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 suppresses the received power when the received power is excessive, and supplies only the power necessary for charging the battery.

[0005] In a non-contact power supply system, the received power depends on the resonance or coupling state of a resonance circuit related to the positional relationship between the power receiving device and the power transmitting device. That is, it is difficult for the power receiving device to predict in advance the received power. Therefore, the power receiving device needs to confirm the received power before starting the control of the DC power supplied to the load. When the load is a battery, the power receiving devices within the range of the power transmission distance of the power transmitting device start power reception on the condition of insufficient remaining battery capacity. However, the confirmation of 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 an inrush power exceeding the power required for charging the battery. The inrush power may cause, for example, deterioration of the battery as a load or deterioration of EMC. Therefore, a technique for preventing inrush power has been demanded in the power receiving device of the non-contact power supply system.

Means for Solving the Problems

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

[0007] According to one aspect of the present disclosure, there is provided a power receiving device (100, 100x) that receives AC power non - contactlessly by a magnetic field. The power receiving device includes a resonance circuit (110) including a power receiving coil (111) that receives the AC power, where the magnitude of the AC power varies according to a resonance or coupling state; a rectifier circuit (120, 120x) that converts the AC power into DC power; a load device (130) that starts consuming the DC power based on a predetermined reference related to power; and an adjustment circuit (140, 140x) including a switch (Sw) that shorts the input terminals (P1, P2) of the rectifier circuit, and the adjustment circuit adjusts the supply power (Pa) supplied to the load device among the AC power between the power receiving coil and the load device. The power receiving device further includes a power receiving sensor (160) that detects power reception by the DC power, and a control circuit (150, 150x) that controls the power receiving device. The control circuit includes a short - circuit mode in which the terminals are short - circuited for a predetermined short - circuit period every half - cycle in one cycle (Ca) of the AC power, and a power - supply mode in which the terminals are opened during a power - supply period excluding the short - circuit period in the half - cycle. The power receiving sensor controls to make the power - supply ratio (D), which is the ratio of the power - supply period in the half - cycle until the start of reception of the AC power, 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 can make the supply power the predetermined target power (Pt). After the start of consumption of the DC power, the power receiving sensor controls to increase the power - supply ratio to be equal to or less than the target ratio.

[0008] In such a configuration, in the power receiving device of the present disclosure, the power received varies according to the resonance state of the resonance circuit or the magnetic coupling state. Therefore, the power supply ratio that can achieve the target power also varies depending on the resonance or coupling state. Further, in such a configuration, in the power receiving state of the power receiving device of the present disclosure, the consumption of DC power by the load device may start. For this reason, the power receiving device of the present disclosure can prevent the inrush power exceeding the target power even when the consumption of DC power by the load device starts, by starting power reception after setting the power supply ratio to be smaller than the minimum target ratio. Further, after the consumption of DC power starts, the power receiving device of the present disclosure can efficiently supply power to the load device while suppressing the inrush power by increasing the power supply ratio.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Embodiments for Carrying Out the Invention

[0010] A. First Embodiment: A-1. Configuration of the Device: The non-contact power supply system 10 shown in FIG. 1 supplies power to the load device 130 non-contact by a magnetic field. As shown in FIG. 1, the non-contact power supply system 10 includes a power transmission device 200 and a power reception device 100. The non-contact power supply system 10 supplies power to the power reception device 100 from the power transmission device 200 non-contact. The non-contact power supply system 10 supplies power non-contact to, for example, the power reception device 100 mounted on a vehicle.

[0011] The power transmission device 200 supplies AC power to the power reception device 100 non-contact by a magnetic field. The power transmission device 200 includes an AC power supply device 210 and a power transmission resonance 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, and converts the AC power supplied from the utility power 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 the power reception coil 111 and resonates. 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 resonant capacitor 221 resonates the power transmission resonant circuit 220 with AC power of the operating frequency in a state where the power transmission coil 222 and the power reception coil 111 are magnetically coupled. That is, the capacitance of the power transmission resonant capacitor 221 is set such that the operating frequency and the resonant frequency of the power transmission resonant circuit 220 substantially coincide in a state where the power transmission coil 222 and the power reception 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 reception coil 111 by magnetically coupling with the power reception 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 reception coil 111 mounted on the vehicle. The positional relationship between the power transmission coil 222 and the power reception coil 111 will be described in detail later.

