Power receiving equipment and contactless power transmission system

Abstract

To provide a power reception device and a non-contact power transmission system, capable of realizing an excellent communication performance.SOLUTION: A power reception device is a power reception 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 modulated wave obtained by performing an amplitude modulation on a power wave, and includes: a power reception circuit that receives a power supplied from the power transmission device in a non-contact manner, and supplies the power to a load via a first power supply line and a second power supply line; a secondary side modulation circuit that performs the amplitude modulation on the power wave with a modulation signal containing power reception side load information supplied from the load; and a secondary side demodulation circuit that is connected to the first power sully line, and demodulates, from the modulated wave, power transmission side load information from the power transmission device. The secondary side modulation circuit includes: a first modulation circuit that is connected to the first power supply line; and a second modulation circuit that is connected to the second power supply line.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a power receiving device and a non-contact power transmission system.

Background Art

[0002] Conventionally, a non-contact power transmission system (WPT: Wireless Power Transfer) capable of non-contact power supply from a primary power transmission device to a secondary power receiving device is known. In addition, a system has been proposed in which information regarding a load (for example, sensors) connected to the power receiving device (hereinafter referred to as "load information") is transmitted and received using a power wave as a carrier wave (for example, see Patent Document 1). According to the system described in Patent Document 1, wireless power supply and wireless information communication can be simultaneously performed on a common transmission path, and the circuit configuration can be simplified.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the non-contact power transmission system described above, for example, a power wave is amplitude-modulated with a modulation signal including transmission-side load information S1 and reception-side load information S2, whereby power supply from the power transmission device 50 to the power receiving device 60 and transmission and reception of load information between the two are performed (see FIG. 1). The power receiving device 60 is provided with a secondary-side modulation circuit 63 having a modulation capacitor. The modulation capacitor of the secondary-side modulation circuit 63 is used to modulate the power wave, but also affects the resonance state in the power receiving circuit 61. Therefore, the waveform of the modulated power wave (hereinafter referred to as "modulated wave") may be distorted and the communication performance may deteriorate due to the operation of the secondary-side modulation circuit 63 (for example, on / off of a switching element).

[0005] Furthermore, as shown in Figure 1, when the secondary modulation circuit 63 and the secondary demodulation circuit 65 are connected in parallel to the power supply line in the power receiving device 60, the secondary demodulation circuit 65 is susceptible to the modulation signal output from the secondary modulation circuit 63, which can easily cause a phenomenon known as self-interference and potentially degrade communication performance.

[0006] The purpose of this disclosure is to provide a power receiving device and a contactless power transmission system that can achieve excellent communication performance. [Means for solving the problem]

[0007] The power receiving device related to this disclosure is A power receiving device for a contactless power transmission system, configured to enable power supply from a power transmission device and transmission and reception of information between the power transmission device and the power transmission device using a modulated wave obtained by amplitude modulation of a power wave, A power receiving circuit that receives power supplied from the power transmission device in a contactless manner and supplies it to a load via a first power supply line and a second power supply line, A secondary modulation circuit that amplitude modulates the power wave with a modulation signal that includes power receiving load information supplied from the load, The system includes a secondary demodulation circuit connected to the first power supply line, which demodulates power-transmitting load information from the power transmission device from the modulated wave, The secondary modulation circuit is A first modulation circuit connected to the first power supply line, The second modulation circuit is connected to the second power supply line, and death, The first modulation circuit is configured to process the power-receiving load information as first power-receiving load information, The second modulation circuit is configured to process the powered load information as second powered load information, The impedances of the first modulation circuit and the second modulation circuit are adjusted such that the signal strength indicating the first power-receiving load information is less than the signal strength indicating the second power-receiving load information. .

