference related to electricity. That is, the load device 130 is not always charging. For example, a load device 130 including a battery will begin charging when the remaining charge is below a certain reference value to prevent overcharging. Thus, the load device 130 may not consume DC power sometimes while the receiving device 100 is energized. However, the load device 130 may sometimes begin to consume DC power while the receiving device 100 is energized. The consumption of DC power during energization will be explained in detail later.

[0052] The power Pa supplied to the load device 130 is the power regulated by the regulating circuit 140 based on the target power Pt. For example, in the case of the load device 130 including a battery, the target power Pt is specified based on the battery's rated current. Batteries can overheat due to overcurrent. This can sometimes reduce battery life. Therefore, the target power Pt is specified as the power that meets a current value below the rated current. Furthermore, the battery may sometimes have its protection circuit cut off the current supplied at a current lower than the battery's rated current.

[0053] The control circuit 150 controls the power receiving device 100. The control circuit 150 includes a control unit 151 and a drive circuit 152.

[0054] The drive circuit 152 drives the switch Sw. More specifically, the drive circuit 152 outputs the power required to drive the switch Sw according to the command of the control unit 151. The drive circuit 152 is connected to the gate of each of the switches Sw in the synchronous rectifier circuit 120. The drive circuit 152 drives the switch Sw by applying the gate voltage required for the switching Sw to turn on and off. Furthermore, in Figure 1 In order to facilitate understanding of the technology, the connection between the drive circuit 152 and the gate has been omitted.

[0055] The control unit 151 generates signals to control the on and off actions of the control switch Sw. The control unit 151 is configured, for example, as a microcomputer, including a CPU, ROM, RAM, etc. (not shown). The control unit 151 includes an adjustment unit 151a as a functional unit. The function of the adjustment unit 151a will be described later. The control unit 151 is connected to the power sensor 160. Based on the current value obtained by the power sensor 160, the control unit 151 executes short-circuit mode and power supply mode.

[0056] A-2. Short-circuit mode and power supply mode: The control circuit 150 includes a short-circuit mode and a power supply mode as control modes. During each half-cycle of one cycle Ca of the AC power supply, within a predetermined short-circuit period, the control circuit 150 executes a short-circuit mode that short-circuits the terminals of the input of the synchronous rectifier circuit 120. During the power supply period, excluding the short-circuit period, during the power supply period of one half-cycle Ca, the control circuit 150 executes a power supply mode that opens the terminals. Figures 2-5 The operation of the power receiving device 100, implemented in short-circuit mode and power supply mode, during one cycle Ca of AC power is explained. Figures 2-5 The upper part of the diagram shows the waveform of an alternating current of one cycle Ca, and the lower part shows the circuit diagram of the power transmission device 200. However, for ease of understanding, the diagrams of the power receiving resonant circuit 110, the smoothing capacitor 170, the control circuit 150, etc., are omitted.

[0057] exist Figure 2 In the power supply mode during the positive half-cycle of the AC power, period a, the direction of the AC current flowing through the synchronous rectifier circuit 120 is illustrated by arrow Aia. During period a, the control circuit 150 controls at least the low-side switch SwL of the first bridge arm circuit 121 of the two switches Sw of the regulating circuit 140 to be in the open state. As a result, the AC current flows to the load device 130 via the high-side switch SwH of the first bridge arm circuit 121. That is, the energized power Pr is supplied to the load device 130.

[0058] exist Figure 3 During the short-circuit mode (period b) of the positive half-cycle of the AC power, the direction of the AC current flowing through the synchronous rectifier circuit 120 is illustrated by arrow Aib. During period b, the control circuit 150 controls at least the low-side switch SwL of the first bridge arm circuit 121 of the two switches Sw of the regulating circuit 140 to be in the ON state. The AC current does not flow to the load device 130 because the input terminals P1 and P2 of the synchronous rectifier circuit 120 are short-circuited. That is, the powered power Pr is not supplied to the load device 130.

