Power transmission device and program

Abstract

A power transmission device (100), which supplies power in a non-contact manner to a power receiving device (200) having a power receiving coil (212), is provided with: a power transmission coil (112); a power transmission resonance circuit (110) having a power transmission resonance capacitor (114) connected in parallel with the power transmission coil; a third-stage resonance circuit (310); and a power transmission control unit (180) that controls the three-stage resonant switching element. The third-stage resonance circuit (310) includes: a third-stage coil (312); a third-stage resonant capacitor (314) connected in parallel with the third-stage coil; and a third-stage resonant switching element (316) connected in parallel with the third-stage coil. The three-stage resonant switching element switches the resonant state and the non-resonant state of the three-stage resonant circuit. When switching from a power-on state in which power is supplied to the power receiving device to a standby state in which power is not supplied to the power receiving device, the power transmission control unit short-circuits the third-stage resonant switching element and switches the third-stage coil and the third-stage resonant capacitor to a non-resonant state.

Description

Citation of related applications

[0001] This application is based on Japanese Patent Application No. 2022-109648 filed on July 7, 2022, and the contents thereof are incorporated herein by reference. Technical Field

[0002] The present disclosure relates to a power transmission device and a program. Background Art

[0003] A power transmission device is known that reduces the input impedance in a relative state where the power receiving coil and the power transmitting coil are relative to each other to supply power from the power transmitting device to the power receiving device, and increases the input impedance of the power transmission resonance circuit in a non-relative state, thereby suppressing the current supply from the power transmitting device to the power receiving device (for example, Japanese Patent Publication No. 2021-23094). In this power transmission device, a semiconductor element such as a bidirectional switch is used as a switching circuit, and the input impedance of the power transmission resonance circuit is switched by switching the semiconductor element. Summary of the invention

[0004] However, in the conventional structure, a protection circuit is sometimes required, for example, to prevent a failure of a semiconductor element in the on state, so-called a short circuit failure, from inducing failure of other components of the power transmission device. In this case, an increase in the number of components of the power transmission device or an increase in size becomes a problem.

[0005] The present disclosure is made to solve at least a part of the above-mentioned technical problems and can be implemented as the following aspects or application examples.

[0006] According to one embodiment of the present disclosure, there is provided a power transmission device that supplies power to a power receiving device having a power receiving coil in a non-contact manner. The power transmission device includes a power transmission resonance circuit, a three-level resonance circuit, and a power transmission control unit. The power transmission resonance circuit includes a power transmission coil magnetically coupled to the power receiving coil and a power transmission resonance capacitor connected in series with the power transmission coil. The three-level resonance circuit includes: a three-level coil magnetically coupled to the power transmission coil and the power receiving coil; a three-level resonance capacitor connected in parallel with the three-level coil; and a three-level resonance switching element connected in parallel with the three-level coil, and switches the resonance state and non-resonance state of the three-level resonance circuit by switching the opening and short circuit of the three-level resonance switching element. The power transmission control unit controls the three-level resonance switching element. When switching from a power-on state in which power is supplied to the power receiving device to a standby state in which power is not supplied to the power receiving device, the power transmission control unit short-circuits the three-level resonance switching element and switches the three-level coil and the three-level resonance capacitor to a non-resonance state.

[0007] According to the power transmission device of this mode, by short-circuiting the three-stage resonance switching element, the three-stage coil and the three-stage resonance capacitor can be placed in a non-resonant state. Therefore, even in the case of a short-circuit failure of the three-stage resonance switching element, damage to other structural elements of the power transmission device can be suppressed or prevented without providing a protection circuit or the like. Therefore, an increase in the number of components of the power transmission device or an increase in size can be suppressed or prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. Figure 1 1 is a schematic diagram showing the configuration of the power transmission device according to the first embodiment. Figure 2 It is a schematic configuration diagram showing a power transmission device according to a second embodiment. Figure 3 It is a schematic configuration diagram showing a power transmission device according to a third embodiment. DETAILED DESCRIPTION

[0009] A. First Implementation Method: like Figure 1 As shown, the contactless power supply system includes the power transmission device 100 of the first embodiment and the power receiving device 200 to which power is supplied in a contactless manner from the power transmission device 100. The power receiving device 200 is installed in various devices that operate using power, such as electronic equipment and electric vehicles. The power receiving device 200 includes a power receiving resonance circuit 210, a power receiving circuit 220, and a battery 230.

[0010] 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 with the power receiving coil 212. In the power receiving resonance circuit 210, for example, a resonance method (also referred to as "SS method") realized by a primary series and a secondary series capacitor is applied. The power receiving resonance circuit 210 is a resonance circuit that obtains AC power induced by the power receiving coil 212 in a state of resonance coupling in which the power receiving coil 212 is magnetically coupled to the power transmitting coil 112.