[0008] The contactless power transmission system relating to this disclosure is The above-mentioned power receiving device, The system includes a power transmission device capable of supplying power to the power receiving device and transmitting and receiving information with the power receiving device. [Effects of the Invention]

[0009] According to the present disclosure, a power receiving device and a non-contact power transmission system capable of realizing excellent communication performance can be provided.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a conventional non-contact power transmission system. [Figure 2] FIG. 2 is a diagram showing a schematic configuration of a non-contact power transmission system according to an embodiment. [Figure 3] FIG. 3 is a diagram showing an example of the waveform of a modulated wave according to an embodiment. [Figure 4] FIG. 4 is a diagram showing an example of the circuit configuration of a power transmission circuit and a primary-side modulation circuit. [Figure 5] FIG. 5 is a diagram showing an example of the circuit configuration of a power receiving circuit and a secondary-side modulation circuit. [Figure 6] FIG. 6 is a diagram showing the waveform of a conventional modulated wave. [Figure 7] FIG. 7 is a diagram showing another example of the waveform of a modulated wave according to an embodiment. [Figure 8] FIG. 8 is a diagram showing another example of the circuit configuration of a power transmission circuit and a primary-side modulation circuit.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] FIG. 2 is a diagram showing a schematic configuration of a non-contact power transmission system 1 according to an embodiment of the present disclosure.

[0013] As shown in FIG. 2, the non-contact power transmission system 1 includes a power transmission device 10 on the primary side and a power receiving device 20 on the secondary side. The non-contact power transmission system 1 is configured to perform non-contact power supply from the power transmission device 10 to the power receiving device 20 by the magnetic resonance / resonance method and to be able to transmit and receive information between the two.

[0014] The non-contact power transmission system 1 is used, for example, to detect the rotational state of the pedals of an electric bicycle. In this case, the power transmission device 10 is installed on the bicycle body equipped with a battery, and the power reception device 20 is installed on the movable part on the pedal side that rotates with respect to the bicycle body.

[0015] The power reception device 20 has a sensor 28 as an example of a load. The sensor 28 may be mounted on the substrate of the power reception device 20 or may be connected to the substrate of the power reception 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 the shaft when the pedal is depressed and outputs it as an electrical signal. The sensor 28 is supplied with power non-contact from the power transmission device 10 to the power reception device 20.

[0016] Between the power transmission device 10 and the power reception device 20, power feeding and load information S are transmitted and received non-contact by a modulated wave HF obtained by amplitude-modulating (AM: Amplitude Modulation) a power wave (carrier wave) with a modulation signal. The modulated wave HF includes, as load information S, transmission-side load information S1 transmitted from the power transmission device 10 to the power reception device 20 and reception-side load information S2 transmitted from the power reception device 20 to the power transmission device 10 (see FIG. 3). The transmission-side load information S1 is, for example, calling information for instructing transmission of detection information to the sensor 28. The reception-side load information S2 is the detection information detected by the sensor 28.

[0017] As shown in FIG. 3, the modulated wave HF is a wave obtained by amplitude-modulating a power wave with a modulation signal having a frequency f, and repeats the strength (amplitude) of the signal intensity at a modulation period 1 / f. In the modulated wave HF, for example, a portion with a strong signal intensity is used as a communication signal indicating the load information S. Here, the first half of the communication signal is used for transmission and reception of the transmission-side load information S1, and the second half is used for transmission and reception of the reception-side load information S2. For example, data (binary "0" and "1") indicating the transmission-side load information S1 is represented by a depression from a reference level, and data indicating the reception-side load information S2 is represented by a protrusion from the reference level.

[0018] 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, and a power supply circuit 16, etc.

[0019] The power transmission circuit 11 is, for example, a resonant circuit having a power transmission coil 111 and a resonant capacitor 112 (see Figure 4). The resonant capacitor 112 is connected in series with the power supply line F from the power supply circuit 16 to the power transmission coil 111. The output terminal of the power transmission coil 111 is connected to ground.

[0020] The primary control circuit 12 controls the primary modulation circuit 13 so that the power wave is modulated with a low-frequency modulation signal that includes the transmitting load information S1. The primary control circuit 12 also controls the primary demodulation circuit 15 so that the receiving load information S2, which is superimposed on the modulated wave HF, is extracted.

[0021] The primary-side modulation circuit 13 modulates the power wave with a modulation signal that includes the power transmission load information S1. The primary-side modulation circuit 13 is connected between the power transmission line F and ground. The primary-side modulation circuit 13 includes, for example, a switching element 131, a modulation capacitor 132, and a resistor 133 (see Figure 4). The switching element 131, the modulation capacitor 132, and the resistor 133 are connected in series 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 condition is set such that the waveform of the modulated wave HF collapses (becomes concave compared to the reference waveform).

