Power receiving device

Abstract

To provide a power reception device that executes high-efficient power adjustment control.SOLUTION: A power reception device 200 executes power supply control that repeats a first rectification mode M1 in which a first high-side switch and a second low-side switch are turned on and a first low-side switch and a second high-side switch are turned off by detecting energization of a first bridge circuit, and a second rectification mode M3 in which the first low-side switch and the second high-side switch are turned on and the first high-side switch and the second low-side switch are turned off by detecting energization of a second bridge circuit in switching control of a synchronous rectification circuit 240, and executes power adjustment control including a first commutation mode M2 in which the first high-side switch is turned off and the first low-side switch is turned on in the first rectification mode, and a second commutation mode M4 in which the second high-side switch is turned off and the second low-side switch is turned on in the second rectification mode.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] There is known a power receiving device including a power receiving coil that transmits and receives power by magnetic coupling with a power transmitting coil connected to a power transmitting side DC / AC conversion circuit, a power receiving side AC / DC conversion circuit connected to the power receiving coil, an output capacitor connected to a DC output side of the power receiving side AC / DC conversion circuit, and a current sensor that measures a current flowing through a load connected to the output capacitor (for example, Patent Document 1). In this power receiving device, when the voltage of the load is controlled within a predetermined range by the power transmitting side DC / AC conversion circuit, the period of the commutation mode for making the current to the capacitor zero is changed by power adjustment control of the power receiving side AC / DC conversion circuit according to the load current value detected by the current sensor. This power adjustment control is power adjustment control based on so-called diode rectification, and only some rectifying elements are switched and controlled during the commutation mode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in diode rectification, power loss may increase. In this case, there is a possibility that the size of the devices of the power receiving device increases and the system efficiency decreases. Therefore, in the power receiving device, high efficiency by synchronous rectification has been desired from the viewpoint of suppressing power loss.

Means for Solving the Problems

[0005] The present disclosure can be realized in the following forms.

[0006] According to one embodiment of the present disclosure, a power receiving device (200, 200b, 200c, 200d, 200e) is provided for contactlessly receiving AC power transmitted from a power transmission device (100) and supplying it to a load device. This power receiving device comprises a power receiving resonant circuit (210) having a power receiving coil (212) and a resonant capacitor (214) for causing the power receiving coil to resonate; a synchronous rectifier circuit (240) having a plurality of bridge circuits including a first bridge circuit (241) having a first high-side switch (241H) and a first low-side switch (241L), and a second bridge circuit (242) having a second high-side switch (242H) and a second low-side switch (242L), which converts the AC power received by the power receiving coil into DC power; and a control unit (290) for controlling the plurality of bridge circuits. The control unit repeatedly performs power supply control by detecting the energization of the first bridge circuit, thereby turning on the first high-side switch and the second low-side switch and turning off the first low-side switch and the second high-side switch in a first rectification mode (M1); and detecting the energization of the second bridge circuit, thereby turning on the first low-side switch and the second high-side switch and turning off the first high-side switch and the second low-side switch in a second rectification mode (M3). The control unit also performs power adjustment control including a first commutation mode (M2) in the first rectification mode, where the first high-side switch is turned off and the first low-side switch is turned on; and a second commutation mode (M4) in the second rectification mode, where the second high-side switch is turned off and the second low-side switch is turned on.

[0007] This type of power receiving device enables highly efficient power adjustment control by switching the on / off state of each rectifier element in a synchronous rectifier circuit. [Brief explanation of the drawing]

[0008] [Figure 1] An explanatory diagram showing the schematic configuration of a contactless power supply system equipped with a power receiving device according to the first embodiment. [Figure 2] A timing chart illustrating the switching control of the synchronous rectifier circuit performed by the power receiving device. [Figure 3] A schematic diagram illustrating the operating state of the rectifier element and the current flow in the first rectification mode. [Figure 4] A schematic diagram illustrating the operating state of the rectifier element and the current flow in the first commutation mode. [Figure 5] A schematic diagram illustrating the operating state of the rectifier element and the current flow in the second rectification mode. [Figure 6] A schematic diagram illustrating the operating state of the rectifier element and the current flow in the second commutation mode. [Figure 7] An explanatory diagram showing the configuration of a power receiving device according to the second embodiment. [Figure 8] A timing chart showing details of peak current mode control. [Figure 9] An explanatory diagram showing the configuration of a power receiving device according to the third embodiment. [Figure 10] An explanatory diagram showing the configuration of the power receiving device according to the fourth embodiment. [Figure 11] An explanatory diagram showing the configuration of a power receiving device according to the fifth embodiment. [Figure 12] A first explanatory diagram showing the configuration of a contactless power supply system according to another embodiment. [Figure 13] A second explanatory diagram showing the configuration of a contactless power supply system according to another embodiment. [Figure 14] A third explanatory diagram showing the configuration of a contactless power supply system according to another embodiment. [Figure 15] A fourth explanatory diagram showing the configuration of a contactless power supply system according to another embodiment. [Modes for carrying out the invention]

[0009] A. First Embodiment: As shown in Figure 1, the contactless power supply system comprises a power transmission device 100 and a power receiving device 200, and supplies power from the power transmission device 100 to the power receiving device 200 without contact. The power transmission device 100 comprises a power transmission resonant circuit 110 and an AC power supply device 130.

[0010] The power transmission resonant circuit 110 includes a power transmission coil 112 and a power transmission resonant capacitor 114 connected in series with the power transmission coil 112. The power transmission resonant capacitor 114 is a resonant capacitor for resonating the power supplied to the power transmission coil 112. The capacitance of the power transmission resonant capacitor 114 during power supply is set based on the self-inductance of the power transmission coil 112 so that the operating frequency and the resonant frequency approximately coincide. The power transmission resonant circuit 110 utilizes the electromagnetic induction phenomenon to transmit AC power induced in the power transmission coil 112 to the power receiving coil 212 in a resonant coupling state in which the power transmission coil 112 and the power receiving coil 212 are magnetically coupled. The operating frequency of the power transmission device 100 can be set arbitrarily. In this embodiment, the operating frequency of the power transmission device 100 is, for example, 85 kHz, and is set using a predetermined power transmission frequency stipulated by the Radio Law, etc.

[0011] The AC power supply unit 130 supplies AC power at a predetermined operating frequency to the power transmission resonant circuit 110. The AC power supply unit 130 includes a power supply circuit and a power transmission circuit. The power supply circuit is, for example, an AC / DC converter circuit, which converts AC power supplied from an external power source such as a grid power supply into DC power. The power transmission circuit is an inverter or the like that converts the DC power supplied from the power supply circuit into AC power at an operating frequency. The power transmission circuit may further include a rectifier circuit, a filter circuit, and so on.

[0012] The power receiving device 200 receives AC power transmitted from the power transmitting device 100 in a contactless manner and supplies it to the load device. The power receiving device 200 is mounted on various devices that operate using electricity, such as electronic devices and electric vehicles. The power receiving device 200 includes a power receiving resonant circuit 210, an immittance converter 230, a synchronous rectifier circuit 240, a smoothing capacitor 250, and a battery 260.

