Wireless power supply device and wireless power supply system

Abstract

To provide a wireless power supply device and a wireless power supply system that have simple configurations and can suppress interference to peripheral apparatuses when power supply radio waves have high power.SOLUTION: A master unit 100 of a wireless power supply system supplies power to a slave unit 200 by a communication / directivity control period and a power supply period that are time-divided with each other, and transmission power of a power supply radio wave during the power supply period is larger than transmission power of a communication signal during a propagation path control period.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a wireless power feeder and a wireless power feed system that feed power wirelessly using microwaves. [Background technology]

[0002] In recent years, wireless power supply, which supplies power contactlessly, has been put to practical use in various fields. In particular, wireless power supply using microwaves (hereinafter referred to as microwave power supply) is capable of supplying power over long distances and is suitable for use in, for example, RFID (radio frequency identifier) ​​systems.

[0003] In microwave power transmission, increasing the transmission power is required to further increase the power supply distance. However, increasing the transmission power poses the challenge of preventing interference with surrounding devices due to the power supply waves. There are three types of interference that are of concern: (1) An increase in adjacent channel leakage power causes interference with other wireless devices using other channels in the same frequency band (RFID in the case of the 920 MHz band). (2) It causes interference with wireless sensor systems on adjacent lines. (3) Causing malfunctions of other production equipment.

[0004] It is also known that microwave power transmission can improve power transmission efficiency by controlling the antenna's directivity (propagation path control) by optimizing the amplitude and phase of the antenna of the parent device during communication between the parent and child devices. In this case, the center frequency is modulated during communication between the parent and child devices during propagation path control, and the power spectrum spreads. The spread of the power spectrum at high power levels can cause interference with adjacent channels, posing a risk of disrupting other systems.

[0005] Patent Document 1 discloses a technology for using different frequency bands for communication signals and power feeding radio waves. That is, the 2.4 GHz frequency band is used for communication signals, and the 5 GHz frequency band (which is less congested than 2.4 GHz) is used for power feeding radio waves. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-97302 Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, it is believed that by using the less congested 5 GHz frequency band for the power supply radio waves, interference with surrounding devices due to the power supply radio waves can be suppressed even if the power supply radio waves are high power. However, using two different frequency bands requires two systems of RF circuits for wireless communication, which creates a problem of complicated device configuration.

[0008] Propagation path control includes a method of estimating the propagation path characteristics between the master unit and the slave unit (propagation path estimation) and adjusting the antenna directivity to optimize the estimated propagation path characteristics, and a method in which the master unit estimates the direction of the slave unit (direction estimation) and adjusts the antenna directivity to the estimated direction of the slave unit. Propagation path estimation is superior in terms of the effectiveness of optimizing antenna directivity because it can feed power to the slave unit in the optimal power feeding direction even when the optimal power feeding direction to the slave unit differs from the direction of the slave unit due to the influence of obstructions, etc. However, since the propagation path of radio waves varies depending on the frequency, propagation path estimation cannot be performed unless the communication signal and the power feeding signal use the same frequency. Therefore, the method of Patent Document 1, in which the communication signal and the power feeding radio wave use different frequency bands, has the problem of being unable to perform propagation path estimation.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wireless power feeder and a wireless power feed system that have a simple configuration and can suppress interference with surrounding devices when the power feed radio waves are high power. [Means for solving the problem]

[0010] In order to solve the above problems, a wireless power feeder according to a first aspect of the present invention is a wireless power feeder used as a parent device in a wireless power feed system, the wireless power feeder having an antenna with adjustable directivity, and feeding power to a child device in the wireless power feed system in a propagation path control period and a power feeding period that are time-divided from each other, and during the propagation path control period, communicating with the child device and adjusting the directivity of the antenna, and during the power feeding period, transmitting power feeding radio waves while maintaining the directivity of the antenna adjusted during the propagation path control period, the communication signal during the propagation path control period and the power feeding radio waves are transmitted by the same antenna, and the transmission power of the power feeding radio waves during the power feeding period is set to be greater than the transmission power of the communication signal during the propagation path control period.

[0011] According to the above configuration, by dividing the propagation path control period and the power feeding period into time periods, interference can be suppressed by reducing the transmission power during the propagation path control period, and by increasing the transmission power while suppressing the spread of the power spectrum during the power feeding period, it is possible to suppress interference with surrounding devices when the power feeding radio waves are set to high power. Furthermore, when differentiating the transmission power between the propagation path control period and the power feeding period, only one RF circuit is required for wireless communication, which avoids complicating the device configuration.