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

[0018] The power reception resonant circuit 110 magnetically couples with and resonates with the power transmission coil 222. The power reception resonant circuit 110 includes a power reception coil 111 and a power reception resonant capacitor 112 connected in series to the power reception coil 111. That is, the power reception resonant circuit 110 is a series resonant circuit.

[0019] The power receiving coil 111 magnetically couples with the power transmitting coil 222 by receiving the magnetic field emitted by the power transmitting coil 222. The power receiving coil 111 is mounted on the vehicle in a state facing the ground. The power receiving coil 111 receives the magnetic field emitted by the power transmitting coil 222 by facing the power transmitting coil 222 laid on the ground. Thereby, the power receiving coil 111 receives the AC power of the power receiving device 100 in a non-contact manner. In this specification, the AC power received by the power receiving coil 111 is referred to as received power Pr.

[0020] The power receiving resonance capacitor 112 resonates the power receiving resonance circuit 110 with AC power of the operating frequency in a state where the power receiving coil 111 and the power transmitting coil 222 are magnetically coupled. That is, the capacitance of the power receiving resonance capacitor 112 is set such that the operating frequency and the resonance frequency of the power receiving resonance circuit 110 substantially coincide in a state where the power transmitting coil 222 and the power receiving coil 111 are magnetically coupled.

[0021] Note that the received power Pr varies according to the state where the power receiving coil 111 and the power transmitting coil 222 are magnetically coupled and the resonance state of the power receiving resonance circuit 110. That is, the received power Pr also varies depending on the relationship between the operating frequency and the resonance frequency. However, for ease of understanding of the technology, in the description of this specification, it is described as a state where the operating frequency and the resonance frequency coincide. The relationship between the state where the power receiving coil 111 and the power transmitting coil 222 are magnetically coupled and the received power Pr will be described later.

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

[0023] The synchronous rectification circuit 120 converts the received AC power into DC power. In this embodiment, the synchronous rectification circuit 120 is a single-phase rectification circuit that uses four MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) as rectifying elements. The synchronous rectification circuit 120 includes two leg circuits, a first leg circuit 121 and a second leg circuit 122. Note that the synchronous rectification circuit 120 is also simply referred to as the rectification circuit 120.

[0024] In a leg circuit, two switches Sw are connected in series. Further, the leg circuit connects the positive electrode line Lp and the negative electrode line Ln of the DC power. One of the output terminals of the power reception resonance circuit 110 is connected between the two switches Sw of the leg circuit. That is, the position between the two switches Sw of the leg circuit is the input terminal position in the synchronous rectification circuit 120. Note that regarding the input terminal of the synchronous rectification circuit 120, the leg circuit having the terminal P1 is the first leg circuit 121. The leg circuit having the terminal P2 is the second leg circuit 122.

[0025] The two switches Sw in the leg circuit are composed of a first switch SwH as a rectifying element on the positive electrode line Lp side and a second switch SwL as a rectifying element on the negative electrode line Ln side. That is, the switch Sw constitutes all of the rectifying elements in the synchronous rectification circuit 120.

[0026] The switch Sw of the leg circuit includes a parallel diode Di connected in parallel with the reverse direction with respect to the forward direction of the switch Sw. The parallel diode Di is, for example, the body diode of the MOSFET. That is, the drain of the switch Sw is arranged on the positive electrode line Lp side, and the source of the switch Sw is arranged on the negative electrode 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. Further, the gate of the switch Sw is connected to the control circuit 150. The switch Sw is driven by receiving a voltage corresponding to the command of the control circuit 150 at the gate.

[0027] In this specification, the positive electrode line Lp side is also referred to as the high side, and the negative electrode line Ln side 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] That is, the synchronous rectification circuit 120 rectifies the AC power input from the power receiving resonance circuit 110 by the switch Sw. The DC power rectified by the synchronous rectification 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 among the received power Pr, which is AC power, between the power receiving coil 111 and the load device 130. The adjustment circuit 140 includes a switch Sw that short - circuits the input terminals of the synchronous rectification circuit 120. Note that the switch Sw of the adjustment circuit 140 is also the low side switch SwL of the synchronous rectification circuit 120.