[0059] exist Figure 4 During the negative half-cycle of the AC power supply mode, period c, the direction of the AC current flowing through the synchronous rectifier circuit 120 is illustrated by arrow Aic. During period c, the control circuit 150 controls at least the low-side switch SwL of the second bridge arm circuit 122 of the two switches Sw of the regulating circuit 140 to be in the open state. As a result, the AC current flows to the load device 130 via the high-side switch SwH of the second bridge arm circuit 122. That is, the energized power Pr is supplied to the load device 130.

[0060] exist Figure 5 During the short-circuit mode period d in the negative half-cycle of the AC power, the direction of the AC current flowing through the synchronous rectifier circuit 120 is illustrated by arrow Aid. During period d, the control circuit 150 controls at least the low-side switch SwL of the second bridge arm circuit 122 of the two switches Sw of the regulating circuit 140 to be in the ON state. The AC current does not flow to the load device 130 because the input terminals P1 and P2 of the synchronous rectifier circuit 120 are short-circuited. That is, the energized power Pr is not supplied to the load device 130.

[0061] In this specification, periods b and d are referred to as short-circuit periods, which are the periods of the short-circuit mode. Periods a and c are referred to as power supply periods, which are the periods of the power supply mode. Within each half-cycle of one cycle Ca of the AC power supply, the control circuit 150 executes the short-circuit mode during the short-circuit period and the power supply mode during the power supply period. To achieve a predetermined target power Pt, the control circuit 150 regulates the power supply Pa to the load device 130 by executing either the short-circuit mode or the power supply mode.

[0062] A-3. Methods for regulating the supply of electricity: exist Figure 6 The upper part of the diagram shows the receiving coil 111 and the transmitting coil 222 facing each other. Additionally, in... Figure 6 The figure shows the state of the receiving coil 111 and the power supply coil 222 laid on the ground as viewed from the side. The receiving coil 111 is located above the ground because it is installed on the vehicle.

[0063] The received power Pr varies depending on the magnetic coupling state between the receiving coil 111 and the transmitting coil 222. More specifically, the received power Pr depends on the relative position of the receiving coil 111 with respect to the transmitting coil 222. Figure 6 The relationship between the relative position of the receiving coil 111 and the transmitting coil 222 and the magnitude of the received power Pr is shown in solid line diagram at the center. In this embodiment, the facing state is when the central axis CL1 of the receiving coil 111 is aligned with and opposite the central axis CL2 of the transmitting coil 222. Figure 6 As shown, the received electric current Pr is at its maximum when the object is directly facing the target. The maximum electric current Pr is called the maximum electric current Pm. The further away from the directly facing target, the lower the received electric current Pr becomes.

[0064] The supplied power Pa is regulated by the regulating circuit 140. More specifically, the regulating circuit 140 regulates the supplied power Pa by executing a power supply mode or a short-circuit mode according to the instructions of the control circuit 150. The control circuit 150 regulates the supplied power Pa by changing the proportion of the power supply period in half-cycles of the AC power. This proportion of the power supply period in half-cycles is referred to as the power supply ratio D or duty cycle D.

[0065] exist Figure 6 The lower part of the diagram illustrates the relationship between the relative position of the receiving coil 111 and the transmitting coil 222 and the power supply ratio D used to make the supplied power Pa equal to the target power Pt. The ratio used at any receiving position to make the supplied power Pa match the target power Pt is called the target ratio Dt. Figure 6 The solid line at the bottom represents the target proportion Dt.

[0066] To ensure that the supplied power Pa matches the target power Pt, the power supply ratio D needs to be minimized when the received power Pr is the maximum power Pm. In this specification, this power supply ratio D is referred to as the minimum target ratio Dm. That is, the minimum target ratio Dm is determined based on the maximum power Pm and the target power Pt. However, to facilitate the adjustment of the supplied power Pa, the target power Pt is preferably 80% or less of the maximum power Pm. As an example, in... Figure 6 The lower part sets the minimum target ratio Dm to 0.5.