[0022] The primary low-pass filter 14 removes the high-frequency components of the power wave contained in the modulated HF wave, allowing only the low-frequency components of the communication signal to pass through. The primary low-pass filter 14 is composed of, for example, a full-wave rectifier circuit. The primary demodulation circuit 15 demodulates the communication signal that has passed through the primary low-pass filter 14 to extract the receiving-side load information S2 and outputs it to the primary control circuit 12.

[0023] The power supply circuit 16 includes an oscillator circuit (logic IC) that generates a power wave. The oscillator circuit converts, for example, the voltage supplied from the battery into a high-frequency (e.g., 8 MHz) AC voltage and outputs it.

[0024] The power receiving device 20 includes a power receiving circuit 21, a secondary control circuit 22, a secondary modulation circuit 30, a secondary low-pass filter 24, a secondary demodulation circuit 25, a rectifier circuit 26, and a regulator 27, etc.

[0025] The power receiving circuit 21 includes, for example, a power receiving coil 211 and resonant capacitors 212 and 213 (see Figure 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, connecting the first power supply line F1 and the second power supply line F2.

[0026] The secondary control circuit 22 controls the secondary modulation circuit 30 so that the power wave is modulated with a low-frequency modulation signal including the receiving-side load information S2. The secondary control circuit 22 also controls the secondary demodulation circuit 25 so that the transmitting-side load information S1 superimposed on the modulated wave HF is extracted. The secondary control circuit 22 may be mounted on the circuit board of the power receiving device 20, or it may be a microcontroller mounted on the sensor 28.

[0027] The secondary modulation circuit 30 amplitude modulates the power wave with a modulation signal that includes power-receiving load information S2 supplied from the sensor 28. The secondary modulation circuit 30 has a first modulation circuit 31 and a second modulation circuit 32. The first modulation circuit 31 and the second modulation circuit 32 are connected in parallel between the power-receiving circuit 21 and the secondary control circuit 22. The first modulation circuit 31 is connected to one of the first power supply lines F1 which is connected to the power-receiving coil 211. The second modulation circuit 32 is connected to the other of the second power supply lines F2 which is connected to the power-receiving coil 211.

[0028] The first modulation circuit 31 is configured to process the powered load information S2 as the first powered load information S21. Specifically, the first modulation circuit 31 includes, for example, a switching element 311, a modulation capacitor 312, and a resistor 313 (see Figure 5). The switching element 311, the modulation capacitor 312, and the resistor 313 are connected in series from the ground side. For example, when the switching element 311 is turned on by the secondary control circuit 22, the modulation capacitor 312 is inserted in parallel with the powered coil 211, and the magnetic resonance condition is set such that the waveform of the communication signal included in the modulated wave HF expands to the positive side (protrudes to the positive side compared to the reference waveform).

[0029] Similarly, the second modulation circuit 32 includes, for example, a switching element 321, a modulation capacitor 322, and a resistor 323 (see Figure 5). The switching element 321, the modulation capacitor 322, and the resistor 323 are connected in series from the ground side. For example, when the switching element 321 is turned on by the secondary control circuit 22, the modulation capacitor 322 is inserted in parallel with the power receiving coil 211, and the magnetic resonance condition is set such that the waveform of the communication signal included in the modulated wave HF expands to the negative side (protrudes to the negative side compared to the reference waveform).

[0030] The receiving-side load information S2 is superimposed on the communication signal as first receiving-side load information S21 and second receiving-side load information S22 by the first modulation circuit 31 and the second modulation circuit 32. The first receiving-side load information S21, superimposed by the first modulation circuit 31, appears, for example, as a positive convex waveform in the communication signal. The second receiving-side load information S22, superimposed by the second modulation circuit 32, appears, for example, as a negative convex waveform in the communication signal (see Figure 3).

[0031] Furthermore, the impedances of the first modulation circuit 31 and the second modulation circuit 32 are adjusted such that the signal strength (corresponding to the height of the convex waveform) indicating the first power-receiving load information S21 is smaller than the signal strength indicating the second power-receiving load information S22. The impedances of the first modulation circuit 31 and the second modulation circuit 32 are adjusted, for example, by the capacitances of the modulation capacitors 312 and 322 (see Figure 7).

