Method and apparatus of load detection for a planar wireless power system

• US 8,232,793 B2
• Filed: 09/12/2008
• Issued: 07/31/2012
• Est. Priority Date: 09/12/2008
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Lin, Jenshan, Low, Zhen Ning
• Primary Examiner(s): Velez, Roberto
• Application Number:
  US12/209,784
• Publication Number:
  US 20100066349A1
• Time in Patent Office: 1,418 Days
• Field of Search: None
• US Class Current: 324/126
• CPC Class Codes: H02J 50/10 using inductive coupling
• 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 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

Embodiments of the subject invention relate to a method and apparatus for determining information regarding a load in a planar wireless power transfer system by extracting system operating parameters from one or more test points in the transmitter circuit. As shown in FIG. 1, a specific embodiment showing three test points in the transmitter circuit from which operating parameters can be extracted. The transmitter circuit is designed to produce a magnetic field, by driving the transmitter coil, which inductively couples to a receiver coil such that power is provided to a receiver. By extracting operating parameters from the transmitter circuit, the receiver does not need to incorporate sophisticated signal processing and can be manufactured with low cost.

Claims

1. A method of determining information regarding a load for a planar wireless power transfer system, comprising:

driving a transmitter coil of a planar wireless power transfer system with a drive amplifier;

measuring a transmitter coil voltage provided by the drive amplifier to the transmitter coil, wherein the transmitter coil voltage is measured from a circuit physically and directly connected in parallel with the transmitter coil, the circuit comprising a diode and a capacitor; and

determining information regarding a load positioned proximate to the transmitter coil based at least in part upon the measured transmitter coil.

2. The method according to claim 1, wherein determining information regarding the load proximate the transmitter coil comprises comparing the transmitter coil voltage over a period of time with an a priori curve in the transmitter coil voltage and power delivered to load space.

3. The method according to claim 1, further comprising:

measuring a transmitter supply current provided to the drive amplifier.

4. The method according to claim 3, wherein the transmitter supply current is measured on a high side of a power supply, wherein the power supply supplies power to the drive amplifier.

5. The method according to claim 4, wherein the transmitter supply current is measured via a current sensing resistor.

6. The method according to claim 5, wherein the transmitter supply current is measured via an amplifier across the current sensing resistor.

7. The method according to claim 3, wherein the transmitter supply current is measured on a low side of a power supply, wherein the power supply supplies power to the driver amplifier.

8. The method according to claim 7, wherein the transmitter supply current is measured via a current sensing resistor.

9. The method according to claim 8, wherein the transmitter supply current is measured via an amplifier across the current sensing resistor.

10. The method according to claim 3, wherein the transmitter coil voltage is measured at a high side of the transmitter coil.

11. The coil method according to claim 10, wherein the transmitter coil voltage is measured via a rectification circuit.

12. The method according to claim 11, wherein the rectification circuit comprises a diode and a charge holding capacitor.

13. The method according to claim 3, wherein information regarding the load is determined via analysis of the transmitter supply current and the transmitter coil voltage space.

14. The method according to claim 3, further comprising:

measuring a transmitter coil current passing through the transmitter coil.

15. The method according to claim 14, wherein information regarding the load is determined via analysis of the transmitter supply current, the transmitter coil voltage, and the transmitter coil current space.

16. The method according to claim 3, wherein the transmitter supply current is measured over a period of time, wherein the transmitter coil voltage is measured over the period of time.

17. The method according to claim 16, wherein the information regarding the load comprises the charge status of the load.

18. The method according to claim 3, wherein the information regarding the load comprises the charge status of the load.

19. The method according to claim 3, wherein the information regarding the load comprises whether the load is operating properly.

20. The method according to claim 3, wherein the information regarding the load comprises whether a valid load is proximate to the transmitter coil.

21. The method according to claim 3, wherein the transmitter supply current and the transmitter coil voltage are measured at a point in time, wherein the information regarding the load is whether there is no load, a valid load, or a faulty load.

22. The method according to claim 3, wherein the transmitter supply current and the transmitter coil voltage are measured at a point in time, wherein the information regarding the load is whether the load is operating properly.

23. The method according to claim 1, wherein the information regarding the load is the charging status of the load.

24. A method of determining information regarding a load for planar wireless power transfer system, comprising:

driving a transmitter coil of a planar wireless power transfer system with a drive amplifier;

measuring a transmitter coil current passing through the transmitter coil, wherein the transmitter coil current is measured from a circuit connected across a resistor that is physically and directly connected in series with the transmitter coil, the circuit comprising a differential amplifier, a diode, and a capacitor; and

determining information regarding a load positioned proximate to the transmitter coil based at least in part upon the measured transmitter coil current.

25. The method according to claim 24, wherein determining information regarding the load proximate the transmitter coil comprises comparing the transmitter coil current over a period of time with a priori curve in the transmitter coil current and power delivered to load space.

26. The method according to claim 24, further comprising:

measuring a transmitter supply current provided to the drive amplifier.

27. The method according to claim 26, wherein the transmitter coil current is measured on high side of the transmitting coil.

28. The coil method according to claim 27, wherein the transmitter coil current is measured via a current sensing resistor.

29. The method according to claim 28, wherein the transmitter coil current is measured via an amplifier across the current sensing resistor.

30. The method according to claim 29, wherein an output of the amplifier is input into a rectification circuit.

31. The method according to claim 30, wherein the rectification circuit comprises a diode and a charge holding capacitor.

32. The method according to claim 26, wherein the transmitter coil current is measured at a low side of the transmitting coil.

33. The method according to claim 32, wherein the transmitter coil current is measured via a current sensing resistor.

34. The method according to claim 33, wherein the transmitter coil current is measured via an amplifier across the current sensing resistor.

35. The method according to claim 34, wherein an output of the amplifier is input to a rectification circuit.

36. The method according to claim 35, wherein the rectification circuit comprises a diode and a charge holding capacitor.

37. The method according to claim 26, wherein information regarding the load is determined via analysis of the transmitter supply current and the transmitter coil current space.

38. The method according to claim 26, wherein the transmitter supply current is measured over a period of time, wherein the transmitter coil current is measured over a period of time.

39. The method according to claim 38, wherein the information regarding the load comprises the charge status of the load.

40. The method according to claim 26, wherein the information regarding the load comprises the charge status of the load.

41. The method according to claim 26, wherein the information regarding the load comprises whether the load is operating properly.

42. The method according to claim 26, wherein the information regarding the load comprises whether a valid load is proximate to the transmitter coil.

43. The method according to claim 26, wherein the transmitter supply current and the transmitter coil current are measured at a point in time, wherein the information regarding the load is whether there is no load, a valid load, or a faulty load.

44. The method according to claim 26, wherein the transmitter supply current and the transmitter coil current are measured at a point in time, wherein the information regarding the load is whether the load is operating properly.