[0067] Furthermore, to ensure that the supplied power Pa matches the target power Pt, the further the received power Pr is from the maximum power Pm, the greater the power supply ratio D needs to be. However, depending on the relative position of the receiving coil 111 relative to the transmitting coil 222, the received power Pr may sometimes be lower than the target power Pt. In this case, the control circuit 150 sets the power supply ratio D to its maximum value. That is, the control circuit 150 does not execute the short-circuit mode. Therefore, as Figure 6 As shown by the solid line at the bottom, at the position where the received power Pr is lower than the target power Pt, the target ratio Dt is the maximum power supply ratio D.

[0068] exist Figure 7 The upper part of the diagram shows the state where the central axis CL1 is offset from the central axis CL2, and the receiving coil 111 and the transmitting coil 222 are opposite each other. Figure 7 In the center, the diagram is shown in Figure 7 The power received Pr is shown in the state of the receiving coil 111 and the transmitting coil 222 shown at the top. Figure 7 The lower part of the diagram shows the supplied power Pa from the start of energization until a steady state is reached. As described above, the load device 130 sometimes begins to consume DC power while energized. In this case, after the control circuit 150 detects the energized power Pr via the energized sensor 160, it begins to adjust the supplied power Pa by the adjustment circuit 140. That is, the supplied power Pa is adjusted with a delay from the start of energization to match the target power Pt. Therefore, as... Figure 7 As shown by curve C1 at the bottom, when the control circuit 150 described later is not used, the supplied power Pa immediately exceeds the target power Pt and reaches the received power Pr after the power reception begins. In this specification, the phenomenon that the supplied power Pa immediately exceeds the target power Pt after the power reception begins, as shown by curve C1, is referred to as surge power or power overshoot.

[0069] Figure 7 The lower curve C2 represents the shift in the supplied power Pa when the control circuit 150 suppresses surge power. The control of the control circuit 150 will be explained below.

[0070] A-4. Control methods for the power receiving device: use Figure 8 The processing performed by the control circuit 150 will be described. The control circuit 150 begins processing upon startup of the power receiving device 100. For example, the control circuit 150 receives power from the vehicle equipped with the power receiving device 100, thereby starting the power receiving device 100.

[0071] exist Figure 8 In step S100, the control circuit 150 adjusts the power supply ratio D based on the power receiving sensor 160 before the start of AC power reception. More specifically, the control circuit 150 controls the power supply ratio D to be set to a ratio Ds less than a minimum target ratio Dm, where the minimum target ratio Dm is the minimum value of the target ratio Dt corresponding to the coupling state, which enables the supplied power Pa to reach a predetermined target power Pt. As described above, the minimum target ratio Dm is determined based on the maximum power Pm and the target power Pt. For example, as... Figure 6 As shown in the lower part, the control circuit 150 sets the power supply ratio D to a ratio Ds that is smaller than 0.5 of the minimum target ratio Dm.

[0072] Therefore, when generating the supplied power Pa, such as Figure 7 As shown in the lower part, the supplied power Pa becomes lower than the target power Pt because the power supply ratio D is less than the minimum target ratio Dm, which is a ratio Ds. Therefore, when the receiving device 100 is energized, even if the load device 130 starts consuming DC power, the supplied power Pa will not exceed the target power Pt. That is, no surge power is generated in the receiving device 100.

[0073] exist Figure 8 In step S200, the control circuit 150 determines whether power is received based on the power sensor 160. When power is detected, the control circuit 150 initiates the process in step S300. When no power is detected, the control circuit 150 repeats the process in step S200.

[0074] exist Figure 8 In step S300, the control circuit 150 determines whether the load device 130 has started consuming DC power. The control circuit 150 determines this based, for example, on the current value obtained by the current sensor 160. When the load device 130 starts consuming DC power, the control circuit 150 causes the process to proceed to step S400. When the load device 130 has not started consuming DC power, the control circuit 150 causes the process to return to step S200.

[0075] exist Figure 8In step S400, the control circuit 150, based on the power receiving sensor 160, controls the supply ratio D to increase to the target ratio Dt after DC power consumption begins. That is, the control circuit 150 increases the supply power Pa to the target power Pt by increasing the supply ratio D (which is less than the minimum target ratio Dm) based on the target ratio Dt. Thus, the power receiving device 100 can prevent power surges and supply the load device 130 with the required supply power Pa to meet the target power Pt.