[0032] The secondary low-pass filter 24 removes the high-frequency components of the power wave contained in the modulated HF wave, allowing only the low-frequency components of the communication signal to pass through. The secondary low-pass filter 24 is composed of, for example, a half-wave rectifier circuit. The secondary demodulation circuit 25 demodulates the communication signal that has passed through the secondary low-pass filter 24 to extract the power transmission load information S1 and outputs it to the secondary control circuit 22.

[0033] The rectifier circuit 26 rectifies and smooths 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 while maintaining a constant output voltage.

[0034] In the non-contact power transmission system 1, when an alternating current flows through the transmitting coil 111, a magnetic field is generated around the transmitting coil 111. The magnetic flux linked with both the transmitting coil 111 and the receiving coil 211 creates a potential difference (voltage) in the receiving coil 211. This induces a current to flow through the receiving coil 211, and power is supplied to the sensor 28 via the rectifier circuit 26 and the regulator 27.

[0035] Sensor 28 operates using the supplied power as its driving source. Sensor 28 also operates based on the transmitting-side load information S1 transmitted superimposed on the modulated wave HF, and transmits the detection result as receiving-side load information S2 to the power transmission device 10.

[0036] In conventional contactless power transmission systems (see Figure 1), one of the first and second power transmission lines F1 (for example, the first power transmission line F1) can be connected to ground via a modulation circuit, while the other (for example, the second power transmission line F2) is in a floating state for contactless power transmission using AC voltage. As a result, the waveform of the modulated HF wave is distorted in conjunction with the operation of the secondary side modulation circuit (for example, the on / off switching of the switching element), and depending on the degree, the communication signal may be lost (see Figure 6).

[0037] In contrast, in this embodiment, the secondary modulation circuit 30 is composed of a first modulation circuit 31 connected to the first power supply line F1 and a second modulation circuit 32 connected to the second power supply line F2. This allows the first power supply line F1 and the second power supply line F2 to be connected to ground via the first modulation circuit 31 and the second modulation circuit 32, respectively, and the waveform of the modulated wave HF can be made into a stable shape that is symmetrical on the positive and negative sides, as shown in Figure 3.

[0038] Furthermore, the receiving-side load information S2 is divided into first receiving-side load information S21 and second receiving-side load information S22, and superimposed on the modulated wave via separate transmission paths. As a result, the intensity of the signals representing each piece of information is smaller than the intensity of the signal representing the original receiving-side load information S2. In other words, although a modulated signal is input from the secondary-side modulation circuit 30 (first modulation circuit 31) to the secondary-side demodulation circuit 25, the intensity of the signal representing the receiving-side load information included in this modulated signal is reduced. Therefore, so-called self-interference, where the modulated signal from the first modulation circuit 31 is input to the sensor 28 via the secondary-side demodulation circuit 25 and adversely affects it, can be suppressed. For example, if the intensity of the signal representing the receiving-side load information included in the modulated signal from the secondary-side modulation circuit 30 is high, it may cause malfunctions such as exceeding the voltage withstand line of the sensor 28 or preventing the transmission-side load information S1 from being properly demodulated. However, in this embodiment, the occurrence of such malfunctions can be suppressed.

[0039] In particular, as shown in Figure 7, by making the intensity of the signal indicating the first receiving-side load information S21 smaller than the intensity of the signal indicating the second receiving-side load information S22, the occurrence of the above-mentioned self-interference can be effectively suppressed. In this case, if the secondary low-pass filter 24 is configured as a half-wave rectifier circuit, the signal indicating the second receiving-side load information S22 is removed during demodulation and does not affect the sensor 28. Therefore, the intensity of the signal indicating the second receiving-side load information S22 can be increased. Also, if the primary low-pass filter 14 of the power transmission device 10 is configured as a full-wave rectifier circuit, both the first receiving-side load information S21 and the second receiving-side load information S22 are demodulated as receiving-side load information S2, so the problem of the power transmission device 10 being unable to identify the receiving-side load information S2 does not occur.

[0040] As described above, the power receiving device 20 and the non-contact power transmission system 1 according to this embodiment are equipped with the following features individually or in appropriate combinations.