[0030] The adjustment circuit 140 short - circuits the input terminals of the synchronous rectification circuit 120 by turning on the two low side switches SwL of the synchronous rectification circuit 120. Thereby, the AC power is not rectified by the synchronous rectification circuit 120. The adjustment circuit 140 opens the input terminals of the synchronous rectification circuit 120 by turning off at least one of the two low side switches SwL of the synchronous rectification circuit 120. Thereby, the AC power is rectified by the synchronous rectification circuit 120 and is output as DC power from the synchronous rectification circuit 120. In this specification, the state in which the input terminals of the synchronous rectification 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 rectification circuit 120 are opened 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 rectification circuit 120 and the load device 130. The smoothing capacitor 170 smoothes the DC current and DC voltage supplied to the load device 130.

[0032] The power reception sensor 160 detects power reception by DC power. More specifically, the power reception sensor 160 detects the current flowing through the load device 130 due to power reception. That is, the power reception sensor 160 is a current sensor that measures the current value of DC power. The power reception sensor 160 is connected in series between the output of the synchronous rectification circuit 120 and the load device 130.

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

[0034] The load device 130 starts consuming DC power based on a predetermined standard related to power. That is, the load device 130 does not always perform charging. For example, the load device 130 including a battery starts charging when the remaining amount becomes less than a certain reference value in order to prevent overcharging. Thus, the load device 130 may not consume DC power when the power reception device 100 is in a power reception state. Further, the load device 130 may start consuming DC power when the power reception device 100 is in a power reception state. The consumption of DC power during power reception will be described in detail later.

[0035] The supplied power Pa supplied to the load device 130 is the power adjusted based on the target power Pt by the adjustment circuit 140. For example, in the case of the load device 130 including a battery, the target power Pt is determined based on the rated current of the battery. The battery may overheat due to an overcurrent being applied, which may reduce the life of the battery. For this reason, the target power Pt is determined as power that satisfies a current value equal to or less than the rated current. In addition, the battery may cut off the current flowing through it at a current lower than the rated current of the battery by its protection circuit.

[0036] The control circuit 150 controls the power receiving device 100. The control circuit 150 includes 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 for driving the switch Sw according to the command of the control unit 151. The drive circuit 152 is connected to the respective gates of all the switches Sw of the synchronous rectification circuit 120. The drive circuit 152 drives the switch Sw by applying the gate voltage necessary for the on and off operations of the switch Sw to the gate of the switch Sw. In FIG. 1, for ease of understanding of the technology, the connection between the drive circuit 152 and the gate is omitted.

[0038] The control unit 151 generates a signal for controlling the on and off operations of the switch Sw. The control unit 151 is mainly composed of, for example, a microcomputer, and includes a CPU, a ROM, a 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. The control unit 151 executes a short - circuit mode and a power supply mode based on the current value acquired by the power receiving sensor 160.

[0039] A - 2. Short - circuit mode and power supply mode: The control circuit 150 has a short - circuit mode and a power supply mode as control modes. The control circuit 150 executes a short - circuit mode in which the input terminals of the synchronous rectification circuit 120 are short - circuited during a predetermined short - circuit period for each half - cycle in one cycle Ca of the AC power. The control circuit 150 executes a power supply mode in which the terminals are opened during the power supply period excluding the short - circuit period in one of the half - cycles in one cycle Ca. Using FIGS. 2 to 5, the operation of the power receiving device 100 in the short - circuit mode and the power supply mode in one cycle Ca of the AC power will be described. In FIGS. 2 to 5, the waveform of the AC current in one cycle Ca is shown at the top, and the circuit diagram of the power transmission device 200 is shown at the bottom. However, for ease of understanding of the technology, some illustrations such as the power receiving resonance circuit 110, the smoothing capacitor 170, and the control circuit 150 are omitted.

[0040] In FIG. 2, during period a of the power supply mode in 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 Aia. During period a, the control circuit 150 controls at least the low-side switch SwL of the first leg circuit 121 among the two switches Sw of the adjustment circuit 140 to be in the off state. Thereby, the AC current flows through the high-side switch SwH of the first leg circuit 121 to the load device 130. That is, the received power Pr is supplied to the load device 130.

[0041] In FIG. 3, during period b of the short-circuit mode in 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 leg circuit 121 among the two switches Sw of the adjustment 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 received power Pr is not supplied to the load device 130.