[0076] Furthermore, the functional unit executing step S100 in the control unit 151 is the adjustment unit 151a. The adjustment unit 151a determines the power supply ratio D based on the current value of the DC power. More specifically, the adjustment unit 151a determines the power supply ratio D through PI control based on the difference between the current value Ib flowing through the load device 130 and the current value It based on the target power Pt. The current value Ib flowing through the load device 130 is the current value acquired by the current sensor 160. The current value It is determined by the control unit 151 based on the predetermined target power Pt.

[0077] exist Figure 8 In step S500, the control circuit 150 determines whether the load device 130 has stopped consuming DC power. The control circuit 150 determines this based, for example, on the current value obtained by the current sensor 160. When the load device 130 is consuming DC power, the control circuit 150 repeats step S500. When the load device 130 is not consuming DC power, the control circuit 150 proceeds to step S600.

[0078] exist Figure 8 In step S600, the control circuit 150 determines whether the powered device 100 should be stopped. The control circuit 150 receives, for example, a command to stop the powered device 100 from the control device of the vehicle equipped with the powered device 100. If the control circuit 150 does not receive a command to stop the powered device 100, the process proceeds to step S700. If the control circuit 150 receives a command to stop the powered device 100, the process ends.

[0079] exist Figure 8 In step S700, the control circuit 150 returns the power supply ratio D to the ratio Ds set in step S100. That is, the control circuit 150 controls the power supply ratio D to be less than the minimum target ratio Dm, where the minimum target ratio Dm is the smallest target ratio Dt that corresponds to the coupling state and enables the supplied power Pa to reach a predetermined target power Pt. After processing in step S700, the control circuit 150 returns the processing to step S200.

[0080] That is, in this manner, the power received by the power receiving device 100 of this disclosure varies depending on the state of resonance of the resonant circuit or the state of magnetic coupling. Therefore, the power supply ratio D that enables the supplied power Pa to reach the target power Pt also varies depending on the state of resonance or coupling. Furthermore, in this manner, when the power receiving device 100 of this disclosure is energized, there is a situation where the load device 130 begins to consume DC power. Therefore, the power receiving device 100 of this disclosure begins to receive power after the power supply ratio D is less than the minimum target ratio Dm, thereby preventing surge power exceeding the target power Pt even when the load device 130 begins to consume DC power. Furthermore, after the consumption of DC power begins, the power receiving device 100 of this disclosure can suppress surge power and efficiently supply power to the load device 130 by increasing the power supply ratio D.

[0081] Furthermore, in this manner, the rectifier circuit 120 can also function as the regulating circuit 140. That is, the power receiving device 100 of this disclosure does not require the regulating circuit 140 and the rectifier circuit 120 to be constructed separately, thus enabling cost reduction and miniaturization of the device. The method of separately constructing the regulating circuit 140 and the rectifier circuit 120 will be explained later.

[0082] B. Second implementation method: The control circuit 150 of the first embodiment may further include a limiter 151b. The limiter 151b limits the power supply ratio D determined by the adjustment unit 151a. Based on this, the limiter 151b relaxes the limit at a slower rate than the speed at which the adjustment unit 151a determines the power supply ratio D. Figure 9 As shown, in the control system of the power receiving device 100, the limiter 151b is disposed between the adjustment unit 151a and the adjustment circuit 140.

[0083] As described above, the regulating unit 151a determines the power supply ratio D using PI control based on the difference between the current value Ib flowing through the load device 130 and the current value It based on the target power Pt. The limiter 151b receives instructions from the control regulating circuit 140 issued by the regulating unit 151a. Specifically, the instructions from the control regulating circuit 140 issued by the regulating unit 151a are instructions to determine the power supply ratio D. Therefore, the opening time of the switch Sw of the regulating circuit 140 is controlled. Furthermore, the control speed of the limiter 151b is measured by comparing the changes in the signals of the regulating unit 151a and the limiter 151b using an oscilloscope.