[0041] In other words, the power receiving device 20 is a power receiving device of the non-contact power transmission system 1, configured to enable power supply from the power transmitting device 10 and transmission and reception of information between the power transmitting device 10 and the power receiving device 10 using a modulated wave HF obtained by amplitude modulation of the power wave. The power receiving device 20 includes a power receiving circuit 21 that receives power supplied from the power transmitting device 10 in a non-contact manner and supplies it to the sensor 28 (load) via the first power supply line F1 and the second power supply line F2, a secondary-side modulation circuit 30 that amplitude modulates the power wave with a modulation signal including power receiving-side load information S2 supplied from the sensor 28, and a secondary-side demodulation circuit 25 connected to the first power supply line F1 that demodulates the power transmitting-side load information S1 from the power transmitting device 10 from the modulated wave HF. The secondary-side modulation circuit 30 includes a first modulation circuit 31 connected to the first power supply line F1 and a second modulation circuit 32 connected to the second power supply line F2.

[0042] The power receiving device 20 can make the waveform of the modulated HF wave a stable shape with symmetrical positive and negative sides, as shown in Figure 3. Furthermore, the power receiving device 20 can suppress the occurrence of self-interference due to the influence of the modulation signal. Therefore, the communication quality in the contactless power transmission system 1 can be significantly improved.

[0043] Furthermore, in the power receiving device 20, the first modulation circuit 31 is configured to process the power receiving side load information S2 as first power receiving side load information S21, and the second modulation circuit 32 is configured to process the power receiving side load information S2 as second power receiving side load information S22. The impedances of the first modulation circuit 31 and the second modulation circuit 32 are adjusted so that the signal strength indicating the first power receiving side load information S21 is smaller than the signal strength indicating the second power receiving side load information S22. This makes it possible to more effectively suppress the occurrence of self-interference in the power receiving device 20.

[0044] Furthermore, in the power receiving device 20, the first modulation circuit 31 expands the communication signal included in the modulated wave HF to the positive side to form a convex waveform indicating the first power receiving side load information S21, and the second modulation circuit 32 expands the communication signal to the negative side to form a convex waveform indicating the second power receiving side load information S22. Thus, problems associated with reducing the intensity of the signal indicating the first power receiving side load information S21 and increasing the intensity of the signal indicating the second power receiving side load information S22 can be easily avoided by the configuration of the rectifier circuit.

[0045] The present inventors have described the invention in detail based on embodiments above, but this paper is not limited to the above embodiments and can be modified without departing from the spirit of the invention.

[0046] For example, the configuration of each circuit in the contactless power transmission system 1 is not limited to the configuration shown in the embodiment. For example, as shown in Figure 8, the power receiving device 20 may be appropriately provided with components for impedance matching, such as capacitors 41 and 42. Similarly, the power transmitting device 10 may also be appropriately provided with components for impedance matching.

[0047] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this book is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of symbols]

[0048] 1. Contactless power transmission system 10 Power transmission equipment 20 Power receiving equipment 21 Power receiving circuit 25 Secondary side demodulation circuit 28. Sensor (Load) 30 Secondary Modulation Circuit 31. First Modulation Circuit 32 Second Modulation Circuit

Claims

1. A power receiving device for a contactless power transmission system, configured to enable power supply from a power transmission device and transmission and reception of information between the power transmission device and the power transmission device using a modulated wave obtained by amplitude modulation of a power wave, A power receiving circuit that receives power supplied from the power transmission device in a contactless manner and supplies it to a load via a first power supply line and a second power supply line, A secondary modulation circuit that amplitude modulates the power wave with a modulation signal that includes power receiving load information supplied from the load, The system includes a secondary demodulation circuit connected to the first power supply line, which demodulates power-transmitting load information from the power transmission device from the modulated wave, The secondary modulation circuit is A first modulation circuit connected to the first power supply line, It has a second modulation circuit connected to the second power supply line, The first modulation circuit is configured to process the power-receiving load information as first power-receiving load information, The second modulation circuit is configured to process the power-receiving load information as second power-receiving load information. The impedances of the first modulation circuit and the second modulation circuit are adjusted such that the signal strength indicating the first power-receiving load information is less than the signal strength indicating the second power-receiving load information. Power receiving device.

2. The first modulation circuit extends the communication signal included in the modulated wave to the positive side to form a convex waveform representing the first power-receiving load information. The second modulation circuit extends the communication signal to the negative side to form a convex waveform representing the second power-receiving load information. The power receiving device according to claim 1.

3. The power receiving device according to claim 1, A power transmission device capable of supplying power to the power receiving device and transmitting and receiving information with the power receiving device, A contactless power transmission system equipped with the following features.

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