Power control

• US 8,803,359 B2
• Filed: 11/05/2008
• Issued: 08/12/2014
• Est. Priority Date: 11/05/2007
• Status: Expired due to Fees

• Current Assignee: Auckland UniServices Limited (Auckland University)
• Original Assignee: Auckland UniServices Limited (Auckland University)
• Inventors: Boys, John Talbot
• Primary Examiner(s): KAPLAN, HAL IRA
• Application Number:
  US12/734,486
• Publication Number:
  US 20110116290A1
• Time in Patent Office: 2,106 Days
• Field of Search: 307/38
• US Class Current: 307/38
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02M 1/4241 using a resonant converter
• CPC Class Codes: H02M 7/23 arranged for operation in parallel H02M7/2176 takes precedence
• 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

Abstract

A pick-up circuit for an inductive power transfer (IPT) system includes a series-tuned pick-up coil and a plurality of parallel AC processing circuits provided between the series-tuned pick-up coil and an output, each processing circuit being adapted to produce an output signal based directly or indirectly at least in part on a voltage of the series-tuned pick-up coil and including a switch for selectively coupling the processing circuit to the output so as to selectively provide the respective output signal to the output of the pick-up circuit.

Claims

1. A pick-up circuit for an inductive power transfer (IPT) system comprising a series-tuned pick-up coil and a plurality of parallel AC processing circuits provided between the series-tuned pick-up coil and an output, each processing circuit being adapted to produce an output signal based directly or indirectly at least in part on a voltage of the series-tuned pick-up coil and comprising a switch for selectively coupling the processing circuit to the output so as to selectively provide the respective output signal to the output of the pick-up circuit.

2. The pick-up circuit of claim 1 wherein the series-tuned pick-up coil forms a voltage source and each processing circuit is configured to convert an AC voltage from the voltage source to a DC current source output signal.

3. The pick-up circuit of claim 1 wherein the switch of each circuit may be independently actuated, such that any number of the switches may be switched on or off at any point in time.

4. The pick-up circuit of claim 1, wherein the number of processing circuits coupled to the output at any time is proportional to the instantaneous power requirement of a load associated with the output of the pick-up circuit.

5. The pick-up circuit of claim 1, further comprising a controller configured to control each switch of the plurality of processing circuits.

6. The pick-up circuit of claim 5, wherein the controller is configured to control each switch of the plurality of processing circuits so as to maintain the output voltage at, or substantially equal to, a predetermined value whereby a substantially constant output voltage is maintained as an external load associated with the output of the pick-up circuit varies.

7. The pick-up circuit of claim 5, wherein the controller is configured to employ a sequential switching strategy, whereby thermal loads on at least two of the plurality of processing circuits are equalized.

8. The pick-up circuit of claim 5, wherein the controller is configured to cycle a load between redundant processing circuits.

9. The pick-up circuit of claim 5, wherein the controller is configured to synchronize actuation of the switches with the zero voltage crossings of a single phase mains power supply input to a power supply of the IPT system.

10. The pick-up circuit of claim 5, wherein the controller is configured to weight current drawn from each of the processing circuits so as to maintain a desired power factor.

11. The pick-up circuit of claim 10, wherein the controller is configured to approximate a sinusoidal waveform in the output signal.

12. The pick-up circuit of claim 5, wherein the controller is configured to switch on and/or off processing circuits so as to produce a desired output waveform fundamental while reducing harmonics.

13. An inductive power transfer (IPT) system including the IPT pick-up circuit according to claim 1.

14. A method of controlling a pick-up in an inductive power transfer (IPT) system, the method comprising the steps of:

providing a plurality of parallel AC processing circuits, each adapted to produce an output signal based directly or indirectly at least in part on an input voltage, wherein the input voltage is generated by inductive power transfer; and

selectively coupling any number of the output signals to an output of the pick-up.

15. The method of claim 14, wherein the output signal is in the form of a current.

16. The method of claim 14, wherein the number of output signals coupled to the pick-up output is proportional to the power requirement of a load associated with the pick-up output.

17. The method of claim 14, wherein the particular combination of processing circuits coupled to the pick-up output is varied to cycle a load between redundant processing circuits.

18. The method of claim 14, wherein the number of processing circuits coupled to the pick-up output is varied to approximate a desired output waveform fundamental.

19. The method of claim 14, wherein the coupling and/or decoupling of the processing circuits is synchronized with the zero voltage crossings of a single phase mains power supply input to a power supply of the IPT system.