[0013] The power receiving resonance circuit 210 includes a power receiving coil 212 and a power receiving resonance capacitor 214 as a resonance capacitor connected in series to the power receiving coil 212. The capacitance of the power receiving resonance capacitor 214 during power supply is set so that the operating frequency and the resonance frequency substantially coincide, for example, based on the self-inductance of the power receiving coil 212. When the power receiving coil 212 is in a facing state facing the power transmission coil 112, the power transmission coil 112 and the power receiving coil 212 are electromagnetically coupled. The power receiving resonance circuit 210 non-contact receives the alternating current power induced from the power transmission coil 112 to the power receiving coil 212 in a resonance coupling state where the power receiving coil 212 and the power transmission coil 112 are magnetically coupled. In the present embodiment, the power receiving resonance capacitor 214 includes a first capacitor 214P on the positive electrode side and a second capacitor 214N on the negative electrode side. By arranging resonance capacitors on both the positive electrode and the negative electrode, common mode noise can be suppressed. Note that the second capacitor 214N on the negative electrode side can be omitted.

[0014] The immittance converter 230 removes harmonic noise that may be present in the AC power received by the power receiving resonant circuit 210. In this embodiment, the immittance converter 230 is a so-called T-LCL type immittance converter comprising an input-side first reactor 232 and an output-side first reactor 234, and a capacitor 235, which are located on the positive side. The inductances of the reactors 232 and 234 and the capacitance of the capacitor 235 are set so that immittance characteristics are obtained at the operating frequency. In this embodiment, the immittance converter 230 further comprises an input-side second reactor 236 and an output-side second reactor 238, which are located on the negative side. By placing reactors on both the positive and negative sides, common-mode noise can be suppressed. Note that the input-side second reactor 236 and the output-side second reactor 238 can be omitted. Furthermore, the immittance converter 230 can also be a so-called CL-type immittance converter, which omits the input-side first reactor 232 and the input-side second reactor 236, instead of the T-LCL type. In this case, the output-side second reactor 238 can also be omitted.

[0015] The synchronous rectification circuit 240 converts the AC power received by the power receiving coil 212 into DC power that can be supplied to the battery 260. The synchronous rectification circuit 240 includes a plurality of bridge circuits. In the present embodiment, the synchronous rectification circuit 240 is a single-phase bridge rectifier that uses four MOSFETs (metal-oxide-semiconductor field-effect transistors) as rectifying elements. More specifically, the synchronous rectification circuit 240 includes two bridge circuits: a first bridge circuit 241 having a first high-side switch 241H and a first low-side switch 241L, and a second bridge circuit 242 having a second high-side switch 242H and a second low-side switch 242L. The single-phase bridge rectifier is sometimes also called a full-bridge circuit. Note that the synchronous rectification circuit 240 is not limited to a single-phase bridge rectifier, and for example, various full-wave rectifiers such as a three-phase bridge rectification circuit including three bridge circuits having six rectifying elements or a 12-phase rectification having a plurality of three-phase bridge rectification circuits may be used.

[0016] Each rectifier element is controlled by the control circuit 290 and switched by a gate signal generated, for example, by a bootstrap circuit. The current rectified by the synchronous rectifier circuit 240 is smoothed by the charging and discharging of a smoothing capacitor 250 connected in parallel with the battery 260. Note that the rectifier elements are not limited to MOSFETs, but may also be junction FETs (JFETs) or IGBTs (Insulated Gate Bipolar Transistors), and various switching elements having body diodes or parallel-connected diodes can be used. Body diodes are sometimes also called parasitic diodes or internal diodes. In the following description, the body diode of the first high-side switch 241H will also be called the "first high-side body diode," the body diode of the first low-side switch 241L will also be called the "first low-side body diode," the body diode of the second high-side switch 242H will also be called the "second high-side body diode," and the body diode of the second low-side switch 242L will also be called the "second low-side body diode."

[0017] A first voltage detection circuit 271 and a second voltage detection circuit 272 are connected to the synchronous rectifier circuit 240. In this embodiment, the first voltage detection circuit 271 is connected to both ends of the first low-side switch 241L and functions as a first voltage detection unit that detects the terminal voltage V11 of the first low-side switch 241L, i.e., the drain-source voltage (hereinafter also referred to as "DS voltage"). The second voltage detection circuit 272 is connected to both ends of the second low-side switch 242L and functions as a second voltage detection unit that detects the terminal voltage V12 of the second low-side switch 242L. The detection results of each DS voltage are output to the control circuit 290. As a result, the control circuit 290 can detect the rising edge of the terminal voltage at the first low-side switch 241L and the rising edge of the terminal voltage at the second low-side switch 242L. Alternatively, instead of the first low-side switch 241L, the first voltage detection circuit 271 may be connected to both ends of the first high-side switch 241H to detect the falling edge of the terminal voltage at the first high-side switch 241H, thereby detecting the DS voltage of the first high-side switch 241H. Furthermore, instead of the second low-side switch 242L, the second voltage detection circuit 272 may be connected to both ends of the second high-side switch 242H to detect the falling edge of the terminal voltage at the second high-side switch 242H, thereby detecting the DS voltage of the second high-side switch 242H.

[0018] As shown in Figure 1, in the power receiving device 200 of this embodiment, an output current detection circuit 274 is provided between the smoothing capacitor 250 and the battery 260. The output current detection circuit 274 is connected in series with the battery 260 and functions as a first current detection unit that detects the output current of the synchronous rectifier circuit 240. In the example in Figure 1, the output current of the synchronous rectifier circuit 240 is the output current I1 that has been smoothed by the smoothing capacitor 250. The output current I1 detected by the output current detection circuit 274 is output to the control circuit 290.

[0019] Battery 260 is an example of a load device that utilizes AC power induced in the power receiving resonant circuit 210. Battery 260 can be charged by supplying AC power obtained from the power receiving resonant circuit 210. The power charged in battery 260 is used, for example, in a device mounted on the power receiving device 200. In the example in Figure 1, the load device includes a synchronous rectifier circuit 240 and a smoothing capacitor 250. The load device is not limited to the synchronous rectifier circuit 240, smoothing capacitor 250, and battery 260, and various devices that utilize AC power output from the power receiving resonant circuit 210 can be applied.

[0020] The control circuit 290 is a microcomputer or logic circuit having a CPU (not shown) and memory such as ROM or RAM. The memory stores programs for realizing each of the functions provided in this embodiment, such as the functions of the control unit that controls the switching of each rectifier element of the synchronous rectifier circuit 240. The CPU loads these programs into RAM and executes them, thereby realizing some or all of these functions. The control circuit 290 can control the first bridge circuit 241 and the second bridge circuit 242 separately and independently.

[0021] The control circuit 290 includes a counter (not shown) for timing. In the following description, the counter used for timing in the switching control of the first bridge circuit 241 will also be referred to as the "first counter," and the counter used for timing in the switching control of the second bridge circuit 242 will also be referred to as the "second counter." The control circuit 290 may also be equipped with a clock instead of counters.