[0012] The wireless power feeder may be configured to transmit only a carrier signal of the communication signal as the power feed radio wave.

[0013] With the above configuration, the power supply radio waves during the power supply period are unmodulated signals, so even if the transmission power is increased, the power spectrum does not widen, so there is no interference with adjacent frequency channels and no impact on other surrounding devices (receivers) using adjacent channels. Furthermore, even if the radio waves reach other surrounding devices, they will not malfunction because they are unmodulated signals.

[0014] In order to solve the above-mentioned problems, a wireless power supply system according to a second aspect of the present invention is a wireless power supply system that supplies power wirelessly from a parent unit to a child unit, and is characterized in that the parent unit is the wireless power supply device described above.

[0015] Furthermore, the wireless power supply system can be configured to perform two-way communication between the parent device and the child device during the propagation path control period, and to transmit power unidirectionally from the parent device to the child device during the power supply period.

[0016] The wireless power supply system may be configured such that communication between the master device and the slave device during the propagation path control period is passive communication.

[0017] According to the above configuration, since the receiving sensitivity of the slave unit is low in passive communication, radio waves from a master unit of the same adjacent system cannot reach the slave unit, and interference between adjacent systems can be prevented. [Effects of the Invention]

[0018] The wireless power feeder and the wireless power feed system of the present invention have a simple configuration and exhibit an effect of being able to suppress interference with surrounding devices when the power feed radio waves are high power. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram showing a basic configuration of a master unit used in a wireless power supply system according to an embodiment of the present invention. [Figure 2]1 is a block diagram showing a basic configuration of a slave unit used in a wireless power supply system according to an embodiment of the present invention. [Figure 3] 10 is a graph showing the radio wave intensity of a signal transmitted from a master unit. [Figure 4] 1 is a flowchart illustrating a power supply method in a wireless power supply system according to an embodiment of the present invention. [Figure 5] FIG. 2 is a block diagram showing an example of the configuration of a transmission amplifier unit. [Figure 6] FIG. 10 is a block diagram showing another example configuration of the transmission amplifier unit. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021] Fig. 1 is a block diagram showing the basic configuration of a master unit (wireless power supply device) 100 used in a wireless power supply system according to this embodiment (hereinafter referred to as the present system). Fig. 2 is a block diagram showing the basic configuration of a slave unit 200 used in the present system. In the present system, a plurality of slave units 200 can be used with one master unit 100.

[0022] As shown in FIG. 1, the base station 100 includes a processing unit 101, a DAC (Digital / Analog Converter) 102, a carrier signal oscillator 103, a first mixer 104, a transmission amplifier 105, a transmission / reception separator 106, a reception amplifier 107, a second mixer 108, an ADC (Analog / Digital Converter) 109, and an antenna 110.

[0023] The processing unit 101 is a main control unit that controls the entire parent device 100, and in particular has the function of controlling communication and directivity during power supply. The DAC 102 performs digital-to-analog conversion of the data generated by the processing unit 101. The carrier signal oscillator 103 generates a carrier signal (carrier wave). The carrier signal here is a microwave signal. The first mixer 104 combines the analog-converted data into a carrier signal. The output of the first mixer 104 is amplified by the transmission amplifier 105 and transmitted to the child device 200 via the transmission / reception separator 106 and antenna 110.

[0024] The transmission amplifier 105 is capable of switching the amplification factor under control of the processing unit 101. This allows the output power from the transmission amplifier 105 to be varied between two or more levels or continuously. The antenna 110 is an array antenna having n element antennas, and the antenna directivity can be controlled by electrically controlling the amplitude and phase of the element antennas. The directivity of the antenna 110 is controlled by an antenna control unit 101a included in the processing unit 101.

[0025] In this system, in communication between the master unit and the slave unit, master unit 100 also receives a communication signal from slave unit 200. The communication signal (received signal) from slave unit 200 is sent to reception amplifier 107 via antenna 110 and transmission / reception separator 106, and is amplified by reception amplifier 107. Transmission / reception separator 106 separates the paths of the transmission signal transmitted from master unit 100 and the reception signal received by master unit 100.

[0026] The received signal amplified by the receiving amplifier 107 is combined in the second mixer 108 with the carrier signal generated in the carrier signal oscillator 103. The combination of the carrier signals here is for quadrature demodulation. That is, propagation path estimation is performed using amplitude information and phase information extracted by the quadrature demodulation. After the quadrature demodulation, high frequency components are cut by an LPF. The output of the second mixer 108 (a combined wave of the received signal and carrier signal) is analog-to-digital converted by the ADC 109 and then input to the processing unit 101. The processing unit 101 performs communication and directivity control based on the input received signal. As shown in FIG. 2, the slave device 200 includes a matching circuit 201, a demodulation circuit 202, a rectification circuit 203, a modulation circuit 204, a control unit 205, a load unit 206, and an antenna 207.