[0084] By employing this method, the supply ratio D corresponding to the fluctuating power is limited by the limiter 151b. Furthermore, the limiter 151b relaxes the limit more slowly than it determines the supply ratio D. For example, when the received power changes due to disturbances, the power receiving device 100 of this disclosure will not change the supply ratio D according to the power fluctuations. Therefore, the power receiving device 100 of this disclosure can stably perform surge power suppression control.

[0085] C. Third implementation method: In the above embodiment, the control circuit 150 can also execute short-circuit mode and power supply mode as follows. Based on the power receiving sensor 160, the control circuit 150 executes short-circuit mode and power supply mode during a first time interval including the start of power receiving, using the low-side switch SwL and the parallel diode Di connected in parallel with the high-side switch SwH. That is, during the first time interval including the start of power receiving, the control circuit 150 controls the high-side switch SwH to be in an open state, thereby rectifying the received power Pr using the parallel diode Di.

[0086] Furthermore, based on the power sensor 160, in a second time interval following the first time interval, when the power sensor 160 detects a predetermined reference current, the control circuit 150 executes a short-circuit mode and a power supply mode using the low-side switch SwL and the high-side switch SwH. That is, the control circuit 150 initiates the switching operation of the high-side switch SwH for rectifying the AC power. The reference current is, for example, 20% of the current value of the target power Pt.

[0087] By employing this method, the power receiving device 100 of this disclosure rectifies AC power via the first switch SwH on the positive line Lp when a current exceeding the reference current flows through the power receiving device 100. For example, in a switch Sw such as a MOSFET, the voltage between the drain and source can sometimes be distorted when the current flowing between the drain and source is low. In this case, if the MOSFET's on / off state is determined based on the voltage between the drain and source, the voltage distortion between the drain and source can sometimes lead to unstable control. The power receiving device 100 of this disclosure uses the parallel diode Di of the first switch SwH for rectification at the start of power receiving with a small current, thereby enabling more stable rectification compared to rectification via the first switch SwH.

[0088] D. Fourth implementation method: In the first embodiment, the regulating circuit 140 is constituted by the switch Sw of the synchronous rectifier circuit 120. However, the regulating circuit 140 may also be configured separately from the synchronous rectifier circuit 120. Figure 10The figure shows an adjustment circuit 140x, separate from the rectifier circuit 120x and including a switch Swx that short-circuits the terminals of the input of the rectifier circuit 120x. More specifically, the switch Swx of the adjustment circuit 140x is connected in parallel with the rectifier circuit 120x between the resonant circuit 110 and the rectifier circuit 120x. The switch Swx uses a semiconductor relay. Additionally, for structures different from the first embodiment, an 'x' is added to the reference numerals of the first embodiment.

[0089] When the regulating circuit 140x and the rectifier circuit 120x are configured separately, the rectifier circuit 120x can also be composed solely of rectifier diodes. Figure 10 The diagram shows the rectifier circuit 120x consisting only of rectifier diodes. In this case, the drive circuit 152 of the control circuit 150 in the fourth embodiment only controls the regulating circuit 140x. When the regulating circuit 140x of the fourth embodiment executes the power supply mode, as... Figure 10 As indicated by arrow D1, the positive current of the alternating current flows to the load device 130 via the rectifier diode on the positive line Lp side of the rectifier circuit 120x. When the regulation circuit 140x of the fourth embodiment executes the short-circuit mode, as... Figure 10 As indicated by arrow D2, the positive current of the AC power does not flow to the rectifier circuit 120x, but returns to the power receiving resonant circuit 110 via the switch Swx of the regulating circuit 140x. Similarly, the negative current of the AC power flows through both the power supply mode and the short-circuit mode.

[0090] By adopting this method, the power receiving device 100x of this disclosure can easily achieve control of the supply power Pa compared to the method in which the regulating circuit 140 is composed of the switch Sw of the rectifier circuit 120 including the switch Sw.

