Power receiving device

Abstract

To provide technology that prevents inrush power in a power receiving device of a contactless power feeding system.SOLUTION: Provided is a power receiving device that contactlessly receives AC power, and comprises a resonance circuit for receiving AC power, a rectification circuit, a load device, an adjustment circuit for adjusting supply power and provided with a switch for shorting between the input terminals of the rectification circuit, a power receiving sensor, and a control circuit. The control circuit includes a short-circuiting mode and a power feeding mode, and exercises control, by the power receiving sensor, to reduce a power feeding ratio representing a ratio of power feeding period to be smaller than a minimum target ratio representing the minimum value of target ratio that corresponds to a resonance or coupling state where supply power can be raised or lowered to predetermined target power before starting to receive AC power, and exercises control, by the power receiving sensor, to increase the power feeding ratio to or below the target ratio after consumption of DC power begins.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a power receiving device.

Background Art

[0002] In a power receiving device of a non-contact power supply system, for example, as in Patent Document 1, a switching element may be used in a rectifier circuit that rectifies AC power received by power reception. In the following description, the switching element is referred to as a switch. In Patent Document 1, a resonance circuit that receives AC power is connected to a load via a rectifier circuit. The technique of Patent Document 1 controls a period in which DC power is supplied to the load and a period in which AC power is circulated between the resonance circuit and the rectifier circuit by controlling the rectifier circuit with a switch. That is, the power receiving device in Patent Document 1 controls the DC power supplied to the load.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The control of the DC power supplied to the load is performed, for example, to prevent overcharging when the load is a battery. More specifically, the control of the DC power supplied to the load supplies only the power necessary for charging the battery by suppressing the received power when the received power is excessive.

[0005] In contactless power supply systems, the power received depends on the resonance or coupling state of a resonant circuit related to the positional relationship between the power receiving device and the power transmitting device. In other words, it is difficult for the power receiving device to predict the power to be received in advance. For this reason, the power receiving device needs to check the received power before starting to control the DC power supplied to the load. If the load is a battery, a power receiving device within the transmission range of the power transmitting device will start receiving power when the battery charge is insufficient. However, checking the received power delays the control of the DC power supplied to the load. As a result, the DC power supplied to the load temporarily becomes excessive as inrush power, exceeding the power required to charge the battery. Inrush power can cause, for example, degradation of the battery as a load or deterioration of EMC. Therefore, there has been a need for technology to prevent inrush power in power receiving devices of contactless power supply systems. [Means for solving the problem]

[0006] This disclosure can be implemented in the following forms:

[0007] According to one embodiment of the present disclosure, a power receiving device (100, 100x) is provided for receiving AC power non-contactually by a magnetic field. The power receiving device includes a resonant circuit (110) including a power receiving coil (111) for receiving the AC power, wherein the magnitude of the AC power differs depending on the state of resonance or coupling, and a rectifier circuit (120, 120x) for converting the AC power into DC power. The DC power consumed A load device (130) and an adjustment circuit (140, 140x) comprising a switch (Sw) that short-circuits the input terminals (P1, P2) of the rectifier circuit, wherein the adjustment circuit adjusts the supply power (Pa) of the AC power supplied to the load device between the power receiving coil and the load device, The AC power or the DC powerThe device comprises a power receiving sensor (160) for detecting power reception and a control circuit (150, 150x) for controlling the power receiving device, wherein the control circuit includes a short-circuit mode in which the terminals are short-circuited during a predetermined short-circuit period in each half-cycle of one cycle (Ca) of the AC power, and a power supply mode in which the terminals are opened during the power supply period in the half-cycle excluding the short-circuit period, and the power receiving sensor controls the power supply ratio (D), which is the ratio of the power supply period in the half-cycle, to a ratio smaller than the minimum target ratio (Dm), which is the minimum value of the target ratio (Dt) corresponding to the coupling state that allows the supplied power to reach a predetermined target power (Pt), before the start of AC power reception, and the power receiving sensor controls the power supply ratio (D), which is the ratio of the power supply period in the half-cycle, to a ratio smaller than the minimum target ratio (Dm), which is the minimum value of the target ratio (Dt) corresponding to the coupling state that allows the supplied power to reach a predetermined target power (Pt), and the power receiving sensor controls After detecting the aforementioned power reception The system controls the power supply ratio to increase it to a level below the target ratio.

[0008] In this configuration, the power received by the power receiving device of the present disclosure differs depending on the resonance state of the resonant circuit or the state of magnetic coupling. Therefore, the power supply ratio that allows the supplied power to reach the target power also differs depending on the resonance or coupling state. Furthermore, in this configuration, the power receiving device of the present disclosure may begin consuming DC power from a load device while receiving power. Therefore, by starting power reception after reducing the power supply ratio to less than the minimum target ratio, the power receiving device of the present disclosure can prevent inrush power exceeding the target power even when DC power consumption by the load device begins. Furthermore, by increasing the power supply ratio after DC power consumption has begun, the power receiving device of the present disclosure can efficiently supply power to the load device while suppressing inrush power. [Brief explanation of the drawing]

[0009] [Figure 1] An explanatory diagram showing the configuration of the contactless power supply system of the first embodiment. [Figure 2] An explanatory diagram showing the power supply mode. [Figure 3] An explanatory diagram showing the short-circuit mode. [Figure 4] An explanatory diagram showing the power supply mode. [Figure 5] An explanatory diagram showing the short-circuit mode. [Figure 6] An explanatory diagram showing the power received. [Figure 7] An explanatory diagram showing the power supply at the start of power reception. [Figure 8] A flowchart illustrating the control process performed by the control circuit. [Figure 9] A block diagram showing the configuration of the control system of the second embodiment. [Figure 10] An explanatory diagram showing a power receiving device according to the fourth embodiment. [Figure 11] An explanatory diagram showing a modified filter circuit. [Figure 12] An explanatory diagram showing a modified filter circuit. [Figure 13] An explanatory diagram showing the power received in a modified example. [Modes for carrying out the invention]

[0010] A. First Embodiment: A-1. Device Configuration: The contactless power supply system 10 shown in Figure 1 supplies power to the load device 130 contactlessly using a magnetic field. As shown in Figure 1, the contactless power supply system 10 comprises a power transmission device 200 and a power receiving device 100. The contactless power supply system 10 supplies power from the power transmission device 200 to the power receiving device 100 contactlessly. The contactless power supply system 10 supplies power contactlessly to a power receiving device 100 mounted on a vehicle, for example.