[0042] In FIG. 4, during period c of the power supply mode 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 Aic. During period c, the control circuit 150 controls at least the low-side switch SwL of the second leg circuit 122 among the two switches Sw of the adjustment circuit 140 to be in the off state. Thereby, the AC current flows through the high-side switch SwH of the second leg circuit 122 to the load device 130. That is, the received power Pr is supplied to the load device 130.

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

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

[0045] A - 3. Method for adjusting the supply power: In the upper part of FIG. 6, the state where the power - receiving coil 111 and the power - transmitting coil 222 face each other is illustrated. In FIG. 6, the state of the power - receiving coil 111, which is located away from the ground by being mounted on a vehicle, and the power - transmitting coil 222 laid on the ground, as seen from the side, is illustrated.

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

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

[0048] In the lower part of FIG. 6, the relationship between the relative position of the power receiving coil 111 with respect to the power transmitting coil 222 and the power supply ratio D for making the supply power Pa the target power Pt is illustrated. At any power receiving position, the ratio for making the supply power Pa match the target power Pt is referred to as the target ratio Dt. The solid line in the lower part of FIG. 6 indicates the target ratio Dt.

[0049] In order to make the supply power Pa match the target power Pt, when the received power Pr is the maximum power Pm, it is necessary to make the power supply ratio D the smallest. The power supply ratio D at this time 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, in order to facilitate the adjustment of the supply power Pa, the target power Pt is preferably 80% or less of the maximum power Pm. In the lower part of FIG. 6, as an example, the minimum target ratio Dm is set to 0.5.

[0050] Furthermore, in order to make the supply power Pa match the target power Pt, it is necessary to increase the power supply ratio D as the received power Pr moves away from the maximum power Pm. However, the received power Pr may be less than the target power Pt depending on the relative position of the power receiving coil 111 with respect to the power transmitting coil 222. In this case, the control circuit 150 sets the power supply ratio D to the maximum value. That is, the control circuit 150 does not execute the short - circuit mode. Therefore, as shown by the solid line in the lower part of FIG. 6, the target ratio Dt becomes the maximum power supply ratio D at the position where the received power Pr less than the target power Pt is received.

[0051] At the upper part of FIG. 7, a state is illustrated in which the central axis CL1 and the central axis CL2 are displaced, and the power receiving coil 111 and the power transmitting coil 222 are facing each other. At the center of FIG. 7, the received power Pr in the state of the power receiving coil 111 and the power transmitting coil 222 shown in the upper part of FIG. 7 is illustrated. The lower part of FIG. 7 illustrates the supply power Pa from the start of power reception until the steady state is reached. As described above, the load device 130 may start consuming DC power when in the power receiving state. In this case, after detecting the received power Pr by the power reception sensor 160, the control circuit 150 starts adjusting the supply power Pa by the adjustment circuit 140. That is, the supply 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 in the lower part of FIG. 7, when the control by the control circuit 150 described later is not performed, immediately after the start of power reception, the supply power Pa exceeds the target power Pt and reaches the received power Pr. In this specification, as shown by the curve C1, the phenomenon that the supply power Pa exceeds the target power Pt immediately after the start of power reception is called the inrush power or the overshoot of power.

[0052] The curve C2 in the lower part of FIG. 7 shows the transition of the supply power Pa when the inrush power is suppressed by the control circuit 150. The control by the control circuit 150 will be described below.

[0053] A-4. Control Method of Power Receiving Device: The process performed by the control circuit 150 will be described with reference to FIG. 8. The control circuit 150 starts the process when the power receiving device 100 is activated. The power receiving device 100 is activated, for example, when the control circuit 150 receives power supply from a vehicle on which the power receiving device 100 is mounted.

[0054] In step S100 of FIG. 8, the control circuit 150 adjusts the power supply ratio D by the power reception sensor 160 until 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 according to the coupling state that can make the supply power Pa reach the 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 shown in the lower part of FIG. 6, the control circuit 150 makes the power supply ratio D a ratio Ds smaller than 0.5 as the minimum target ratio Dm.

