JP2024065609A - Power transmission device and non-contact power transmission system - Google Patents

Abstract

To provide a power transmission device and a non-contact power transmission system, capable of realizing an excellent communication performance.SOLUTION: A power transmission device is a power transmission device of a non-contact power transmission system, that is configured to enable a transmission and a reception of a power supply from a power transmission device and information between itself and the power transmission device by performing an amplitude modulation on a power wave, and comprises: a power transmission circuit that transmits a power in a non-contact manner to the power reception device; a power supply circuit that converts a power supply voltage into an AC voltage of a high frequency and outputs it to the power transmission circuit; and a snubber circuit that suppresses a spike-like noise that may be caused in the AC voltage. The snubber circuit includes: a first snubber circuit arranged between a power supply line from the power supply circuit to the power transmission circuit and an input voltage point; and a second snubber circuit arranged between the power supply line and a ground.SELECTED DRAWING: Figure 4

Description

This disclosure relates to a power transmission device and a non-contact power transmission system.

Conventionally, a contactless power transfer system (WPT: Wireless Power Transfer) capable of contactlessly supplying power from a primary power transmission device to a secondary power receiving device has been known. Also proposed is a system that transmits and receives information (hereinafter referred to as "load information") related to a load (e.g., sensors) connected to the power receiving device using power waves as a carrier wave (see, for example, Patent Document 1). According to the system described in Patent Document 1, wireless power supply and wireless information communication can be performed simultaneously through a common transmission path, which simplifies the circuit configuration.

JP 2016-197965 A

In the above-mentioned contactless power transmission system, for example, a power wave is amplitude-modulated with a modulation signal including power transmission side load information S1 and power receiving side load information S2, thereby supplying power from the power transmission device 50 to the power receiving device 60 and transmitting and receiving load information between them (see FIG. 1). In this case, in the power transmission device 50, the power supply circuit 56 includes an oscillator circuit (logic IC) that generates a high-frequency (e.g., 8 MHz) power wave. Therefore, EMI is likely to occur, and the EMI strength is also high, which may degrade communication performance.

The objective of this disclosure is to provide a power transmission device and a non-contact power transmission system that can achieve excellent communication performance.

The power transmitting device according to the present disclosure includes:
A power transmission device of a non-contact power transmission system configured to be able to supply power to a power receiving device and transmit and receive information between the power receiving device and the power receiving device by using a modulated wave obtained by amplitude-modulating a power wave,
a power transmission circuit that transmits power to the power receiving device in a wireless manner;
a power supply circuit that converts a power supply voltage into a high-frequency AC voltage and outputs the high-frequency AC voltage to the power transmission circuit;
a snubber circuit for suppressing spike noise that may occur in the AC voltage;
The snubber circuit comprises:
a first snubber circuit disposed between a power supply line from the power supply circuit to the power transmission circuit and an input voltage point;
and a second snubber circuit disposed between the power supply line and ground.

The contactless power transmission system according to the present disclosure comprises:
The above power transmitting device;
The power supply system further includes a power receiving device capable of receiving power from the power transmitting device and transmitting and receiving information to and from the power transmitting device.

This disclosure provides a power transmission device and a non-contact power transmission system that can achieve excellent communication performance.

FIG. 1 is a diagram showing a schematic configuration of a conventional non-contact power transmission system. FIG. 2 is a diagram showing a schematic configuration of a contactless power transfer system according to an embodiment. FIG. 3 is a diagram showing an example of a waveform of a modulated wave according to the embodiment. FIG. 4 is a diagram illustrating an example of a circuit configuration of a power transmission circuit and a primary side modulation circuit. FIG. 5 is a diagram showing an example of a circuit configuration of the power receiving circuit and the secondary side modulation circuit. FIG. 6 is a diagram showing an example of a power waveform obtained by the power transmitting device. FIG. 7 is a diagram showing another example of a snubber circuit.

The following describes in detail the embodiments of the present disclosure with reference to the drawings.

Figure 2 is a diagram showing the schematic configuration of a contactless power transmission system 1 according to one embodiment of the present disclosure.

As shown in FIG. 2, the contactless power transfer system 1 includes a primary-side power transmission device 10 and a secondary-side power receiving device 20. The contactless power transfer system 1 is configured to supply power from the power transmission device 10 to the power receiving device 20 in a contactless manner using a magnetic resonance/resonance method, and to transmit and receive information between the two devices.

