Operating a Wireless Power Transfer System at Multiple Frequencies

• US 20150333530A1
• Filed: 05/19/2014
• Published: 11/19/2015
• Est. Priority Date: 05/19/2014
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moyer, Todd K., Terlizzi, Jeffrey J., Alves, Jeffrey M.
• Granted Patent: US 10,135,303 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 5/00 Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• 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 7/02 for charging batteries from ac mains by converters

Abstract

A transmitter device in an inductive energy transfer system includes a first transmitter coil operatively connected to a first resonant circuitry. A receiver device includes a first receiver coil operatively connected to a first resonant circuitry. The first transmitter coil and the first receiver coil form a first transformer. The transmitter device, the receiver device, or both the transmitter and receiver devices can also include an auxiliary coil or inductor, which may form an auxiliary transformer. Energy can be transferred from the transmitter device to the receiver device using the first transformer or the auxiliary transformer. The transfer of energy may be adaptively adjusted based on the efficiency of the energy transfer. For example, the transfer of energy can be adjusted based on the operating conditions of the load.

Claims

1. A receiver device for use in an inductive energy transfer system, comprising:

a first receiver coil operatively connected to an input of an AC-to-DC converter;

a first resonant circuitry operatively connected between the first receiver coil and the input of the AC-to-DC converter, wherein the first resonant circuitry is associated with a first resonant frequency;

an auxiliary receiver coil operatively connected to the input of the AC-to-DC converter; and

an auxiliary resonant circuitry operatively connected between the second receiver coil and the input of the AC-to-DC converter, wherein the second resonant circuitry is associated with a second resonant frequency that is different from the first resonant frequency.

2. The receiver device as in claim 1, further comprising a switching device operatively connected between the first resonant circuitry and the input of the AC-to-DC converter and operatively connected between the auxiliary resonant circuitry and the input of the AC-to-DC converter.

3. The receiver device as in claim 2, further comprising a processing device operatively connected to the switching device for controlling a state of the switch.

4. The receiver device as in claim 3, further comprising an auxiliary rectifier operatively connected to the switching device and a load.

5. The receiver device as in claim 1, further comprising a load operatively connected to an output of the AC-to-DC converter.

6. The receiver device as in claim 5, wherein the load comprises a rechargeable battery.

7. The receiver device as in claim 1, wherein the first and the auxiliary resonant circuitry each comprise a capacitor.

8. The receiver device as in claim 1, wherein the AC-to-DC converter comprises a diode bridge.

9. The receiver device as in claim 1, wherein the AC-to-DC converter comprises a synchronous rectifier.

10. The receiver device as in claim 1, wherein the second resonant frequency is higher than the first resonant frequency.

11. A transmitter device for use in an inductive energy transfer system, comprising:

a DC-to-AC converter operatively connected to a first resonant circuitry and an auxiliary resonant circuitry, wherein the first resonant circuitry is associated with a first resonant frequency and the auxiliary resonant circuitry is associated with a second resonant frequency different from the first resonant frequency;

a first transmitter coil operatively connected to the first resonant circuitry; and

an auxiliary transmitter coil operatively connected to the auxiliary resonant circuitry.

12. The transmitter device as in claim 11, further comprising a power supply operatively connected to the DC-to-AC converter.

13. The transmitter device as in claim 11, wherein the second resonant frequency is higher than the first resonant frequency.

14. The transmitter device as in claim 11, wherein the first resonant circuitry and the auxiliary resonant circuitry each comprise a capacitor.

15. The transmitter device as in claim 11, further comprising a sense circuitry operatively connected to the load and a processing device operatively connected to the sense circuitry.

16. A method for operating an inductive energy transfer system, comprising:

transferring energy from a transmitter device to a receiver device using a first transformer in a power transfer mode; and

transferring energy from the transmitter device to the receiver device using an auxiliary transformer in a low energy transfer mode.

17. The method as in claim 16, further comprising:

monitoring a load in the receiver device; and

changing to a different transfer mode based on an operating condition of the load.

18. The method as in claim 16, wherein the transmitter device pings the receiver device in the low energy transfer mode.

19. The method as in claim 16, further comprising monitoring transfer efficiency during the power transfer mode and adjusting at least one of a frequency and a signal level to increase the transfer efficiency.

20. The method as in claim 16, wherein the power transfer mode is associated with a first resonant frequency and the low energy transfer mode is associated with a second resonant frequency that is higher than the first resonant frequency.