WIRELESS POWER RECEIVING APPARATUS

• US 20170149291A1
• Filed: 11/16/2016
• Published: 05/25/2017
• Est. Priority Date: 11/20/2015
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: IWASAKI, TATSUYA, NOZAWA, Takeshi, YASUOKA, Kazuyoshi, YAMAMOTO, Isao
• Granted Patent: US 10,505,396 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

Abstract

A rectifier circuit includes an H-bridge circuit, and rectifies an AC current that flows through a reception antenna. A smoothing capacitor smoothes the output of the rectifier circuit. A demodulator demodulates an FSK-modulated electric power signal. A first comparator compares a voltage V_AC1 at a first AC input terminal with a first threshold voltage V_TH1, and generates a first detection signal. A second comparator compares a voltage V_AC2 at a second AC input terminal with a second threshold voltage V_TH2, and generates a second detection signal. A clock generating circuit generates a frequency detection clock CLK_OUT that transits according to a predetermined edge type of the first detection signal and a predetermined edge type of the second detection signal. A frequency detection circuit detects the frequency of the frequency detection clock.

Claims

1. A wireless power receiving apparatus that receives an electric power signal from a wireless power transmission apparatus, the wireless power receiving apparatus comprising:

a reception antenna comprising a reception coil structured to receive the electric power signal;

a rectifier circuit structured to rectify an AC current that flows through the reception antenna;

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

a demodulator structured to demodulate the electric power signal subjected to FSK (Frequency Shift Keying) modulation,

wherein the rectifier circuit comprises;

an H-bridge circuit comprising a first AC input terminal and a second AC input terminal coupled to the reception antenna; and

a synchronous rectification controller structured to control the H-bridge circuit,

and wherein the demodulator comprises;

a first comparator structured to compare a voltage at the first AC input terminal with a first threshold voltage, so as to generate a first detection signal;

a second comparator structured to compare a voltage at the second AC input terminal with a second threshold voltage, so as to generate a second detection signal;

a clock generating circuit structured to generate a frequency detection clock that transits according to a given edge of the first detection signal and a given edge of the second detection signal; and

a frequency detection circuit structured to detect a frequency of the frequency detection clock.

2. The wireless power receiving apparatus according to claim 1, wherein the clock generating circuit is structured to generate the frequency detection clock according to a positive edge of the second detection signal and a subsequent negative edge of the first detection signal.

3. The wireless power receiving apparatus according to claim 2, wherein the clock generating circuit comprises:

an inverter structured to invert the first detection signal; and

a logic circuit structured to generate the frequency detection clock according to the second detection signal and the first detection signal inverted by the inverter.

4. The wireless power receiving apparatus according to claim 3, wherein the clock generating circuit is structured to perform retiming of the inverted first detection signal and the second detection signal using an internal clock.

5. The wireless power receiving apparatus according to claim 4, wherein the clock generating circuit further comprises:

a first chattering removal circuit structured to judge that a valid transition has occurred in the first detection signal when the first detection signal remains at the same level over M cycles (M represents an integer of 2 or more) of the internal clock; and

a second chattering removal circuit structured to judge that a valid transition has occurred in the second detection signal when the second detection signal remains at the same level over N cycles (N represents an integer of 2 or more) of the internal clock.

6. The wireless power receiving apparatus according to claim 2, wherein the clock generating circuit comprises:

a first one-shot circuit arranged on a path of the inverted first detection signal; and

a second one-shot circuit arranged on a path of the second detection signal.

7. The wireless power receiving apparatus according to claim 4, wherein the frequency detection circuit is structured to measure the frequency of the frequency detection clock using the internal clock.

8. The wireless power receiving apparatus according to claim 1, wherein the clock generating circuit is structured to generate the frequency detection clock according to a negative edge of the second detection signal and a subsequent negative edge of the first detection signal.

9. The wireless power receiving apparatus according to claim 1, wherein the synchronous rectification controller is structured to control the bridge circuit based on the first detection signal and the second detection signal.

10. The wireless power receiving apparatus according to claim 1, that conforms to the Qi standard.

11. An electronic device comprising the wireless power receiving apparatus according to claim 1.

12. A demodulating method for demodulating an electric power signal that is transmitted from a wireless power transmission apparatus and that is subjected to FSK (Frequency Shift Keying) modulation, the demodulating method comprising:

receiving the electric power signal by means of a reception antenna comprising a reception coil;

rectifying, by means of an H-bridge circuit connected to the reception antenna, an AC current that flows through the reception antenna;

comparing a voltage at a first AC input terminal configured as a connection node that connects the H-bridge circuit and one end of the reception antenna with a first threshold voltage, so as to generate a first detection signal;

comparing a voltage at a second AC input terminal configured as a connection node that connects the H-bridge circuit and the other end of the reception antenna with a second threshold voltage, so as to generate a second detection signal;

generating a frequency detection clock according to a given edge of the first detection signal and a given edge of the second detection signal; and

detecting a frequency of the frequency detection clock.

13. A wireless power receiving apparatus that receives an electric power signal from a wireless power transmission apparatus, the wireless power receiving apparatus comprising:

a reception antenna comprising a reception coil structured to receive the electric power signal;

a rectifier circuit structured to rectify an AC current that flows through the reception antenna;

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

a demodulator structured to demodulate the electric power signal subjected to FSK (Frequency Shift Keying) modulation; and

a ringing suppressor structured to shift a parallel resonance frequency of the reception antenna during reception of an FSK signal.

