JP7635061B2 - Power transmission device and wireless power supply system - Google Patents

Description

The present invention relates to a power transmission device and a wireless power supply system.

A technology has been developed that transmits the power output by a power source to a load in a non-contact manner without directly connecting the load and the power source. This technology is called wireless power supply and is applied to power supply to unmanned transport vehicles and the like. When powering an unmanned transport vehicle, it is often the case that a DC load such as a battery mounted on the unmanned transport vehicle is powered, so a conventional wireless power supply system converts AC power from a commercial AC power source into DC power and transmits this DC power. On the other hand, there is an increasing demand for power supply to AC loads such as a robot arm mounted on the unmanned transport vehicle in addition to DC loads such as a battery mounted on the unmanned transport vehicle. To power such AC loads, it is necessary to provide an inverter circuit in the power receiving device that converts the DC power transmitted from the power transmitting device of the wireless power supply system into AC power. However, providing an inverter circuit in the power receiving device causes problems such as an increase in the weight, size, and cost of the power receiving device. In order to solve such problems, Patent Document 1 proposes a wireless power supply system that can transmit AC power.

JP 2015-211565 A

However, in the wireless power supply system described in Patent Document 1, DC power cannot be output from the power receiving device. In addition, in the wireless power supply system described in Patent Document 1, although AC power can be output from the power receiving device, the magnitude of the output AC voltage cannot be arbitrarily adjusted according to the type of AC load (for example, a type of AC load such as a 100V AC load or a 200V AC load).

The present invention aims to propose a power transmission device and a wireless power supply system that can selectively transmit DC power and AC power. It also aims to propose a power transmission device and a wireless power supply system that can arbitrarily adjust the magnitude of the AC voltage output from the power receiving device.

In order to solve the above-mentioned problems, the power transmission device according to the present invention is a power transmission device that wirelessly transmits power to a power receiving device, and is equipped with a power factor correction rectifier circuit having a switching element, which converts an AC signal supplied from an AC power source into a full-wave rectified signal by switching the switching element at a constant PWM width, and when a load connected to the power receiving device is a DC load, the power factor correction rectifier circuit converts the AC signal supplied from the AC power source into a DC signal by switching the switching element at a variable PWM width, an inverter circuit that converts the full-wave rectified signal or the DC signal into a high-frequency signal, and a power transmission coil that wirelessly transmits the high-frequency signal to the power receiving device by electromagnetic induction. With this configuration, DC power and AC power can be selectively transmitted to the power receiving device.

The power factor correction rectifier circuit may adjust the magnitude of the AC voltage output from the power receiving device by changing the value of the constant PWM width to another constant value.

The wireless power supply system according to the present invention includes a power transmitting device and a power receiving device. The power transmitting device includes a power factor correcting rectifier circuit including a switching element, which converts a first AC signal supplied from an AC power source into a first full-wave rectified signal by switching the switching element at a constant PWM width when a load connected to the power receiving device is an AC load, and converts the first AC signal supplied from the AC power source into a first DC signal by switching the switching element at a variable PWM width when a load connected to the power receiving device is a DC load, a first inverter circuit that converts the first full-wave rectified signal or the first DC signal into a high-frequency signal, and a power transmitting coil that transmits the high-frequency signal. The power receiving device includes a power receiving coil that receives a high-frequency signal, a rectifier circuit that rectifies the high-frequency signal into a second full-wave rectified signal when the load connected to the power receiving device is an AC load, and rectifies the high-frequency signal into a second DC signal when the load connected to the power receiving device is a DC load, and a second inverter circuit that converts the second full-wave rectified signal into a second AC signal and supplies the second AC signal to the AC load when the load connected to the power receiving device is an AC load, and supplies the second DC signal to the DC load when the load connected to the power receiving device is a DC load. With this configuration, DC power and AC power can be selectively transmitted to the power receiving device.