[0011] The power receiving circuit 220 converts the AC power output from the power receiving resonance circuit 210 into DC power. The power receiving circuit 220 includes, for example, a filter circuit, a rectifier circuit for converting the AC power into DC power, and a power conversion circuit for converting the AC power into DC power suitable for charging the battery 230. The DC power output from the power receiving circuit 220 can be used for charging the battery 230, etc.

[0012] The power transmission device 100 includes a power transmission resonance circuit 110, a three-stage resonance circuit 310, and a power transmission control unit 180. Figure 1In the example of , the power transmission device 100 further includes a current sensor 118, a power supply circuit 140, a power transmission circuit 130, and a magnetic flux detection unit 170. The power supply circuit 140 is, for example, an AC / DC conversion circuit, which converts AC power from an AC power supply such as a system power supply into DC power and supplies it to the power transmission circuit 130. The power transmission circuit 130 is a device including an inverter, etc., which converts the DC power supplied from the power supply circuit 140 into AC power of a predetermined operating frequency (angular frequency) and supplies it to the power transmission resonance circuit 110. The power transmission circuit 130 may further include a rectifier circuit, a filter circuit, etc.

[0013] The power transmission resonance circuit 110 transmits AC power induced by the power transmission coil 112 to the power receiving resonance circuit 210 of the power receiving device 200 by using electromagnetic induction. The power transmission resonance circuit 110 includes the power transmission coil 112 and a power transmission resonance capacitor 114 connected in series to the power transmission coil 112.

[0014] The power transmission resonant capacitor 114 is a resonant capacitor for resonating the power supplied to the power transmission coil 112. In the present embodiment, the power transmission resonant capacitor 114 includes: a first capacitor 114t; a power transmission switching element 116 connected in series with the first capacitor 114t; and a second capacitor 114s connected in parallel with the first capacitor 114t and the power transmission switching element 116. The power transmission resonant capacitor 114 is a variable capacitor whose capacitance can be changed according to the on / off switching of the power transmission switching element 116.

[0015] The power transmission switching element 116 functions as a current switching unit for switching the magnitude of the current flowing through the power transmission resonance circuit 110. In the present embodiment, the power transmission switching element 116 is a semiconductor element for controlling current, such as an IGBT, a MOSFET, or a FET, and switches the input impedance Z1 of the power transmission resonance circuit 110 under the control of the power transmission control unit 180. Figure 1 As shown, in this embodiment, the power transmission switching element 116 is composed of a bidirectional switch. The method of switching the magnitude of the current flowing through the power transmission resonance circuit 110 as the current switching unit is not limited to the method of switching the value of the input impedance, and may also be a method of switching the capacitance, turning on and off the power supply, etc. In addition, the power transmission switching element 116 is not limited to a bidirectional switch, and may also be a unidirectional switch.

[0016] The capacitance of the second capacitor 114s is set to a value smaller than the capacitance of the first capacitor 114t. The first capacitor 114t is connected in parallel with the second capacitor 114s when the power transmission switching element 116 is short-circuited (on), and is open when the power transmission switching element 116 is open (off). Therefore, the capacitance of the power transmission resonance capacitor 114 is the value of the capacitance of the second capacitor 114s when the power transmission switching element 116 is open, and is the sum of the capacitance of the first capacitor 114t and the capacitance of the second capacitor 114s when the power transmission switching element 116 is short-circuited.

[0017] The sum of the capacitance of the first capacitor 114t and the capacitance of the second capacitor 114s is set using the angular frequency of the pre-determined operating frequency for the resonance of the power transmission resonant capacitor 114 and the power transmission coil 112. The capacitance of the power transmission resonant capacitor 114 when supplying power to the power receiving device 200 only needs to be set to the self-inductance resonance with respect to the power transmission coil 112, so it can be set to a relatively small value. Therefore, the capacitance of the first capacitor 114t and the capacitance of the second capacitor 114s used for the power transmission resonant capacitor 114 can be set to relatively small values, and the size of the capacitor can be suppressed. The capacitance of the second capacitor 114s determines the standby current flowing through the power transmission coil 112 when no power is supplied.

[0018] The current sensor 118 detects the current value I1 flowing through the power transmission resonant circuit 110. The detection result of the current sensor 118 is used to determine whether the power transmission coil 112 and the power receiving coil 212 are in a relative state or a non-relative state. In addition, since the voltage applied to the power transmission coil 112 also changes in the same way as the current, a voltage sensor for detecting the voltage value V1 applied to the power transmission coil 112 may be provided instead of the current sensor 118. In addition, a magnetic flux detection element such as a magnetic sensor or a coil that detects the magnetic field (magnetic flux) near the power transmission coil 112 may be provided instead of the current sensor 118. A relatively small inductance such as a shunt resistor or a wiring inductance may be configured instead of the current sensor 118 or together with it, and the voltage generated in the power transmission resonant capacitor 114 due to the current flowing through the power transmission coil 112 may be detected instead of the current value or together with it.