[0011] The power transmission device 200 supplies AC power to the power receiving device 100 non-contactually using a magnetic field. The power transmission device 200 includes an AC power supply device 210 and a power transmission resonant circuit 220.

[0012] The AC power supply device 210 supplies AC power of a predetermined operating frequency to the power transmission resonance 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 the AC power supplied from the utility 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 of the operating frequency. The operating frequency is set according to the resonance frequency described later. In the present embodiment, the operating frequency of the AC power supply device 210 is, for example, 85 kHz, and is set using a predetermined power transmission frequency defined by the Radio Law or the like.

[0013] The power transmission resonance circuit 220 magnetically couples with and resonates with the power receiving coil 111. The power transmission resonance circuit 220 includes a power transmission coil 222 and a power transmission resonance capacitor 221 connected in parallel to the power transmission coil 222. That is, the power transmission resonance circuit 220 is a parallel resonance circuit.

[0014] The power transmission resonance capacitor 221 resonates the power transmission resonance circuit 220 with AC power of the operating frequency in a state where the power transmission coil 222 and the power receiving coil 111 are magnetically coupled. That is, the capacitance of the power transmission resonance capacitor 221 is set so that the operating frequency and the resonance frequency of the power transmission resonance circuit 220 substantially coincide in a state where the power transmission coil 222 and the power receiving coil 111 are magnetically coupled.

[0015] The power transmission coil 222 generates a magnetic field corresponding to the operating frequency of the AC power supply device 210. Further, the power transmission coil 222 transmits AC power to the power receiving coil 111 by magnetically coupling with the power receiving coil 111. That is, the power transmission coil 222 performs non-contact power transmission by utilizing the electromagnetic induction phenomenon.

[0016] The power transmission coil 222 is laid on the ground and used. More specifically, the power transmission coil 222 is laid on the ground in a direction that can face the power receiving coil 111 mounted on the vehicle. The positional relationship between the power transmission coil 222 and the power receiving coil 111 will be described in detail later.

[0017] The power receiving device 100 receives AC power from the power transmitting device 200 in a non-contact manner using a magnetic field. The power receiving device 100 includes a power receiving resonant circuit 110, a synchronous rectifier circuit 120, a load device 130, an adjustment circuit 140, a power receiving sensor 160, a control circuit 150, and a smoothing capacitor 170. The power receiving device 100 is mounted on a vehicle.

[0018] The power receiving resonant circuit 110 is magnetically coupled to the power transmitting coil 222 and resonates with it. It comprises a power receiving coil 111 and a power receiving resonant capacitor 112 connected in series with the power receiving coil 111. In other words, the power receiving resonant circuit 110 is a series resonant circuit.

[0019] The receiving coil 111 is magnetically coupled to the transmitting coil 222 by receiving the magnetic field emitted by the transmitting coil 222. The receiving coil 111 is mounted on the vehicle facing away from the ground. By facing the transmitting coil 222 which is laid on the ground, the receiving coil 111 receives the magnetic field emitted by the transmitting coil 222. As a result, the receiving coil 111 receives AC power from the power 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.

[0020] The receiving resonant capacitor 112 causes the receiving resonant circuit 110 to resonate with the AC power at the operating frequency when the receiving coil 111 and the transmitting coil 222 are magnetically coupled. In other words, the capacitance of the receiving resonant capacitor 112 is set so that the operating frequency and the resonant frequency of the receiving resonant circuit 110 approximately coincide when the transmitting coil 222 and the receiving coil 111 are magnetically coupled.

[0021] The received power Pr varies depending on the magnetic coupling state of the receiving coil 111 and the transmitting coil 222, and the resonance state of the receiving resonant circuit 110. In other words, the received power Pr also varies depending on the relationship between the operating frequency and the resonant frequency. However, for the sake of ease of understanding the technology, this specification will describe the state in which the operating frequency and the resonant frequency coincide. The relationship between the magnetic coupling state of the receiving coil 111 and the transmitting coil 222 and the received power Pr will be explained later.

[0022] In this embodiment, the power receiving resonant capacitor 112 comprises a positive first capacitor 112P and a negative second capacitor 112N. By arranging resonant capacitors on both the positive and negative sides, common-mode noise can be suppressed. In this specification, the power receiving resonant circuit 110 is also simply referred to as the resonant circuit.

[0023] 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 that uses four MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) as rectifying elements. The synchronous rectifier circuit 120 has two leg circuits: a first leg circuit 121 and a second leg circuit 122. The synchronous rectifier circuit 120 is also simply referred to as the rectifier circuit 120.

