Tuning methods and apparatus for inductively coupled power transfer (ICPT) systems

• US 20090302933A1
• Filed: 04/28/2006
• Published: 12/10/2009
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Auckland UniServices Limited (Auckland University)
• Original Assignee: Auckland UniServices Limited (Auckland University)
• Inventors: Boys, John Talbot, Covic, Grant Anthony
• Granted Patent: US 8,183,938 B2
• Time in Patent Office: Days
• US Class Current: 327/553
• CPC Class Codes: H01F 29/14 with variable magnetic bias amplitude modulation by means of variable impedance element H03C1/08 ; magnetic amplifiers H03F; circuits for automatic telephonic communication H04M3/00
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H03J 5/246 using electronic means H03J5/244 takes precedence

Abstract

A method is provided for controlling a resonant circuit (1) of an ICPT system. The resonant circuit has a controlled variable reactance (2), and a predetermined perturbation is introduced in the magnitude of variable reactance. The change in a property of the resonant circuit in response to the perturbation is sensed, and the variable reactance is varied to alter the resonant frequency of the circuit in response to the sensed change.

Claims

1. A method for controlling a resonant circuit of an ICPT system, the method including the steps of:

introducing a predetermined perturbation in a magnitude of a variable reactance in the resonant circuit;

sensing a change in a property of the resonant circuit in response to the perturbation, and;

varying the variable reactance to alter the resonant frequency of the circuit in response to the sensed change.

2. A method as claimed in claim 1 wherein the sensed change is used to determine whether the frequency of operation of the circuit is above or below the resonant frequency of the circuit.

3. A method as claimed in claim 1 wherein the step of varying the variable reactance comprises varying the reactance to bring the resonant frequency of the circuit toward a frequency of operation.

4. A method as claimed in claim 1 wherein the step of varying the variable reactance comprises providing a desired output of the circuit and varying the reactance to change the resonant frequency of the circuit to bring an output of the resonant circuit toward a desired output.

5. A method as claimed in claim 1 wherein the perturbation is cyclical.

6. A method as claimed in claim 1 including a step of integrating the sensed change to provide a control signal for varying the variable reactance.

7. A method as claimed in claim 1 wherein the step of introducing a predetermined perturbation includes applying an alternating control signal of predetermined magnitude to the variable reactance.

8. A method as claimed in claim 1 wherein the perturbation varies the variable reactance in such a way as to alter the frequency of the resonant circuit over a range of approximately 1%.

9. A method as claimed in claim 1 wherein the perturbation results in the frequency of the resonant circuit being changed in a cyclical fashion at a rate of approximately 20 Hz.

10. A method as claimed in claim 1 wherein the sensed change in a property of the resonance circuit is the current which is either increased or decreased in response to the perturbation, to provide an indication as to whether the frequency of the resonant circuit is less than or greater than a natural frequency of the circuit.

11. A method as claimed in claim 1 wherein the step of varying the variable reactance comprises varying a current applied to a saturable inductor.

12. An ICPT system including a resonant circuit having a variable reactance, and control means adapted to:

controllably vary a variable reactance in the resonant circuit;

introduce a predetermined perturbation in a magnitude of the variable reactance;

sense a change in a property of the resonant circuit in response to the perturbation, and;

vary the variable reactance to alter the resonant frequency of the circuit in response to the sensed change.

13. An ICPT system as claimed in claim 12 wherein control means controls the perturbation to be cyclical.

14. An ICPT system as claimed in claim 12 wherein the control means includes an integrator to integrate the sensed change to provide a control signal for varying the variable reactance.

15. An ICPT system as claimed in claim 12 wherein the variable reactance comprises a variable capacitance.

16. An ICPT system as claimed in claim 12 wherein the variable reactance comprises a variable inductance.

17. An ICPT system as claimed in claim 16 wherein the variable reactance comprises a saturable inductor.

18. An ICPT system pick-up including a resonant circuit having a variable reactance, and control means adapted to:

controllably vary a variable reactance in the resonant circuit;

introduce a predetermined perturbation in a magnitude of the variable reactance;

sense a change in a property of the resonant circuit in response to the perturbation, and;

vary the variable reactance to alter the resonant frequency of the circuit in response to the sensed change.

19. An ICPT system power supply including a resonant circuit having a variable reactance, and control means adapted to:

controllably vary a variable reactance in the resonant circuit;

introduce a predetermined perturbation in a magnitude of the variable reactance;

sense a change in a property of the resonant circuit in response to the perturbation, and;

vary the variable reactance to alter the resonant frequency of the circuit in response to the sensed change.

20. A method for controlling a resonant circuit of an ICPT system substantially as herein described with reference to any one of the embodiments shown in the drawings.

21. An ICPT system substantially as herein described with reference to any one of the embodiments shown in the drawings.

22. An ICPT system pick-up substantially as herein described with reference to any one of the embodiments shown in the drawings.

23. An ICPT system power supply substantially as herein described with reference to any one of the embodiments shown in the drawings.