[0022] The switching control of rectifier elements in power supply control and power adjustment control performed by the control circuit 290 will be explained using Figures 3 to 6 as appropriate, along with Figure 2. The horizontal axis in Figure 2 is the time axis (unit: μsec.). The vertical axis shows the on / off status of each rectifier element, whether the body diodes in each rectifier element are energized or not, and the pulse counting results of the first counter and the second counter. The top row of Figure 2 schematically shows the timing of the "start," "half-period," and "one period" of the period in the switching control of the first bridge circuit 241. "One period" is the same as the operating frequency, and the output current from the immittance converter 230 reverses every half period. In this embodiment, "one period" coincides with 85 kHz as the power transmission frequency. Note that, for convenience, the first voltage detection circuit 271, the second voltage detection circuit 272, the output current detection circuit 274, and the control circuit 290 are omitted from Figures 3 to 6.

[0023] Prior to time T0 in Figure 2, the synchronous rectifier circuit 240 is in a non-opposing state where the receiving coil 212 and the transmitting coil 112 are not facing each other. In the non-opposing state, the synchronous rectifier circuit 240 waits with all rectifying elements turned off (open). When the receiving coil 212 and the transmitting coil 112 are in an opposing state, the receiving resonant circuit 210 receives AC power from the transmitting coil 112 via the receiving coil 212. At this time, the output current from the immittance converter 230 conducts the body diode of the first high-side switch 241H, as shown as signal S1 in Figure 2. As a result, at time T0, the terminal voltage of the first low-side switch 241L rises. The rise in the terminal voltage is detected by the first voltage detection circuit 271.

[0024] The control circuit 290 detects the energization of the first bridge circuit 241 by detecting the rising edge of the terminal voltage of the first low-side switch 241L from the detection result of the first voltage detection circuit 271. The control circuit 290 outputs a predetermined gate-source voltage (hereinafter also called "GS voltage") to the first high-side switch 241H and the second low-side switch 242L via the bootstrap circuit, switching the first high-side switch 241H and the second low-side switch 242L to ON (short-circuit). The switching control cycle of the first bridge circuit 241 starts from this point, and the control circuit 290 starts timing using the first counter. In the first cycle, the first low-side switch 241L and the second high-side switch 242H are in the OFF (open) state. From the second cycle onward, the first low-side switch 241L and the second high-side switch 242H are in the ON state, in which case the control circuit 290 switches to OFF.

[0025] As a result, as shown in Figure 3, current flows in the direction ID1 indicated by the arrow, and current flows to the smoothing capacitor 250 and the battery 260. As shown in Figures 2 and 3, the on / off state of each rectifier element during this period is also called the "first rectification mode M1". In Figures 3 to 6, rectifier elements in the ON (short-circuited) state are shown with solid lines, and rectifier elements in the OFF (open-circuited) state are shown with dashed lines.

[0026] If power adjustment control is not performed, the first rectification mode M1 switches to the second rectification mode M3 after half a cycle by the first counter or one cycle by the second counter, and thereafter the first rectification mode M1 and the second rectification mode M3 are repeated in the same manner. In contrast, as shown in Figure 2, when power adjustment control is performed, the control circuit 290 adjusts the length of the first commutation mode within one cycle by adjusting the timing of switching from the first rectification mode M1 to the first commutation mode. Power adjustment control is performed, for example, when the State of Charge (SOC) of the battery 260 is high, or when the amount of charge to the battery 260 is to be reduced, and the load device lowers the input current value or sets a reference current as a target value to raise the input current value that has already been lowered. The control circuit 290 calculates the duration of the first commutation mode using the current value detected by the output current detection circuit 274 and the reference current, and calculates the threshold value TH1 of the first counter corresponding to the duration of the first commutation mode. Furthermore, to determine the duration of the first commutation mode, a table showing the correspondence between the current value detected by the output current detection circuit 274 and the reference current and the duration of the first commutation mode may be used.

[0027] In this embodiment, as shown by arrow P1 in Figure 2, in the power adjustment control, the switching timing from the first rectification mode M1 to the first commutation mode is made shorter than half a period, i.e., half a predetermined power transmission frequency, thereby creating a period during which no current flows to the smoothing capacitor 250 and the battery 260. This makes the ON time of the first low-side switch 241L in the power adjustment control longer than half a period. With this configuration, compared to power adjustment control that switches from the first rectification mode to the first commutation mode at a timing exceeding half a period, the capacitance of the capacitor in the bootstrap circuit used to drive the gate of the first bridge circuit 241 can be reduced, and the size of the power receiving device 200 can be suppressed.

[0028] At time T1 shown in Figure 2, the count value of the first counter becomes greater than or equal to the threshold TH1, and the control circuit 290 switches the first high-side switch 241H to off (open) and switches the first low-side switch 241L to on (short-circuit). In this embodiment, in order to provide a so-called dead time, after the first high-side switch 241H has been switched off, the first low-side switch 241L is switched on at a predetermined interval of time T10. As a result, as shown in Figure 4, current flows in the direction ID2 indicated by the arrow, the input voltage becomes zero, and no current flows to the smoothing capacitor 250 and the battery 260. As shown in Figures 2 and 4, the state of each rectifier element during this period is also called the "first commutation mode M2".

[0029] The time T2 shown in Figure 2 is half a cycle in the switching control of the first bridge circuit 241 and corresponds to one cycle in the switching control of the second bridge circuit 242. In the first cycle, when the control circuit 290 detects that half a cycle has been reached in the switching control of the first bridge circuit 241 using the first counter, or one cycle in the switching control of the second bridge circuit 242 using the second counter, it switches the second low-side switch 242L to the off position. From the second cycle onward, the control circuit 290 turns off the second low-side switch 242L for each cycle determined by the second counter. In this embodiment, in order to provide a period during which the body diode of the second high-side switch 242H is conductive, the control circuit 290 switches off the second low-side switch 242L at a time T20 that is a predetermined interval shorter than the time T2 which is half a cycle.

[0030] At time T20, when the second high-side switch 242H and the second low-side switch 242L are in the off state, the output current from the immittance converter 230 conducts through the body diode of the second high-side switch 242H, as shown as signal S2 in Figure 2. As a result, at time T2, the terminal voltage of the second low-side switch 242L rises. This terminal voltage is detected by the second voltage detection circuit 272.

[0031] The control circuit 290 detects the energization of the second bridge circuit 242 by detecting the rising edge of the terminal voltage of the second low-side switch 242L from the detection result of the second voltage detection circuit 272. The control circuit 290 outputs a predetermined GS voltage to the first low-side switch 241L and the second high-side switch 242H, switching the first low-side switch 241L and the second high-side switch 242H to ON, and switching the first high-side switch 241H and the second low-side switch 242L to OFF. As shown in Figure 2, after the first commutation mode M2, the first high-side switch 241H is already OFF, and the first low-side switch 241L is already ON. As a result, as shown in Figure 5, current flows in the direction ID3 indicated by the arrow, and current flows to the smoothing capacitor 250 and the battery 260. The switching control period of the second bridge circuit 242 begins when the first low-side switch 241L and the second high-side switch 242H are switched on, and the control circuit 290 begins timing using the second counter. As shown in Figures 2 and 5, the state of each rectifier element during this period is also called the "second rectification mode M3".