The power receiving device may include a detection circuit that detects the vicinity of a zero crossing point of the second full-wave rectified signal from the voltage of the second full-wave rectified signal. The second inverter circuit may convert the second full-wave rectified signal into a second AC signal according to the detection result of the vicinity of the zero crossing point. With this configuration, the vicinity of a zero crossing point of the second full-wave rectified signal can be detected from the voltage of the second full-wave rectified signal without using a current sensor.

The detection circuit may include a light-emitting element whose light emission is controlled according to the voltage of the second full-wave rectified signal, and a light-receiving element whose energization state is controlled according to the light-emitting state of the light-emitting element, and the detection circuit may detect the cross point at the timing when the energization state of the light-receiving element switches from on to off. With this configuration, it is possible to accurately detect the vicinity of the zero cross point of the second full-wave rectified signal without using a high-precision and high-cost current sensor.

The power receiving device may be mounted on a moving body such as an unmanned carrier vehicle. This allows the power receiving device to supply an AC signal to an AC load such as a robot arm mounted on a moving body such as an unmanned carrier vehicle.

According to the present invention, DC power and AC power can be selectively transmitted to a power receiving device. In addition, the magnitude of the AC voltage output from the power receiving device can be adjusted as desired.

1 is a diagram illustrating an example of a configuration of a wireless power supply system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a circuit configuration of a power transmitting device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a circuit configuration of a power receiving device according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a circuit configuration of an inverter circuit and a power receiving control circuit according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a circuit configuration of a drive circuit according to an embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention. 5A to 5C are diagrams illustrating voltage signals of various parts of the wireless power supply system in the process of transmitting power from a commercial AC power source to a load through the wireless power supply system according to the embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Here, the same reference numerals indicate the same components, and duplicated explanations will be omitted.

Fig. 1 is an explanatory diagram showing an example of the configuration of a wireless power supply system 10 according to an embodiment of the present invention. The wireless power supply system 10 includes a power transmission device 20 that converts power from a commercial AC power source 50 into a high-frequency signal and transmits it wirelessly, and a power receiving device 30 that receives the high-frequency signal from the power transmission device 20 by electromagnetic induction and supplies it to a load 41. The power receiving device 30 is mounted on a moving body 40. The load 41 is a DC load such as a battery mounted on the moving body 40, or an AC load such as a robot arm mounted on the moving body 40. The moving body 40 is, for example, an unmanned transport vehicle.

Figure 2 is an explanatory diagram showing an example of the circuit configuration of the power transmission device 20. The power transmission device 20 includes a power factor correction rectifier circuit 21, a filter circuit 22, an inverter circuit 23, a power transmission coil 24, and a power transmission control circuit 25. The power transmission control circuit 25 controls the switching operations of the power factor correction rectifier circuit 21 and the inverter circuit 23.

The power factor correction rectifier circuit 21 includes a rectifier circuit 211 and a boost chopper 212 connected to the output side of the rectifier circuit 211. The rectifier circuit 211 is a single-phase full-wave rectifier circuit composed of multiple bridge-connected diodes D5, D6, D7, and D8. The rectifier circuit 211 rectifies the AC signal from the commercial AC power source 50. The boost chopper 212 is composed of a smoothing reactor L1, a backflow prevention diode D9, and a switching element Tr5. The boost chopper 212 controls the input current flowing through the smoothing reactor L1 to be the same as a full-wave rectified waveform in phase with the voltage, thereby making the input current into a signal waveform in phase with the voltage.

When the load 41 connected to the power receiving device 30 is an AC load, the power factor correction rectifier circuit 21 converts the AC signal supplied from the commercial AC power source 50 into a full-wave rectified signal by switching the switching element Tr5 at a constant PWM (Pulse Wide Modulation) width. At this time, the value of the constant PWM width is determined according to the magnitude of the AC voltage output from the power receiving device 30. The power factor correction rectifier circuit 21 can adjust the magnitude of the AC voltage output from the power receiving device 30 by changing the value of the constant PWM width to another constant value. On the other hand, when the load 41 connected to the power receiving device 30 is a DC load, the power factor correction rectifier circuit 21 converts the AC signal supplied from the commercial AC power source 50 into a DC signal by switching the switching element Tr5 at a variable PWM width. That is, the power factor correction rectifier circuit 21 variably controls the PWM width so that the output voltage from the power factor correction rectifier circuit 21 is constant.

