SELECTABLE RESONANT FREQUENCY TRANSCUTANEOUS ENERGY TRANSFER SYSTEM

• US 20110101790A1
• Filed: 01/20/2009
• Published: 05/05/2011
• Est. Priority Date: 01/18/2008
• Status: Active Grant

• Current Assignee: Millar Instruments Limited (Kaha Sciences Ltd.)
• Original Assignee: Telemetry Research Limited
• Inventors: Budgett, David
• Granted Patent: US 9,125,242 B2
• Time in Patent Office: Days
• US Class Current: 307/104
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61F 2250/0001 Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61M 2205/3507 with implanted devices, e.g. external control
• CPC Class Codes: A61M 2205/8243 by induction
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 3/34 Arrangements for transfer of electric power between networks of substantially different frequency
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/402 the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas
• 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: H05B 6/06 Control, e.g. of temperature, of power
• CPC Class Codes: H05B 6/08 using compensating or balancing arrangements

Abstract

An inductive power transfer system includes a number of controllable reactive components (3, 6, 12, 13, 16) that allow the resonant frequency of a primary and/or secondary resonant circuit to be controllably varied to thereby control power available to a load (10).

Claims

1. An inductive power transfer system for supplying power to an electrical load located in a living body, the system including:

a primary power supply located externally of the living body having a primary resonant circuit and being capable of providing an electromagnetic field;

an inductive power pick-up implanted within the living body having a pick-up resonant circuit and being capable of receiving power from the electromagnetic field provided by the primary power supply to supply power to the electrical load;

a plurality of controllable reactive components, the controllable reactive components being associated with one or both of the primary resonant circuit and the pick-up resonant circuit;

control means to increase or decrease the power available to the load by controlling one or more of the controllable reactive components to thereby vary the resonant frequency of the primary resonant circuit and/or the pick-up resonant circuit.

2. An inductive power transfer system as claimed in claim 1 wherein the controllable reactive components are associated with the pick-up resonant circuit.

3. An inductive power transfer system as claimed in claim 1 wherein the controllable reactive components are associated with the primary resonant circuit.

4. An inductive power transfer system as claimed in claim 1 wherein at least one of the controllable reactive components is associated with the pick-up resonant circuit and at least one of the controllable reactive components is associated with the primary resonant circuit.

5. An inductive power transfer system as claimed in any one of the preceding claims wherein at least one of the controllable reactive components is switched into or out of connection with the resonant circuit with which it is associated at substantially the rate of the resonant frequency and another controllable reactive component is switched at a slower rate.

6. An inductive power transfer system as claimed in any one of the preceding claims wherein at least one controllable reactive component comprises a plurality of discrete reactive components and the control means is operable to selectively switch a selected discrete reactive component into or out of connection with the resonant circuit with which the controllable reactive component is associated.

7. An inductive power transfer system as claimed in any one of the preceding claims wherein at least one of the controllable reactive components is implemented by altering the material properties of an inductor core or capacitor plate.

8. An inductive power transfer system as claimed in any one of the preceding claims wherein at least one of the controllable reactive components is implemented by switching in, or out, conducting sections of a coil associated with the primary resonant circuit altering the inductance of the coil and/or to alter the direction of the magnetic field produced by the coil.

9. An inductive power transfer system as claimed in any one of the preceding claims wherein at least one controllable reactive component is implemented by cycle by cycle switching of additional reactive components, the timing of the switching determining an effective resultant reactance.

10. An inductive power transfer system as claimed in claim 1 wherein the control means is able to operate at a lower frequency limit and/or operate at a higher frequency limit by using a combination of a fast response controllable reactive component and a slow response controllable reactive component compared to the operating frequency range obtained by using a single controllable reactive component.

11. An inductive power transfer system as claimed in claim 10 wherein the fast response controllable reactive component provides a fine tuning capability and the slower response controllable reactive component provides discrete changes in frequency bands such that the combined effect is a continuous range of frequency adjustment.

12. An inductive power transfer system as claimed in any one of the preceding claims wherein the system includes:

a sensor to provide an indication of temperature in the vicinity of the pick-up, and the controller is operable to control the controllable reactive components in response to the temperature indication provided by the sensor.

13. An inductive power transfer system as claimed in claim 1 wherein the controllable reactive components include a plurality of discrete capacitors of similar value associated with the pick-up resonant circuit and the control means includes a switching means to enable one or more of the discrete capacitors to be connected or disconnected to or from the resonant circuit independently from the state of other discrete capacitors, and whereby the control means is operable to determine the state of the switching means and compensate for a failure in any discrete capacitor.

14. An inductive power transfer system as claimed in claim 4 wherein the resonant frequency for operation of the system is selectable by control of the controllable reactive components between a first operating frequency providing maximum efficiency at a lower power transfer level and a second frequency providing maximum power transfer at a lower efficiency.

15. An inductive power transfer system as claimed in claim 4 wherein the control means is operable to control the controllable reactive components to provide a first power transfer level, and to control the controllable reactive components to provide a second power transfer level.