[0032] If power adjustment control is not performed, the second rectification mode M3 is switched to the first rectification mode M1 after one cycle by the first counter or half a cycle by the second counter. In this disclosure, "one cycle" and "half a cycle" include the time when one cycle or half a cycle has elapsed, and the time when a predetermined interval has been moved forward or backward from one cycle or half a cycle to allow the dead time or body diode to conduct. As shown in Figure 2, when power adjustment control is performed, the control circuit 290 adjusts the length of the second commutation mode M4 within one cycle by adjusting the switching timing from the second rectification mode M3 to the second commutation mode. In this embodiment, the control circuit 290 determines the duration of the second commutation mode M4 using the current value detected by the output current detection circuit 274 and the reference current, similar to the duration of the first commutation mode M2, and determines the threshold TH1 of the second counter corresponding to the duration of the second commutation mode M4.

[0033] In this embodiment, as shown by arrow P2 in Figure 2, in power adjustment control, the switching timing from the second rectification mode M3 to the second commutation mode is made shorter than half the period of the power transmission frequency, thereby creating a period during which no current flows to the smoothing capacitor 250 and the battery 260. By configuring it in this way, the on time of the second low-side switch 242L in power adjustment control is made longer than half a period. By configuring it in this way, the increase in the capacitance of the bootstrap capacitor of the second bridge circuit 242 can be reduced, and the size of the power receiving device 200 can be suppressed.

[0034] At time T3 shown in Figure 2, the count value of the second counter becomes greater than or equal to the threshold TH1, and the control circuit 290 switches the second high-side switch 242H to the off position and the second low-side switch 242L to the on position. In this embodiment, in order to provide a dead time, the second low-side switch 242L is switched to the on position at a predetermined interval T30 after the second high-side switch 242H has been switched to the off position. As a result, as shown in Figure 6, current flows in the direction ID4 indicated by the arrow, the input voltage becomes zero, and no current flows to the smoothing capacitor 250 and the battery 260. As shown in Figures 2 and 6, the state of each rectifier element during this period is also called the "second commutation mode M4".

[0035] The first rectification mode M1 and the second rectification mode M3 are included in "power supply control," which supplies power to the load device, including the battery 260, by controlling the synchronous rectification circuit 240. The first commutation mode M2 ​​and the second commutation mode M4 correspond to "power adjustment control," which reduces the power supply by providing a period during which the current flowing to the load device is zero. The first commutation mode M2 ​​is switched from the first rectification mode M1, and the second commutation mode M4 is switched from the second rectification mode M3.

[0036] At time T4 shown in Figure 2, this corresponds to one cycle in the switching control of the first bridge circuit 241. When the control circuit 290 detects, for example, that one cycle has been reached by the first counter, it switches the first low-side switch 241L to the off position. Whether or not one cycle has been reached can be determined, for example, by whether or not the count value from the first counter has become equal to or greater than a predetermined threshold TH2 corresponding to one cycle.

[0037] Here, if the first low-side switch 241L remains ON, the body diode of the first high-side switch 241H does not conduct. Therefore, for example, if the first low-side switch 241L remains ON for more than one cycle, it may not be possible to detect the energization of the first bridge circuit 241, and periodic synchronous rectification operation may not be possible. In this embodiment, the control circuit 290 switches the first low-side switch 241L OFF every cycle corresponding to the power transmission frequency, thereby enabling more reliable periodic synchronous rectification operation than, for example, detecting the falling edge of the DS voltage of the first high-side switch 241H using a sensor and switching the first low-side switch 241L OFF. Furthermore, in this embodiment, the control circuit 290 also switches the first low-side switch 241L OFF at a time T40 that is a predetermined interval shorter than time T4, in order to provide a period during which the body diode of the first high-side switch 241H conducts.

[0038] When the output current from the immittance converter 230 conducts the body diode of the first high-side switch 241H, the control circuit 290 detects the energization of the first bridge circuit 241 and starts the second cycle of the first rectification mode M1, and repeats similarly thereafter. In the second cycle and beyond, as shown at time T5 in Figure 2, the control circuit 290 switches off the second low-side switch 242L by detecting one cycle using the second counter, for example, when the count value of the second counter becomes greater than or equal to the threshold TH2. This makes it possible to repeat periodic synchronous rectification operation more reliably than when, for example, a sensor is used to detect the falling edge of the DS voltage of the second high-side switch 242H and switch off the second low-side switch 242L. In this embodiment, in order to provide a period during which the body diode of the second high-side switch 242H conducts, the control circuit 290 switches off the second low-side switch 242L at a time T50 that is a predetermined interval shorter than the time T5 which is half a cycle.

[0039] As described above, the power receiving device 200 of this embodiment includes a power receiving resonant circuit 210 having a power receiving coil 212 and a resonant capacitor, a synchronous rectifier circuit 240 having a first bridge circuit 241 having a first high-side switch 241H and a first low-side switch 241L and a second bridge circuit 242 having a second high-side switch 242H and a second low-side switch 242L, and a control circuit 290 that controls the first bridge circuit 241 and the second bridge circuit 242. The control circuit 290 repeatedly performs power supply control by detecting the energization of the first bridge circuit 241, thereby turning on the first high-side switch 241H and the second low-side switch 242L and turning off the first low-side switch 241L and the second high-side switch 242H; and by detecting the energization of the second bridge circuit 242, thereby turning on the first low-side switch 241L and the second high-side switch 242H and turning off the first high-side switch 241H and the second low-side switch 242L. The control circuit 290 also performs power adjustment control including a first commutation mode M2 ​​in the first rectification mode M1, where the first high-side switch 241H is turned off and the first low-side switch 241L is turned on; and a second commutation mode M4 in the second rectification mode M3, where the second high-side switch 242H is turned off and the second low-side switch 242L is turned on. According to the power receiving device 200 of this embodiment, highly efficient power adjustment control can be performed by switching control that switches each rectifier element of the synchronous rectifier circuit 240 on and off. Therefore, power loss of the power receiving device 200 can be suppressed.

[0040] The power receiving device 200 of this embodiment further includes an output current detection circuit 274 for detecting the output current I1 of the synchronous rectification circuit 240. In power adjustment control, the control circuit 290 uses the detected value of the output current detection circuit 274 and the reference current as a target value requested by the load device to adjust the switching timing from the first rectification mode M1 to the first commutation mode M2 ​​and the switching timing from the second rectification mode M3 to the second commutation mode M4. Therefore, appropriate power supply based on the request from the load device can be performed.

[0041] The power receiving device 200 of this embodiment further includes a first voltage detection circuit 271 that detects the terminal voltage V11 of the first low-side switch 241L. The control circuit 290 acquires the detection result of the first voltage detection circuit 271 and detects the rising edge of the terminal voltage V11 at the first low-side switch 241L, thereby detecting the energization of the first bridge circuit 241. Power supply control and power adjustment control can be performed with a simple voltage detection configuration, and it is easy to make the configuration less expensive than that of a current sensor.