The switching element Tr5 is switched in response to a drive signal from the power transmission control circuit 25. The switching frequency of the switching element Tr5 does not need to be the same as the frequency of the commercial AC power supply 50, and may be different.

The filter circuit 22 is a π-type LC filter composed of capacitors C1 and C2 and a reactor L2. High-frequency components caused by the switching of the switching element Tr5 of the power factor correction rectifier circuit 21 are superimposed on the output signal (full-wave rectified signal or DC signal) from the power factor correction rectifier circuit 21. The filter circuit 22 removes unnecessary high-frequency components superimposed on the output signal from the power factor correction rectifier circuit 21.

The inverter circuit 23 includes a plurality of switching elements. The inverter circuit 23 receives the output signal (full-wave rectified signal or DC signal) output from the power factor correction rectifier circuit 21 through the filter circuit 22, and converts the output signal into a high-frequency signal separated into positive and negative signals by switching control of each switching element in the inverter circuit 23. Each switching element in the inverter circuit 23 is switched and controlled in response to a drive signal from the power transmission control circuit 25 so that wireless power transmission by electromagnetic induction is performed between the power transmission unit 30 and the power receiving unit 40. The switching frequency of each switching element in the inverter circuit 23 does not need to be the same as the switching frequency of the switching element Tr5 in the power factor correction rectifier circuit 21, and may be different.

The power transmission coil 24 converts the high-frequency signal output from the inverter circuit 23 into a high-frequency magnetic flux. This allows the power transmission coil 24 to wirelessly transmit the high-frequency signal to the power receiving device 30 through electromagnetic induction. The power transmission coil 24 may be, for example, a single coil, a series resonant circuit in which a coil and a capacitor are connected in series, or a parallel resonant circuit in which a coil and a capacitor are connected in parallel.

Figure 3 is an explanatory diagram showing an example of the circuit configuration of the power receiving device 30. The power receiving device 30 includes a power receiving coil 31, a rectifier circuit 32, a filter circuit 33, an inverter circuit 34, and a power receiving control circuit 35. The power receiving control circuit 35 controls the switching operation of the inverter circuit 34.

The receiving coil 31 converts the high-frequency magnetic flux from the transmitting coil 24 into a high-frequency signal. This allows the receiving coil 31 to receive the high-frequency signal through electromagnetic induction. The receiving coil 31 may be, for example, a single coil, a series resonant circuit in which a coil and a capacitor are connected in series, or a parallel resonant circuit in which a coil and a capacitor are connected in parallel.

The rectifier circuit 32 is a single-phase full-wave rectifier circuit composed of multiple bridge-connected diodes D10, D11, D12, and D13. When the load 41 connected to the power receiving device 30 is an AC load, the rectifier circuit 32 rectifies the high-frequency signal output from the power receiving coil 31 into a full-wave rectified signal. When the load 41 connected to the power receiving device 30 is a DC load, the rectifier circuit 32 rectifies the high-frequency signal output from the power receiving coil 31 into a DC signal.

The filter circuit 33 is an LC filter composed of a reactor L3 and a capacitor C3. High-frequency components associated with the switching of the switching elements in the inverter circuit 23 are superimposed on the high-frequency signal output from the inverter circuit 23, and these high-frequency components are also superimposed on the signal (full-wave rectified signal or DC signal) output from the rectifier circuit 32. The filter circuit 33 removes unnecessary high-frequency components superimposed on the signal (full-wave rectified signal or DC signal) output from the rectifier circuit 32.

