WIRELESS POWER RECEIVER

• US 20170346344A1
• Filed: 05/25/2017
• Published: 11/30/2017
• Est. Priority Date: 05/27/2016
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: UCHIMOTO, Daisuke
• Granted Patent: US 10,714,976 B2
• Time in Patent Office: Days
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

A reception antenna includes a reception coil which receives a power signal. A rectification circuit rectifies an alternating current flowing to the reception antenna. A smoothing capacitor smoothes an output of the rectification circuit. A waveform stabilizer is enabled when a power receiver satisfies a predetermined condition and shifts a parallel resonance frequency of the reception antenna.

Claims

1. A wireless power receiver structured to receive a power signal from a wireless power transmitter, the wireless power receiver comprising:

a reception antenna having a reception coil structured to receive the power signal;

a rectification circuit structured to rectify an alternating current flowing to the reception antenna;

a smoothing capacitor structured to smooth an output of the rectification circuit; and

a waveform stabilizer structured to be enabled when the wireless power receiver satisfies a predetermined condition and to shift a parallel resonance frequency of the reception antenna.

2. The wireless power receiver according to claim 1, wherein

the waveform stabilizer is structured to be enabled when an output current of the wireless power receiver is more than a predetermined threshold.

3. The wireless power receiver according to claim 1, wherein

the waveform stabilizer is structured to be enabled when an output current of the wireless power receiver is included in a predetermined range.

4. The wireless power receiver according to claim 1, wherein

the waveform stabilizer is structured to be enabled when load power or reception power of the wireless power receiver is included in a predetermined range.

5. The wireless power receiver according to claim 1, wherein

the rectification circuit includes an H bridge circuit which has a first alternating-current input terminal and a second alternating-current input terminal connected to the reception antenna and a synchronous rectification controller which controls the H bridge circuit.

6. The wireless power receiver according to claim 5, wherein

when an output current of the wireless power receiver is smaller than a predetermined threshold, the synchronous rectification controller controls the H bridge circuit in a semi-synchronous rectification mode and when the output current is larger than the predetermined threshold, the synchronous rectification controller controls the H bridge circuit in a full-synchronous rectification mode, and

when the H bridge circuit is operated in the full-synchronous rectification mode, the waveform stabilizer is enabled.

7. The wireless power receiver according to claim 1, wherein

the waveform stabilizer includes a first capacitor and a first switch which are provided in series between one end of the reception antenna and a ground, a second capacitor and a second switch which are provided in series between the other end of the reception antenna and the ground, and a driver which turns on the first switch and the second switch in an enabled state.

8. The wireless power receiver according to claim 7, wherein

terminals of low potential sides of the first switch and the second switch are connected to a common node, and

the waveform stabilizer further includes a resistor which is provided between the common node and the ground.

9. The wireless power receiver according to claim 7, wherein

the waveform stabilizer further includes a first resistor which is provided in series with the first capacitor and the first switch between one end of the reception antenna and the ground and a second resistor which is provided in series with the second capacitor and the second switch between the other end of the reception antenna and the ground.

10. The wireless power receiver according to claim 1, further comprising:

an AM modulator which is connected to the reception antenna and changes the parallel resonance frequency of the reception antenna according to an AM modulation signal.

11. The wireless power receiver according to claim 10, wherein

the waveform stabilizer is configured to share at least a part with the AM modulator.

12. The wireless power receiver according to claim 10, wherein

the waveform stabilizer is structured to be disabled in an operation section of the AM modulator.

13. The wireless power receiver according to claim 1, wherein

the waveform stabilizer is structured to be not enabled before position detection by the wireless power transmitter is completed.

14. The wireless power receiver according to claim 1, wherein

the wireless power receiver corresponds to a Qi standard.

15. An electronic apparatus including the wireless power receiver according to claim 1.

16. A power reception control circuit used in a wireless power receiver, the power reception control circuit comprising:

a first alternating-current input terminal and a second alternating-current input terminal which are connected to a reception antenna receiving a power signal from a wireless power transmitter;

a rectification circuit which is connected to the first alternating-current input terminal and the second alternating-current input terminal and structured to rectify an alternating current flowing to the reception antenna;

a rectification terminal to which a smoothing capacitor smoothing an output of the rectification circuit is connected; and

a waveform stabilizer structured to be enabled when the wireless power receiver satisfies a predetermined condition and shifts a parallel resonance frequency of the reception antenna.

17. A control method for a wireless power receiver receiving a power signal from a wireless power transmitter, the control method comprising:

receiving the power signal by a reception antenna including a reception coil;

rectifying an alternating current flowing to the reception antenna by a rectification circuit;

smoothing an output of the rectification circuit; and

shifting a parallel resonance frequency of the reception antenna, when the wireless power receiver satisfies a predetermined condition.