[0091] E. Variations: In the above embodiments, the power receiving device 100 may also include a filter circuit between the power receiving resonant circuit 110 and the adjustment circuit 140. More specifically, such as Figure 11 The filter circuit FL1, Figure 12 Similar to the filter circuit FL2, the power receiving device 100 may include a passive impedance filter. In addition to the passive impedance filter, the power receiving device 100 may also include a bandpass filter. Furthermore, in Figure 11 , Figure 12 The example shown is the power receiving device 100 of the first embodiment, but the power receiving device 100x of the fourth embodiment may also include filter circuit FL1 and filter circuit FL2.

[0092] By adopting this method, the power receiving device 100 can achieve constant current characteristics of AC power and harmonic suppression function.

[0093] F. Variations: In the above embodiment, the received power Pr is at its maximum when the transmitting coil 222 and the receiving coil 111 are directly opposite each other. Furthermore, the power Pr decreases the further away from direct alignment. However, depending on the resonance mode of the transmitting resonant circuit 220 and the receiving resonant circuit 110, such as... Figure 13 As shown, there is also a case where the received electric current Pr increases the further away from the directly opposite state. Specifically, the situation is as follows: the power supply resonant circuit 220 and the power receiving resonant circuit 110 are composed of a power supply resonant circuit 220 in series with a power supply resonant capacitor 221 and a power receiving resonant circuit 110 in series with a power receiving coil 111 and a power receiving resonant capacitor 112. That is, the case is that both the power supply resonant circuit 220 and the power receiving resonant circuit 110 are series resonant circuits. In this case, the received electric current Pr is minimum when the power supply coil 222 and the power receiving coil 111 are directly opposite each other. Furthermore, the received electric current Pr increases the further away from the directly opposite state. Therefore, the minimum target ratio Dm is the target ratio Dt at the position where the relative positions of the power supply coil 222 and the power receiving coil 111 are farthest from each other in the opposite state. Figure 13 In the same manner as in the above embodiments, the power receiving device 100 is controlled so that the power receiving device 100 of this disclosure can suppress surge power and efficiently supply power to the load device 130.

[0094] G. Variation example: (1) In the above embodiment, the power receiving device 100 is installed in a vehicle. However, the power receiving device 100 may also be installed in other moving bodies. For example, the power receiving device 100 may also be installed in an aircraft.

[0095] (2) In the above embodiments, the power transmission circuit may also include a rectifier circuit, a filter circuit, etc.

[0096] (3) In the above embodiment, switch Sw constitutes all the rectifier elements that make up the synchronous rectifier circuit 120. However, switch Sw only needs to constitute at least a portion of the rectifier elements that make up the synchronous rectifier circuit 120. For example, switch Sw may only constitute the rectifier element on the negative line Ln side. In this case, the rectifier element on the positive line Lp side is composed of a rectifier diode.

[0097] (4) In the first embodiment, the power receiving sensor 160 is a current sensor that measures the current value of DC power. The power receiving sensor 160 may also be other sensors. For example, the power receiving sensor 160 may also be a voltage sensor that measures the voltage of DC power. In addition, the power receiving sensor 160 may also be composed of multiple sensors. For example, the power receiving sensor 160 may also be composed of a sensor that detects the power received by AC power and a sensor that detects the power consumption of the load device 130 by DC power.

[0098] (5) In the above embodiment, a battery is shown as the load device 130. However, the load device 130 is not limited to a battery. The load device 130 may also be a lighting device, a power device, etc. When the load device 130 is a lighting device, a power device, etc., the load device 130 starts to consume DC power based on the start-up of the device.

[0099] (6) In the above embodiment, the target power Pt is predetermined according to the specifications of the load device 130. However, the target power Pt is not limited to being predetermined by the specifications of the load device 130. For example, the target power Pt may also be determined based on the rated power of the receiving device 100 as a circuit, the power demand of the grid power supply that supplies power to the transmitting device 200, etc.

[0100] (7) In the above embodiment, the minimum target ratio Dm is exemplified as 0.5. However, the minimum target ratio Dm is not limited to 0.5. The minimum target ratio Dm is sometimes 0.2, 0.7, etc.