The inverter circuit 34 includes a plurality of switching elements. When the load 41 connected to the power receiving device 30 is an AC load, the inverter circuit 34 converts the full-wave rectified signal into an AC signal by controlling each switching element in the inverter circuit 34 at the same frequency as the commercial AC power source 50 so that the positive and negative of the signal waveform are switched at the timing when the voltage of the full-wave rectified signal output from the rectifier circuit 32 through the filter circuit 33 becomes zero, and supplies this AC signal to the load 41. When the load 41 connected to the power receiving device 30 is a DC load, the inverter circuit 34 supplies the DC signal output from the rectifier circuit 32 through the filter circuit 33 to the load 41 as it is by constantly turning on a specific switching element among the plurality of switching elements in the inverter circuit 34. Note that each switching element in the inverter circuit 34 is switched and controlled in response to a drive signal from the power receiving control circuit 35.

Figure 4 is an explanatory diagram showing an example of the circuit configuration of the inverter circuit 34 and the power receiving control circuit 35. The inverter circuit 34 includes a first leg 341 and a second leg 342. The first leg 341 is connected in series with an upper arm consisting of a switching element Tr1 and a feedback diode D1 connected in anti-parallel to it, and a lower arm consisting of a switching element Tr2 and a feedback diode D2 connected in anti-parallel to it. The second leg 342 is connected in series with an upper arm consisting of a switching element Tr3 and a feedback diode D3 connected in anti-parallel to it, and a lower arm consisting of a switching element Tr4 and a feedback diode D4 connected in anti-parallel to it.

A connection point 343 between the upper arm of the first leg 341 and the upper arm of the second leg 342, and a connection point 344 between the lower arm of the first leg 341 and the lower arm of the second leg 342 are input terminals of the inverter circuit 34. A connection point 345 between the upper arm and the lower arm of the first leg 341, and a connection point 346 between the upper arm and the lower arm of the second leg 342 are output terminals of the inverter circuit 34. The output terminal of the inverter circuit 34 is connected to the load 41.

The power receiving control circuit 35 includes a detection circuit 351, a drive signal generation circuit 352, and a drive circuit 353. When the load 41 connected to the power receiving device 30 is an AC load, a full-wave rectified signal is input from the rectifier circuit 32 through the filter circuit 33 to the inverter circuit 34. The detection circuit 351 detects the vicinity of the zero cross point of the full-wave rectified signal from the voltage of the full-wave rectified signal. Here, the zero cross point of the full-wave rectified signal means the timing (time) when the voltage value of the full-wave rectified signal becomes zero. In addition, the vicinity of the zero cross point of the full-wave rectified signal means the timing (time) when the voltage value of the full-wave rectified signal becomes less than the threshold voltage (i.e., greater than or equal to zero and less than the threshold voltage). The threshold voltage may be, for example, about several percent (e.g., 2 to 3%) of the maximum value of the full-wave rectified signal.

The detection circuit 351 includes resistors R1 and R2 that divide the voltage of the full-wave rectified signal applied to the input terminals (connection points 343 and 344) of the inverter circuit 34, a light-emitting diode (light-emitting element) D14 whose light emission is controlled according to the voltage divided by the resistors R1 and R2, and a phototransistor (light-receiving element) Tr6 whose conduction state is controlled according to the light-emitting state of the light-emitting diode D14. The voltage divided by the resistors R1 and R2 is applied to the anode of the light-emitting diode D14. The cathode of the light-emitting diode D14 is connected to ground. The collector of the phototransistor Tr6 is connected to the power supply Vcc through a resistor R3. The emitter of the phototransistor Tr6 is connected to ground. Near the zero cross point of the full-wave rectified signal applied to the input terminal (connection points 343, 344) of the inverter circuit 34, the voltage applied to the anode of the light-emitting diode D14 drops to the extent that the light-emitting state of the light-emitting diode D14 changes from on to off. When the light-emitting state of the light-emitting diode D14 changes from on to off with the drop in the voltage applied to the anode of the light-emitting diode D14, the conduction state of the phototransistor Tr6 changes from on to off. The detection circuit 351 detects the cross point of the full-wave rectified signal at the timing when the conduction state of the phototransistor Tr6 changes from on to off. When the conduction state of the phototransistor Tr6 changes from on to off, the detection signal DET output from the detection circuit 351 to the drive signal generation circuit 352 changes from low level to high level. Note that when the conduction state of the phototransistor Tr6 is on, the detection signal DET is at low level. When the power supply state of the phototransistor Tr6 is off, the detection signal DET is at a high level.