The non-contact power transmission system 1 is used, for example, to detect the rotation state of the pedals of an electric bicycle. In this case, the power transmission device 10 is installed on the bicycle body on which the battery is mounted, and the power receiving device 20 is installed on a movable part on the pedal side that rotates relative to the bicycle body.

The power receiving device 20 has a sensor 28 as an example of a load. The sensor 28 may be mounted on the board of the power receiving device 20, or may be connected to the board of the power receiving device 20 via a cable or the like. The sensor 28 is, for example, a strain sensor capable of detecting deformation of an object. The sensor 28 detects, for example, the instantaneous deformation of a shaft when the pedal is depressed, and outputs it as an electrical signal. The sensor 28 is supplied with power that is contactlessly supplied from the power transmitting device 10 to the power receiving device 20.

Between the power transmitting device 10 and the power receiving device 20, power is supplied and load information S is transmitted and received contactlessly using modulated waves HF, which are power waves (carrier waves) that have been amplitude modulated (AM: Amplitude Modulation) with a modulation signal. The modulated waves HF include, as load information S, power transmitting side load information S1 transmitted from the power transmitting device 10 to the power receiving device 20 and power receiving side load information S2 transmitted from the power receiving device 20 to the power transmitting device 10 (see FIG. 3). The power transmitting side load information S1 is, for example, call information that instructs the sensor 28 to transmit detection information. The power receiving side load information S2 is detection information detected by the sensor 28.

As shown in FIG. 3, the modulated wave HF is a wave obtained by amplitude-modulating a power wave with a modulation signal of frequency f, and the signal strength (amplitude) repeatedly increases and decreases with a modulation period of 1/f. In the modulated wave HF, for example, the portion with strong signal strength is used as a communication signal indicating load information S. Here, the first half of the communication signal is used to transmit and receive power transmission side load information S1, and the second half is used to transmit and receive power reception side load information S2. For example, data indicating power transmission side load information S1 (binary "0" and "1") is represented by a concave from a reference level, and data indicating power reception side load information S2 is represented by a convex from the reference level.

The power transmission device 10 includes a power transmission circuit 11, a primary side control circuit 12, a primary side modulation circuit 13, a primary side low-pass filter 14, a primary side demodulation circuit 15, a power supply circuit 16, and a snubber circuit 30.

The power transmission circuit 11 is, for example, a resonant circuit having a power transmission coil 111 and a resonant capacitor 112 (see FIG. 4). The resonant capacitor 112 is connected in series to a power supply line F that runs from the power supply circuit 16 to the power transmission coil 111. The output end of the power transmission coil 111 is connected to ground.

The primary side control circuit 12 controls the primary side modulation circuit 13 so that the power wave is modulated with a low-frequency modulation signal including the power transmission side load information S1. The primary side control circuit 12 also controls the primary side demodulation circuit 15 so that the power receiving side load information S2 superimposed on the modulated wave HF is extracted.

The primary side modulation circuit 13 modulates the power wave with a modulation signal including the power transmission side load information S1. The primary side modulation circuit 13 is connected between the power supply line F and the ground. The primary side modulation circuit 13 has, for example, a switching element 131, a modulation capacitor 132, and a resistor 133 (see FIG. 4). The switching element 131, the modulation capacitor 132, and the resistor 133 are connected in series, in that order, from the ground side. For example, when the switching element 131 is turned on by the primary side control circuit 12, the modulation capacitor 132 is inserted in parallel with the power transmission coil 111, and the magnetic resonance conditions are set so that the waveform of the modulated wave HF contracts (becomes concave from the reference waveform).

The primary side low-pass filter 14 removes the high-frequency components of the power wave contained in the modulated wave HF and passes only the low-frequency components of the communication signal. The primary side low-pass filter 14 is composed of, for example, a full-wave rectifier circuit. The primary side demodulation circuit 15 demodulates the communication signal that has passed through the primary side low-pass filter 14 to extract the receiving side load information S2 and outputs it to the primary side control circuit 12.

The power supply circuit 16 includes an oscillator circuit 161 (logic IC) that generates a power wave. The oscillator circuit 161 converts the voltage supplied from a battery, for example, into a high-frequency (e.g., 8 MHz) AC voltage and outputs it.

