POWER SUPPLY CONTROL IN WIRELESS POWER TRANSFER SYSTEMS

• US 20140054971A1
• Filed: 03/14/2013
• Published: 02/27/2014
• Est. Priority Date: 08/24/2012
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: Qualcomm, Inc.
• Inventors: Kissin, Michael, Keeling, Nicholas A., Beaver, Jonathan, Van Boheemen, Edward
• Granted Patent: US 9,859,956 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: B60L 2210/30 AC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• 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: 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 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: H02M 7/4818 with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits
• CPC Class Codes: H04B 5/24 Inductive coupling
• 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
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

This disclosure provides systems, methods and apparatus for wireless power transfer and particularly wireless power transfer to remote system such as electric vehicles. In one aspect an apparatus for use with a wireless power transfer transmitter device comprising a first inductive element for generating a magnetic field, is provided. The apparatus comprises a direct current (DC) power source having an adjustable output voltage. The apparatus also comprises an inverter configured to convert the adjustable output voltage of the DC power source to alternating current. The apparatus also comprises at least one controller configured to receive an indication of current in the first inductive element and control the output voltage of the DC power source in response to the indication of current in the first inductive element. The apparatus reduces distortion signals in the alternating current output of the inverter while maintaining current in the inductive element substantially constant.

Claims

1. An apparatus for wireless power transfer, the apparatus comprising

a direct current (DC) power source having an adjustable output voltage;

an inverter configured to convert the adjustable output voltage to an alternating current;

a first inductive element configured to receive the alternating current from the inverter and generate a magnetic field; and

at least one controller configured to reduce at least one distortion signal in the alternating current while maintaining the alternating current in the first inductive element substantially constant.

2. The apparatus of claim 1, wherein the at least one distortion signal comprises at least one odd harmonic component of the alternating current.

3. The apparatus of claim 1, wherein the inverter comprises at least one switching element, and is further configured to convert a current of the adjustable output voltage to the alternating current.

4. The apparatus of claim 1, wherein the at least one controller is configured to receive an indication of a level of the alternating current in the first inductive element.

5. The apparatus of claim 4, wherein the level of the alternating current is based on a direct measurement of current in the first inductive element.

6. The apparatus of claim 4, wherein the indication of the level of the alternating current is based on a direct measurement of current induced in a second inductive element by the magnetic field generated by the first inductive element.

7. The apparatus of claim 4, wherein the at least one controller is configured to control at least one of the adjustable output voltage of the DC power source and a conduction angle of the at least one switching element to reduce the at least one distortion signal in the alternating current based on the indication of the current level in the first inductive element.

8. The apparatus of claim 1, wherein the at least one controller controls the conduction angle of the at least one switching element to reduce the total harmonic distortion of the alternating current.

9. The apparatus of claim 7, wherein the at least one controller is configured to control the conduction angle of the at least one switching element within a range of substantially 120 degrees to 140 degrees.

10. The apparatus of claim 7, wherein the at least one controller is configured to control the adjustable output voltage of the DC power source and control the conduction angle of the at least one switching element based on power demand.

11. The apparatus of claim 7, wherein the controller is configured to increase the output voltage of the DC power source and adjust the conduction angle within the range of substantially 90 degrees to 160 degrees.

12. The apparatus of claim 7, wherein the controller is configured to control the conduction angle of the at least one switching element before controlling the output voltage of the DC power source.

13. The apparatus of claim 7, wherein the controller is configured to determine control settings for the adjustable output voltage of the DC power source and the conduction angle of at least one switching element.

14. The apparatus of claim 13, wherein the controller is configured to modify control settings based on power demand variations.

15. A method of controlling wireless power transfer, the method comprising:

providing to an inverter a direct current having an adjustable output voltage;

converting the adjustable output voltage to an alternating current;

supplying the alternating current to a first inductive element;

controlling the adjustable output voltage of the direct current to reduce the at least one distortion signal in the alternating current while maintaining the alternating current substantially constant in the first inductive element; and

generating a magnetic field for transferring wireless power to an inductive element.

16. The method of claim 15, wherein the at least one distortion signal comprises at least one odd harmonic component of the alternating current.

17. The method of claim 15, the method further comprising converting a current of the adjustable output voltage to the alternating current.

18. The method of claim 16, the method further comprising:

receiving an indication of the level of the alternating current in the first inductive element; and

controlling the adjustable output voltage of the DC power source based on the level of the alternating current in the first inductive element.

19. The method of claim 18, wherein the indication of a current level is a direct measurement of alternating current in the first inductive element.

20. The method of claim 18, wherein the indication of a current level is a measurement of current induced in a second inductive element by the magnetic field generated by the first inductive element.

21. The method of claim 18, the method further comprising controlling the conduction angle of at least one switching element in response to the current level in the first inductive element.

22. The method of claim 21, wherein controlling the conduction angle of the at least one switching element reduces the at least one distortion signal of the alternating current.

23. The method of claim 22, wherein the conduction angle of the switching elements is controlled within a range of substantially 120 degrees to 140 degrees.

24. The method of claim 22, the method further comprising determining control settings for adjustable output voltage of the DC power source and the conduction angle of at least one switching element based on power demand.

25. The method of claim 24, further comprising modifying control settings for adjustable output voltage of the DC power source and the conduction angle of at least one switching element are settings based on power demand variations.

26. An apparatus for wireless power transfer, the apparatus comprising

means for providing a direct current having an adjustable output voltage;

means for converting the adjustable output voltage to an alternating current;

means for receiving the alternating current from the means for converting;

means for generating a magnetic field; and

means for reducing the at least one distortion signal in the alternating current while maintaining the alternating current substantially constant, in the means for receiving the alternating current.

27. The apparatus of claim 26, wherein the means for reducing the at least one distortion signal comprises controlling the adjustable output voltage of the direct current.

28. The apparatus of claim 26, wherein the at least one distortion signal comprises at least one odd harmonic component of the alternating current.

29. The apparatus of claim 27, the apparatus further comprising means for converting a current of the adjustable output voltage to the alternating current.

30. The apparatus of claim 28, the apparatus further comprising:

means for receiving an indication of the level of the alternating current in the inductive element; and

means for controlling the adjustable output voltage of the DC power source based on the level of the alternating current in the first inductive element.

31. The apparatus of claim 29, wherein the indication of a current level is a direct measurement of alternating current in the first inductive element.

32. The apparatus of claim 29, wherein the indication of a current level is a measurement of current induced in a second inductive element by the magnetic field generated by the first inductive element.

33. The apparatus of claim 29, further comprising means for controlling the conduction angle of at least one switching element in response to the current level in the first inductive element.

34. The apparatus of claim 33, wherein controlling the conduction angle of the at least one switching element reduces the at least one distortion signal of the alternating current.

35. The apparatus of claim 33, wherein the conduction angle of the at least one switching element is controlled within a range of substantially 120 degrees to 140 degrees.

36. The apparatus of claim 33, wherein the means for controlling the adjustable output voltage of the DC power source and controlling the conduction angle of the at least one switching element are based on power demand.

37. The apparatus of claim 33, further comprising means for determining control settings for the adjustable output voltage of the DC power source and the conduction angle of the at least one switching element.

38. The apparatus of claim 37, further comprising modifying control settings for the adjustable output voltage of the DC power source and the conduction angle of the at least one switching element are settings based on power demand variations.