[0019] like Figure 1As shown, the three-stage resonant circuit 310 is a parallel resonant circuit of the so-called primary parallel secondary series method (also called "PS method") in which a three-stage coil 312 and a three-stage resonant capacitor 314 are connected in parallel. In the present embodiment, the three-stage resonant circuit 310 is a circuit independent of the power transmission resonant circuit 110. The three-stage resonant circuit 310 includes: a three-stage coil 312; a three-stage resonant capacitor 314 connected in parallel with the three-stage coil 312 as a resonant capacitor; and a three-stage resonant switching element 316 connected in parallel with the three-stage coil 312. The three-stage resonant circuit 310 is configured so that the three-stage coil 312 is in a state of being magnetically coupled with the power transmission coil 112 and the power receiving coil 212, respectively. In addition, in Figure 1 In the figure, two parallel straight lines are used to indicate that the coils are in a state of mutual magnetic coupling.

[0020] In the present embodiment, the three-stage resonant circuit 310 includes a current sensor 318. The current sensor 318 detects the current value flowing through the three-stage resonant circuit 310. The detection result of the current sensor 318 is used to determine whether the power transmission coil 112 and the power receiving coil 212 are in a relative state or a non-relative state. In addition, instead of the current sensor 318, a voltage sensor that detects the voltage value applied to the three-stage resonant circuit 310, a magnetic sensor that detects the magnetic flux generated in the three-stage resonant circuit 310, etc. may be applied. In the present embodiment, an example is shown in which the power transmission device 100 includes both the current sensor 118 and the current sensor 318, but it may include only one of the current sensor 118 and the current sensor 318.

[0021] The tertiary resonance switching element 316 is a semiconductor element for controlling current, such as an IGBT, a MOSFET, or a FET, and switches the resonant state and the non-resonant state of the tertiary coil 312 and the tertiary resonance capacitor 314 by changing the impedance of the tertiary coil 312 and the tertiary resonance capacitor 314. The tertiary resonance switching element 316 is controlled by the power transmission control unit 180. In addition, in the present disclosure, the resonant state is not limited to the state in which the resonant capacitor and the coil resonate, but also includes the state in which the resonant capacitor and the coil can resonate in the circuit structure.

[0022] For example, when the three-stage resonance switching element 316 is connected in series with the three-stage coil 312 and the three-stage resonance capacitor 314, if the three-stage resonance switching element 316 as a semiconductor element fails in the on state due to being closed and fixed, that is, a so-called short-circuit failure occurs, the three-stage resonance circuit 310 is fixed in the resonance state. In this case, for example, if another power transmission coil 112 exists near one power transmission coil 112 and the other power transmission coil 112 starts to supply power to the power receiving coil 212, the magnetic flux generated by the other power transmission coil 112 may be amplified by the three-stage resonance circuit 310. As a result, the leakage electromagnetic field (EMF: Electromagnetic Fields) in the three-stage resonance circuit 310 may increase, or the voltage in the three-stage coil 312 may increase. In addition, in this state, when the other power transmission coil 112 is magnetically coupled to the one power transmission coil 112, the voltage applied to the one power transmission coil 112 increases, and a voltage exceeding the rated value may be applied to the semiconductor element such as the power transmission switching element 116, thereby inducing a short-circuit failure.

[0023] In the present embodiment, when the tertiary resonance switching element 316 is short-circuited (on), the tertiary coil 312 and the tertiary resonance capacitor 314 can be in a non-resonant state, and when the tertiary resonance switching element 316 is open (off), the tertiary coil 312 and the tertiary resonance capacitor 314 can be in a resonant state. Therefore, for example, even if a short-circuit failure occurs in the tertiary resonance switching element 316, since the tertiary resonance circuit 310 is fixed in a non-resonant state, failures of various parts of the power transmission device 100 such as a short-circuit failure of the power transmission switching element 116 can be suppressed or prevented.

[0024] The magnetic flux detection unit 170 detects the magnetic flux generated near the power transmission coil 112. In the power transmission device 100, an AC voltage supplied from the power transmission circuit 130 is applied between the terminals of the power transmission coil 112, and a magnetic flux corresponding to the AC standby current flowing through the power transmission coil 112 is generated. When the power receiving device 200 approaches the power transmission device 100 in this state and becomes an opposing state, magnetic coupling is generated between the power receiving coil 212 and the power transmission coil 112, and the power receiving coil 212 generates an induced magnetic flux as the degree of coupling increases. The induced magnetic flux increases the magnetic flux interlinked with the power transmission coil 112. The detection result of the magnetic flux detection unit 170 is output to the power transmission control unit 180.