[0042] The power receiving device 200 of this embodiment further includes a second voltage detection circuit 272 for detecting the terminal voltage V12 at the second low-side switch 242L. The control circuit 290 acquires the detection result of the second voltage detection circuit 272 and detects the rising edge of the terminal voltage V12 at the second low-side switch 242L, thereby detecting the energization of the second bridge circuit 242. Power supply control and power adjustment control can be performed with a simple voltage detection configuration, and it is easy to make the configuration less expensive than that of a current sensor.

[0043] According to the power receiving device 200 of this embodiment, the control circuit 290 switches the first low-side switch 241L to the OFF position if it is ON at time T4, which is the time after one cycle corresponding to a predetermined power transmission frequency has elapsed since the first high-side switch 241H was turned ON in the first rectification mode M1. Since the first low-side switch 241L can be switched OFF at each cycle of the power transmission frequency, the periodic synchronous rectification operation can be reliably repeated compared to, for example, the case where the first low-side switch 241L is switched OFF by detecting the falling edge of the DS voltage of the first high-side switch 241H using a sensor or the like. Furthermore, in the power receiving device 200 of this embodiment, by switching the first low-side switch 241L OFF at a time T40 which is shorter than time T4, the body diode of the first high-side switch 241H can be made conductive before one cycle has elapsed, and the synchronous rectification operation at each cycle of the power transmission frequency can be repeated more reliably.

[0044] According to the power receiving device 200 of this embodiment, the control circuit 290 switches the second low-side switch 242L to the OFF position if it is ON at time T5, which is the time after one cycle corresponding to a predetermined power transmission frequency has elapsed since the second high-side switch 242H was turned ON in the second rectification mode M3. Since the second low-side switch 242L can be switched OFF at each cycle of the power transmission frequency, periodic synchronous rectification can be reliably repeated compared to, for example, detecting the falling edge of the DS voltage of the second high-side switch 242H using a sensor or the like. Furthermore, in the power receiving device 200 of this embodiment, by switching the second low-side switch 242L OFF at a time T50 which is shorter than time T5, the body diode of the second high-side switch 242H can be made to conduct before one cycle has elapsed, thereby more reliably repeating synchronous rectification for each cycle of the power transmission frequency.

[0045] In the power receiving device 200 of this embodiment, the control circuit 290 sets the switching timing from the first rectification mode M1 to the first commutation mode M2 ​​and the switching timing from the second rectification mode M3 to the second commutation mode M4 to be shorter than half a cycle of a predetermined power transmission frequency. Therefore, the on time of the first low-side switch 241L and the second low-side switch 242L in power adjustment control can be made longer than half a cycle. Compared to the case where the on time of the first high-side switch 241H and the second high-side switch 242H is made longer, the capacitance of the bootstrap capacitors in the first bridge circuit 241 and the second bridge circuit 242 can be reduced, and the size of the power receiving device 200 can be suppressed.

[0046] B. Second Embodiment: As shown in Figure 7, the power receiving device 200b according to the second embodiment differs from the power receiving device 200 of the first embodiment in that it further includes an input current detection circuit 276 and a control circuit 290b instead of a control circuit 290, but the other configurations are the same. In this embodiment, the control circuit 290b adjusts the switching timing from the first rectification mode M1 to the first commutation mode M2 ​​and the switching timing from the second rectification mode M3 to the second commutation mode M4 by peak current mode control. The figure shows an example in which, because the difference between the reference current and the output current I1 is large, feedback control is performed using peak current mode control to bring the output current I1 closer to the reference current.

[0047] The input current detection circuit 276 is positioned between the immittance converter 230 and the synchronous rectifier circuit 240 and functions as a second current detection unit that detects the input current of the synchronous rectifier circuit 240. The control circuit 290b includes, in addition to the functional configuration of the control circuit 290 in the first embodiment, a full-wave rectifier circuit 291, a first integrating circuit 292, a constant current control unit 293, a comparator 294, a switch signal generation circuit 296, and a reset circuit 299. As shown in the top row of Figure 8, the AC current waveform V1 detected by the synchronous rectifier circuit 240 is input to the full-wave rectifier circuit 291. The full-wave rectifier circuit 291 full-wave rectifies the input current waveform V1 and generates the current waveform V2 shown in Figure 8, which is output to the first integrating circuit 292. The full-wave rectifier circuit 291 can be any known full-wave rectifier circuit, such as a full-bridge circuit with four diodes.

[0048] The first integrating circuit 292 integrates the full-wave rectified current waveform V2 with respect to phase or time to generate the current waveform V3 shown in Figure 8. Since the waveform of current waveform V1 is a sine wave, the current waveform V3 is converted to a cosine wave by the integration of the first integrating circuit 292. In other words, the current waveform V2, which is represented as sin(x)sin(x), is converted to a current waveform V3 that is -cos(x) by integration. As the current waveform V2 shown in Figure 8 remains a sine wave, the current value increases and decreases with respect to the time axis, so it is not suitable for peak current mode control. In contrast, in this embodiment, any current waveform that shows an increasing trend with respect to the horizontal axis, such as the current waveform V3, can be used for peak current mode control.

[0049] The reset circuit 299 resets the calculation result of the first integrating circuit 292 at predetermined intervals. In this embodiment, the reset circuit 299 is set to reset the calculation result of the first integrating circuit 292 when it detects the rising edge H1 of the DS voltage of the first low-side switch 241L and the rising edge H2 of the DS voltage of the second low-side switch 242L, for example, as shown by waveforms R1 and R2 in Figure 8. With this configuration, the calculation result of the first integrating circuit 292 can be reset every half cycle of the power transmission frequency, and peak current mode control can be performed every half cycle in the switching control of the first bridge circuit 241 and the second bridge circuit 242.

[0050] The constant current control unit 293 outputs an output current V4 based on a comparison between the reference current requested from the load device and the output current I1 of the synchronous rectifier circuit 240 detected by the output current detection circuit 274. For example, when increasing the current flowing to the battery 260, the constant current control unit 293 outputs a large output current V4 to reduce the difference between the two, and when decreasing the current flowing to the battery 260, it outputs a small output current V4 to increase the difference between the two.

[0051] The comparator 294 compares the output current V4 with the current waveform V3, and outputs the H-level signal V5 shown in Figure 8 when the current waveform V3 is greater than or equal to the output current V4. The switch signal generation circuit 296 controls each switching element of the synchronous rectifier circuit 240. The switch signal generation circuit 296 also functions as a control unit that controls the switching of each rectifier element of the synchronous rectifier circuit 240 described above, and further performs switching control based on the H-level signal V5 to adjust the switching timing from the first rectification mode M1 to the first commutation mode M2, and from the second rectification mode M3 to the second commutation mode M4. Specifically, when the switch signal generation circuit 296 detects an H-level signal V5 in the first rectification mode M1, it turns off the first high-side switch 241H and turns on the first low-side switch 241L to switch to the first commutation mode M2. When it detects an H-level signal V5 in the first commutation mode M2, it turns off the second high-side switch 242H and turns on the second low-side switch 242L to switch to the second commutation mode M4. As shown in Figure 8, in peak current mode control, the output current V4 of the constant current control unit 293 is increased by increasing the reference current, so the periods TM1 to TM4 of the first commutation mode M2 ​​and the second commutation mode M4 are gradually shortened, and the input current of the battery 260 gradually increases.