[0027] Matching circuit 201 matches the impedance of antenna 207 with that of demodulation circuit 202 and modulation circuit 204. Demodulation circuit 202 demodulates the received signal (communication signal) received from base unit 100. Rectification circuit 203 converts the received signal (power-supply radio wave) received from base unit 100 into direct current and supplies it to other processing units as operating power. In FIG. 2, the power supply line from rectification circuit 203 is indicated by a dashed arrow. Modulation circuit 204 modulates the transmission signal transmitted by handset 200. Control unit 205 performs overall control of handset 200 and controls load unit 206. Load unit 206 is a functional unit (e.g., a sensor) having a predetermined function, and has various input / output functions so as to operate in response to control unit 205.

[0028] Next, a method of feeding power to the slave unit 200 in this system will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a graph showing the radio wave intensity of a signal transmitted from the master unit 100. Fig. 4 is a flowchart showing the method of feeding power in this system (control on the master unit 100 side).

[0029] As shown in Fig. 3, power is supplied from the parent device 100 to the child device 200 during a communication / directivity control period (propagation path control period) and a power supply period, which are time-divided from each other. Note that the power supply period and the communication / directivity control period do not necessarily have to be consecutive. The child device 200 may be started up using power accumulated during the power supply period, or may be started up by recovering power for communication only from a communication signal.

[0030] In the communication / directivity control period, master device 100 sets the amplification factor of transmission amplifier 105 to a communication level (low power) (S1).

[0031] During the communication and directivity control period, bidirectional communication is performed between the parent device 100 and the child device 200, and propagation path control is performed based on the results of this communication. Specifically, the parent device 100 transmits a communication signal to the child device 200 (S2) and receives a reply signal from the child device 200 (S3). Based on the reply signal from the child device 200, a propagation coefficient is estimated and a transmission weight is calculated (S4). Once the transmission weight is calculated, the amplitude and phase of the element antennas in the antenna 110 are controlled based on the calculation result, and the directivity of the antenna 110 is optimized (propagation path control). By optimizing the antenna directivity, it is possible to improve the power supply efficiency in the subsequent power supply period. Such a propagation path control method is well known. Also, in FIG. 3, a power supply period for activating the child device 200 is initially provided, but the directivity of the antenna 110 is not optimized during this initial power supply period.

[0032] When the propagation path control ends, in order to switch from the communication / directivity control period to the power feeding period, parent device 100 sets the amplification factor of transmission amplifier 105 to a power feeding level (high power) (S5) and transmits power feeding radio waves to child device 200 (S6). During the power feeding period, power is transmitted by one-way radio wave transmission from parent device 100 to child device 200. Furthermore, the power feeding radio waves transmitted by parent device 100 during the power feeding period are unmodulated signals. That is, during the power feeding period, processing unit 101 of parent device 100 does not generate data to be superimposed on the carrier signal, and only the carrier signal is amplified and transmitted as the power feeding radio waves.

[0033] In this system, the transmission power of the base unit 100 differs between the power supply period and the communication / directivity control period, with the transmission power being higher during the power supply period. This makes it possible to increase the power supply distance by increasing the transmission power during the power supply period. Because the transmission signal during the power supply period is an unmodulated signal, transmission can be performed without expanding the power spectrum even if the transmission power is increased, and interference with other devices (receivers) outside this system that use adjacent frequency channels can be avoided. Furthermore, even if radio waves reach other devices, they will not malfunction because they are unmodulated signals.

[0034] On the other hand, during the communication and directivity control period, the transmission power is reduced to suppress the spread of the power spectrum and reduce radio wave interference. Since the same antenna 110 is used for transmission from parent device 100 during the power supply period and the communication and directivity control period, the antenna directivity adjusted (optimized) during the communication and directivity control period is maintained during the subsequent power supply period, even if the transmission power is different.

[0035] As shown in Fig. 1, master unit 100 in this system has a single RF circuit (DAC 102, carrier signal oscillator 103, first mixer 104, transmission amplifier 105, etc.) for wireless communication, and the device configuration is simple. However, to make the transmission power of master unit 100 different between the power supply period and the communication / directivity control period, master unit 100 switches the amplification factor in transmission amplifier 105. In other words, transmission amplifier 105 needs to have two or more outputs or be configured to vary the output continuously. An example configuration of such a transmission amplifier 105 will be described with reference to Figs. 5 and 6.