[0025] The power transmission control unit 180 is a microcomputer or a logic circuit having a CPU and a memory (not shown). The power transmission control unit 180 obtains the detection results of the magnetic flux detection unit 170, the current sensor 118, and the current sensor 318, and controls the power transmission switching element 116 and the three-stage resonance switching element 316 to be turned on and off according to the obtained results.

[0026] The power transmission control unit 180 determines that the power transmission coil 112 and the power receiving coil 212 are in a relative state when it detects that the magnetic flux near the power transmission coil 112 has increased to above a certain value, for example by comparing the detection result of the magnetic flux detection unit 170 on the magnetic flux interlinked with the power transmission coil 112 with a predetermined threshold value.

[0027] When it is determined that the power transmission control unit 180 is in the relative state, the power transmission control unit 180 switches the power transmission device 100 to the power-on state. More specifically, the power transmission control unit 180 short-circuits the power transmission switching element 116 to increase the capacitance of the power transmission resonance capacitor 114, thereby switching the input impedance Z1 of the power transmission resonance circuit 110 to a smaller value, thereby switching to a state in which a large current for power supply flows through the power transmission resonance circuit 110, and opens the three-stage resonance switching element 316 to switch the three-stage coil 312 and the three-stage resonance capacitor 314 to a resonance state. As a result, the power transmission device 100 is in the power-on state, and power is supplied from the power transmission coil 112 to the power receiving coil 212. The power receiving resonance circuit 210 receives the AC power induced from the power transmission device 100 to the power receiving coil 212 in a non-contact manner in a state in which the power receiving coil 212 is magnetically coupled to the power transmission coil 112.

[0028] The power transmission control unit 180 detects that the current flowing through the power transmission coil 112 has decreased to less than a certain value by comparing the detection result of the current value flowing through the power transmission resonance circuit 110 by the current sensor 118 with a predetermined threshold value, and determines that the power transmission coil 112 and the power receiving coil 212 are in a non-opposite state. Instead of or in addition to the current sensor 118, the power transmission coil 112 and the power receiving coil 212 may be determined to be in a non-opposite state by comparing the detection result of the current value flowing through the three-stage resonance circuit 310 by the current sensor 318 with a predetermined threshold value.

[0029] When it is determined that the power transmission control unit 180 is in the non-relative state, the power transmission control unit 180 switches the power transmission device 100 to the standby state. More specifically, the power transmission control unit 180 switches the input impedance Z1 of the power transmission resonance circuit 110 to a larger value by opening the power transmission switching element 116 to reduce the capacitance of the power transmission resonance capacitor 114, thereby switching to a state in which a small current for standby flows through the power transmission resonance circuit 110, and short-circuits the three-stage resonance switching element 316 to switch the three-stage coil 312 and the three-stage resonance capacitor 314 to a non-resonant state. As a result, the power transmission device 100 enters a standby state in which a standby current flows through the power transmission coil 112, and stops the power supply from the power transmission coil 112 to the power receiving coil 212. In addition, the "standby state of the power transmission device 100" refers to a state in which the power transmission circuit 130 is driven but power is not supplied to the power receiving device 200. The power transmission control unit 180 can also control the on / off of the power transmission circuit 130 to switch on / off the power supply from the power supply to the power transmission resonance circuit 110. For example, when a predetermined time has passed after the power transmission device 100 has entered the standby state, or when the power receiving device 200 is not detected, the power transmission control unit 180 switches the power transmission device 100 to the stop state by turning off the power transmission circuit 130, thereby suppressing power loss in the power transmission device 100.

[0030] In the present embodiment, the power transmission control unit 180 first opens (disconnects) the power transmission switching element 116, and then short-circuits (turns on) the three-stage resonance switching element 316. That is, the power transmission switching element 116 is switched at a time point when the current value I1 flowing through the power transmission coil 112 decreases. By configuring in this way, the generation of surge voltage can be suppressed or prevented. In addition, in the case where the generation of surge voltage is not a problem, the short-circuiting of the three-stage resonance switching element 316 and the opening of the power transmission switching element 116 can be performed simultaneously or in any order.

[0031] As described above, according to the power transmission device 100 of the present embodiment, the three-level resonance circuit 310 includes the three-level coil 312 and the three-level resonance capacitor 314, and the three-level resonance switching element 316 connected in parallel with the three-level coil 312. The three-level resonance switching element 316 switches the resonance state and the non-resonance state of the three-level resonance circuit 310 by switching the three-level resonance switching element 316 to open and short circuit. When switching to the standby state in which power is not supplied to the power receiving device 200, the power transmission control unit 180 short-circuits the three-level resonance switching element 316 to switch the three-level coil 312 and the three-level resonance capacitor 314 to the non-resonance state. According to the power transmission device 100 of the present embodiment, the three-level coil 312 and the three-level resonance capacitor 314 can be brought into the non-resonance state by short-circuiting the three-level resonance switching element 316. Therefore, for example, even when the three-level resonance switching element 316 is short-circuited, the three-level resonance circuit 310 can be fixed in the non-resonance state. Therefore, it is not necessary to provide a protection circuit for preventing failure of each part of the power transmission device 100 due to a short-circuit failure, and it is possible to suppress or prevent an increase in the number of components or an increase in size of the power transmission device 100 .