16. An inductive power transfer system as claimed in claim 1 wherein the pick-up includes:

a first pick-up coil;

a second pick-up coil;

a resonant capacitor;

a switching matrix to enable the coils and capacitor to be selectively electrically connected in a plurality of different configurations;

and wherein the control means is operable to control the switching matrix to provide a required circuit configuration.

17. An inductive power transfer system as claimed in claim 16 whereby the control means is operable to select a circuit configuration which provides power to the load when one of the coils or capacitors fails.

18. An inductive power transfer system as claimed in claim 16 whereby the control means is operable to select circuit configurations that enable different pick-up coils to be used at different times.

19. An inductive power transfer system as claimed in claim 16 whereby the control means is operable to select circuit configurations that enable different pick-up coils to be used when supplying different load requirements.

20. A method of inductive power transfer for supplying power to an electrical load located in a living body, the method including the steps of:

controlling the power available to the load by controlling a plurality of controllable reactive components associated with resonant circuits of one or both of a primary resonant circuit located externally of the living body and a pick-up resonant circuit implanted within the living body to vary the resonant frequency of the primary resonant circuit and/or the pick-up resonant circuit.

21. A method as claimed in claim 20 wherein at least one of the controllable reactive components is switched into or out of connection with the resonant circuit with which it is associated at substantially the rate of the resonant frequency and another controllable reactive component is switched at a slower rate.

22. A method as claimed in claim 20 wherein at least one controllable reactive component includes a plurality of discrete reactive components and the method includes selecting one, or a number, of the plurality of discrete components and switching the selected component(s) into connection with the resonant circuit with which the controllable component is associated.

25. A method as claimed in claim 21 including using the controlled component which is switched substantially at the rate of the resonant frequency to provide a fine tuning capability using the slower switched component(s) to provide a discrete jump in one or more frequency bands such that the combined effect is a continuous range of frequency adjustment.

26. A method as claimed in claim 20 including selecting a first set of reactive components providing maximum efficiency at a lower power transfer level and a second set of reactive components providing maximum power transfer at a lower efficiency.

23. A method as claimed in 20 wherein at least one variable reactive component is implemented by altering the material properties of the inductor core or capacitor plate

24. A method as claimed in 20 including controlling at least one controllable reactive component by cycle by cycle switching of additional reactive components, the timing of the switching determining the effective resultant reactance.

27. A method as claimed in 20 including selectively electrically connecting:

a first pick-up coil;

a second pick-up coil;

a resonant capacitor;

in a plurality of different configurations to control the reactance of a controllable reactance.

28. A method as claimed in claim 27 including selecting a configuration that provides power to the load when one of the components fails.

29. A method as claimed in claim 27 that includes selectively a configuration that enables different pick-up coils to be used at different times.

30. A method as claimed in claim 27 that includes selecting a configuration that enables different pick-up coils to be used when supplying different load requirements.

31. An inductive power transfer system including:

a primary power supply having a primary resonant circuit and being capable of providing an electromagnetic field;

an inductive power pick-up having a pick-up resonant circuit and being capable of receiving power from the electromagnetic field provided by the primary power supply to supply power to an electrical load;

control means to increase or decrease the power available to the load by controlling a first or a second controllable reactive component associated with the primary resonant circuit or the pick-up resonant circuit to thereby vary the resonant frequency of the primary resonant circuit and/or the pick-up resonant circuit by;

(i) controlling the first controllable reactive component to vary the resonant frequency of the respective resonant circuit over a plurality of current or voltage cycles, or

(ii) controlling the second controllably variable reactive component to vary the resonant frequency of the respective resonant circuit in each current or voltage cycle.

32. A method of inductive power transfer, the method including the steps of:

controlling the power available to a load by controlling a plurality of controllable reactive components associated with one or both of a primary resonant circuit and a pick-up resonant circuit.

33. A method as claimed in claim 32 including selecting a first set of reactive components providing a high efficiency at a low power transfer level and a second set of reactive components providing a high level of power transfer at a low efficiency.

34. A method as claimed in claim 32 or 33 wherein at least one of the controllable reactive components is switched into or out of connection with the resonant circuit with which it is associated at substantially the rate of the resonant frequency and another controllable reactive component is switched at a slower rate.

35. An inductive power transfer system including:

a primary power supply having a primary resonant circuit and being capable of providing an electromagnetic field;

an inductive power pick-up having a pick-up resonant circuit and being capable of receiving power from the electromagnetic field provided by the primary power supply to supply power to an electrical load;

a plurality of controllable reactive components, the controllable reactive components being associated with one or both of the primary resonant circuit and the pick-up resonant circuit;

control means to increase or decrease the power available to the load by controlling one or more of the controllable reactive components.

36. An inductive power transfer system as claimed in claim 35 wherein the control means selects a first set of reactive components providing a high efficiency at a low power transfer level and a second set of reactive components providing a high level of power transfer at a low efficiency;

a primary power supply having a primary resonant circuit and being capable of providing an electromagnetic field.

37. An inductive power transfer system as claimed in claim 35 or claim 36 wherein at least one of the controllable reactive components is switched into or out of connection with the resonant circuit with which it is associated at substantially the rate of the resonant frequency and another controllable reactive component is switched at a slower rate.