Adaptive rectifier and method of operation

• US 9,831,684 B2
• Filed: 03/13/2015
• Issued: 11/28/2017
• Est. Priority Date: 08/08/2014
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Lisi, Gianpaolo, Desai, Nachiket V., Arora, Sakshi, Subramonian, Rajaram, Socci, Gerard, Du, Dingkun
• Primary Examiner(s): Deberadinis, Robert
• Application Number:
  US14/657,685
• Publication Number:
  US 20160043562A1
• Time in Patent Office: 991 Days
• Field of Search: 307104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• 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 7/00308 Overvoltage protection

Abstract

A wireless power transfer system includes a wireless power receiver having a rectifier. The rectifier includes switches. The wireless power receiver is operable to control the switches for ensuring a complex impedance at the input of the rectifier.

Claims

1. A wireless power transfer system, comprising:

a wireless power receiver including;

a rectifier including switches and a rectifier input having first and second rectifier input nodes;

a secondary coil having a first terminal coupled to the first rectifier input node, and having a second terminal coupled to the second rectifier input node; and

control circuitry to control the switches, including varying states of the switches to ensure a complex impedance at the rectifier input by shifting a phase of a voltage between the first and second rectifier input nodes relative to a phase of the secondary coil.

2. The wireless power transfer system of claim 1, wherein the control circuitry is configured to control the switches to ensure the complex impedance with variable phase into the rectifier.

3. The wireless power transfer system of claim 2, wherein the control circuitry is configured to control an output pulse width for control of a first parameter and to control a phase of the output pulse to adjust a second parameter.

4. The wireless power transfer system of claim 3, wherein the first parameter is output current to a load, and the second parameter is efficiency of the wireless power receiver.

5. The wireless power transfer system of claim 3, wherein the first parameter is voltage to a load, and the second parameter is efficiency of the wireless power receiver.

6. The wireless power transfer system of claim 2, wherein the control circuitry is configured to control a phase of the complex impedance at the rectifier input, so that a resistance of the rectifier input is negative.

7. The wireless power transfer system of claim 6, wherein the wireless power receiver is configured to transfer power to a wireless power transmitter when the resistance of the input to the rectifier is negative.

8. The wireless power transfer system of claim 1, further comprising:

a wireless power transmitter configured to;

sense current phase changes resulting from reflected impedance of the rectifier in the wireless power receiver; and

control a parameter in the wireless power transmitter in response to the reflected impedance of the rectifier in the wireless power receiver.

9. The wireless power transfer system of claim 1, wherein the complex impedance is a variable impedance, and the wireless power receiver is configured to encode information in the variable impedance at the rectifier input.

10. The wireless power transfer system of claim 9, further comprising:

a wireless power transmitter configured to;

sense changes in the variable impedance reflected from the wireless power receiver; and

decode information encoded in the changes.

11. The wireless power transfer system of claim 1, wherein the control circuitry is configured to control the switches in the rectifier to at least partially discharge a voltage at an output of the rectifier, for preventing a magnitude of that voltage from exceeding a maximum value.

12. A method of controlling a wireless power transfer system, the method comprising:

controlling, by control circuitry in a wireless power receiver, switches in a rectifier that includes a rectifier input having first and second rectifier input nodes, wherein controlling the switches includes varying states of the switches to ensure a complex impedance at the rectifier input by shifting a phase of a voltage between the first and second rectifier input nodes relative to a phase of a secondary coil, the secondary coil having a first terminal coupled to the first rectifier input node, and having a second terminal coupled to the second rectifier input node.

13. The method of claim 12, further comprising:

controlling, by the control circuitry in the wireless power receiver, the switches in the rectifier to control two different operating parameters of the wireless receiver.

14. The method of claim 12, further comprising:

controlling, by the control circuitry in the wireless power receiver, the switches in the rectifier to control a phase of the complex impedance at the rectifier input, so that a resistance of the rectifier input is negative.

15. The method of claim 14, further comprising:

wirelessly transferring, by the wireless power receiver, power to a wireless power transmitter.

16. The method of claim 12, wherein the complex impedance is a variable impedance, and the method further comprises:

encoding, by the wireless power receiver, information in the variable impedance at the rectifier input.

17. The method of claim 16, further comprising:

sensing, by a wireless power transmitter, changes in the variable impedance reflected from the wireless power receiver; and

decoding, by the wireless power transmitter, information encoded in the changes.

18. The method of claim 12, further comprising:

controlling, by the control circuitry in the wireless power receiver, the switches in the rectifier to at least partially discharge a voltage at an output of the rectifier, for preventing a magnitude of that voltage from exceeding a maximum value.