[0032] According to the power transmission device 100 of the present embodiment, the power transmission control unit 180 opens the three-stage resonance switching element 316 and switches the three-stage coil 312 and the three-stage resonance capacitor 314 to the resonance state when switching to the power supply state for supplying power to the power receiving device 200. Since the three-stage resonance switching element 316 is opened when power is supplied to the power receiving device 200, current does not flow through the three-stage resonance switching element 316. Therefore, power loss in the three-stage resonance switching element 316 can be suppressed or prevented. In addition, since a large current can be suppressed from flowing through the three-stage resonance switching element 316 when power is supplied, the current capacity of the three-stage resonance switching element 316 can be reduced, and the size of the power transmission device 100 can be suppressed or prevented. In addition, the increase in standby capacitance due to the parasitic capacitance of the three-stage resonance switching element 316 in the non-resonant state can be suppressed, and the generation of a resonance point on the power supply side can be suppressed. Therefore, the electromagnetic compatibility (EMC: Electromagnetic Compatibility) of the power transmission device 100 is improved, and the performance of the power supply circuit 140 can be suppressed or prevented.

[0033] The power transmission device 100 according to the present embodiment further includes a power transmission switching element 116 as a current switching unit, which is controlled by the power transmission control unit 180 and switches the magnitude of the current flowing through the power transmission resonance circuit 110. When switching from the power-on state to the standby state, the power transmission control unit 180 further controls the power transmission switching element 116 to switch the current flowing through the power transmission resonance circuit 110 to a current smaller than the current flowing through the power transmission resonance circuit 110 in the power-on state. When power is not supplied to the power receiving device 200, it is possible to suppress or prevent unnecessary power that does not contribute to power transmission from being supplied to the power transmission resonance circuit 110.

[0034] According to the power transmission device 100 of the present embodiment, when the power transmission state is shifted to the standby state, the power transmission control unit 180 controls the power transmission switching element 116 to switch the current flowing through the power transmission resonance circuit 110 to a larger value so as to switch the power transmission resonance circuit 110 to the resonance state, and then short-circuits the three-stage resonance switching element 316 to switch the three-stage coil 312 and the three-stage resonance capacitor 314 to the non-resonance state. Therefore, a sharp increase in impedance can be suppressed or prevented, and a large surge voltage can be suppressed or prevented from being generated in the three-stage resonance circuit 310.

[0035] B. Second Implementation Method: like Figure 2 As shown, the power transmission device 100b of the second embodiment is different from the power transmission device 100 of the first embodiment in that it includes a three-stage resonant circuit 310b, and the other structures are the same. Figure 1 In the power transmission device 100 of the first embodiment shown, an example is shown in which the three-stage resonance circuit 310 is provided as a closed circuit independent of the power transmission resonance circuit 110. In contrast, in the power transmission device 100b of this embodiment, the three-stage resonance circuit 310b is connected in series with the power transmission coil 112 of the power transmission resonance circuit 110.

[0036] The configuration of the three-stage resonant circuit 310b is the same as that of the three-stage resonant circuit 310 shown in the first embodiment, and the three-stage resonant capacitor 314 is connected in parallel with the three-stage coil 312, and the three-stage resonant switching element 316 is connected in parallel with the three-stage coil 312. The setting of the capacitance of the power transmission resonant capacitor 114 and the like is the same as that of the first embodiment, and the power transmission resonant capacitor 114 and the power transmission coil 112 in the short-circuited state of the power transmission switching element 116 are set to resonate at an angular frequency of a predetermined operating frequency. The setting of the capacitance of the three-stage resonant capacitor 314 is also the same as that of the first embodiment, and the three-stage resonant capacitor 314 and the three-stage coil 312 are set to resonate at an angular frequency of a predetermined operating frequency.

[0037] According to the power transmission device 100b of this embodiment, the three-stage resonant circuit 310b is connected in series with the power transmission resonant circuit 110. In the power transmission device 100b of this embodiment, the three-stage coil 312 and the three-stage resonant capacitor 314 can also be placed in a non-resonant state by short-circuiting the three-stage resonant switching element 316. Therefore, it is not necessary to provide a protection circuit for preventing failures of various parts of the power transmission device 100b due to a short-circuit failure, and it is possible to suppress or prevent an increase in the number of components or an increase in size of the power transmission device 100b.

