VARIABLE CAPACITOR FOR RESONANT POWER TRANSFER SYSTEMS

• US 20150207330A1
• Filed: 07/29/2013
• Published: 07/23/2015
• Est. Priority Date: 07/27/2012
• Status: Active Grant

• Current Assignee: TC1 LLC (Abbott Laboratories Incorporated)
• Original Assignee: Thoratec LLC
• Inventors: Petersen, Ethan
• Granted Patent: US 10,383,990 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02J 5/00 Circuit arrangements for transfer of electric power between ac networks and dc networks H02J3/36 takes precedence
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence

Abstract

Systems and designs for tuning a wireless power transfer system are provided, which may include any number of features. In one embodiment, a wireless power transfer system can include first and second switched capacitor circuits electrically connected to opposite poles of the inductor of a resonator in the wireless power system. The first and second switched capacitor circuits can be switched on and off with MOSFETS to change a capacitance of the circuits, and thus an effective capacitance of the resonator. Methods of use are also provided.

Claims

1. A resonator of a wireless power transfer system, comprising:

an inductor adapted to receive or transmit wireless power;

first and second switched capacitor circuits electrically connected to opposite poles of the inductor, each of the first and second switched capacitor circuits comprising a first capacitor in series with a MOSFET and a second capacitor in parallel with the first capacitor; and

a controller electrically connected to the first and second switched capacitor circuits, the controller configured to switch the MOSFETS on and off to change a capacitance of the first and second switched capacitor circuits to adjust an effective capacitance of the resonator.

2. The resonator of claim 1, wherein the controller can be configured to turn the MOSFETS during a 50% duty cycle to achieve a minimum effective capacitance of the wireless power transfer system.

3. The resonator of claim 1, wherein the controller can be configured to turn the MOSFETS during a 100% duty cycle to achieve a maximum effective capacitance of the wireless power transfer system.

4. The resonator of claim 1 wherein the controller is configured to control the effective capacitance of the wireless power transfer system to optimize a power transfer efficiency of the wireless power transfer system.

5. The resonator of claim 1 wherein the controller is configured to control the effective capacitance of the wireless power transfer system to optimize a coupling coefficient of the wireless power transfer system.

6. The resonator of claim 1 wherein the controller is configured to monitor a system parameter in response to the adjusted effective capacitance, and to iteratively adjust effective capacitance in the direction that improves performance of the system parameter.

7. The resonator of claim 1 wherein the system parameter comprises a coupling coefficient of the wireless power transfer system.

8. The resonator of claim 1 wherein the system parameter comprises a power transfer efficiency of the wireless power transfer system.

9. The resonator of claim 1, wherein the resonator comprises a receiver resonator adapted to be implanted within a patient.

10. The resonator of claim 9 wherein the inductor is configured to receive wireless power from an external transmitter resonator disposed outside the patient.

11. A method of controlling a wireless power transfer system, comprising the steps of:

transmitting or receiving wireless power with an inductor of a resonator; and

adjusting with a controller an effective capacitance of the resonator by changing a capacitance of first and second switched capacitor circuits connected to opposite poles of the inductor.

12. The method of claim 11 wherein the adjusting step further comprises turning on and off MOSFETS in the first and second switched capacitor circuits to switch capacitors in series with the MOSFETS in an out of the circuit.

13. The method of claim 11 further comprising monitoring a system parameter in response to adjusting the effective capacitance, and iteratively adjusting the effective capacitance in the direction that improves performance of the system parameter.

14. The method of claim 11 wherein the system parameter comprises a coupling coefficient of the wireless power transfer system.

15. The method of claim 11 wherein the system parameter comprises a power transfer efficiency of the wireless power transfer system.