[0036] 5, transmission amplification unit 105 is configured by connecting preamplifier 105a, power amplifier 105b, and variable attenuator 105c in series. The power of a signal (RF in) input to transmission amplification unit 105 is amplified by preamplifier 105a and power amplifier 105b, and then attenuated by variable attenuator 105c. Transmission amplification unit 105 can vary the power of an output signal (RF out) in multiple levels or continuously by adjusting the attenuation amount of variable attenuator 105c using a control signal from processing unit 101. Alternatively, instead of using variable attenuator 105c, the power of the output signal can be varied in multiple levels or continuously by directly adjusting the amplification factor of preamplifier 105a or power amplifier 105b.

[0037] In the example shown in FIG. 6, the transmission amplification unit 105 is configured with a power divider 105d, a switch circuit 105e including multiple switch elements, multiple power amplifiers 105f, and a power combiner 105g. The power divider 105d equally divides the power of a signal (RF in) input to the transmission amplification unit 105 among multiple signal lines and outputs the divided signals. A power amplifier 105f is connected to each of the multiple signal lines output from the power divider 105d. Furthermore, a switch element included in the switch circuit 105e is connected to each of the multiple signal lines output from the power divider 105d. However, switch elements do not need to be connected to all signal lines output from the power divider 105d, and some signal lines may not be connected to switch elements. The switch circuit 105e can switch the switch elements on and off according to a control signal from the processing unit 101, thereby changing the number of signals to be amplified by the power amplifier 105f. The power combiner 105g combines the outputs from the multiple power amplifiers 105f to generate an output signal (RF out). That is, the transmission amplification unit 105 switches the number of signals to be amplified in response to a control signal from the processing unit 101, and can vary the power of the output signal (RF out) to multiple values.

[0038] The wireless power supply system according to the present invention can be suitably used, for example, in a sensor system used in a production line in a factory or the like. In a production line in a factory or the like, a sensor system is required to control the operation of various robots (welding robots, assembly robots, etc.). This sensor system supplies power wirelessly from a power supply device, which is a parent device, to a wireless sensor, which is a child device (having a sensor as a load). The wireless sensor that receives the power uses the power to perform a predetermined sensing operation.

[0039] As mentioned above, this system can suppress radio interference with adjacent frequency channels by increasing the transmission power during the power supply period and decreasing the transmission power during the communication and directivity control period. This means that this sensor system can be introduced even if wireless devices (such as RFID) using the same frequency band are used in factories, etc.

[0040] In addition, in this system, communication between the parent device and the child device during the communication and directivity control period is preferably passive communication (where the child device 200 initiates the data transfer connection). Passive communication generally has lower signal reception sensitivity in the child device than active communication, and does not cause interference when the same sensor system is installed on adjacent production lines.

[0041] The embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0042] 100 Parent unit (wireless power supply device) 101 Processing section 102 DAC 103 Carrier signal oscillator 104 First Mixer 105 Transmission amplifier 106 Transmission and reception separation unit 107 Receiving amplifier 108 Second Mixer 109 ADC 110 Antenna 200 handsets 201 Matching Circuit 202 Demodulation Circuit 203 Rectifier circuit 204 Modulation Circuit 205 Control Unit 206 Load section 207 Antenna

Claims

1. A wireless power supply device used as a master unit of a wireless power supply system, It has an antenna with adjustable directivity, power supply to the slave device of the wireless power supply system is performed in a propagation path control period and a power supply period which are time-divided from each other, during the propagation path control period, bidirectional communication with the slave device is performed by the antenna to adjust the directivity of the antenna, and during the power supply period, power supply radio waves are transmitted from the antenna in a state where the directivity of the antenna adjusted during the propagation path control period is maintained, transmitting the communication radio waves for the two-way communication during the propagation path control period and the power feeding radio waves during the power feeding period from the same antenna, and setting a transmission power of the power feeding radio waves during the power feeding period to be higher than a transmission power of the communication radio waves during the propagation path control period; The wireless power supply device, wherein communication between the master device and the slave device during the propagation path control period is passive communication.

2. The wireless power supply device according to claim 1, A wireless power supply device that transmits only a carrier signal for a communication signal as the power supply radio wave.

3. A wireless power supply system that wirelessly supplies power from a parent device to a child device, 3. A wireless power supply system, wherein the master unit is the wireless power supply device according to claim 1.

4. The wireless power supply system according to claim 3, During the propagation path control period, two-way communication is performed between the parent device and the child device; The wireless power supply system is characterized in that, during the power supply period, power is transmitted in one direction from the parent device to the child device.

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