The drive signal generation circuit 352 generates a drive signal VG14 for driving the switching elements Tr1 and Tr4, and a drive signal VG23 for driving the switching elements Tr2 and Tr3 from the detection signal DET. The drive circuit 353 generates a drive signal VG1 for driving the switching element Tr1, and a drive signal VG4 for driving the switching element Tr4 from the drive signal VG14, and generates a drive signal VG2 for driving the switching element Tr2, and a drive signal VG3 for driving the switching element Tr3 from the drive signal VG23.

Figure 5 is a diagram showing an example of the circuit configuration of the drive circuit 353. The drive circuit 353 includes an insulating drive circuit 3531 that generates a drive signal VG1 for the switching element Tr1, an insulating drive circuit 3532 that generates a drive signal VG2 for the switching element Tr2, an insulating drive circuit 3533 that generates a drive signal VG3 for the switching element Tr3, and an insulating drive circuit 3534 that generates a drive signal VG4 for the switching element Tr4.

The isolated drive circuit 3531 includes a light-emitting diode (light-emitting element) D15, whose light emission is controlled by the voltage of the drive signal VG14 input through resistor R4, and a phototransistor (light-receiving element) Tr15, whose conduction state is controlled according to the light-emitting state of the light-emitting diode D15. The cathode of the light-emitting diode D15 is connected to ground. The collector of the phototransistor Tr15 is connected to the power supply Vcc. The emitter of the phototransistor Tr15 is connected to ground. The collector voltage of the phototransistor Tr15 is divided by resistors R5 and R6, and the voltage is output from the isolated drive circuit 3531 to the gate of the switching element Tr1 as the drive signal VG1.

The isolated drive circuit 3532 includes a light-emitting diode (light-emitting element) D16 whose light emission is controlled by the voltage of the drive signal VG23 input through resistor R7, and a phototransistor (light-receiving element) Tr16 whose conduction state is controlled according to the light-emitting state of the light-emitting diode D16. The cathode of the light-emitting diode D16 is connected to ground. The collector of the phototransistor Tr16 is connected to the power supply Vcc. The emitter of the phototransistor Tr16 is connected to ground. The collector voltage of the phototransistor Tr16 is divided by resistors R8 and R9, and the voltage is output from the isolated drive circuit 3532 to the gate of the switching element Tr2 as the drive signal VG2.

The isolated drive circuit 3533 includes a light-emitting diode (light-emitting element) D17 whose light emission is controlled by the voltage of the drive signal VG23 input through resistor R10, and a phototransistor (light-receiving element) Tr17 whose conduction state is controlled according to the light-emitting state of the light-emitting diode D17. The cathode of the light-emitting diode D17 is connected to ground. The collector of the phototransistor Tr17 is connected to the power supply Vcc. The emitter of the phototransistor Tr17 is connected to ground. The collector voltage of the phototransistor Tr17 is divided by resistors R11 and R12, and the voltage is output from the isolated drive circuit 3533 to the gate of the switching element Tr3 as the drive signal VG3.

The isolated drive circuit 3534 includes a light-emitting diode (light-emitting element) D18, whose light emission is controlled by the voltage of the drive signal VG14 input through resistor R13, and a phototransistor (light-receiving element) Tr18, whose conduction state is controlled according to the light-emitting state of the light-emitting diode D18. The cathode of the light-emitting diode D18 is connected to ground. The collector of the phototransistor Tr18 is connected to the power supply Vcc. The emitter of the phototransistor Tr18 is connected to ground. The collector voltage of the phototransistor Tr18 is divided by resistors R14 and R15, and the voltage is output from the isolated drive circuit 3534 to the gate of the switching element Tr4 as the drive signal VG4.

