Tuning circuitry for a wireless power system

1. A wireless power transfer (WPT) system for wirelessly providing high-frequency AC power to an electric vehicle (EV) or a plug-in electric vehicle (PEV), the system comprising:

an off-board transmitter including:

an inverter having an output;

a transmitter coil configured to wirelessly transmit the high-frequency AC power; and

a resonant tuning network comprising first circuitry coupled to the transmitter coil and second circuitry coupled between the output of the inverter and the first circuitry;

wherein the first circuitry includes:

a first inductor and a first capacitor connected in series to the transmitter coil, and

a second capacitor connected in parallel to the first capacitor and the transmitter coil;

wherein the second circuitry is configured to cause inductive operation of the inverter at a switching frequency of the inverter that corresponds to a power factor in a range 0.80 to 0.99;

wherein the second circuitry includes:

a second inductor connected in series to the first inductor of the first circuitry, and

a second capacitor connected in series to the second inductor, and

wherein inductance of the second inductor and capacitance of the second capacitor are configured to cause the second circuitry to

resonate at the switching frequency of the inverter,

establish zero voltage switching operation for the inverter at a switching frequency of the inverter, and

mitigate current harmonics of the inverter.

2. The WPT system of claim 1 , wherein the second inductor includes additional winding that is wound on a core of the first inductor, and wherein the additional winding extends a winding of the first inductor.

3. The WPT system of claim 1 , wherein the inductive operation of the inverter caused by the configuration of the second circuitry corresponds to a power factor in a range of 0.95 to 0.99.

4. The WPT system of claim 1 , wherein a fundamental frequency of the high-frequency AC power is in a range of 3 kHz-10 MHz.

5. The WPT system of claim 4 , wherein the fundamental frequency is about 85 kHz.

6. The WPT system of claim 1 , comprising a wireless power receiver including:

a receiver comprising a pick-up coil, the receiver configured to receive the high-frequency AC power when the transmitter coil and the pick-up coil are disposed adjacent to each other, a receiver side resonant tuning network, and a high-frequency rectifier to provide DC current to a receiver-side load.

7. The WPT system of claim 6 wherein the receiver-side load is a battery.

8. A system for wirelessly transferring power to a remote device, the system comprising:

a transmitter configured to wirelessly transmit power to a receiver of the remote device;

switching circuitry coupled to the transmitter, the switching circuitry configured to receive power from a power supply, the switching circuitry configured to supply power to the transmitter based on the power received from the power supply;

control circuitry operably coupled to the switching circuitry, the control circuitry configured to direct operation of the switching circuitry according to a switching frequency;

first tuning circuitry coupled directly to the transmitter, the first tuning circuitry including a first inductor and a first capacitor connected in series with the transmitter, the first tuning circuitry including a second capacitor connected in parallel to the first capacitor and the transmitter; and

second tuning circuitry coupled directly to the switching circuitry, the second tuning circuitry operable to direct power from the switching circuitry to the first tuning circuitry for supply to the transmitter, the second tuning circuitry including a reactance operable to

establish (i) inductive operation of the switching circuitry at the switching frequency of the switching circuitry that corresponds to a power factor in a range 0.80 to 0.99, and (ii) zero voltage switching operation for the switching circuitry at the switching frequency of the switching circuitry, and

mitigate current harmonics of the switching circuitry,

wherein the second tuning circuitry includes a second inductor provided in series with, and different from, the first inductor of the first tuning circuitry, wherein an inductance of the second inductor defines at least a portion of the reactance of the second tuning circuitry.

9. The system of claim 8 wherein the first inductor includes a main winding portion, and wherein the second inductor corresponds to a supplemental winding portion of the first inductor.

10. The system of claim 8 wherein the first inductor includes an inductor core with a magnetic airgap, and wherein the second inductor is established by reducing the magnetic airgap of the first inductor.

11. The system of claim 8 wherein the second tuning circuitry includes a third capacitor provided in series with the second inductor and the first inductor of the first tuning circuitry, wherein a capacitance of the third capacitor and the inductance of the second inductor define the reactance of the second tuning circuitry.

12. The system of claim 8 wherein the second tuning circuitry includes a third capacitor provided in series with the first inductor of the first tuning circuitry, wherein a capacitance of the third capacitor defines at least a portion of the reactance of the second tuning circuitry.

13. The system of claim 8 comprising the remote device, wherein the remote device includes a load, and wherein the remote device is operable to supply power received from the transmitter, via the receiver, to the load.

14. The system of claim 8 wherein the power factor corresponding to the established inductive operation of the switching circuitry is in a range of 0.95 to 0.99.

15. The system of claim 8 wherein the switching frequency is between 3 kHz and MHz.

16. The system of claim 15 wherein the switching frequency is about 85 kHz.

17. The system of claim 15 wherein the switching frequency is varied by the control circuitry.