The snubber circuit 30 suppresses spike-like noise that may occur in the AC voltage output from the power supply circuit 16. The snubber circuit 30 reduces the noise contained in the AC voltage, improving EMI characteristics.

The snubber circuit 30 has a first snubber circuit 31 connected between the power supply line F and the input voltage point Vcc, and a second snubber circuit 32 connected between the power supply line F and ground.

The first snubber circuit 31 absorbs the noise component N1 immediately after the AC voltage rises (see FIG. 6). The first snubber circuit 31 is an RC circuit having a resistor 311 and a capacitor 312 connected in series.

The second snubber circuit 32 absorbs the noise component N2 immediately after the AC voltage falls (see FIG. 6). The second snubber circuit 32 is an RC circuit having a resistor 321 and a capacitor 322 connected in series.

In the first snubber circuit 31 and the second snubber circuit 32, the noise components N1 and N2 are stored in the capacitors 312 and 322 and are converted to heat by the resistors.

Note that the circuit configurations of the first snubber circuit 31 and the second snubber circuit 32 are merely examples and are not limited to these. For example, as shown in FIG. 7, an active clamp circuit may be applied as the snubber circuit 30.

The first snubber circuit 31A has a switching element 313 and a capacitor 314 connected in series. The first snubber circuit 31A also has a drive circuit 315 that controls the operation of the switching element 313. The drive circuit 315 is connected to the input side of the oscillator circuit 161.

The second snubber circuit 32A has a switching element 323 and a capacitor 324 connected in series. The second snubber circuit 32A also has a drive circuit 325 that controls the operation of the switching element 323. The drive circuit 325 is connected to the input side of the oscillator circuit 161.

In the first snubber circuit 31A and the second snubber circuit 32A, the noise components N1 and N2 are stored in the capacitors 314 and 324, and are regenerated to the power supply via the switching elements 313 and 323.

The power receiving device 20 includes a power receiving circuit 21, a secondary side control circuit 22, a secondary side modulation circuit 30, a secondary side low-pass filter 24, a secondary side demodulation circuit 25, a rectifier circuit 26, and a regulator 27.

The power receiving circuit 21 has, for example, a power receiving coil 211 and resonant capacitors 212 and 213 (see FIG. 5). The resonant capacitor 212 is connected in series with the power receiving coil 211 on the first power supply line F1 between the power receiving coil 211 and the rectifier circuit 26. The resonant capacitor 213 is connected in parallel with the power receiving coil 211 between the power receiving coil 211 and the rectifier circuit 26.

The secondary side control circuit 22 controls the secondary side modulation circuit 30 so that the power wave is modulated with a low-frequency modulation signal including the power receiving side load information S2. The secondary side control circuit 22 also controls the secondary side demodulation circuit 25 so that the power transmitting side load information S1 superimposed on the modulated wave HF is extracted. The secondary side control circuit 22 may be implemented on the board of the power receiving device 20, or may be a microcontroller mounted on the sensor 28.

The secondary side modulation circuit 23 modulates the power wave with a modulation signal including the power receiving side load information S2. The secondary side modulation circuit 23 has, for example, a switching element 231, a modulation capacitor 232, and a resistor 233 (see FIG. 4). The switching element 231, the modulation capacitor 232, and the resistor 233 are connected in series, starting from the ground side. For example, when the switching element 231 is turned on by the secondary side control circuit 22, the modulation capacitor 232 is inserted in parallel with the power receiving coil 211, and the magnetic resonance conditions are set so that the waveform of the modulated wave HF is expanded (protruding from the reference waveform).

The secondary side low pass filter 24 removes the high frequency components of the power wave contained in the modulated wave HF and passes only the low frequency components of the communication signal. The secondary side low pass filter 24 is composed of, for example, a half wave rectifier circuit. The secondary side demodulation circuit 25 demodulates the communication signal that has passed through the secondary side low pass filter 24 to extract the power transmission side load information S1 and outputs it to the secondary side control circuit 22.

The rectifier circuit 26 rectifies and smoothes the AC voltage induced in the power receiving coil 211, converts it to a DC voltage, and outputs it to the regulator 27. The regulator 27 supplies the power supplied from the rectifier circuit 26 to the sensor 28 with a constant output voltage.

