WIRELESS POWER TRANSMISSION SYSTEM AND WIRELESS POWER TRANSMISSION APPARATUS

• US 20120200158A1
• Filed: 10/08/2009
• Published: 08/09/2012
• Est. Priority Date: 10/08/2009
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takei, Ken
• Application Number:
  US13/500,709
• Publication Number:
  US 20120200158A1
• Time in Patent Office: Days
• US Class Current: 307/31
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices

Abstract

A wireless power transmission system is a system essentially includes a small number of transmitters and a large number of receivers having unique IDs, in which the transmitter collectively controls variable reactance inside the transmitter and the receiver by using the same ID so as to perform one-to-multiple power transmission. Specifically, aiming to achieve the one-to-multiple wireless power transmission system capable of adaptively controlling a power transmission efficiency, the transmitter registers a unique ID transmitted by the receiver, and requests the receiver to report on power reception state for each ID, thereby collectively controlling variable reactance inside the transmitter and the receiver according to the content of the report so that the power transmission efficiency inside the system is dynamically optimized.

Claims

1. A wireless power transmission system comprising one transmitter and a plurality of receivers,

wherein the transmitter includes an antenna, a variable reactance circuit of transmitting part, a control circuit of transmitting part, a modulator of transmitting part, and a carrier wave generation circuit;

each of the receivers includes an antenna, a variable reactance circuit of receiving part, a demodulator of receiving part, a control circuit of receiving part, a rectifying circuit, and an ID memory device;

an ID unique to each one of the receivers is applied to each of the receivers;

the transmitter controls the variable reactance circuit of transmitting part by the control circuit of transmitting part, and transmits the ID and a control command; and

each of the receivers receives the ID and the control command transmitted from the transmitter, and the receiver having its received ID matches an ID unique to the receiver stored in the ID memory device controls the variable reactance circuit of receiving part by the control circuit of receiving part.

2. The wireless power transmission system according to claim 1,

wherein control of the variable reactance circuit of transmitting part of the transmitter, and control of the variable reactance circuit of receiving part of a single or a plurality of receivers are alternately performed in a chronologic order.

3. The wireless power transmission system according to claim 2,

wherein the transmitter further includes a directional coupler and a detector circuit, and, out of the outputs of the carrier wave generation circuit, power reflected by the antenna of the transmitter and not outputted to the outside of the transmitter but returned to the inside of the transmitter is detected, and the variable reactance circuit of transmitting part is adjusted by the control circuit of transmitting part so that the returned power is minimum;

and

each of the receivers adjusts the variable reactance circuit of transmitting part by the control circuit of receiving part so that the power obtained by the rectifying circuit is the maximum.

4. The wireless power transmission system according to claim 3,

wherein the transmitter further comprises a demodulator of transmitting part and a memory circuit;

each of the receivers further comprises a demodulator of receiving part;

each of the receivers transmits a control state of a variable reactance circuit, received power, and a unique ID stored in an ID memory device in advance to the transmitter by using the demodulator of receiving part; and

the transmitter reads a transmitted content of the receiver by the demodulator of transmitting part, and writes a receiver ID, the control state of the variable reactance circuit, and the received power in a receiver state transition table existing inside the memory circuit.

5. The wireless power transmission system according to claim 4,

wherein the transmitter updates a result of reading a content of the receiver state transition table and the transmitted content of the receiver for each of the receiver IDs.

6. The wireless power transmission system according to claim 5,

wherein the transmitter has a maximum allowable output power value, and,

when a transmission output exceeds the maximum allowable output power value, a signal for requesting stop of power reception is transmitted together with a unique ID of the receiver to any one of a single or a plurality of receivers performing exchanges of information, and out of the receivers having received the signal, the receivers having matching unique IDs perform a stopping operation of the power reception by the control circuit of receiving part.

7. The wireless power transmission system according to claim 6,

wherein the receiver stopping reception of power is sequentially selected from the receivers corresponding to IDs of smaller received power written in the receiver state transition table inside the memory circuit of the transmitter.

8. The wireless power transmission system according to claim 7,

wherein the control state of the variable reactance circuit written in the receiver state transition table inside the memory circuit of the transmitter is sequentially selected from the receiver corresponding to the ID which has not yet reached a stable state in the power reception during the control.

9. The wireless power transmission system according to claim 8,

wherein the transmitter has a first time slot for transmitting a control command to the receiver at a fixed time interval;

a control signal is transmitted to the receiver together with the ID sequentially for each ID written in the receiver state transition table at the first time slot; and

the receiver receives the control signal, and when the ID included in the received signal matches its own ID, the receiver transmits a control state of the variable reactance circuit, received power, and a unique ID stored in the ID memory device in advance to the transmitter by using the modulator of receiving part.

10. The wireless power transmission system according to claim 9,

wherein, when output power of the transmitter exceeds a preset maximum allowable output power value, a receiver control signal is transmitted with giving priority to the ID of the receiver smaller in received power written in the receiver state transition table.

11. The wireless power transmission system according to claim 10,

wherein, when the output power of the transmitter exceeds the preset maximum allowable output power value, the receiver control signal is transmitted with giving priority to the ID with a control state of the variable reactance circuit written in the receiver state transition table being under control and the power reception which has not yet reached a stable state.