Next, the transition of voltage signals in each part of the wireless power supply system 10 during the process of transmitting power from the commercial AC power source 50 to the load 41 through the wireless power supply system 10 when the load 41 is an AC load will be described with reference to Figures 6 to 9.

In FIG. 6, reference numeral 901 denotes a voltage signal obtained by full-wave rectifying the AC signal from the commercial AC power supply 50 using the rectifier circuit 211. Reference numeral 902 denotes a voltage signal obtained by removing, using the filter circuit 22, unnecessary high-frequency components superimposed on the output signal from the power factor correction rectifier circuit 21. Reference numeral 903 denotes a period corresponding to a half cycle of the commercial AC power supply 50.

In FIG. 7, reference numeral 101 indicates the voltage waveform of the high-frequency signal output from the inverter circuit 23. Reference numeral 102 indicates a period corresponding to a half cycle of the commercial AC power supply 50.

In FIG. 8, reference numeral 121 denotes a voltage signal obtained by removing unnecessary high-frequency components superimposed on the output signal from the rectifier circuit 32 using the filter circuit 33. Reference numeral 122 denotes a period corresponding to a half cycle of the commercial AC power supply 50.

In FIG. 9, reference numeral 131 indicates the voltage waveform of the AC signal output from the inverter circuit 34. Reference numeral 132 indicates a period corresponding to one cycle of the commercial AC power supply 50.

Next, the transition of voltage signals in each part of the wireless power supply system 10 during the process of transmitting power from the commercial AC power source 50 to the load 41 through the wireless power supply system 10 when the load 41 is a DC load will be described with reference to Figures 12 to 14.

In FIG. 10, reference numeral 141 denotes a voltage waveform of an AC signal from the commercial AC power supply 50. Reference numeral 142 denotes a voltage signal obtained by full-wave rectifying the AC signal from the commercial AC power supply 50 by the rectifier circuit 211.

In FIG. 11, reference numeral 151 denotes a voltage signal output from the power factor correction rectifier circuit 21. Reference numeral 152 denotes a voltage signal obtained by removing unnecessary high-frequency components superimposed on the output signal from the power factor correction rectifier circuit 21 using the filter circuit 22.

In FIG. 12, reference numeral 181 denotes a voltage signal obtained by full-wave rectifying the high-frequency signal output from the receiving coil 31 by the rectifier circuit 32. Reference numeral 191 denotes a voltage signal obtained by removing unnecessary high-frequency components superimposed on the output signal from the rectifier circuit 32 by the filter circuit 33. The inverter circuit 34 supplies the DC signal output from the rectifier circuit 32 through the filter circuit 33 directly to the load 41 by constantly turning on specific switching elements (e.g., switching elements Tr1 and Tr4) among the multiple switching elements in the inverter circuit 34.

The switching elements Tr1 to Tr5 and Tr15 to Tr18 are semiconductor switches such as IGBTs (Insulated Gate Bipolar Transistors), bipolar transistors, and MOS transistors (Metal Oxide Semiconductor Field Effect Transistors).

The power factor correction rectifier circuit 21 is not limited to a boost chopper type that outputs a voltage higher than the input power supply voltage, but may be, for example, a step-down converter type that outputs a voltage lower than the input power supply voltage, or a step-up/step-down converter type that outputs a voltage higher or lower than the input power supply voltage. The power factor correction rectifier circuit 21 is not limited to one that includes a rectifier circuit 211, but may be, for example, a bridgeless type.

When it is not necessary to remove the switching noise of the power factor correction rectifier circuit 21, the filter circuit 22 may be a capacitor only. For example, a full bridge circuit, a half bridge circuit, an E-class inverter, a push-pull system, etc. may be used as the circuit configuration of the inverter circuit 23. The rectifier circuit 32 is not limited to a diode bridge rectifier circuit, and may be a synchronous rectifier circuit using a switching element, or a rectifier circuit using a center tap.