14. The wireless power receiving apparatus according to claim 13, wherein the ringing suppressor comprises:

a first capacitor and a first switch arranged in series between one end of the reception antenna and a ground;

a second capacitor and a second switch arranged in series between the other end of the reception antenna and the ground; and

a control circuit structured to control the first switch and the second switch.

15. The wireless power receiving apparatus according to claim 14, wherein the ringing suppressor further comprises a resistor arranged between the ground and a connection node that connects the first switch and the second switch.

16. The wireless power receiving apparatus according to claim 13, further comprising an AM modulator structured to change the parallel resonance frequency of the reception antenna according to an AM modulated signal,

wherein the ringing suppressor is structured to control the AM modulator.

17. The wireless power receiving apparatus according to claim 16, wherein the AM modulator comprises:

a first capacitor and a first switch arranged in series between one end of the reception antenna and the ground; and

a second capacitor and a second switch arranged in series between the other end of the reception antenna and the ground,

wherein the ringing suppressor comprises a logic gate structured to perform logical operation on the AM modulated signal and a reception period signal that indicates a period of reception of the FSK signal,

and wherein the ringing suppressor is structured to control the first switch and the second switch based on an output signal of the logic gate.

18. The wireless power receiving apparatus according to claim 13, wherein the rectifier circuit comprises:

an H-bridge circuit that comprises a first AC input terminal and a second AC input terminal coupled to the reception antenna; and

a synchronous rectification controller structured to control the H-bridge circuit,

and wherein the demodulator comprises;

a first comparator structured to compare a voltage at the first AC input terminal with a first threshold voltage, so as to generate a first detection signal;

a second comparator structured to compare a voltage at the second AC input terminal with a second threshold voltage, so as to generate a second detection signal;

a clock generating circuit structured to generate a frequency detection clock that transits according to a given edge of the first detection signal and a given edge of the second detection signal; and

a frequency detection circuit structured to detect the frequency of the frequency detection clock.

19. The wireless power receiving apparatus according to claim 18, wherein the clock generating circuit is structured to generate the frequency detection clock according to a positive edge of the second detection signal and a subsequent negative edge of the first detection signal.

20. The wireless power receiving apparatus according to claim 19, wherein the clock generating circuit comprises:

an inverter structured to invert the first detection signal; and

a logic circuit structured to generate the frequency detection clock according to the second detection signal and the first detection signal inverted by the inverter.

21. The wireless power receiving apparatus according to claim 20, wherein the clock generating circuit is structured to perform retiming of the inverted first detection signal and the second detection signal using an internal clock.

22. The wireless power receiving apparatus according to claim 21, wherein the clock generating circuit further comprises:

a first chattering removal circuit structured to judge that a valid transition has occurred in the first detection signal when the first detection signal remains at the same level over M cycles (M represents an integer of 2 or more) of the internal clock; and

a second chattering removal circuit structured to judge that a valid transition has occurred in the second detection signal when the second detection signal remains at the same level over N cycles (N represents an integer of 2 or more) of the internal clock.

23. The wireless power receiving apparatus according to claim 19, wherein the clock generating circuit comprises:

a first one-shot circuit arranged on a path of the inverted first detection signal; and

a second one-shot circuit arranged on a path of the second detection signal.

24. The wireless power receiving apparatus according to claim 21, wherein the frequency detection circuit is structured to measure the frequency of the frequency detection clock using the internal clock.

25. The wireless power receiving apparatus according to claim 18, wherein the clock generating circuit is structured to generate the frequency detection clock according to a negative edge of the second detection signal and a subsequent negative edge of the first detection signal.

26. The wireless power receiving apparatus according to claim 18, wherein the synchronous rectification controller is structured to control the bridge circuit based on the first detection signal and the second detection signal.

27. The wireless power receiving apparatus according to claim 13, that conforms to the Qi standard.

28. An electronic device comprising the wireless power receiving apparatus according to claim 13.

29. A demodulating method for demodulating an electric power signal that is transmitted from a wireless power transmission apparatus and that is subjected to FSK (Frequency Shift Keying) modulation, the demodulating method comprising:

receiving the electric power signal by means of a reception antenna comprising a reception coil;

rectifying, by means of an H-bridge circuit connected to the reception antenna, an AC current that flows through the reception antenna;

demodulating the electric power signal subjected to the FSK (Frequency Shift Keying) modulation; and

adjusting a parallel resonance frequency of the reception antenna during a period of reception of an FSK signal.

30. The demodulating method according to claim 29, further comprising:

comparing a voltage at a first AC input terminal configured as a connection node that connects the H-bridge circuit and one end of the reception antenna with a first threshold voltage, so as to generate a first detection signal;

comparing a voltage at a second AC input terminal configured as a connection node that connects the H-bridge circuit and the other end of the reception antenna with a second threshold voltage, so as to generate a second detection signal;

generating a frequency detection clock that transits according to a given edge of the first detection signal and a given edge of the second detection signal; and

detecting a frequency of the frequency detection clock.