[0038] C. Third Implementation Method: like Figure 3 As shown, the power transmission device 100c of the third embodiment includes a power transmission resonance circuit 110c, a current sensor 118, a power transmission resonance switching element 126, a power transmission circuit 130, a power supply circuit 140, a magnetic flux detection unit 170, and a power transmission control unit 180. The power transmission device 100c of the third embodiment is different from the power transmission device 100 of the first embodiment in that it includes a power transmission resonance circuit 110c instead of the power transmission resonance circuit 110, does not include the three-stage resonance circuit 310, includes a power transmission resonance switching element 126, and includes a power transmission switching element 116c instead of the power transmission switching element 116. The other structures are the same.

[0039] The power transmission resonance circuit 110c is different from the power transmission resonance circuit 110 in that it includes a power transmission resonance capacitor 114c instead of the power transmission resonance capacitor 114. The power transmission resonance capacitor 114c is a resonance capacitor for resonating the power supplied to the power transmission coil 112. Unlike the power transmission resonance capacitor 114, the power transmission resonance capacitor 114c is not a variable capacitor but a capacitor having a predetermined capacitance. The power transmission resonance circuit 110c is a parallel resonance circuit in which the power transmission coil 112 and the power transmission resonance capacitor 114c are connected in parallel, and is configured by a so-called PS method.

[0040] The power transmission switching element 116c switches on and off the power supply from the power transmission circuit 130 to the power transmission resonance circuit 110c under the control of the power transmission control unit 180. In the present embodiment, the power transmission switching element 116c is a bidirectional switch provided between the power transmission circuit 130 and the power transmission resonance circuit 110c. In the power transmission switching element 116c, a semiconductor element for controlling current, such as IGBT, MOSFET, or FET, can be used, as in the power transmission switching element 116. The power transmission control unit 180 turns on the power supply from the power transmission circuit 130 to the power transmission resonance circuit 110c by short-circuiting (turning on) the power transmission switching element 116c, and turns off the power supply from the power transmission circuit 130 to the power transmission resonance circuit 110c by opening (turning off) the power transmission switching element 116c.

[0041] exist Figure 3 In the example, the power transmission switching element 116c is arranged only on the positive side between the power transmission circuit 130 and the power transmission resonance circuit 110c. However, the power transmission switching element 116c is not limited to this, and the bidirectional switch may be arranged separately on the positive side and the negative side. According to the power transmission device 100c configured in this way, by dividing the cut-off portion of the power supply from the power transmission circuit 130 to the power transmission resonance circuit 110c into the positive side and the negative side, the so-called common mode noise generated on the positive side and the negative side can be suppressed or prevented.

[0042] The power transmission resonance switching element 126 switches the resonant state and non-resonant state of the power transmission coil 112 and the power transmission resonance capacitor 114c by changing the impedance of the power transmission coil 112 and the power transmission resonance capacitor 114c. The power transmission resonance switching element 126, like the power transmission switching element 116c, can be a semiconductor element for controlling current, such as IGBT, MOSFET, or FET. The power transmission control unit 180 short-circuits (turns on) the power transmission resonance switching element 126 to put the power transmission coil 112 and the power transmission resonance capacitor 114c into a non-resonant state, and opens (turns off) the power transmission resonance switching element 126 to put the power transmission coil 112 and the power transmission resonance capacitor 114c into a resonant state capable of resonance.

[0043] The power transmission device 100c of this embodiment includes a power transmission resonance switching element 126 connected in parallel to the power transmission resonance circuit 110c and a power transmission control unit 180 that controls the power transmission resonance switching element 126. The power transmission resonance switching element 126 switches the resonance state and the non-resonance state of the power transmission resonance circuit 110c by switching the impedance of the power transmission coil 112 and the power transmission resonance capacitor 114c. When the power transmission device 100c is switched from the power-on state to the standby state, the power transmission control unit 180 short-circuits the power transmission resonance switching element 126 to switch the power transmission coil 112 and the power transmission resonance capacitor 114c to the non-resonance state. According to the power transmission device 100c of this embodiment, the power transmission coil 112 and the power transmission resonance capacitor 114c can be brought into a non-resonance state by short-circuiting the power transmission resonance switching element 126. Therefore, for example, even if the power transmission resonance switching element 126 is short-circuited, the power transmission resonance circuit 110c can be fixed in a non-resonance state. Therefore, it is not necessary to provide a protection circuit for preventing failure of each part of the power transmission device 100 c due to a short-circuit failure, and it is possible to suppress or prevent an increase in the number of components or an increase in size of the power transmission device 100 c.