[0052] The power receiving device 200 of this embodiment further includes an input current detection circuit 276 that detects a current waveform V1 which is the input current of the synchronous rectifier circuit 240, a full-wave rectifier circuit 291 that outputs a current waveform V2 obtained by full-wave rectifying the current waveform V1 detected by the input current detection circuit 276, and a first integrating circuit 292 that outputs a current waveform V3 obtained by integrating the current waveform V2 obtained by full-wave rectification by the full-wave rectifier circuit 291. The control circuit 290b adjusts the switching timing from the first rectification mode M1 to the first commutation mode M2 ​​and the switching timing from the second rectification mode M3 to the second commutation mode M4 by peak current mode control using the output current I1 and reference current, which are detected values ​​of the output current detection circuit 274, along with the current waveform V3 integrated by the first integrating circuit 292. With this form of power receiving device 200, the current waveform can be converted into a cosine wave that shows an increasing trend with respect to the time axis by the first integrating circuit 292, and peak current mode control can be performed. Therefore, the response performance and line regulation characteristics of the switching control circuit 290b can be improved. Consequently, even when the AC power received from the power transmission device 100 changes significantly, such as when the opposing state between the power transmission device 100 and the power receiving device 200 changes significantly, stable power supply control and power adjustment control can be performed. In addition, the influence of noise on the current waveform can be reduced by using the first integrating circuit 292.

[0053] C. Third Embodiment: As shown in Figure 9, the power receiving device 200c according to the third embodiment differs from the power receiving device 200b of the second embodiment shown in Figure 7 in that it includes a C current detection circuit 278 and a control circuit 290c instead of the input current detection circuit 276 and control circuit 290b, but the other configurations are the same. In the power receiving device 200b of the second embodiment, an example was shown in which the control circuit 290b performs peak current mode control using the input current of the synchronous rectifier circuit 240 detected by the input current detection circuit 276. In contrast, the power receiving device 200c according to the third embodiment performs peak current mode control using the output current of the synchronous rectifier circuit 240 detected by the C current detection circuit 278.

[0054] The C current detection circuit 278 is located on the output side of the synchronous rectifier circuit 240 and functions as a third current detection circuit that detects the output current of the synchronous rectifier circuit 240. As shown in Figure 9, when the power receiving device 200c is equipped with a smoothing capacitor 250, the C current detection circuit 278 is located between the smoothing capacitor 250 and the synchronous rectifier circuit 240. The output current of the synchronous rectifier circuit 240 detected by the C current detection circuit 278 is a full-wave rectified current waveform V2C, similar to the current waveform V2 of the input current of the synchronous rectifier circuit 240 shown in Figure 8, and is different from the current waveform V1 of the input current of the synchronous rectifier circuit 240.

[0055] The control circuit 290c differs from the control circuit 290b shown in the second embodiment in that it does not have a full-wave rectifier circuit 291 and has a second integrator circuit 292c instead of the first integrator circuit 292, but its other configurations are the same as the control circuit 290b. The second integrator circuit 292c has the same function as the first integrator circuit 292, and integrates the full-wave rectified current waveform V2C with respect to phase or time to output the current waveform V3 shown in Figure 8. Therefore, even with the power receiving device 200c of this embodiment, peak current mode control similar to that of the second embodiment can be performed.

[0056] According to the power receiving device 200c of this embodiment, the control circuit 290c performs peak current mode control using the output current I1 and reference current, which are detected values ​​of the output current detection circuit 274, along with the current waveform V3 integrated by the second integrating circuit 292c, to adjust the switching timing from the first rectification mode M1 to the first commutation mode M2, and the switching timing from the second rectification mode M3 to the second commutation mode M4, similar to the second embodiment described above. According to the power receiving device 200c of this embodiment, peak current mode control can be performed while the control circuit 290c has a simplified configuration in which the full-wave rectification circuit 291 is omitted.

[0057] D. Fourth Embodiment: As shown in Figure 10, the power receiving device 200d according to the fourth embodiment differs from the power receiving device 200b of the second embodiment shown in Figure 7 in that it includes a reactor voltage acquisition unit 297 and a control circuit 290d instead of the input current detection circuit 276 and control circuit 290b, but the other configurations are the same as those of the power receiving device 200b of the second embodiment. The power receiving device 200d according to the fourth embodiment performs peak current mode control using the voltage of the output side reactor of the immitance converter 230 detected by the reactor voltage acquisition unit 297.

[0058] In this embodiment, the reactor voltage acquisition unit 297 acquires the voltage of the output-side first reactor 234 as the output-side reactor of the immittance converter 230. More specifically, the reactor voltage acquisition unit 297 is a coil that acquires the voltage waveform obtained by magnetic coupling with the output-side first reactor 234. Figure 9 shows the state in which the receiving-side reactor voltage acquisition unit 297 is magnetically coupled to the output-side first reactor 234 by two parallel lines. The reactor voltage acquisition unit 297 can be formed, for example, by winding an electrical conductor around the core (iron core) of the output-side first reactor 234. Note that the reactor voltage acquisition unit 297 may acquire the voltage waveform of the output-side second reactor 238 instead of the output-side first reactor 234 as the output-side reactor of the immittance converter 230.

[0059] The control circuit 290d differs from the control circuit 290b shown in the second embodiment in that it further includes a third integrating circuit 298 and a fourth integrating circuit 292d instead of the first integrating circuit 292, but its other configurations are the same as the control circuit 290b. The third integrating circuit 298 integrates the voltage waveform of the output-side first reactor 234 acquired by the reactor voltage acquisition unit 297 with respect to phase or time and outputs it to the full-wave rectifier circuit 291. By integrating the voltage waveform of the output-side first reactor 234, a current waveform V1D that is approximately the same as the current flowing through the output-side first reactor 234 can be obtained. The full-wave rectifier circuit 291 full-wave rectifies the input current waveform V1D and generates the current waveform V2 shown in Figure 8. The fourth integrating circuit 292d, similar to the first integrating circuit 292, integrates the current waveform V2 with respect to phase or time and outputs the current waveform V3, and thereafter, peak current mode control similar to the second embodiment is performed.

[0060] As described above, in the power receiving device 200d of this embodiment, the control circuit 290d performs peak current mode control using the output current I1 and reference current, which are detected values ​​of the output current detection circuit 274, along with the current waveform V3 obtained by integrating the current waveform V2 acquired by the reactor voltage acquisition unit 297 and full-wave rectified by the full-wave rectifier circuit 291, with the fourth integrating circuit 292d. Similar to the second embodiment, it adjusts the switching timing from the first rectification mode M1 to the first commutation mode M2, and the switching timing from the second rectification mode M3 to the second commutation mode M4. According to the power receiving device 200d of this embodiment, the current of the power receiving device 200d can be detected by a simple configuration, such as wrapping an electrical conductor around the core (iron core) of the output-side first reactor 234, and peak current mode control can be performed without providing a current sensor.

