NON-RESONANT AND QUASI-RESONANT SYSTEM FOR WIRELESS POWER TRANSMISSION TO MULTIPLE RECEIVERS

• US 20120169136A1
• Filed: 12/19/2011
• Published: 07/05/2012
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Socci, Gerard G., Djabbari, Ali, Mahmodieh, Kosha, Lisi, Gianpaolo
• Granted Patent: US 9,088,307 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A wireless power transfer system includes: a non-resonant transmitter, or a transmitter with a resonant circuit; and a non-resonant receiver, or a receiver with a resonant circuit. In some implementations, a transmitter with a resonant circuit is operated away from its resonance frequency. In some implementations, a receiver with a resonant circuit is operated away from the transmitter resonance frequency and/or the transmitter operating frequency. In some implementations, the selection of receiver resonance frequency is based on receiver power requirements. Thus, wireless power transfer may be accomplished by operating away from resonance in a quasi-resonant or non-resonant mode, and further may be accomplished using a non-resonant transmitter and/or a non-resonant receiver. Effective power transfer may also be achieved between a transmitter and multiple receivers. A combination of resonant and non-resonant transmitter and receiver(s) may be used for power transfer.

Claims

1. A wireless power transfer system, comprising:

a transmitter including a resonant circuit having a transmitter resonance frequency; and

a receiver including a resonant circuit having a receiver resonance frequency, the receiver configured such that the receiver resonance frequency is different from the transmitter resonance frequency.

2. The wireless power transfer system of claim 1, the selection of receiver resonance frequency being based on receiver power requirements.

3. The wireless power transfer system of claim 1, the transmitter including a power transfer coil, and further including a power supply providing alternating current (AC) power to the transmitter resonant circuit, the frequency of the AC power being such that the transmitter resonant circuit is operated at a frequency different than the transmitter resonance frequency while the transmitter is providing power through the power transfer coil during normal operation.

4. The wireless power transfer system of claim 3, the frequency of the AC power being adjusted to effect a change of the voltage across the power transfer coil based upon a desired change of magnetic field intensity

5. The wireless power transfer system of claim 1, the receiver being one of two or more receivers, the transmitter operated at a quasi-resonant or non-resonant frequency that causes a magnetic field to be generated that is substantially unaffected by the loading of the two or more receivers.

6. The wireless power transfer system of claim 1, the receiver being a first receiver having a first resonance frequency, further comprising:

a second receiver including a resonant circuit having a second receiver resonance frequency, the second receiver configured such that the second receiver resonance frequency is different from the transmitter resonance frequency and different from the first receiver resonance frequency.

7. The wireless power transfer system of claim 1, further comprising a communications link between the transmitter and receiver, communications from the receiver to the transmitter including identification of at least one of receiver type, receiver resonant frequency, and receiver input power requirements.

8. The wireless power transfer system of claim 1, the receiver included in an electronic device, the receiver configured to provide transferred power to circuits in the electronic device, thereby functioning as the power source for the circuits during normal operation.

9. The wireless power transfer system of claim 1, the receiver included in an electronic device, the receiver configured to provide transferred power to a battery in the electronic device, thereby charging the battery.

10. A wireless power transfer transmitter, comprising:

a resonant circuit with a transmitter resonance frequency;

the resonant circuit including a power transfer coil; and

a power supply providing alternating current (AC) power to the input of the resonant circuit;

the frequency of the AC power being such that the resonant circuit is operated at a frequency different than the transmitter resonance frequency while the transmitter is providing power through the power transfer coil during normal operation.

11. The wireless power transfer transmitter of claim 10, the frequency of the AC power being adjusted to effect a change of the voltage across the power transfer coil, the amount of adjustment of the frequency of the AC power being determined based upon a desired change of magnetic field intensity.

12. The wireless power transfer transmitter of claim 11, the adjustment of the frequency of the AC power being in response to a received communication indicating that a receiver in the proximity of the transmitter is requesting increased magnetic field intensity.

13. The wireless power transfer transmitter of claim 11, the adjustment of the frequency of the AC power being in response to the transmitter identifying multiple receivers in the proximity of the transmitter.

14. A wireless transmitter, comprising:

a power transfer coil; and

a power supply providing alternating current (AC) power to the power transfer coil such that a magnetic field is generated at the power transfer coil and thereby power is available for wireless transfer to one or more receivers;

the transmitter being a non-resonant transmitter.

15. The wireless transmitter of claim 14, the transmitter rendered non-resonant by virtue of operating the transmitter at a frequency away from resonance.

16. The wireless transmitter of claim 14, the transmitter being non-resonant by virtue of the absence of a resonant capacitor.

17. The wireless transmitter of claim 14, the voltage of the AC power provided to the power transfer coil being dynamically adjustable.

18. The wireless transmitter of claim 17, further comprising a communication interface between the transmitter and a receiver, the transmitter receiving a communication from a receiver in the proximity of the transmitter indicating that the receiver is requesting increased magnetic field intensity, and in response the transmitter adjusting the voltage of the AC power provided to the power transfer coil.

19. The wireless transmitter of claim 17, further comprising a communication interface for communication between the transmitter and multiple receivers, the transmitter identifying multiple receivers in the proximity of the transmitter, and adjusting the voltage of the AC power in response.

20. The wireless transmitter of claim 14, the frequency of the AC power provided to the power transfer coil being dynamically adjustable.

21. The wireless transmitter of claim 20, the frequency being adjusted in response to a receiver being in the proximity of the transmitter.

22. The wireless transmitter of claim 14, the magnetic field intensity being substantially independent of loading on the power transfer coil, the loading being caused by at least one of a receiver and a metal object in proximity to the transmitter.

23. The wireless transmitter of claim 14, the power supply having as an input high voltage alternating current (AC) power, the power supply having an intermediate stage with an AC-DC converter for converting the high voltage AC power to high voltage direct current (DC) power and a final stage for converting the DC power to AC power for delivery to the power transfer coil.

24. The wireless transmitter of claim 23, the intermediate stage being a rectifier bridge.

25. The wireless transmitter of claim 23, the final stage including a set of switches, each switch having a capacitor electrically in parallel to the switch for zero-voltage switching.