[0024] The leg circuit consists of two switches Sw connected in series. Furthermore, the leg circuit connects the positive line Lp and the negative line Ln of the DC power. One of the output terminals of the power receiving resonant circuit 110 is connected between the two switches Sw of the leg circuit. In other words, the space between the two switches Sw of the leg circuit is the position of the input terminal in the synchronous rectifier circuit 120. Regarding the input terminals of the synchronous rectifier circuit 120, the leg circuit having terminal P1 is the first leg circuit 121, and the leg circuit having terminal P2 is the second leg circuit 122.

[0025] The two switches Sw in the REG circuit consist of a first switch SwH as a rectifier element on the positive electrode line Lp side and a second switch SwL as a rectifier element on the negative electrode line Ln side. In other words, the switches Sw constitute all of the rectifier elements in the synchronous rectifier circuit 120.

[0026] The switch Sw of the REG circuit is equipped with a parallel diode Di connected in parallel with respect to the forward direction of the switch Sw, facing in the opposite direction to the forward direction of the switch Sw. The parallel diode Di is, for example, the body diode of a MOSFET. That is, the drain of the switch Sw is located on the positive line Lp side, and the source of the switch Sw is located 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 the switch Sw is connected to the control circuit 150. The switch Sw is driven by receiving a voltage at its gate in accordance with the command of the control circuit 150.

[0027] In this specification, the positive electrode line Lp is also referred to as the high side, and the negative electrode line Ln is also 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 also referred to as the low-side switch SwL.

[0028] In other words, the synchronous rectifier circuit 120 rectifies the AC power input from the power receiving resonant circuit 110 using a switch Sw. The DC power rectified by the synchronous rectifier circuit 120 is output to the load device 130 through the positive electrode line Lp and the negative electrode line Ln.

[0029] The adjustment circuit 140 adjusts the supply power Pa supplied to the load device 130 from the received power Pr, which is AC power, between the receiving coil 111 and the load device 130. The adjustment circuit 140 is equipped with a switch Sw that short-circuits the input terminals of the synchronous rectifier circuit 120. Note that the switch Sw of the adjustment circuit 140 is also the low-side switch SwL of the synchronous rectifier circuit 120.

[0030] The adjustment circuit 140 short-circuits the input terminals of the synchronous rectifier circuit 120 by turning on the two low-side switches SwL of the synchronous rectifier circuit 120. As a result, AC power is not rectified by the synchronous rectifier circuit 120. The adjustment 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 of the synchronous rectifier circuit 120. As a result, AC power is rectified by the synchronous rectifier circuit 120 and output as DC power from the synchronous rectifier circuit 120. In this specification, the state in which the input terminals of the synchronous rectifier circuit 120 are short-circuited by the adjustment circuit 140 is called the short-circuit mode. The state in which the input terminals of the synchronous rectifier circuit 120 are open by the adjustment circuit 140 is called the power supply mode. Each mode will be described in detail later.

[0031] The 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.

[0032] The power receiving sensor 160 detects power reception by DC power. More specifically, the power receiving sensor 160 detects the current flowing to the load device 130 due to power reception. In other words, the power receiving sensor 160 is a current sensor that measures the current value of DC power. The power receiving sensor 160 is connected in series with the output of the synchronous rectifier circuit 120 and the load device 130.

[0033] The load device 130 consumes DC power. The load device 130 is a device that includes, for example, a battery and a battery protection circuit. The load device 130 is charged by receiving the supplied power Pa output from the synchronous rectifier circuit 120. The power charged in the load device 130 is used, for example, in a vehicle mounted on the power receiving device 100.

[0034] The load device 130 begins consuming DC power based on predetermined criteria related to power. In other words, the load device 130 does not always charge. For example, a load device 130 including a battery will begin charging when the remaining charge falls below a certain standard value to prevent overcharging. Thus, the load device 130 may not consume DC power when the power receiving device 100 is receiving power. Furthermore, the load device 130 may begin consuming DC power when the power receiving device 100 is receiving power. The consumption of DC power during power reception will be explained in detail later.

[0035] The power supplied Pa to the load device 130 is power adjusted by the adjustment circuit 140 based on the target power Pt. For example, in the case of a load device 130 that includes a battery, the target power Pt is determined based on the battery's rated current. Batteries overheat when overcurrents are passed through them. This can reduce the battery's lifespan. Therefore, the target power Pt is set to a power that satisfies a current value less than or equal to the rated current. In addition, batteries may have protection circuits that interrupt currents that are lower than the battery's rated current.

[0036] The control circuit 150 controls the power receiving device 100. The control circuit 150 comprises a control unit 151 and a drive circuit 152.

[0037] The drive circuit 152 drives the switch Sw. More specifically, the drive circuit 152 outputs the power necessary to drive the switch Sw in response to a command from 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 necessary for the on and off operation of the switch Sw to the gate of the switch Sw. Note that in Figure 1, the connection between the drive circuit 152 and the gate is omitted for the sake of easier understanding of the technology.

[0038] The control unit 151 generates signals to control the on and off operation of the switch Sw. The control unit 151 is mainly composed of a microcomputer, and includes 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 receiving sensor 160. Based on the current value acquired by the power receiving sensor 160, the control unit 151 executes short-circuit mode and power supply mode.

[0039] A-2. Short-circuit mode and power supply mode: The control circuit 150 has two control modes: a short-circuit mode and a power supply mode. The control circuit 150 performs a short-circuit mode, short-circuiting the input terminals of the synchronous rectifier circuit 120 for a predetermined short-circuit period at each half-cycle of one cycle Ca of AC power. The control circuit 150 also performs a power supply mode, opening the terminals during the power supply period, excluding the short-circuit period, within the half-cycle of one cycle Ca. Figures 2 to 5 illustrate the operation of the power receiving device 100 in both the short-circuit mode and the power supply mode within one cycle Ca of AC power. Figures 2 to 5 show the waveform of the AC current for one cycle Ca at the top and the circuit diagram of the power transmitting device 200 at the bottom. However, to facilitate understanding of the technology, some diagrams, such as the power receiving resonant circuit 110, the smoothing capacitor 170, and the control circuit 150, have been omitted.