[0055] Thereby, when the supply power Pa is generated, as shown in the lower part of FIG. 7, the supply power Pa becomes a power Ps lower than the target power Pt with the power supply ratio D of a ratio Ds smaller than the minimum target ratio Dm. Therefore, even when the load device 130 starts consuming DC power in the power receiving state of the power receiving device 100, the supply power Pa does not exceed the target power Pt. That is, no inrush power occurs in the power receiving device 100.

[0056] In step S200 of FIG. 8, the control circuit 150 determines power reception by the power reception sensor 160. When the control circuit 150 detects power reception, the process proceeds to S300. When the control circuit 150 does not detect power reception, the process of step S200 is repeated.

[0057] In step S300 of FIG. 8, the control circuit 150 determines the start of DC power consumption by the load device 130. The control circuit 150 determines the start of DC power consumption by the load device 130 based on, for example, the current value acquired by the power reception sensor 160. When the control circuit 150 starts DC power consumption by the load device 130, the process proceeds to step S400. When the control circuit 150 does not start DC power consumption by the load device 130, the process returns to step S200.

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

[0059] Note that the functional unit that performs step S100 in the control unit 151 is the adjustment unit 151a. The adjustment unit 151a determines the power feeding ratio D based on the current value of the DC power. More specifically, the adjustment unit 151a determines the power feeding 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. Note that 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 the predetermined target power Pt by the control unit 151.

[0060] In step S500 of FIG. 8, the control circuit 150 determines the stop of the DC power consumption by the load device 130. The control circuit 150 determines the stop of the DC power consumption by the load device 130 based on, for example, the current value acquired by the power receiving sensor 160. When the load device 130 consumes DC power, the control circuit 150 repeats step S500. When the load device 130 does not consume DC power, the control circuit 150 proceeds to step S600.

[0061] In step S600 of FIG. 8, the control circuit 150 determines the stop of the power receiving device 100. The control circuit 150 receives a command to stop the power receiving device 100 from, for example, the control device of the vehicle on which the power receiving device 100 is mounted. When the control circuit 150 does not receive a command to stop the power receiving device 100, the control circuit 150 proceeds to step S700. When the control circuit 150 receives a command to stop the power receiving device 100, the control circuit 150 ends the process.

[0062] In step S700 of FIG. 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 be a ratio Ds smaller than the minimum target ratio Dm among the target ratios Dt corresponding to the state of coupling capable of making the supplied power Pa the predetermined target power Pt. After the process of step S700, the control circuit 150 returns the process to step S200.

[0063] That is, in such a form, in the power receiving device 100 of the present disclosure, the power received varies according to the resonance state of the resonance circuit or the magnetic coupling state. For this reason, the power supply ratio D capable of making the supplied power Pa the target power Pt also varies depending on the resonance or coupling state. Further, in such a form, in the power receiving device 100 of the present disclosure, when the consumption of DC power by the load device 130 is started in the power receiving state. For this reason, the power receiving device 100 of the present disclosure can prevent the inrush power exceeding the target power Pt even when the consumption of DC power by the load device 130 is started by starting power reception after making the power supply ratio D smaller than the minimum target ratio Dm. Further, the power receiving device 100 of the present disclosure can efficiently supply power to the load device 130 while suppressing the inrush power by increasing the power supply ratio D after the consumption of DC power is started.

[0064] Furthermore, in such a form, the rectifier circuit 120 can also function as the adjustment circuit 140. That is, since it is not necessary to separately configure the adjustment circuit 140 and the rectifier circuit 120 in the power receiving device 100 of the present disclosure, it is possible to reduce the cost of the device and miniaturize the device. A form in which the adjustment circuit 140 and the rectifier circuit 120 are separately configured 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 restricts the power supply ratio D determined by the adjustment unit 151a. Moreover, 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 FIG. 9, the limiter 151b is arranged 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 for controlling the adjustment circuit 140 by the adjustment unit 151a. The command for controlling the adjustment circuit 140 by the adjustment unit 151a is specifically a command for determining the power supply ratio D. Thereby, 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 with an oscilloscope.

[0067] With such a configuration, the power supply ratio D corresponding to the fluctuating power is restricted by the limiter 151b. Furthermore, the relaxation of the restriction of the limiter 151b is slower than the determination of the power supply ratio D. For example, when the power received by the power receiving device 100 of the present disclosure fluctuates due to an external disturbance, the power supply ratio D is not changed in response to the power fluctuation. Therefore, the power receiving device 100 of the present disclosure can stably perform the control for suppressing the inrush power.

