Temperature compensation in a wireless transfer system

• US 8,692,412 B2
• Filed: 03/30/2010
• Issued: 04/08/2014
• Est. Priority Date: 09/27/2008
• Status: Active Grant

Abstract

Described herein are improved configurations for a resonator for wireless power transfer that includes a conductor forming one or more loops and having an inductance L, a network of capacitors, having a capacitance, C, and a desired electrical parameter, coupled to the conductor, the network having at least one capacitor of a first type with a first temperature profile of the electrical parameter, and the network having at least one capacitor of a second type with a second temperature profile of the electrical parameter.

Claims

1. A resonator for wireless power transfer comprising:

a conductor forming one or more loops and having an inductance L,

a network of capacitors, having a capacitance, C, and a desired electrical parameter, coupled to the conductor, the network having at least one capacitor of a first type with a first temperature profile of the electrical parameter, and the network having at least one capacitor of a second type with a second temperature profile of the electrical parameter.

2. The resonator of claim 1, wherein said first temperature profile of the first type of capacitor is complementary to the second temperature profile of the second type of capacitor such that there is less change in the electrical parameter of the network due to a temperature change than when only a one type of capacitor is used.

3. The resonator of claim 2, wherein the electrical parameter is capacitance.

4. The resonator of claim 2, wherein the electrical parameter is resistance.

5. The resonator of claim 2, wherein the resonator has a resonant frequency, ˜

1/sqrt (LC), and wherein the network of capacitors are used to tune the resonant frequency.

6. The resonator of claim 2, further comprising a power source coupled to the resonator and driving the resonator with an oscillating voltage.

7. The resonator of claim 6, wherein the capacitors are for matching the impedance between the power source and the resonator at a certain frequency.

8. The resonator of claim 1, wherein there is substantially zero change in the electrical parameter due to a temperature change.

9. The resonator of claim 1, wherein the resonator has a quality factor Q>

100.

10. A resonator for wireless power transfer comprising:

a conductor forming one or more loops,

two or more types of electrical components having different temperature profiles for an electrical parameter, the electrical components forming a network connected to said conductor,

wherein the electrical components are arranged such that the temperature profiles of the components are complementary and there is less change in the electrical parameter of a circuit comprising the network and the conductor due to a temperature change than when only a one type of component is used.

11. The resonator of claim 10, wherein there is substantially zero change in the electrical parameter due to a temperature change.

12. The resonator of claim 10, wherein at least one of the electrical components is a capacitor.

13. The resonator of claim 10, wherein at least one of the electrical components is an inductor.

14. The resonator of claim 10, wherein the electrical parameter is capacitance.

15. The resonator of claim 10, wherein the electrical parameter is inductance.

16. The resonator of claim 10, wherein the electrical parameter is resistance.

17. The resonator of claim 10, further comprising a power source coupled to the resonator and driving the resonator with an oscillating voltage.

18. The resonator of claim 17, wherein the electrical components are for matching the impedance between the power source and the resonator at a certain frequency.

19. The resonator of claim 10, wherein the resonator has a quality factor Q>

100.

20. A resonator for wireless power transfer comprising:

a conductor forming one or more loops,

at least one capacitor, having a temperature profile and connected to said conductor,

wherein the at least one capacitor tunes a resonant frequency of the resonator and wherein the temperature profile of the at least one capacitor is chosen to detune the resonator from the resonant frequency when the temperature exceeds an operating range of the resonator.

21. The resonator of claim 20, wherein the operating range does not exceed 100 degrees Celsius.

22. The resonator of claim 20, wherein the detuning of the resonator is caused by a capacitance change.

23. The resonator of claim 20, wherein the resonator is detuned by at least 1 KHz from its resonant frequency when the temperature exceeds the operating range of the resonator.

24. The resonator of claim 20, wherein the resonator is detuned by at least 10 KHz from its resonant frequency when the temperature exceeds the operating range of the resonator.

25. The resonator of claim 20, wherein the resonator is detuned by at least 100 KHz from its resonant frequency when the temperature exceeds the operating range of the resonator.

26. The resonator of claim 20, wherein the resonator has a quality factor Q>

100.