12. The wireless power transmission system according to claim 11,

wherein, when the receiver stops the power reception and the received power is zero across the plurality of first time slots because of a control state of the variable reactance circuit equivalent to the receiver of the unique ID received by the transmitter and the received power, the transmitter deletes the ID and the control state of the variable reactance circuit and also the received power written in the receiver state transition table inside the store circuit.

13. The wireless power transmission system according to claim 12,

wherein the transmitter further includes a receiver state history table and a clock inside the memory circuit;

and,

when the ID, the control state of the variable reactance circuit, and the received power written in the receiver state transition table inside the memory circuit are deleted, contents and time of the deletion are sequentially stored in the receiver state history table.

14. The wireless power transmission system according to claim 13,

wherein the transmitter has a second time slot being different from the first time slot;

the receiver transmits its own ID at a specific transmission interval;

the transmitter receives an ID signal from the receiver at the second time slot, and writes the ID signal in the receiver state transition table inside the memory circuit, and transmits a signal for stopping the transmission of its own ID having a transmission interval unique to the receiver from the receiver together with the ID; and

the receiver receives the signal for stopping the transmission of its own ID having a specific transmission interval, and when the ID included in the reception signal matches its own unique ID, the receiver stops the transmission of its own ID having the unique transmission interval.

15. The wireless power transmission system according to claim 14,

wherein a receiver having stopped power reception by a command from the transmitter transmits its own ID anew at a unique transmission interval, and re-starts the operation of the power reception.

16. The wireless power transmission system according to claim 15,

wherein the first time slot and the second time slot are alternately set on a time axis.

17. The wireless power transmission system according to claim 16,

wherein the transmitter includes a plurality of transmitters provided with carrier wave generators different in frequency;

and

the receiver includes a plurality of receivers provided with carrier wave generators different in frequency.

18. The wireless power transmission system according to claim 17,

wherein charging is performed according to power supplied by using the information stored in the receiver state transition table.

19. A wireless power transmission apparatus comprising one transmitter and a plurality of receivers,

wherein the transmitter includes an antenna, a variable reactance circuit of transmitting part, a control circuit of transmitting part, a modulator of transmitting part, and a carrier wave generation circuit;

each of the receivers includes an antenna, a variable reactance circuit of receiving part, a demodulator of receiving part, a control circuit of receiving part, a rectifying circuit, and an ID memory device;

an ID unique to each one of the receivers is applied to each of the receivers;

the transmitter controls the variable reactance circuit of transmitting part by the control circuit of transmitting part, and transmits the ID and a control command;

each of the receivers receives the ID and the control command transmitted from the transmitter, and the receiver having its received ID matches an ID unique to the receiver stored in the ID memory device controls the variable reactance circuit of receiving part by the control circuit of receiving part,

the wireless power transmission apparatus further comprising a modulator circuit together with the antenna, the variable reactance circuit of receiving part, the demodulator of receiving part, the control circuit of receiving part, the rectifying circuit, and the ID memory device,

the modulator circuit including a semiconductor switch and performing communication to the transmitter by a back-scattering method.

20. The wireless power transmission apparatus according to claim 19,

wherein, as compared with characteristic impedances of the electronic circuits of the transmitter and the receiver, a real part of the self-impedance of the antenna of the transmitter and a real part of the self-impedance of the antenna of the receiver are smaller than real parts of the mutual impedances of the antenna of the transmitter and the antenna of the receiver, respectively.

21. The wireless power transmission apparatus according to claim 20,

wherein the antennas of the transmitter and the receiver are formed by an assembly of a plurality of minute polygonal conductors on a flat surface, and the plurality of minute polygonal conductors are arranged so that the density is symmetrical to an axis of symmetry possessed by the flat surface, and each of power supply points provided on the minute polygonal conductors existing on the antenna of the transmitter and on the antenna of the receiver forms the shortest distance to connect the antenna of the transmitter and the antenna of the receiver, and is distributed apart from the axis of symmetry.

22. The wireless power transmission apparatus according to claim 21,

wherein the antennas of the transmitter and the receiver are achieved on one flat surface.

23. The wireless power transmission apparatus according to claim 22,

wherein the plurality of minute polygonal conductors forming the antennas of the transmitter and the receiver are rectangle-shaped.

24. The wireless power transmission apparatus according to claim 22,

wherein the plurality of minute polygonal conductors forming the antennas of the transmitter and the receiver are triangle-shaped.

25. The wireless power transmission apparatus according to claim 19,

wherein a mutual impedance of an antenna system formed by the antennas of the transmitter and the receiver satisfies the resonance condition.

26. The wireless power transmission apparatus according to claim 25,

wherein a reactance element is loaded on a part of the structure of the antenna of the receiver;

and

the reactance element follows a relative positional change of the antennas of the transmitter and the receiver, and changes a frequency of an electromagnetic wave transmitted by the transmitter in order to maintain the resonance condition.

27. The wireless power transmission apparatus according to claim 26,

wherein a part of the structures of the antenna of the transmitter and the antenna of the receiver is loaded with a variable reactance element;

and

the variable reactance element follows the relative positional change of the antennas of the transmitter and the receiver, and is controlled by the transmitter in order to maintain the resonance condition.

28. The wireless power transmission apparatus according to claim 27,

wherein the variable reactance element is controlled by the transmitter by changing the frequency of the electromagnetic wave transmitted by the transmitter.