[0101] (8) In the above embodiment, the control circuit 150 determines whether the load device 130 starts or stops consuming DC power based on the current value obtained by the power sensor 160. However, the control circuit 150 may also determine whether the load device 130 starts or stops consuming DC power using other methods. For example, the control circuit 150 may be connected to the control device of the load device 130, thereby determining whether the load device 130 starts or stops consuming DC power based on instructions received from the control device of the load device 130.

[0102] (9) In the above embodiment, as an example, the reference current is a current value that is 20% of the current value of the target power Pt. However, the reference current may also be a current value that is 10% or 40% of the current value of the target power Pt, or it may be a reference value based on other currents.

[0103] (10) In the above embodiment, the control unit 151 is configured as a microcomputer, for example. That is, the control unit 151 is configured as a digital circuit. However, the control unit 151 may also be configured as an analog circuit.

[0104] (11) In the above embodiment, the adjustment unit 151a determines the power supply ratio D based on the current value. However, as described above, when the power receiving sensor 160 is a voltage sensor, the adjustment unit 151a may also determine the power supply ratio D based on the voltage value.

[0105] (12) In the above embodiment, the control circuit 150 controls the supply ratio D to increase to the target ratio Dt after the DC power consumption begins, based on the power receiving sensor 160. However, the control circuit 150 may not increase the supply ratio D to match the target ratio Dt. More specifically, the control circuit 150 may simply increase the supply ratio D to a level between the ratio Ds and the target ratio Dt.

[0106] (13) In the above embodiment, the switch Sw of the synchronous rectification circuit 120 is a MOSFET. However, the switch Sw of the synchronous rectification circuit 120 may also be other switching elements. For example, the switch Sw may be a BJT (Bipolar junction transistor) or an IGBT (Insulated Gate Bipolar Transistor).

[0107] (14) In the above embodiment, period b and period d are set as the periods of the short-circuit mode, and period a and period c are set as the periods of the power supply mode. However, it is also possible to set period b and period d as the periods of the power supply mode, and period a and period c as the periods of the short-circuit mode.

[0108] This disclosure is not limited to the above-described embodiments and modifications, and can be implemented in various structures without departing from its spirit. For example, in order to solve some or all of the above-described technical problems, or to achieve some or all of the above-described effects, the technical features in the embodiments and modifications corresponding to the technical features in the various methods described in the Summary of the Invention section can be appropriately replaced or combined. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0109] H. Other methods: The features of this disclosure are as follows.

[0110] (Method 1)

[0111] A power receiving device, The power receiving devices (100, 100x) receive AC power in a non-contact manner via a magnetic field, including: A resonant circuit (110) includes a receiving coil (111) that receives the alternating current, and the magnitude of the alternating current varies depending on the state of resonance or coupling. The rectifier circuit (120, 120x) converts the AC power into DC power; The load device (130) begins to consume the DC power based on a pre-defined reference related to electricity; The regulating circuit (140, 140x) includes a switch (Sw) that short-circuits the terminals (P1, P2) of the input of the rectifier circuit, and regulates the supply power (Pa) of the AC power supplied to the load device between the energized coil and the load device. The power sensor (160) detects power through the DC power; and The control circuit (150, 150x) controls the power receiving device. The control circuit includes: A short-circuit mode, which short-circuits the terminals during a predetermined short-circuit period in each half-cycle of one cycle (Ca) of the AC power supply; and a power supply mode, which opens the terminals during power supply periods other than the short-circuit period in the half-cycle. According to the power receiving sensor, before the start of AC power reception, control is performed to set the power supply ratio (D) to be less than a minimum target ratio (Dm). The power supply ratio is the ratio of the power supply period in the half-cycle, and the minimum target ratio is the minimum value of the target ratio (Dt) corresponding to the state of resonance or coupling that enables the supplied power to reach a predetermined target power (Pt). Based on the power sensor, after the DC power consumption begins, control is performed to increase the power supply ratio to below the target ratio.