[0061] E. Fifth Embodiment: As shown in Figure 11, the power receiving device 200e according to the fifth embodiment differs from the power receiving device 200b of the second embodiment shown in Figure 7 in that it includes an input voltage detection circuit 277 and a control circuit 290e instead of the input current detection circuit 276 and control circuit 290b, but the other configurations are the same. The power receiving device 200e according to the fifth embodiment performs peak current mode control using the input voltage V1E of the synchronous rectifier circuit 240 detected by the input voltage detection circuit 277.

[0062] The input voltage detection circuit 277 is positioned between the power receiving resonant circuit 210 and the immittance converter 230, and detects the input voltage of the immittance converter 230. Here, the immittance converter 230 appears as a constant current source from the output side and outputs a constant current proportional to the input voltage. Therefore, by obtaining the input voltage V1E of the immittance converter 230 instead of the output current from the immittance converter 230 (the input current to the synchronous rectifier circuit 240), peak current mode control can be performed in the same manner as in the second embodiment.

[0063] The control circuit 290e includes a fifth integrating circuit 292e that has the same function as the first integrating circuit 292. The full-wave rectifier circuit 291 outputs a current waveform V2 obtained by full-wave rectifying the input voltage V1E, and the fifth integrating circuit 292e outputs a current waveform V3 by integrating the current waveform V2 with respect to phase or time T0, similar to the second embodiment.

[0064] In this manner, the control circuit 290e adjusts the switching timing from the first rectification mode M1 to the first commutation mode M2 ​​and the switching timing from the second rectification mode M3 to the second commutation mode M4 by peak current mode control using the input voltage V1E of the immittance converter 230. Even with this configuration of the power receiving device 200e, the same effects as in the second embodiment can be obtained.

[0065] F. Other embodiments: (F1) In each of the above embodiments, as shown in Figure 1, an example is shown in which a resonant circuit using a primary series secondary series capacitor (also called the "SS method") is applied to the power transmission resonant circuit 110 and the power receiving resonant circuit 210. In contrast, as shown in Figure 12, the power transmission resonant circuit 110f may be a parallel resonant circuit in which the power transmission resonant capacitor 114f is connected in parallel with the power transmission coil 112, and a primary parallel secondary series method (also called the "PS method") may be applied to the power transmission resonant circuit 110f and the power receiving resonant circuit 210. Also, as shown in Figure 13, the power transmission resonant circuit 110g may include a power transmission resonant capacitor 114g1 connected in parallel with the power transmission coil 112 and a power transmission resonant capacitor 114g2 connected in series with the power transmission coil 112, and a primary parallel series secondary series method (also called the "PSS method") may be applied to the power transmission resonant circuit 110g and the power receiving resonant circuit 210. Furthermore, as shown in Figure 14, the power transmission device 100 may also be provided with a tertiary resonant circuit 310h, which is a circuit independent of the power transmission resonant circuit 110, and in which a tertiary coil 312 and a tertiary resonant capacitor 314 are connected in series. The tertiary resonant circuit 310h is arranged so that the tertiary coil 312 is magnetically coupled to the power transmission coil 112 and the power receiving coil 212, respectively. Alternatively, the tertiary resonant circuit 310h may be configured such that the tertiary coil 312 and the tertiary resonant capacitor 314 are connected in parallel. Also, as shown in Figure 15, the power transmission device 100 may have a tertiary resonant circuit 310i, in which a tertiary coil 312i and a tertiary resonant capacitor 314i are connected in parallel, connected in series with the power transmission coil 112. The tertiary resonant circuit 310i is arranged so that the tertiary coil 312i is magnetically coupled to the power transmission coil 112 and the power receiving coil 212, respectively.

[0066] (F2) In each of the above embodiments, an example was shown in which a first voltage detection circuit 271 is provided to detect the energization of the first bridge circuit 241 by detecting the terminal voltage V11 of the first low-side switch 241L, and a second voltage detection circuit 272 is provided to detect the energization of the second bridge circuit 242 by detecting the terminal voltage V12 of the second low-side switch 242L. In contrast, the power receiving device 200 may be provided with or in conjunction with the first voltage detection circuit 271 to detect the energization of the first bridge circuit 241 by providing a current sensor that detects the energization of the body diode of the first high-side switch 241H. Also, a current sensor may be provided with or in conjunction with the second voltage detection circuit 272 to detect the energization of the second bridge circuit 242 by providing a current sensor that detects the energization of the body diode of the second high-side switch 242H. For example, current sensors can be provided downstream of the first high-side switch 241H and downstream of the second high-side switch 242H. Even with this configuration, it is possible to detect the energization of the first bridge circuit 241 and the second bridge circuit 242.

[0067] (F3) In each of the above embodiments, the control circuit 290 is shown to switch the first high-side switch 241H to ON and the second high-side switch 242H to ON by detecting the rising edge of the DS voltage of the first low-side switch 241L and the second low-side switch 242L. In contrast, the control circuit 290 may also switch the first high-side switch 241H to ON and the second high-side switch 242H to ON by detecting the falling edge of the DS voltage of the first high-side switch 241H and the second high-side switch 242H. In this case, the first voltage detection circuit 271 is connected to both ends of the first high-side switch 241H, and the second voltage detection circuit 272 is connected to both ends of the second high-side switch 242H. Even with this configuration, the same effects as in each of the above embodiments can be obtained.

[0068] (F4) In each of the above embodiments, the control circuit 290 is shown in an example where both the switching timing from the first rectification mode M1 to the first commutation mode M2 ​​and the switching timing from the second rectification mode M3 to the second commutation mode M4 are shorter than half a period of the predetermined power transmission frequency. In contrast, only one of the timings may be shorter than half a period of the power transmission frequency.

[0069] (F5) In each of the above embodiments, the control circuit 290 is shown to repeat periodic synchronous rectification operation in the first bridge circuit 241 by switching off the first low-side switch 241L every period corresponding to the power transmission frequency after the first high-side switch 241H is turned on in the first rectification mode M1. In contrast, the power receiving device 200 may also be provided with a first period detector that detects the period of the current waveform or voltage waveform in the first bridge circuit 241. In this case, the control circuit 290 may switch off the first low-side switch 241L by detecting the passage of one period of the current waveform or voltage waveform in power supply control from the detection result of the first period detector. Even with this form of power receiving device 200, periodic synchronous rectification operation can be repeated more reliably than when the falling edge of the DS voltage of the first high-side switch 241H is detected using a sensor or the like.

[0070] (F6) In each of the above embodiments, the control circuit 290 is shown to repeat periodic synchronous rectification operation in the second bridge circuit 242 by switching the second low-side switch 242L off every period corresponding to the power transmission frequency after the second high-side switch 242H is turned on in the second rectification mode M3. In contrast, the power receiving device 200 may also be provided with a second period detector that detects the period of the current waveform or voltage waveform in the second bridge circuit 242. In this case, the control circuit 290 may switch the second low-side switch 242L off by detecting the passage of one period of the current waveform or voltage waveform in power supply control from the detection result of the second period detector. Even with this form of power receiving device 200, periodic synchronous rectification operation can be repeated more reliably than when the falling edge of the DS voltage of the second high-side switch 242H is detected using a sensor or the like.

[0071] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium.