The detection circuit 351 that detects the vicinity of the zero crossing point of the full-wave rectified signal from the voltage of the full-wave rectified signal is not limited to the photocoupler method described above, but may be, for example, a method using a digital isolator or a method using a comparator that compares the voltage of the full-wave rectified signal with a reference voltage.

According to an embodiment of the present invention, DC power and AC power can be selectively transmitted depending on the load 41. Furthermore, according to an embodiment of the present invention, the magnitude of the AC voltage output from the power receiving device 30 can be arbitrarily adjusted by switching control of the power factor correction rectifier circuit 21. Furthermore, according to an embodiment of the present invention, the timing for switching the output voltage of the inverter device 34 between positive and negative can be determined with high accuracy and at low cost.

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit of the invention, and equivalents are also included in the present invention. In other words, designs modified by a person skilled in the art as appropriate are also included within the scope of the present invention as long as they include the characteristics of the present invention. Furthermore, the elements of the embodiments can be combined to the extent technically possible, and combinations of these are also included within the scope of the present invention as long as they include the characteristics of the present invention.

10...Wireless power supply system 20...Power transmission device 21...Power factor correction rectifier circuit 22...Filter circuit 23...Inverter circuit 24...Power transmission coil 25...Power transmission control circuit 30...Power receiving device 31...Power receiving coil 32...Rectifier circuit 33...Filter circuit 34...Inverter circuit 35...Power receiving control circuit 40...Mobile object 41...Load 50...Commercial AC power source

Claims (5)

A power transmitting device that wirelessly transmits power to a power receiving device,
a power factor correction rectifier circuit including a switching element, which converts an AC signal supplied from an AC power source into a full-wave rectified signal by switching the switching element at a constant PWM width, and when a load connected to the power receiving device is a DC load, converts the AC signal supplied from the AC power source into a DC signal by switching the switching element at a variable PWM width;
an inverter circuit that converts the full-wave rectified signal or the DC signal into a high-frequency signal;
a power transmitting coil that wirelessly transmits the high-frequency signal to the power receiving device by electromagnetic induction;
A power transmission device comprising: The power transmitting device according to claim 1 ,
The power factor correction rectifier circuit adjusts the magnitude of the AC voltage output from the power receiving device by changing the value of the constant PWM width to another constant value. A wireless power supply system including a power transmitting device and a power receiving device,
The power transmitting device is
a power factor correction rectifier circuit including a switching element, which, when a load connected to the power receiving device is an AC load, converts a first AC signal supplied from an AC power source into a first full-wave rectified signal by switching the switching element at a constant PWM width, and, when a load connected to the power receiving device is a DC load, converts the first AC signal supplied from the AC power source into a first DC signal by switching the switching element at a variable PWM width;
a first inverter circuit that converts the first full-wave rectified signal or the first DC signal into a high-frequency signal;
a power transmission coil for transmitting the high-frequency signal,
The power receiving device is
a receiving coil for receiving the high frequency signal;
a rectifier circuit that rectifies the high-frequency signal into a second full-wave rectified signal when a load connected to the power receiving device is an AC load, and rectifies the high-frequency signal into a second DC signal when the load connected to the power receiving device is a DC load;
a second inverter circuit that converts the second full-wave rectified signal into a second AC signal when a load connected to the power receiving device is an AC load, and supplies the second AC signal to the AC load, and that supplies the second DC signal to the DC load when the load connected to the power receiving device is a DC load. The wireless power supply system according to claim 3,
The power receiving device further includes a detection circuit that detects a vicinity of a zero cross point of the second full-wave rectified signal from a voltage of the second full-wave rectified signal,
The second inverter circuit converts the second full-wave rectified signal into a second AC signal in response to a detection result near the zero crossing point. The wireless power supply system according to claim 4,
the detection circuit includes a light-emitting element whose light emission is controlled in response to a voltage of the second full-wave rectified signal, and a light-receiving element whose conduction state is controlled in response to a light-emitting state of the light-emitting element,
The detection circuit detects the cross point at a timing when a power supply state of the light receiving element switches from on to off.

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