INDUCTIVELY COUPLED AC POWER TRANSFER

• US 20110221277A1
• Filed: 09/11/2009
• Published: 09/15/2011
• Est. Priority Date: 09/11/2008
• Status: Active Grant

• Current Assignee: Auckland UniServices Limited (Auckland University)
• Original Assignee: Auckland UniServices Limited (Auckland University)
• Inventors: Boys, John Talbot
• Granted Patent: US 11,522,389 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles

Abstract

An Inductive Power Transfer System pickup provides a controlled AC power supply by controlled variation of the phase angle between the pickup coil induced voltage (jwMI) and the tuning capacitor C voltage. The phase angle can be varied by maintaining the tuning capacitor C voltage substantially constant for a selected time period. Switches S1 and S2 may be used to clamp the tuning capacitor C voltage at substantially zero volts during the selected time period. Switch S1 can be operated to prevent a rise in positive voltage across the tuning capacitor, and switch S2 can be used to prevent the voltage across the tuning capacitor from going negative.

Claims

1. A method of providing an AC supply from an IPT pickup having a pickup coil and tuning capacitor comprising a resonant circuit, the method comprising varying a phase angle between the pickup coil induced voltage and the tuning capacitor voltage to provide a controlled AC supply to an output of the pickup.

2. A method as claimed in claim 1 wherein the phase angle between the pickup coil induced voltage and the tuning capacitor voltage is varied by maintaining the tuning capacitor voltage substantially constant for a selected time period.

3. A method as claimed in claim 2 wherein the selected time period is varied to vary the phase angle.

4. A method as claimed in claim 2 wherein the step of maintaining the tuning capacitor voltage substantially constant comprises clamping the tuning capacitor voltage at substantially zero volts.

5. A method as claimed in claim 4 wherein the step of clamping the tuning capacitor voltage comprises operating a first switch to prevent a rise in positive voltage across the tuning capacitor.

6. A method as claimed in claim 5 wherein the step of clamping the tuning capacitor voltage comprises operating a second switch to prevent the voltage across the tuning capacitor from going negative.

7. A method as claimed in claim 6, further comprising sensing a change in sign of the voltage across the tuning capacitor as a reference for controlling the selected time period.

8. A method as claimed in claim 7, further comprising comparing the output of the pickup with a set point, and increasing or decreasing the selected time period to change the output of the pickup toward the set point.

16. A method as claimed in claim 3 wherein the step of maintaining the tuning capacitor voltage substantially constant comprises clamping the tuning capacitor voltage at substantially zero volts.

17. A method as claimed in claim 16 wherein the step of clamping the tuning capacitor voltage comprises operating a first switch to prevent a rise in positive voltage across the tuning capacitor.

18. A method as claimed in claim 17 wherein the step of clamping the tuning capacitor voltage comprises operating a second switch to prevent the voltage across the tuning capacitor from going negative.

19. A method as claimed in claim 16 wherein the step of clamping the tuning capacitor voltage comprises operating a second switch to prevent the voltage across the tuning capacitor from going negative.

20. A method as claimed in claim 4 wherein the step of clamping the tuning capacitor voltage comprises operating a second switch to prevent the voltage across the tuning capacitor from going negative.

21. A method as claimed in claim 2, further comprising sensing a change in sign of the voltage across the tuning capacitor as a reference for controlling the selected time period.

22. A method as claimed in claim 21, further comprising comparing the output of the pickup with a set point, and increasing or decreasing the selected time period to change the output of the pickup toward the set point.

9. A controller for an IPT pickup having a pickup coil and a tuning capacitor comprising a resonant circuit, the controller including one or more switches to control a tuning capacitor voltage to thereby vary a phase angle between a pickup coil induced voltage and the tuning capacitor voltage whereby the pickup provides a controlled AC supply to an output of the pickup.

10. An IPT pickup comprising a pickup coil and a tuning capacitor comprising a resonant circuit, and a controller to vary a phase angle between a pickup coil induced voltage and a tuning capacitor voltage to thereby provide a controlled AC supply to an output of the pickup.

11. An IPT pickup as claimed in claim 10 and further comprising a rectifier connected to the output of the pickup for providing a DC output.

12. An IPT system including an IPT pickup as claimed in claim 10.

23. An IPT system including an IPT pickup as claimed in claim 11.

13. (canceled)

14. (canceled)

15. (canceled)