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

[0069] Furthermore, when the power - receiving sensor 160 detects a predetermined reference current in a second time interval after the first time interval, the control circuit 150, by means of the power - receiving sensor 160, executes the low - side switch SwL, the high - side switch SwH, and the short - circuit mode and the power - feeding mode. That is, 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] With such a configuration, when a current equal to or greater than the reference current flows through the power - receiving device 100 of the present disclosure, the first switch SwH on the positive - electrode line Lp side rectifies the AC power. For example, in the case of a switch Sw such as a MOSFET, when the current value flowing between the drain and the source is low, the voltage between the drain and the source may be distorted. At this time, in the case of a method of determining the on - off of the MOSFET using the voltage between the drain and the source, the control may become unstable due to the distortion of the voltage between the drain and the source. The power - receiving device 100 of the present disclosure can rectify more stably by using the parallel diode Di of the first switch SwH at the start of power reception when the energized current is small, compared with the form of rectification by the first switch SwH.

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

[0072] When the adjustment circuit 140x is configured separately from the rectification circuit 120x, the rectification circuit 120x may be constituted only by rectifying diodes. In FIG. 10, a form in which the rectification circuit 120x is constituted only by rectifying diodes is illustrated. 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 - feeding mode is executed by the adjustment circuit 140x of the fourth embodiment, as indicated by the arrow D1 in FIG. 10, the positive current of the AC power flows to the load device 130 through the rectifying diode on the positive - electrode line Lp side of the rectification circuit 120x. When the short - circuit mode is executed by the adjustment circuit 140x of the fourth embodiment, as indicated by the arrow D2 in FIG. 10, the positive current of the AC power does not flow through the rectification circuit 120x but returns to the power - receiving resonance circuit 110 through the switch Swx of the adjustment circuit 140x. Regarding the negative current of the AC power, the currents in the power - feeding mode and the short - circuit mode flow in the same way.

[0073] With such a configuration, the power - receiving device 100x of the present disclosure can more easily realize control for adjusting the supplied power Pa than the configuration in which the adjustment circuit 140 is constituted by the switch Sw of the rectification circuit 120 including the switch Sw.

[0074] E. Modification example: In the above embodiment, the power receiving device 100 may include a filter circuit between the power receiving resonance circuit 110 and the adjustment circuit 140. More specifically, the power receiving device 100 may include an impedance filter, such as the filter circuit FL1 in FIG. 11 or the filter circuit FL2 in FIG. 12. In addition to the impedance filter, the power receiving device 100 may include a band-pass filter. Note that FIGS. 11 and 12 illustrate the power receiving device 100 of the first embodiment, but the power receiving device 100x of the fourth embodiment may also include the filter circuit FL1 or the filter circuit FL2.

[0075] By adopting such a configuration, the power receiving device 100 can achieve the constant current characteristic of AC power and the function of suppressing harmonics.

[0076] F. Modification Example: In the above embodiment, the received power Pr is maximized when the power transmission coil 222 and the power receiving coil 111 face each other. Furthermore, the received power Pr decreases as the distance from the facing state increases. However, depending on the resonance method using the power transmission resonance circuit 220 and the power receiving resonance circuit 110, as shown in FIG. 13, the received power Pr may increase as the distance from the facing state increases. Specifically, this is the case where the power transmission resonance circuit 220 and the power receiving resonance circuit 110 are constituted by a power transmission resonance circuit 220 in which the power transmission coil 222 and the power transmission resonance capacitor 221 are connected in series, and a power receiving resonance circuit 110 in which the power receiving coil 111 and the power receiving resonance capacitor 112 are connected in series. That is, it is the case where the power transmission resonance circuit 220 is a series resonance circuit and the power receiving resonance circuit 110 is a series resonance circuit. In this case, the received power Pr is minimized when the power transmission coil 222 and the power receiving coil 111 face each other. Furthermore, the received power Pr increases as the distance from the 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 power transmission coil 222 and the power receiving coil 111 are farthest apart when they face each other. Also in the case of FIG. 13, by controlling the power receiving device 100 in the same manner as in the above embodiment, the power receiving device 100 of the present disclosure can efficiently supply power to the load device 130 while suppressing the inrush power.