[0040] In Figure 2, the direction of the AC current flowing through the synchronous rectifier circuit 120 during period a of the power supply mode in the positive half-cycle of the AC power is illustrated by the arrow Aia. During period a, the control circuit 150 controls at least the low-side switch SwL of the first leg circuit 121, one of the two switches Sw of the adjustment circuit 140, to the off state. As a result, the AC current flows to the load device 130 via the high-side switch SwH of the first leg circuit 121. That is, the received power Pr is supplied to the load device 130.

[0041] In Figure 3, the direction of the AC current flowing through the synchronous rectifier circuit 120 during period b of the short-circuit mode in the positive half-cycle of the AC power is illustrated by the arrow Aib. During period b, the control circuit 150 controls at least the low-side switch SwL of the first leg circuit 121, one of the two switches Sw of the adjustment circuit 140, to 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. In other words, the received power Pr is not supplied to the load device 130.

[0042] In Figure 4, the direction of the AC current flowing through the synchronous rectifier circuit 120 during period c of the power supply mode in the negative half-cycle of AC power is illustrated by the arrow Aic. During period c, the control circuit 150 controls at least the low-side switch SwL of the second leg circuit 122, one of the two switches Sw of the adjustment circuit 140, to the off state. As a result, the AC current flows to the load device 130 via the high-side switch SwH of the second leg circuit 122. That is, the received power Pr is supplied to the load device 130.

[0043] In Figure 5, the direction of the AC current flowing through the synchronous rectifier circuit 120 during the short-circuit mode period d in the negative half-cycle of the AC power is illustrated by the arrow Aid. During period d, the control circuit 150 controls at least the low-side switch SwL of the second leg circuit 122, one of the two switches Sw of the adjustment circuit 140, to 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. In other words, the received power Pr is not supplied to the load device 130.

[0044] In this specification, periods b and d are referred to as the short-circuit period, and periods a and c are referred to as the power supply period, and periods a and c are referred to as the power supply period. The control circuit 150 executes the short-circuit mode during the short-circuit period and the power supply mode during the power supply period for every half-cycle in one cycle Ca of AC power. The control circuit 150 adjusts the power supplied to the load device 130 by executing either the short-circuit mode or the power supply mode in order to reach a predetermined target power Pt.

[0045] A-3. Method for adjusting the power supply: The upper part of Figure 6 shows the receiving coil 111 and the transmitting coil 222 facing each other. Figure 6 also shows the receiving coil 111, which is located above the ground when mounted on a vehicle, and the transmitting coil 222, which is laid on the ground, viewed from the side.

[0046] The received power Pr varies depending on the state of magnetic coupling 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. In the center of Figure 6, the relationship between the relative position of the receiving coil 111 with respect to the transmitting coil 222 and the magnitude of the received power Pr is illustrated by a solid line. In this embodiment, the "facing" state is when the central axis CL1 of the receiving coil 111 and the central axis CL2 of the transmitting coil 222 coincide and face each other. As shown in Figure 6, the received power Pr is greatest in the facing state. The largest power among the received power Pr is called the maximum power Pm. The received power Pr decreases as the position moves away from the facing state.

[0047] The supplied power Pa is adjusted by the adjustment circuit 140. More specifically, the supplied power Pa is adjusted by the adjustment circuit 140 executing a power supply mode or a short-circuit mode in response to a command from the control circuit 150. The control circuit 150 adjusts the supplied power Pa by changing the proportion of the power supply period in half a cycle of AC power. The proportion of the power supply period in half a cycle is called the power supply ratio D or duty cycle D.

[0048] The lower part of Figure 6 illustrates the relationship between the relative position of the receiving coil 111 with respect to the transmitting coil 222 and the power supply ratio D required to bring the supplied power Pa to the target power Pt. The ratio required to match the supplied power Pa to the target power Pt at any given receiving position is called the target ratio Dt. The solid line at the bottom of Figure 6 represents the target ratio Dt.

[0049] To match the supplied power Pa to the target power Pt, the power supply ratio D must be minimized when the received power Pr is at its maximum power Pm. This power supply ratio D is referred to as the minimum target ratio Dm in this specification. 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. In the lower part of Figure 6, the minimum target ratio Dm is set to 0.5 as an example.

[0050] Furthermore, in order to match the supplied power Pa to the target power Pt, the power supply ratio D needs to be increased as the received power Pr deviates from the maximum power Pm. However, the received power Pr may fall below the target power Pt depending on the relative position of the receiving coil 111 with respect to the transmitting coil 222. 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 shown by the solid line at the bottom of Figure 6, the target ratio Dt becomes the maximum power supply ratio D at the position where the received power Pr is below the target power Pt.

[0051] The upper part of Figure 7 illustrates a state where the central axes CL1 and CL2 are misaligned, and the receiving coil 111 and transmitting coil 222 are facing each other. The middle part of Figure 7 illustrates the received power Pr in the state of the receiving coil 111 and transmitting coil 222 shown in the upper part of Figure 7. The lower part of Figure 7 illustrates the supplied power Pa from the start of power reception until a steady state is reached. As mentioned above, the load device 130 may start consuming DC power when receiving power. In this case, the control circuit 150 detects the received power Pr using the receiving sensor 160 and then starts adjusting the supplied power Pa using the adjustment circuit 140. That is, the supplied power Pa is adjusted to match the target power Pt with a delay from the start of power reception. Therefore, as shown by the curve C1 at the bottom of Figure 7, if the control by the control circuit 150, which will be explained later, is not performed, the supplied power Pa will exceed the target power Pt and reach the received power Pr immediately after the start of power reception. In this specification, as shown by curve C1, the phenomenon in which the supplied power Pa exceeds the target power Pt immediately after the start of power reception is referred to as inrush power or power overshoot.

