Transmitter and microwave power transmission system

Patent metadata

Field	Value
Publication number	US-10574094-B2
Application number	US-201815902155-A
Country	US
Kind code	B2
Filing date	Feb 22, 2018
Priority date	Apr 13, 2017
Publication date	Feb 25, 2020
Grant date	Feb 25, 2020

Abstract

Provided is a transmitter which can maximize the efficiency of rectification in a power-receiving electronic device irrespective of the distance therebetween. The transmitter transmits electric power to the electronic device through use of a microwave. The electronic device receives the microwave, converts the microwave to DC power, and uses the DC power as operation power. The transmitter includes a carrier wave generator for generating a carrier wave; a modulating signal generator for generating a modulating signal whose level increases, decreases, or increases and then decreases during one cycle; an amplitude modulator for amplitude-modulating the carrier wave generated by the carrier wave generator by, the modulating signal output from the modulating signal generator and for amplifying the modulated carrier wave and outputting the amplified, modulated carrier wave as a transmission signal; and an antenna for radiating the transmission signal output from the amplitude modulator into a space as the microwave.

First claim

What is claimed is:

1. A transmitter which transmits electric power to an electronic device through wireless transmission of a microwave, the electronic device being configured to receive the microwave, convert the microwave to DC power through use of a rectifying circuit, and use the DC power as operation power, the transmitter comprising:
a carrier wave generator for generating a carrier wave;
a modulating signal generator for generating a modulating signal whose level increases, decreases, or increases and then decreases during one cycle;
an amplitude modulator for amplitude-modulating the carrier wave generated by the carrier wave generator by the modulating signal output from the modulating signal generator and for amplifying;
an antenna for radiating a transmission signal which is amplitude-modulated and output from the amplitude modulator into a space as the microwave.

2. The transmitter according to claim 1 , wherein maximum and minimum values of amplitude of the transmission signal are determined such that, when input power levels of the rectifying circuit of the electronic device which correspond to the maximum and minimum values, respectively, are defined as a maximum input power level and a minimum input power level, respectively, an optimum input power level at which the rectifying circuit has a maximum rectification efficiency falls within a range between the minimum input power level and the maximum input power level.

3. The transmitter according to claim 2 , wherein the maximum value of the amplitude of the transmission signal is determined such that the maximum input power level at the time when the electronic device is located at a maximum distance exceeds the optimum input power level, the maximum distance being a maximum value of a distance from the transmitter within an operable range which is determined with respect to the transmitter and within which the electronic device must operate.

4. The transmitter according to claim 2 , wherein the modulating signal generator generates the modulating signal which varies the amplitude of the transmission signal in accordance with a periodic function such that the amplitude of the transmission signal varies continuously and monotonously between the minimum value and the maximum value.

5. The transmitter according to claim 3 , wherein the modulating signal generator generates the modulating signal which varies the amplitude of the transmission signal in accordance with a periodic function such that the amplitude of the transmission signal varies continuously and monotonously between the minimum value and the maximum value.

6. The transmitter according to claim 1 , wherein the modulating signal is a sawtooth wave, a triangular wave, or a sinusoidal wave.

7. The transmitter according to claim 1 , wherein the length of one cycle of the modulating signal is 0.1 sec to 2 sec.

8. The transmitter according to claim 1 , wherein the microwave radiated from the antenna is a microwave whose duration is equal to or greater than the one cycle of the modulating signal and is radiated intermittently.

9. The transmitter according to claim. 1 , wherein the electronic device is an electronic device which has no battery and has a rectenna and which can perform a wakeup operation through use of electric power produced as a result of rectification of the microwave over a period corresponding to one cycle of the modulating signal.

10. The transmitter according to claim 2 , wherein the electronic device is an electronic device which has no battery and has a rectenna and which can perform a wakeup operation through use of electric power produced as a result of rectification of the microwave over a period corresponding to one cycle of the modulating signal.

11. The transmitter according to claim 1 , wherein the electronic device is a device which transmits a response signal to the transmitter through use of electric power produced as a result of rectification of the microwave over a period corresponding to one cycle of the modulating signal.

12. A microwave power transmission system comprising:
a transmitter for transmitting electric power to an electronic device through wireless transmission of a microwave; and
an electronic device being configured to receive the microwave, convert the microwave to DC power through use of a rectifying circuit, and use the DC power as operation power;
wherein the transmitter comprising:
a carrier wave generator for generating a carrier wave;
a modulating signal generator for generating a modulating signal whose level increases, decreases, or increases and then decreases during one cycle;
an amplitude modulator for amplitude-modulating the carrier wave generated by the carrier wave generator by the modulating signal output from the modulating signal generator and for amplifying;
an antenna for radiating a transmission signal which is amplitude-modulated and output from the amplitude modulator into a space as the microwave; and
wherein a relative distance of the electronic device with respect to the transmitter varies as a result of movement of the electronic device, and
the electronic device receives and rectifies the microwave output from the transmitter and activates a device provided therein through use of electric power produced as a result of rectification of the microwave.

13. The microwave power transmission system according to claim 12 , wherein maximum and minimum values of amplitude of the transmission signal are determined such that, when input power levels of the rectifying circuit of the electronic device which correspond to the maximum and minimum values, respectively, are defined as a maximum input power level and a minimum input power level, respectively, an optimum input power level at which the rectifying circuit has a maximum rectification efficiency falls within a range between the minimum input power level and the maximum input power level.

14. The microwave power transmission system according to claim 13 , wherein the maximum value of the amplitude of the transmission signal is determined such that the maximum input power level at the time when the electronic device is located at a maximum distance exceeds the optimum input power level, the maximum distance being a maximum value of a distance from the transmitter within an operable range which is determined with respect to the transmitter and within which the electronic device must operate.

15. A microwave power transmission system comprising:
a transmitter for transmitting electric power to an electronic device through wireless transmission of a microwave; and
a plurality of electronic devices being configured to receive the microwave, convert the microwave to DC power through use of a rectifying circuit, and use the DC power as operation power;
wherein the transmitter comprising:
a carrier wave generator for generating a carrier wave;
a modulating signal generator for generating a modulating signal whose level increases, decreases, or increases and then decreases during one cycle;
an amplitude modulator for amplitude-modulating the carrier wave generated by the carrier wave generator by the modulating signal output from the modulating signal generator and for amplifying;
an antenna for radiating a transmission signal which is amplitude-modulated and output from the amplitude modulator into a space as the microwave; and
wherein respective relative distances of the plurality of electronic devices with respect to the transmitter differ from one another, and
each of the plurality of electronic devices receives and rectifies the microwave output from the transmitter a

Assignees

• Toyota Chuo Kenkyusho Kk

Inventors

• Ishida Masaya
• Watanabe Toshiaki
• Matsuzawa Shin-Ichiro

Classifications

• H03C1/62

  Modulators in which amplitude of carrier component in output is dependent upon strength of modulating signal, e.g. no carrier output when no modulating signal is present (H03C1/28 - H03C1/34, H03C1/46, H03C1/48 take precedence) · CPC title

• H02J50/80

  involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices · CPC title

• H02J50/20 Primary

  using microwaves or radio frequency waves · CPC title

• H04L27/02

  Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation (H04L27/32 takes precedence) · CPC title

• H04B5/0037

  Electricity · mapped topic