[0077] G. Modification Examples: (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 moving bodies. 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, etc. (3) In the above embodiment, the switch Sw constitutes all of the rectifying elements that make up the synchronous rectifier circuit 120. However, the switch Sw only needs to constitute at least a part of the rectifying elements that make up the synchronous rectifier circuit 120. For example, the switch Sw may only constitute the rectifying elements on the negative electrode line Ln side. In this case, the rectifying elements on the positive electrode line Lp side are constituted by rectifying 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 other sensors. 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 constituted by a plurality of sensors. For example, the power receiving sensor 160 may be constituted by a sensor that detects power reception by AC power and a sensor that detects the 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, a power device, etc. When the load device 130 is a lighting device, a power device, etc., the load device 130 starts consuming DC power based on the activation of the device. (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 the specifications of the load device 130 and is predetermined. For example, the target power Pt may be determined based on the rated power of the power receiving device 100 as a circuit, the power demand of the system power supply that supplies power to the power transmission device 200, etc. (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 may be 0.2, 0.7, etc. (8) In the above embodiment, the control circuit 150 determines the start and stop of the consumption of DC power by the load device 130 based on the current value acquired by the power reception sensor 160. However, the control circuit 150 may determine the start and stop of the consumption of DC power by the load device 130 by other methods. 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 the consumption of DC power by the load device 130 based on a command received from the control device of the load device 130. (9) In the above embodiment, the reference current is exemplified as a current value that is 20% of the current value at the target power Pt. However, the reference current may 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 configured by, for example, a microcomputer. That is, the control unit 151 is configured as a digital circuit. However, the control unit 151 may be configured by 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, when the power reception 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, after the start of the consumption of DC power by the power reception sensor 160, the control circuit 150 performs control to increase the power supply ratio D to the target ratio Dt. However, the control circuit 150 does not necessarily have to increase the power supply ratio D in accordance with the target ratio Dt. More specifically, the control circuit 150 may increase the power supply ratio D between the 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 also 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 the short - circuit mode, and periods a and c are periods of the power - supply mode. However, periods b and d may be periods of the power - supply mode, and periods a and c may be periods of the short - circuit mode.

[0078] The present disclosure is not limited to the above - described embodiments and modifications, and can be realized in various configurations without departing from the gist thereof. For example, the embodiments and modifications corresponding to the technical features in each form described in the summary of the invention can be appropriately replaced or combined in order to solve some or all of the above - mentioned problems or to achieve some or all of the above - mentioned effects. Also, if the technical feature is not described as essential in this specification, it can be appropriately deleted.

[0079] H. Other forms: The features of the present disclosure are shown as follows. (Form 1) A power - receiving device (100, 100x) that receives AC power non - contactlessly by a magnetic field, including a resonance circuit (110) having a power - receiving coil (111) for receiving the AC power, the resonance circuit having different magnitudes of the AC power according to a resonance or coupling state, a rectifier circuit (120, 120x) for converting the AC power into DC power, and a load device (130) for starting consumption of the DC power based on a predetermined standard related to power. An adjustment circuit (140, 140x) comprising a switch (Sw) for short-circuiting between the input terminals (P1, P2) of the rectifier circuit, the adjustment circuit adjusting the supply power (Pa) supplied to the load device among the AC power between the power receiving coil and the load device. A power reception sensor (160) for detecting power reception by the DC power. A control circuit (150, 150x) for controlling the power receiving device. The control circuit In each half cycle of one cycle (Ca) of the AC power, it includes a short-circuit mode for short-circuiting between the terminals during a predetermined short-circuit period, and a power supply mode for opening between the terminals during a power supply period excluding the short-circuit period in the half cycle. Before the start of power reception of the AC power by the power reception sensor, control is performed to make the power supply ratio (D), which is the ratio of the power supply period in the half cycle, 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 can make the supply power a predetermined target power (Pt). A power receiving device that performs control to increase the power supply ratio to be equal to or less than the target ratio after the start of consumption of the DC power by the power reception sensor. (Embodiment 2) The power receiving device according to Embodiment 1, further Comprising a current sensor (160) for measuring the current value of the DC power. The control circuit further An adjustment unit (151a) for determining the power supply ratio based on the current value, and A limiter (151b) for limiting the power supply ratio determined by the adjustment unit, the limiter relaxing the limitation at a slower speed than the speed at which the adjustment unit determines the power supply ratio. (Embodiment 3) The power receiving device according to Embodiment 2, The switch constitutes at least a part of the rectifying element constituting the rectifier circuit. (Embodiment 4) The power receiving device according to Embodiment 3, further The switch which constitutes all of the rectifying elements, further comprising a parallel diode (Di) connected in parallel in a direction opposite to the forward direction of the switch, The rectifying circuit is a leg circuit (121, 122) in which two of the 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 are constituted by a first switch (SwH) on the positive electrode line side and a second switch (SwL) on the negative electrode line side. The control circuit, in a first time interval including the start of power reception by the power reception sensor, executes the short - circuit mode and the power supply mode by the second switch and the parallel diode connected in parallel with the first switch. a power receiving device that, in a second time interval after the first time interval, when the power reception sensor detects a predetermined reference current, executes the short - circuit mode and the power supply mode by the second switch and the first switch.