[0052] The lower curve C2 in Figure 7 shows the change in supplied power Pa when inrush power is suppressed by the control circuit 150. The control by the control circuit 150 will be explained below.

[0053] A-4. Control method for the power receiving device: The processing performed by the control circuit 150 will be explained using Figure 8. The control circuit 150 starts processing when the power receiving device 100 is started. The power receiving device 100 is started, for example, when the control circuit 150 receives power from a vehicle on which the power receiving device 100 is installed.

[0054] In step S100 of Figure 8, the control circuit 150 adjusts the power supply ratio D by 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 a ratio Ds smaller than the minimum target ratio Dm, which is the minimum value of the target ratio Dt corresponding to the coupling state that allows the supplied power Pa to be a predetermined target power Pt. As mentioned above, the minimum target ratio Dm is determined based on the maximum power Pm and the target power Pt. For example, as shown in the lower part of Figure 6, the control circuit 150 sets the power supply ratio D to a ratio Ds smaller than 0.5, which is the minimum target ratio Dm.

[0055] As a result, when a supply power Pa is generated, as shown in the lower part of Figure 7, the supply power Pa will be lower than the target power Pt due to a power supply ratio D that is smaller than the minimum target ratio Dm. Therefore, even when the load device 130 starts consuming DC power, the supply power Pa of the power receiving device 100 will not exceed the target power Pt. In other words, no inrush power is generated in the power receiving device 100.

[0056] In step S200 of Figure 8, the control circuit 150 determines whether power has been received using the power receiving sensor 160. If the control circuit 150 detects power reception, it proceeds to step S300. If the control circuit 150 does not detect power reception, it repeats the process in step S200.

[0057] In step S300 of Figure 8, the control circuit 150 determines when the load device 130 has started consuming DC power. The control circuit 150 determines when the load device 130 has started consuming DC power, for example, based on the current value acquired by the power receiving sensor 160. If the load device 130 starts consuming DC power, the control circuit 150 proceeds to step S400. If the load device 130 does not start consuming DC power, the control circuit 150 returns to step S200.

[0058] In step S400 of Figure 8, the control circuit 150, based on the power receiving sensor 160, controls the power supply ratio D to increase it to the target ratio Dt after the start of DC power consumption. That is, the control circuit 150 increases the power supply ratio D to the target power Pt by increasing the power supply ratio D to a ratio Ds smaller than the minimum target ratio Dm based on the target ratio Dt. As a result, the power receiving device 100 can supply power Pa that satisfies the target power Pt to the load device 130 while preventing inrush power.

[0059] The adjustment unit 151a is the functional unit in the control unit 151 that performs step S100. 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 by 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 power receiving sensor 160. The current value It is determined by the control unit 151 based on a predetermined target power Pt.

[0060] In step S500 of Figure 8, the control circuit 150 determines whether the load device 130 has stopped consuming DC power. The control circuit 150 determines whether the load device 130 has stopped consuming DC power based, for example, on the current value acquired by the power receiving sensor 160. If the load device 130 is consuming DC power, the control circuit 150 repeats step S500. If the load device 130 is not consuming DC power, the control circuit 150 proceeds to step S600.

[0061] In step S600 of Figure 8, the control circuit 150 determines whether to stop the power receiving device 100. The control circuit 150 receives a command to stop the power receiving device 100, for example, from the control device of the vehicle on which the power receiving device 100 is installed. If the control circuit 150 does not receive a command to stop the power receiving device 100, it proceeds to step S700. If the control circuit 150 receives a command to stop the power receiving device 100, it terminates the process.

[0062] In step S700 of Figure 8, 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 a ratio Ds that is smaller than the minimum target ratio Dm among the target ratios Dt that correspond to the coupling state that allows the supplied power Pa to reach a predetermined target power Pt. After processing in step S700, the control circuit 150 returns to step S200.

[0063] In other words, in this configuration, the power received by the power receiving device 100 of the present disclosure differs depending on the resonance state of the resonant circuit or the state of magnetic coupling. Therefore, the power supply ratio D that can bring the supplied power Pa to the target power Pt also differs depending on the resonance or coupling state. Furthermore, in this configuration, the power receiving device 100 of the present disclosure may begin consuming DC power by the load device 130 when receiving power. Therefore, the power receiving device 100 of the present disclosure can prevent inrush power exceeding the target power Pt even when DC power consumption by the load device 130 begins by setting the power supply ratio D to less than the minimum target ratio Dm before starting to receive power. Furthermore, the power receiving device 100 of the present disclosure can efficiently supply power to the load device 130 while suppressing inrush power by increasing the power supply ratio D after DC power consumption has started.

[0064] Furthermore, in this configuration, the rectifier circuit 120 can also function as an adjustment circuit 140. That is, since the power receiving device 100 of this disclosure does not require the adjustment circuit 140 and the rectifier circuit 120 to be configured separately, the cost of the device can be reduced and the device can be made smaller. The configuration in which the adjustment circuit 140 and the rectifier circuit 120 are configured separately will be described later.

[0065] B. Second Embodiment: 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. Furthermore, the limiter 151b relaxes the restriction at a slower speed than the speed at which the adjustment unit 151a determines the power supply ratio D. As shown in Figure 9, the limiter 151b is located between the adjustment unit 151a and the adjustment circuit 140 in the control system of the power receiving device 100.