[0044] According to the power transmission device 100c of the present embodiment, when switching from the standby state to the power-on state, the power transmission control unit 180 opens the power transmission resonance switching element 126, so that the power transmission coil 112 and the power transmission resonance capacitor 114c are in a resonant state. When power is supplied to the power receiving device 200, since the power transmission resonance switching element 126 is opened, current does not flow through the power transmission resonance switching element 126. Therefore, it is possible to suppress or prevent power loss in the power transmission resonance switching element 126. In addition, since it is possible to suppress a large current from flowing through the power transmission resonance switching element 126 during power supply, the current capacity of the power transmission resonance switching element 126 can be reduced, and it is possible to suppress or prevent the power transmission device 100c from being enlarged or increasing in cost. In addition, it is possible to suppress the increase in standby capacitance due to the parasitic capacitance of the power transmission resonance switching element 126 in the non-resonant state, and it is possible to suppress the generation of a resonance point on the power supply side. Therefore, the electromagnetic compatibility (EMC) of the power transmission device 100 c is improved, and the performance degradation of the power supply circuit 140 can be suppressed or prevented.

[0045] According to the power transmission device 100c of the present embodiment, the power transmission switching element 116c is controlled by the power transmission control unit 180 and is used to switch the power supply from the power supply to the power transmission resonance circuit 110c on and off. When switching from the power-on state to the standby state, the power transmission control unit 180 further opens the power transmission switching element 116c to stop the power supply from the power supply to the power transmission resonance circuit 110c. When power is not supplied to the power receiving device 200, it is possible to suppress or prevent unnecessary power that does not contribute to power transmission from being supplied to the power transmission resonance circuit 110c.

[0046] D. Other implementation methods: (D1) In the above-mentioned embodiments, an example of applying the primary parallel secondary series method to the three-stage resonant circuit 310, the three-stage resonant circuit 310b, and the power transmission resonant circuit 110c is shown. In contrast, various circuit structures other than the primary parallel secondary series method can be adopted in the three-stage resonant circuit 310, the three-stage resonant circuit 310b, and the power transmission resonant circuit 110c. For example, it is also possible to adopt a primary series parallel secondary series method (also called "PSS method") that also includes a plurality of resonant capacitors connected in series with the power transmission coil.

[0047] (D2) In the first and second embodiments described above, the power transmission resonant capacitor 114 is an example of a variable capacitor including two capacitors connected in parallel. In contrast, the power transmission resonant capacitor 114 may be a variable capacitor whose capacitance varies according to an input control voltage or the like. In this case, the power transmission switching element 116 outputs the control voltage.

[0048] (D3) In the first and second embodiments described above, an example is shown in which the power transmission switching element 116 for switching the magnitude of the current flowing through the power transmission resonance circuit 110 is included. On the other hand, for example, when it is not necessary for the standby current to flow through the power transmission resonance circuit 110, the power transmission device may be configured not to include the power transmission switching element 116. Similarly, in the power transmission device 100c of the third embodiment, a configuration may also be configured not to include the power transmission switching element 116c.

[0049] (D4) In the first embodiment described above, an example is shown in which the power transmission resonance capacitor 114 includes: a first capacitor 114t, a power transmission switching element 116 connected in series with the first capacitor 114t, and a second capacitor 114s connected in parallel with the first capacitor 114t and the power transmission switching element 116. In contrast, for example, the second capacitor 114s may be omitted. That is, the power transmission resonance circuit 110 may also include a power transmission resonance capacitor 114 including a first capacitor 114t and a power transmission switching element 116 connected in series with the first capacitor 114t. In this case, in a state where the power transmission switching element 116 is short-circuited, the capacitance of the power transmission resonance capacitor 114 is the capacitance of the first capacitor 114t. In a state where the power transmission switching element 116 is open, the output capacity of the power transmission switching element 116 determines the standby current. By configuring in this way, the standby current flowing through the power transmission resonance circuit 110 can be further reduced.

[0050] The control unit and the method of the control unit described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor and a memory, and the above-mentioned processor is programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and the method of the control unit described in the present disclosure may be implemented by a special-purpose computer, which is provided by constituting a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and the method thereof described in the present disclosure may be implemented by one or more special-purpose computers, which are constituted by a combination of a processor and a memory programmed to perform one or more hardware and a processor composed of one or more hardware memories. In addition, the computer program may also be stored in a computer-readable non-temporary tangible storage medium as an instruction executed by a computer.

[0051] The present disclosure is not limited to the above-mentioned embodiments, and can be implemented by various structures within the scope of the above-mentioned subject matter. For example, the technical features in the embodiments corresponding to the technical features in each method described in the invention content section can be appropriately replaced or combined to solve part or all of the above-mentioned technical problems, or to achieve part or all of the above-mentioned effects. In addition, the above-mentioned technical features can be appropriately deleted as long as they are not described as necessary structures in this specification.