[0112] (Method 2)

[0113] The power receiving device according to method 1 further includes a current sensor (160) that measures the current value of the DC power. The control circuit also includes: The regulating unit (151a) determines the power supply ratio based on the current value; and A limiter (151b) limits the power supply ratio determined by the adjustment unit and relaxes the limit at a slower rate than the speed at which the adjustment unit determines the power supply ratio.

[0114] (Method 3)

[0115] The power receiving device according to method 2 The switch constitutes at least a portion of the rectifier element that makes up the rectifier circuit.

[0116] (Method 4)

[0117] The power receiving device according to method 3 The switch constitutes all of the rectifier elements. It also includes a parallel diode (Di) connected in parallel in a reverse direction relative to the positive direction of the switch. The rectifier circuit includes two bridge arm circuits (121, 122) connected in series with the switches. The bridge arm circuits connect the positive line (Lp) and the negative line (Ln) of the DC power. The two switches are composed of a first switch (SwH) on the positive electrode side and a second switch (SwL) on the negative electrode side. The control circuit, based on the power-receiving sensor, executes the short-circuit mode and the power supply mode via the second switch and the parallel diode connected in parallel with the first switch during a first time interval including the start of power reception. According to the power receiving sensor, in a second time interval following the first time interval, when the power receiving sensor detects a predetermined reference current, the short-circuit mode and the power supply mode are executed through the second switch and the first switch.

Claims

1. A power receiving device (100, 100x) that receives alternating current (AC) power in a non-contact manner via a magnetic field, comprising: A resonant circuit (110) includes a receiving coil (111) that receives the alternating current, and the magnitude of the alternating current varies depending on the state of resonance or coupling. The rectifier circuit (120, 120x) converts the AC power into DC power; A load device (130) that consumes the DC power; The regulating circuit (140, 140x) includes a switch (Sw) that short-circuits the terminals (P1, P2) of the input of the rectifier circuit, and regulates the supply power (Pa) of the AC power supplied to the load device between the energized coil and the load device. A power sensor (160) detects the receiving of the AC power or the DC power; as well as The control circuit (150, 150x) controls the power receiving device. The control circuit includes a short-circuit mode that short-circuits the terminals during a predetermined short-circuit period in each half-cycle of one cycle (Ca) of the AC power. And a power supply mode that opens the terminals during power supply periods other than the short-circuit period in the half-cycle. According to the power receiving sensor, before the start of AC power reception, control is performed to set the power supply ratio (D) to be less than a minimum target ratio (Dm). The power supply ratio is the ratio of the power supply period in the half-cycle, and the minimum target ratio is the minimum value of the target ratio (Dt) corresponding to the coupled state that enables the supplied power to become a predetermined target power (Pt). After the power is detected by the power sensor, control is performed to increase the power supply ratio to below the target ratio.

2. The power receiving device according to claim 1, characterized in that, It also includes a current sensor (160) that measures the current value of the DC power. The control circuit also includes: The regulating unit (151a) determines the power supply ratio based on the current value; and A limiter (151b) limits the power supply ratio determined by the adjustment unit and relaxes the limit at a slower rate than the speed at which the adjustment unit determines the power supply ratio.

3. The power receiving device according to claim 2, characterized in that, The switch constitutes at least a portion of the rectifier element that makes up the rectifier circuit.

4. The power receiving device according to claim 1, characterized in that, The switch constitutes all the rectifier elements that make up the rectifier circuit. It also includes a parallel diode (Di) connected in parallel in a reverse direction relative to the positive direction of the switch. The rectifier circuit includes two bridge arm circuits (121, 122) connected in series with the switches. The bridge arm circuits connect the positive line (Lp) and the negative line (Ln) of the DC power. The two switches are composed of a first switch (SwH) on the positive electrode side and a second switch (SwL) on the negative electrode side. The control circuit, based on the power-receiving sensor, executes the short-circuit mode and the power supply mode via the second switch and the parallel diode connected in parallel with the first switch during a first time interval including the start of power reception. According to the power receiving sensor, in a second time interval following the first time interval, when the power receiving sensor detects a predetermined reference current, the short-circuit mode and the power supply mode are executed through the second switch and the first switch.

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