[0066] As described above, the adjustment unit 151a determines the power supply ratio D by 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 a command from the adjustment unit 151a to control the adjustment circuit 140. Specifically, the command from the adjustment unit 151a to control the adjustment circuit 140 is a command to determine the power supply ratio D. As a result, the adjustment circuit 140 controls the off time of the switch Sw. The control speed of the limiter 151b is measured by comparing the signal changes of the adjustment unit 151a and the limiter 151b using an oscilloscope.

[0067] In this configuration, the power supply ratio D, which corresponds to the fluctuating power, is limited by the limiter 151b. Furthermore, the relaxation of the limiter 151b is delayed compared to the determination of the power supply ratio D. For example, the power receiving device 100 of this disclosure does not change the power supply ratio D in accordance with the power fluctuations when the power received fluctuates due to disturbances. Therefore, the power receiving device 100 of this disclosure can stably control the suppression of inrush power.

[0068] C. Third Embodiment: In the above embodiment, the control circuit 150 can also perform short-circuit mode and power supply mode as follows. The control circuit 150, in response to the power receiving sensor 160, performs short-circuit mode and power supply mode with the low-side switch SwL and the parallel diode Di connected in parallel to the high-side switch SwH during a first time interval including the start of power reception. That is, the control circuit 150 controls the high-side switch SwH to the off state during a first time interval including the start of power reception, thereby rectifying the received power Pr with the parallel diode Di.

[0069] Furthermore, the control circuit 150, when the power receiving sensor 160 detects a predetermined reference current in the second time period following the first time period, activates the low-side switch SwL, the high-side switch SwH, and performs short-circuit mode and power supply mode. In other words, the control circuit 150 starts the on / off operation of the high-side switch SwH for the rectification of AC power. The reference current is, for example, a current value that is 20% of the current value at the target power Pt.

[0070] In this configuration, the power receiving device 100 of this disclosure rectifies the AC power using the first switch SwH on the positive electrode line Lp when a current exceeding the reference current flows through the power receiving device 100. For example, with a switch Sw such as a MOSFET, the voltage between the drain and source may be distorted when the current flowing between the drain and source is low. In this case, if the on / off state of the MOSFET is determined using the voltage between the drain and source, the control may become unstable due to the distortion of the voltage between the drain and source. The power receiving device 100 of this disclosure can rectify more stably than the configuration in which rectification is performed by the first switch SwH alone, by using the parallel diode Di of the first switch SwH to rectify at the start of power reception when the current being supplied is small.

[0071] D. Fourth Embodiment: In the first embodiment, the adjustment circuit 140 is configured by a switch Sw of the synchronous rectifier circuit 120. However, the adjustment circuit 140 may be configured separately from the synchronous rectifier circuit 120. Figure 10 shows an adjustment circuit 140x that is separated from the rectifier circuit 120x and includes a switch Swx that short-circuits the input terminals of the rectifier circuit 120x. More specifically, the switch Swx of the adjustment circuit 140x is connected in parallel to the power receiving resonant circuit 110 and the rectifier circuit 120x between the power receiving resonant circuit 110 and the rectifier circuit 120x. A semiconductor relay is used for the switch Swx. Note that configurations different from the first embodiment are denoted by x in the same reference numerals as in the first embodiment.

[0072] If the adjustment circuit 140x is configured separately from the rectifier circuit 120x, the rectifier circuit 120x may consist only of rectifier diodes. Figure 10 illustrates a configuration in which the rectifier circuit 120x consists only of rectifier diodes. In this case, the drive circuit 152 of the control circuit 150 of the fourth embodiment controls only the adjustment circuit 140x. When the power supply mode is performed by the adjustment circuit 140x of the fourth embodiment, as indicated by arrow D1 in Figure 10, the positive current of the AC power flows to the load device 130 via the rectifier diode on the positive line Lp side of the rectifier circuit 120x. When the short-circuit mode is performed by the adjustment circuit 140x of the fourth embodiment, as indicated by arrow D2 in Figure 10, the positive current of the AC power does not flow through the rectifier circuit 120x but returns to the power receiving resonant circuit 110 via the switch Swx of the adjustment circuit 140x. Similarly, the negative current of the AC power flows in both the power supply mode and the short-circuit mode.

[0073] By adopting this configuration, the power receiving device 100x of this disclosure can more easily implement control to adjust the supplied power Pa than a configuration in which the adjustment circuit 140 is configured by a switch Sw of the rectifier circuit 120 equipped with a switch Sw.

[0074] E. Variations: In the above embodiment, the power receiving device 100 may include a filter circuit between the power receiving resonant circuit 110 and the adjustment circuit 140. More specifically, the power receiving device 100 may include an immittance filter, such as the filter circuit FL1 in Figure 11 or the filter circuit FL2 in Figure 12. In addition to the immittance filter, the power receiving device 100 may also include a bandpass filter. Although Figures 11 and 12 illustrate the power receiving device 100 of the first embodiment, the power receiving device 100x of the fourth embodiment may also include filter circuits FL1 and FL2.

[0075] By adopting this configuration, the power receiving device 100 can achieve constant current characteristics for AC power and a function to suppress harmonics.

