WIRELESS POWER SYSTEM

• US 20150280452A1
• Filed: 03/27/2015
• Published: 10/01/2015
• Est. Priority Date: 03/27/2014
• Status: Active Grant

• Current Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Original Assignee: Integrated Device Technology Incorporated (Renesas Electronics Corporation)
• Inventors: Nalbant, Mehmet K.
• Granted Patent: US 9,577,438 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02M 7/217 using semiconductor devices only
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The present disclosure relates wireless power transfer. In some embodiments, DC power is received through one or more inductors and switched to provide alternating current through a TX coil with a pair of power FETs coupled between opposite sides of the TX coil and ground such that current flows through one of the pair of FETs at a time. In some embodiments, the pair of FETs can be driven in adaptive resonant mode to operate at a resonance. In some embodiments, the pair of FETs are driven at a particular frequency.

Claims

1. A transmitter for wireless power transfer, comprising:

a TX coil;

a capacitor coupled across the TX coil;

at least one inductor coupled between a power source and the TX coil; and

a pair of switching FETs including a first switching FET coupled between a first side of the capacitor and ground and a second switching FET coupled between a second side, opposite the first side, of the capacitor and ground, the gates of the first switching FET and the second switching FET being driven to provide an oscillating current through the TX coil.

2. The transmitter of claim 1, wherein the TX coil includes a center-tap, the inductor is coupled between the power source and the center tap, and the switching FETs have drains coupled to the first side and the second side of the capacitor.

3. The transmitter of claim 1, wherein the at least one inductor includes two inductors, a first inductor coupled between the power source and the first side of the capacitor and a second inductor coupled between the power source and the second side of the capacitor.

4. The transmitter of claim 1, wherein the pair of switching FETs are driven in adaptive resonance mode.

5. The transmitter of claim 1, wherein the pair of switching FETs are driven at a frequency at or near a resonant frequency.

6. The transmitter of claim 1, further including a buck-boost circuit coupled between the power source and the at least one inductor.

7. The transmitter of claim 1, further including a frequency shifting circuit coupled between drains of the first switching FET and the second switching FET, the frequency shifting circuit being driven by a modulator.

8. The transmitter of claim 7, wherein data is transmitted as frequency shifts in power transmitted by the TX coil.

9. A receiver, comprising:

a RX coil;

a rectifier coupled across the RX coil; and

a capacitor coupled between the RX coil and ground.

10. The receiver of claim 9, wherein the rectifier includes a first switching FET and a second switching FET, the first switching FET having a drain coupled to a first side of the RX coil and a source coupled to ground and a drain of the second switching FET coupled to a second side of the RX coil and a source of the second switching FET coupled to ground, wherein the gates of the first switching FET and the second switching FET are driven to convert power received at the RX coil substantially to DC power.

11. The receiver of claim 10, wherein the first switching FET and the second switching FET are driven in adaptive resonance mode.

12. The receiver of claim 9, wherein the rectifier is formed of diodes.

13. The receiver of claim 9, further including a demodulator that receives a modulated signal in power received by the RX coil.

14. The receiver of claim 9, further including a modulator for transmission of digital data to a transmitter.

15. A method of wirelessly transmitting power, comprising:

receiving DC power through one or more inductors; and

switching the DC power to provide alternating current through a TX coil with a pair of power FETs coupled between opposite sides of the TX coil and ground such that current flows through one of the pair of FETs at a time.

16. The method of claim 15, wherein switching the DC power including driving the pair of power FETs in adaptive resonance mode.

17. The method of claim 16, wherein driving the pair of power FETs in adaptive resonance mode includes

monitoring a voltage at a drain of a first FET coupled to a first side of the TX coil;

and

switching the first FET from off to on and a second FET from on to off when the voltage decreases to zero volts.

18. The method of claim 17, further including

monitoring a second voltage at a drain of the second FET coupled to a second side of the TX coil;

and

switching the first FET from on to off and the second FET from off to on when the second voltage decreases to zero volts.

19. The method of claim 15, further including providing a buck-boost between the power source and the one or more inductors.

20. The method of claim 15, further including modulating the current through the TX coil to encode digital data into a transmitted power signal.