Explanation of Reference Numerals

[0080] 100, 100x... power receiving device, 110... resonance circuit, 111... power receiving coil, 120, 120x... rectifying circuit, 130... load device, 140, 140x... adjustment circuit, 150, 150x... control circuit, 160... power reception sensor, Ca... one cycle, D... power supply ratio, Dm... minimum target ratio, Dt... target ratio, P1, P2... terminals, Pa... supplied power, Sw... switch

Claims

1. A power receiving device (100, 100x) that receives AC power non - contactlessly by a magnetic field, a resonance circuit (110) including a power receiving coil (111) that receives the AC power, the resonance circuit having different magnitudes of the AC power depending on a resonance or coupling state; a rectification circuit (120, 120x) that converts the AC power into DC power; a load device (130) that starts consuming the DC power based on a predetermined criterion related to power; an adjustment circuit (140, 140x) including a switch (Sw) that shorts the terminals (P1, P2) of the input of the rectification circuit, the adjustment circuit adjusting the supply power (Pa) of the AC power to be 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 DC power; a control circuit (150, 150x) that controls the power receiving device, wherein the control circuit has a short - circuit mode in which the terminals are short - circuited for a predetermined short - circuit period every half - cycle in one cycle (Ca) of the AC power, and a power - feeding mode in which the terminals are opened during a power - feeding period excluding the short - circuit period in the half - cycle; before the start of power reception of the AC power by the power receiving sensor, controls the power - feeding ratio (D), which is the ratio of the power - feeding period in the half - cycle, to be less than a minimum target ratio (Dm), which is the minimum value of a target ratio (Dt) corresponding to the coupling state that can make the supply power a predetermined target power (Pt); after the start of consumption of the DC power by the power receiving sensor, controls to increase the power - feeding ratio to be equal to or less than the target ratio. A power receiving device.

2. The power receiving device according to claim 1, further comprising a current sensor (160) that measures a current value of the DC power, wherein the control circuit further comprises an adjustment unit (151a) that determines the power - feeding ratio based on the current value, and a limiter (151b) that limits the power - feeding ratio determined by the adjustment unit, the limiter relaxing the limitation at a slower speed than the speed at which the adjustment unit determines the power - feeding ratio. A power receiving device.

3. The power receiving device according to claim 2, wherein the switch constitutes at least a part of a rectifying element that constitutes the rectification circuit. A power receiving device.

4. The power receiving device according to claim 3, further comprising wherein the switch constitutes all of the rectifying elements. Furthermore, it includes a parallel diode (Di) connected in parallel and facing in the direction opposite to the forward direction of the switch. The rectifier circuit is a leg circuit (121, 122) in which two of the switches are connected in series, and includes a leg circuit connecting the positive electrode line (Lp) and the negative electrode line (Ln) of the DC power. The two switches are composed of a first switch (SwH) on the positive electrode line side and a second switch (SwL) on the negative electrode line side. The control circuit is In the first time interval including the start of power reception by the power reception sensor, the second switch and the parallel diode connected in parallel with the first switch execute the short - circuit mode and the power supply mode. A power receiving device that, when the power receiving sensor detects a predetermined reference current in a second time interval after the first time interval by the power receiving sensor, executes the short - circuit mode and the power supply mode by the second switch and the first switch.

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