[0076] F. Variations: In the above embodiment, the received power Pr is greatest when the transmitting coil 222 and the receiving coil 111 are directly facing each other. Furthermore, the received power Pr decreases as the position moves away from this direct facing position. However, depending on the resonance method of the transmitting resonant circuit 220 and the receiving resonant circuit 110, as shown in Figure 13, the received power Pr may increase as the position moves away from this direct facing position. Specifically, this is the case when the transmitting resonant circuit 220 and the receiving resonant circuit 110 are composed of a transmitting resonant circuit 220 in which the transmitting coil 222 and the transmitting resonant capacitor 221 are connected in series, and a receiving resonant circuit 110 in which the receiving coil 111 and the receiving resonant capacitor 112 are connected in series. That is, when the transmitting resonant circuit 220 is a series resonant circuit and the receiving resonant circuit 110 is a series resonant circuit. In this case, the received power Pr is greatest when the transmitting coil 222 and the receiving coil 111 are directly facing each other. Furthermore, the received power Pr increases as the position away from the direct facing state increases. As a result, the minimum target ratio Dm becomes the target ratio Dt at the position where the relative positions of the transmitting coil 222 and the receiving coil 111 are furthest apart when they are facing each other. In the case of Figure 13 as well, the receiving device 100 is controlled in the same manner as in the above embodiment, so that the receiving device 100 of this disclosure can efficiently supply power to the load device 130 while suppressing inrush power.

[0077] G. Variant: (1) In the above embodiment, the power receiving device 100 is mounted on a vehicle. However, the power receiving device 100 may be mounted on other mobile devices. For example, the power receiving device 100 may be mounted on an airplane. (2) In the above embodiment, the power transmission circuit may further include a rectifier circuit, a filter circuit, and so on. (3) In the above embodiment, the switch Sw constitutes all of the rectifier elements that make up the synchronous rectifier circuit 120. However, the switch Sw only needs to constitute at least a part of the rectifier elements that make up the synchronous rectifier circuit 120. For example, the switch Sw may only constitute the rectifier elements on the negative electrode line Ln side. In this case, the rectifier elements on the positive electrode line Lp side are made up of rectifier diodes. (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 be any other sensor. For example, the power receiving sensor 160 may be a voltage sensor that measures the voltage of DC power. Furthermore, the power receiving sensor 160 may be composed of multiple sensors. For example, the power receiving sensor 160 may be composed of a sensor that detects power reception by AC power and a sensor that detects power consumption of the load device 130 by DC power. (5) In the above embodiment, a battery is exemplified as the load device 130. However, the load device 130 is not limited to a battery. The load device 130 may be, for example, a lighting device or a power device. When the load device 130 is a lighting device or a power device, the load device 130 starts consuming DC power based on the startup of the device. (6) In the above embodiment, the target power Pt is predetermined by the specifications of the load device 130. However, the target power Pt is not limited to the specifications of the load device 130 and can be predetermined. For example, the target power Pt may be determined based on the rated power of the circuit of the power receiving device 100 or the power demand of the grid power supply that supplies power to the power transmission device 200. (7) In the above embodiment, the minimum target ratio Dm is given as an example of 0.5. However, the minimum target ratio Dm is not limited to 0.5. The minimum target ratio Dm may also be 0.2 or 0.7, etc. (8) In the above embodiment, the control circuit 150 determines the start and stop of DC power consumption by the load device 130 based on the current value acquired by the power receiving sensor 160. However, the control circuit 150 may determine the start and stop of DC power consumption by the load device 130 by other means. For example, the control circuit 150 may be connected to the control device of the load device 130 and determine the start and stop of DC power consumption by the load device 130 based on commands received from the control device of the load device 130. (9) In the above embodiment, the reference current is, as an example, set to a current value that is 20% of the current value at the target power Pt. However, the reference current may also be a current value that is 10% or 40% of the current value at the target power Pt, or a reference value based on other currents. (10) In the above embodiment, the control unit 151 is mainly composed of a microcomputer, for example. That is, the control unit 151 is configured as a digital circuit. However, the control unit 151 may also be composed of an analog circuit. (11) In the above embodiment, the adjustment unit 151a determines the power supply ratio D based on the current value. However, as described above, if the power receiving sensor 160 is a voltage sensor, the adjustment unit 151a may determine the power supply ratio D based on the voltage value. (12) In the above embodiment, the control circuit 150 controls the power supply ratio D to increase to a target ratio Dt after the start of DC power consumption by the power receiving sensor 160. However, the control circuit 150 does not have to increase the power supply ratio D to match the target ratio Dt. More specifically, the control circuit 150 only needs to increase the power supply ratio D between ratio Ds and the target ratio Dt. (13) In the above embodiment, the switch Sw of the synchronous rectifier circuit 120 is a MOSFET. However, the switch Sw of the synchronous rectifier circuit 120 may be other switching elements. The switch Sw may be, for example, a BJT (Bipolar junction transistor) or an IGBT (Insulated Gate Bipolar Transistor). (14) In the above embodiment, periods b and d are periods of short-circuit mode, and periods a and c are periods of power supply mode. However, periods b and d may be periods of power supply mode, and periods a and c may be periods of short-circuit mode.

[0078] This disclosure is not limited to the embodiments and modifications described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments and modifications corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate to solve some or all of the above problems, or to achieve some or all of the above effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate.