[0072] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0073] 100...Transmission device, 200, 200b, 200c, 200d, 200e...Power receiving device, 210...Power receiving resonant circuit, 212...Power receiving coil, 214...Power receiving resonant capacitor, 240...Synchronous rectifier circuit, 241...First bridge circuit, 241H...First high-side switch, 241L...First low-side switch, 242...Second bridge circuit, 242H...Second high-side switch, 242L...Second low-side switch, 290, 290b, 290c, 290d, 290e...Control circuit, M1...First rectification mode, M2...First commutation mode, M3...Second rectification mode, M4...Second commutation mode

Claims

1. A power receiving device (200, 200b, 200c, 200d, 200e) that receives AC power transmitted from a power transmission device (100) in a contactless manner and supplies it to a load device, A power receiving resonant circuit (210) having a power receiving coil (212) and a resonant capacitor (214) for causing the power receiving coil to resonate, A synchronous rectifier circuit (240) has a plurality of bridge circuits, including a first bridge circuit (241) having a first high-side switch (241H) and a first low-side switch (241L), and a second bridge circuit (242) having a second high-side switch (242H) and a second low-side switch (242L), and converts the AC power received by the power receiving coil into DC power, The system includes control units (290, 290b, 290c, 290d, 290e) that control the plurality of bridge circuits, The control unit, A first rectification mode (M1) is in which the first high-side switch and the second low-side switch are turned on and the first low-side switch and the second high-side switch are turned off by detecting the energization of the first bridge circuit, By detecting the energization of the second bridge circuit, a power supply control is performed that repeatedly switches the first low-side switch and the second high-side switch on, and then switches the first high-side switch and the second low-side switch off in a second rectification mode (M3). In the first rectification mode, there is a first commutation mode (M2) in which the first high-side switch is turned off and the first low-side switch is turned on, In the second rectification mode, power adjustment control is performed, which includes a second commutation mode (M4) in which the second high-side switch is turned off and the second low-side switch is turned on. Power receiving device.

2. A power receiving device according to claim 1, Furthermore, it includes a first current detection unit (274) for detecting the output current of the synchronous rectifier circuit, The control unit, In the power adjustment control described above, the switching timing from the first rectification mode to the first commutation mode and the switching timing from the second rectification mode to the second commutation mode are adjusted using the detected value (I1) of the first current detection unit and the reference current. Power receiving device.

3. A power receiving device according to claim 1, Furthermore, it includes a first voltage detection unit (271) for detecting the terminal voltage (V11) of the first high-side switch or the terminal voltage (V11) of the first low-side switch, The control unit, The detection result of the first voltage detection unit is obtained, and the current flow of the first bridge circuit is detected by detecting the falling edge of the terminal voltage at the first high-side switch or the rising edge of the terminal voltage at the first low-side switch. Power receiving device.

4. A power receiving device according to claim 1, Furthermore, it includes a second voltage detection unit (272) that detects the terminal voltage (V12) of the second high-side switch or the terminal voltage (V12) of the second low-side switch. The control unit, The detection result of the second voltage detection unit is obtained, and the current flow of the second bridge circuit is detected by detecting the falling edge of the terminal voltage at the second high-side switch or the rising edge of the terminal voltage at the second low-side switch. Power receiving device.

5. A power receiving device according to claim 1, Furthermore, the circuit includes a first period detector for detecting the period of the current waveform or voltage waveform in the first bridge circuit. The control unit, by detecting the completion of one cycle in the power supply control using the first cycle detector, switches the first low-side switch to the OFF position. Power receiving device.

6. A power receiving device according to claim 5, Furthermore, the circuit includes a second period detector that detects the period of the current waveform or voltage waveform in the second bridge circuit. The control unit, by detecting the completion of one cycle in the power supply control using the second cycle detector, switches the second low-side switch to the OFF position. Power receiving device.

7. A power receiving device according to claim 1, The control unit switches the first low-side switch to the off position at a time shorter than the time elapsed after the first high-side switch is turned on in the first rectification mode, corresponding to one cycle corresponding to a predetermined power transmission frequency. Power receiving device.

8. A power receiving device according to claim 7, The control unit switches the second low-side switch to the off position at a time shorter than the time elapsed from the time the second high-side switch is turned on in the second rectification mode until one cycle corresponding to the power transmission frequency has elapsed. Power receiving device.

9. A power receiving device according to claim 1, The control unit makes at least one of the switching timing from the first rectification mode to the first commutation mode and the switching timing from the second rectification mode to the second commutation mode shorter than half the period of a predetermined power transmission frequency. Power receiving device.

10. A power receiving device according to claim 2, Furthermore, a second current detection unit (276) for detecting the input current of the synchronous rectifier circuit, A full-wave rectifier circuit (291) that full-wave rectifies the input current detected by the second current detection unit, The system includes a first integrating circuit (292) that integrates the current waveform rectified by the full-wave rectifier circuit, The control unit, By using the current waveform integrated by the first integrating circuit along with the detected value of the first current detection unit and the reference current, peak current mode control is performed. The timing for switching from the first rectification mode to the first commutation mode and the timing for switching from the second rectification mode to the second commutation mode are adjusted. Power receiving device.

11. A power receiving device according to claim 2, Furthermore, a third current detection circuit (278) that detects the output current of the synchronous rectifier circuit, The system includes a second integrating circuit (292c) that integrates the current waveform of the output current detected by the third current detection circuit, The control unit, By using the current waveform integrated by the second integrating circuit along with the detected value of the first current detection unit and the reference current, peak current mode control is performed. The timing for switching from the first rectification mode to the first commutation mode and the timing for switching from the second rectification mode to the second commutation mode are adjusted. Power receiving device.

12. A power receiving device according to claim 2, Furthermore, an immitance converter (230) is arranged between the power receiving resonant circuit and the synchronous rectifier circuit, A third integrating circuit (298) that integrates the voltage waveform obtained by magnetic coupling with the output reactors (234, 238) of the immitance converter and outputs it as a current waveform, A full-wave rectifier circuit (291) that full-wave rectifies the current waveform output from the third integrating circuit, The system includes a fourth integrating circuit (292d) that integrates the current waveform rectified by the full-wave rectifier circuit, The control unit, By using the current waveform integrated by the fourth integrating circuit, along with the detected value of the first current detection unit and the reference current, peak current mode control is performed. The timing for switching from the first rectification mode to the first commutation mode and the timing for switching from the second rectification mode to the second commutation mode are adjusted. Power receiving device.

13. A power receiving device according to claim 2, Furthermore, an immitance converter (230) is arranged between the power receiving resonant circuit and the synchronous rectifier circuit, A voltage detection circuit (270) for detecting the input voltage of the immitance converter, A full-wave rectifier circuit (291) that full-wave rectifies the voltage waveform of the input voltage detected by the voltage detection circuit, The system includes a fifth integrating circuit (292e) that integrates the current waveform rectified by the full-wave rectifier circuit, The control unit, By using the current waveform integrated by the fifth integrating circuit along with the detected value of the first current detection unit and the reference current, peak current mode control is performed. The timing for switching from the first rectification mode to the first commutation mode and the timing for switching from the second rectification mode to the second commutation mode are adjusted. Power receiving device.

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