Claims

1. A power transmission device (100, 100b) for supplying electric power to a power receiving device (200) having a power receiving coil (212) in a non-contact manner, It includes a power transmission resonance circuit (110), a three-stage resonance circuit (310, 310b) and a power transmission control unit (180), The power transmission resonance circuit includes a power transmission coil (112) magnetically coupled to the power receiving coil and a power transmission resonance capacitor (114) connected in series with the power transmission coil. The three-stage resonant circuit comprises: A tertiary coil (312) magnetically coupled to the power transmission coil and the power reception coil; A tertiary resonant capacitor (314) connected in parallel with the tertiary coil; as well as A three-stage resonant switching element (316) is connected in parallel with the three-stage coil and switches the resonant state and the non-resonant state of the three-stage resonant circuit by switching the opening and the short circuit of the three-stage resonant switching element. The power transmission control unit controls the three-stage resonance switching element. When switching from a power-on state in which power is supplied to the power receiving device to a standby state in which power is not supplied to the power receiving device, the power transmission control unit short-circuits the three-level resonance switching element and switches the three-level coil and the three-level resonance capacitor to a non-resonant state.

2. The power transmission device according to claim 1, characterized in that: When switching from the standby state to the energized state, the power transmission control unit opens the three-stage resonance switching element to switch the three-stage coil and the three-stage resonance capacitor to a resonance state.

3. The power transmission device according to claim 1, characterized in that: The device further comprises a current switching unit (116), the current switching unit (116) being controlled by the power transmission control unit and used for switching the magnitude of the current flowing through the power transmission resonance circuit. When switching from the energized state to the standby state, the power transmission control unit further controls the current switching unit to switch the current flowing through the power transmission resonance circuit to a current smaller than the current flowing through the power transmission resonance circuit in the energized state.

4. The power transmission device according to claim 3, characterized in that: When transitioning from the power-on state to the standby state, the power transmission control unit controls the current switching unit to short-circuit the three-stage resonance switching element and switch the three-stage coil and the three-stage resonance capacitor to a non-resonant state after switching the current flowing through the power transmission resonance circuit to a current smaller than the current flowing through the power transmission resonance circuit in the power-on state.

5. The power transmission device according to any one of claims 1 to 4, characterized in that: The three-stage resonance circuit is connected in series with the power transmission resonance circuit.

6. A power transmission device (100c) for supplying electric power to a power receiving device (200) having a power receiving coil (212) in a non-contact manner, comprising: a power transmission resonance circuit (110c), the power transmission resonance circuit comprising a power transmission coil (112) magnetically coupled to the power receiving coil, and a power transmission resonance capacitor (114c) connected in parallel to the power transmission coil; a power transmission resonance switching element (126), the power transmission resonance switching element being connected in parallel with the power transmission resonance circuit and switching the resonance state and non-resonance state of the power transmission resonance circuit by switching the impedance of the power transmission coil and the power transmission resonance capacitor; as well as A power transmission control unit (180) for controlling the power transmission resonance switching element. When switching from a power-on state in which power is supplied to the power receiving device to a standby state in which power is not supplied to the power receiving device, the power transmission control unit short-circuits the power transmission resonance switching element to switch the power transmission coil and the power transmission resonance capacitor to a non-resonant state.

7. The power transmission device according to claim 6, characterized in that: When switching from the standby state to the energized state, the power transmission control unit opens the power transmission resonance switching element to bring the power transmission coil and the power transmission resonance capacitor into a resonance state.

8. The power transmission device according to claim 6, characterized in that: The power transmission control unit further includes a power transmission switching element (116c) which is controlled by the power transmission control unit and is used to switch on and off the power supply from the power supply to the power transmission resonance circuit. When switching from the energized state to the standby state, the power transmission control unit further opens the power transmission switching element to stop the supply of electric power from the power supply to the power transmission resonance circuit.

9. A program executed by a computer included in a power transmission device (100, 100b) for supplying electric power to a power receiving device (200) having a power receiving coil (212) in a non-contact manner, When switching from a power-on state in which power is supplied to the power receiving device to a standby state in which power is not supplied to the power receiving device, The computer is caused to execute a function of short-circuiting a tertiary resonance switching element (316) of a tertiary resonance circuit (310, 310b) and switching a tertiary coil (312) and a tertiary resonance capacitor (314) to a non-resonant state, wherein: The three-stage resonant circuit includes the three-stage coil, the three-stage resonant capacitor and the three-stage resonant switching element. The three-stage coil is magnetically coupled to the power transmission coil (112) and the power receiving coil. The power transmission coil is magnetically coupled to the power receiving coil. The three-stage resonant capacitor is connected in parallel with the three-stage coil. The three-stage resonant switching element is connected in parallel with the three-stage coil. The resonant state and the non-resonant state of the three-stage resonant circuit are switched by switching the three-stage resonant switching element open and short-circuited.

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