[0079] H. Other forms: The features of this disclosure are as follows: (Form 1) A power receiving device (100, 100x) that receives AC power non-contactually using a magnetic field, A resonant circuit (110) including a receiving coil (111) that receives the aforementioned AC power, wherein the magnitude of the AC power differs depending on the state of resonance or coupling, A rectifier circuit (120, 120x) that converts the aforementioned AC power to DC power, A load device (130) that starts consuming the DC power based on predetermined standards related to electricity, An adjustment circuit (140, 140x) comprising a switch (Sw) that short-circuits the input terminals (P1, P2) of the rectifier circuit, wherein the adjustment circuit adjusts the supply power (Pa) of the AC power supplied to the load device between the power receiving coil and the load device, A power receiving sensor (160) that detects power reception by the aforementioned DC power, The device includes a control circuit (150, 150x) for controlling the power receiving device, The aforementioned control circuit is The system includes a short-circuit mode in which the terminals are short-circuited during a predetermined short-circuit period for each half-cycle (Ca) of the AC power, and a power supply mode in which the terminals are left open during the power supply period excluding the short-circuit period within the half-cycle. The power receiving sensor controls the power supply ratio (D), which is the ratio of the power supply period in the half-cycle, to a ratio smaller than the minimum target ratio (Dm), which is the minimum value of the target ratio (Dt) corresponding to the resonance or coupling state that allows the supplied power to reach a predetermined target power (Pt), before the start of receiving the AC power. A power receiving device that, based on the power receiving sensor, controls the power supply ratio to increase it to below the target ratio after the consumption of the DC power begins. (Form 2) The power receiving device according to Embodiment 1, further, The system includes a current sensor (160) for measuring the current value of the DC power, The control circuit further, An adjustment unit (151a) that determines the power supply ratio based on the current value, A power receiving device comprising: a limiter (151b) that limits the power supply ratio determined by the adjustment unit, the limiter that relaxes the limit at a speed slower than the speed at which the adjustment unit determines the power supply ratio. (Form 3) A power receiving device according to Embodiment 2, The switch is a power receiving device that constitutes at least a portion of the rectifier elements that make up the rectifier circuit. (Form 4) The power receiving device according to Embodiment 3, further, The aforementioned switch is It constitutes all of the aforementioned rectifier elements, Furthermore, the switch is equipped with a parallel diode (Di) connected in parallel, facing in the opposite direction to the forward direction of the switch. The rectifier circuit is a leg circuit (121, 122) in which two switches are connected in series, and includes a leg circuit that connects the positive electrode line (Lp) and the negative electrode line (Ln) of the DC power. The two switches described above consist of a first switch (SwH) on the positive line side and a second switch (SwL) on the negative line side. The aforementioned control circuit is The power receiving sensor, during a first time interval including the start of power reception, executes the short-circuit mode and the power supply mode using the second switch and the parallel diode connected in parallel to the first switch. A power receiving device that, when the power receiving sensor detects a predetermined reference current in a second time period following the first time period, executes the short-circuit mode and the power supply mode using the second switch and the first switch. [Explanation of symbols]

[0080] 100, 100x... Power receiving device, 110... Resonant circuit, 111... Power receiving coil, 120, 120x... Rectifier circuit, 130... Load device, 140, 140x... Adjustment circuit, 150, 150x... Control circuit, 160... Power receiving sensor, Ca... 1 cycle, D... Power supply ratio, Dm... Minimum target ratio, Dt... Target ratio, P1, P2... Terminals, Pa... Power supply, Sw... Switch

Claims

1. A power receiving device (100, 100x) that receives AC power non-contactually using a magnetic field, A resonant circuit (110) including a receiving coil (111) that receives the aforementioned AC power, wherein the magnitude of the AC power differs depending on the state of resonance or coupling, A rectifier circuit (120, 120x) that converts the AC power to DC power, The aforementioned load device (130) that consumes DC power, An adjustment circuit (140, 140x) comprising a switch (Sw) that short-circuits the input terminals (P1, P2) of the rectifier circuit, wherein the adjustment circuit adjusts the supply power (Pa) of the AC power supplied to the load device between the power receiving coil and the load device, A power receiving sensor (160) for detecting the reception of AC power or DC power, The device includes a control circuit (150, 150x) for controlling the power receiving device, The aforementioned control circuit is The system includes a short-circuit mode in which the terminals are short-circuited during a predetermined short-circuit period for each half-cycle (Ca) of the AC power, and a power supply mode in which the terminals are left open during the power supply period excluding the short-circuit period within the half-cycle. The power receiving sensor controls the power supply ratio (D), which is the ratio of the power supply period in the half-cycle, to a ratio smaller than the minimum target ratio (Dm), which is the minimum value of the target ratio (Dt) corresponding to the coupling state that allows the supplied power to reach a predetermined target power (Pt), before the start of receiving the AC power. A power receiving device that, after detecting the power reception using the power receiving sensor, performs control to increase the power supply ratio to a level below the target ratio.

2. The power receiving device according to claim 1, further, The system includes a current sensor (160) for measuring the current value of the DC power, The control circuit further, An adjustment unit (151a) that determines the power supply ratio based on the current value, A power receiving device comprising: a limiter (151b) that limits the power supply ratio determined by the adjustment unit, the limiter that relaxes the limit at a speed slower than the speed at which the adjustment unit determines the power supply ratio.

3. A power receiving device according to claim 2, The switch is a power receiving device that constitutes at least a portion of the rectifier elements that make up the rectifier circuit.

4. The power receiving device according to claim 1, further, The aforementioned switch is It constitutes all of the rectifier elements that make up the aforementioned rectifier circuit, Furthermore, the switch is equipped with a parallel diode (Di) connected in parallel, facing in the opposite direction to the forward direction of the switch. The rectifier circuit is a leg circuit (121, 122) in which two switches are connected in series, and includes a leg circuit that connects the positive electrode line (Lp) and the negative electrode line (Ln) of the DC power. The two switches described above consist of a first switch (SwH) on the positive electrode line side and a second switch (SwL) on the negative electrode line side. The aforementioned control circuit is The power receiving sensor, during a first time interval including the start of power reception, executes the short-circuit mode and the power supply mode using the second switch and the parallel diode connected in parallel to the first switch. A power receiving device that, when the power receiving sensor detects a predetermined reference current in a second time period following the first time period, executes the short-circuit mode and the power supply mode using the second switch and the first switch.

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