In the contactless power transmission system 1, when an alternating current flows through the power transmission coil 111, a magnetic field is generated around the power transmission coil 111, and a potential difference (voltage) is generated in the power receiving coil 211 due to magnetic flux that interlinks with both the power transmission coil 111 and the power receiving coil 211. Then, an induced current flows through the power receiving coil 211, and power is supplied to the sensor 28 via the rectifier circuit 26 and the regulator 27.

The sensor 28 operates using the supplied power as a power source. The sensor 28 also operates based on the power transmission side load information S1 transmitted superimposed on the modulated wave HF, and transmits the detection result to the power transmission device 10 as power reception side load information S2.

As such, the power transmission device 10 and the contactless power transmission system 1 according to the embodiment have the following features, either alone or in any suitable combination:

That is, the power transmission device 10 is a power transmission device of the contactless power transmission system 1 configured to be able to supply power to the power receiving device 20 and transmit and receive information to and from the power receiving device 20 by using a modulated wave HF that is an amplitude-modulated power wave. The power transmission device 10 includes a power transmission circuit 11 that transmits power to the power receiving device 20 in a contactless manner, a power supply circuit 16 that converts a power supply voltage into a high-frequency AC voltage and outputs it to the power transmission circuit 11, and a snubber circuit 30 that suppresses spike-like noise that may occur in the AC voltage. The snubber circuit 30 includes a first snubber circuit 31 that is arranged between the power supply line F from the power supply circuit 16 to the power transmission circuit 11 and the input voltage point Vcc, and a second snubber circuit 32 that is arranged between the power supply line F and ground.

According to the power transmission device 10, the first snubber circuit 31 and the second snubber circuit 32 effectively reduce the noise N1 immediately after the rise and the noise N2 immediately after the fall contained in the AC voltage, improving the EMI characteristics. Therefore, the communication quality in the contactless power transmission system 1 can be significantly improved.

In addition, in the power transmission device 10, the first snubber circuit 31 and the second snubber circuit 32 are RC circuits having resistors 311, 321 and capacitors 312, 322. This makes it possible to absorb noises N1 and N2 with a simple circuit configuration and improve EMI characteristics.

In addition, in the power transmission device 10, the first snubber circuit 31A and the second snubber circuit 32A are active clamp circuits having switching elements 313, 323 and capacitors 314, 324. As a result, the noise components N1, N2 are stored in the capacitors 314, 324 and regenerated to the power supply via the switching elements 313, 323, so that the EMI characteristics can be improved more efficiently than with an RC circuit.

The invention made by the inventor has been specifically described above based on the embodiment, but the present disclosure is not limited to the above embodiment and can be modified without departing from the gist of the invention.

For example, the configuration of each circuit in the contactless power transfer system 1 is not limited to the configuration shown in the embodiment. For example, the power transmitting device 10 and the power receiving device 20 may be provided with components for impedance matching as appropriate.

The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is indicated by the claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

Reference Signs List 1: Non-contact power transmission system 10: Power transmitting device 20: Power receiving device 11: Power transmitting circuit 16: Power supply circuit 30: Snubber circuit 31: First snubber circuit 32: Second snubber circuit

Claims (4)

A power transmission device of a non-contact power transmission system configured to be able to supply power to a power receiving device and transmit and receive information between the power receiving device and the power receiving device by using a modulated wave obtained by amplitude-modulating a power wave,
a power transmission circuit that transmits power to the power receiving device in a wireless manner;
a power supply circuit that converts a power supply voltage into a high-frequency AC voltage and outputs the high-frequency AC voltage to the power transmission circuit;
a snubber circuit for suppressing spike noise that may occur in the AC voltage;
The snubber circuit comprises:
a first snubber circuit disposed between a power supply line from the power supply circuit to the power transmission circuit and an input voltage point;
a second snubber circuit disposed between the power supply line and ground;
Power transmission equipment. the first snubber circuit and the second snubber circuit are RC circuits having a resistor and a capacitor;
The power transmitting device according to claim 1 . the first snubber circuit and the second snubber circuit are active clamp circuits having a switching element and a capacitor;
The power transmitting device according to claim 1 . The power transmitting device according to claim 1 ;
a power receiving device capable of receiving power from the power transmitting device and transmitting and receiving information to and from the power transmitting device;
A non-contact power transmission system comprising: