Capacitive wireless power transfer circuit and related techniques
Capacitive wireless power transfer systems are provided. In one embodiment, for example, the system comprises two pair of coupled conducting plates; a first matching network coupled to the first pair of conducting plates; and a second matching network coupled to the second pair of conducting plates. At least one of the first and second matching networks comprises an inductor having inductance value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system. In another embodiment, a method of designing a capacitive wireless power transfer system is provided comprising determining a parasitic capacitance value of a capacitive wireless power transfer system and determining an inductance value of an inductor of at least one of the first and second matching network having a value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system.
1. A capacitive wireless power transfer system comprising:
two pair of coupled conducting plates;
a first matching network coupled to the first pair of conducting plates; and
a second matching network coupled to the second pair of conducting plates, wherein at least one of the first and second matching networks comprises an inductor having inductance value selected based on a capacitance value of at least one parasitic capacitor formed by a parasitic interaction between any two conducting plates of the two pair of coupled conducting plates of the capacitive wireless power transfer system.
2. The capacitive wireless power transfer system of claim 1 wherein each of the first and second matching networks comprise at least one matching network stage comprising capacitance solely attributable to the at least one parasitic capacitance of the capacitive wireless power transfer system.
3. The capacitive wireless power transfer system of claim 2 wherein the use of parasitic capacitances in place of at least one discrete capacitor in each of the first and second matching networks of the capacitive wireless power transfer system reduces cost, complexity and probability of failure for the capacitive wireless power transfer system.
4. The capacitive wireless power transfer system of claim 1 wherein each of the first and second matching networks comprise at least one matching network stage comprising a capacitance value based upon a parasitic capacitance of the wireless power transfer system.
5. The capacitance wireless power transfer system of claim 1 wherein the matching network inductor value of the capacitive wireless power transfer system is determined based upon a four-capacitance or a three capacitance equivalent model of a number of parasitic capacitances that exist in the capacitive wireless power transfer system.
6. The capacitive wireless power transfer system of claim 1 wherein each of the first and second matching networks comprise a split-inductor or split-capacitor in the matching network of the capacitive wireless power transfer system to achieve symmetry and enhance power transfer.
7. The capacitive wireless power transfer system of claim 1 wherein at least one pair of conducting plates comprise at least one of the group comprising: circular, elliptical or other corner-free conducting coupling plates.
8. The capacitive wireless power transfer system of claim 7 wherein at least one pair of conducting plates increase power transfer density without risk of arcing.
9. The capacitive wireless power transfer system of claim 1 wherein at least one pair of conducting plates comprise at least one of the group comprising: a covering or a coating of a material with an electric field breakdown strength greater than that of air.
10. The capacitive wireless power transfer system of claim 9 wherein the covering or coating on at least one pair of coupled conducting plates of the capacitive wireless power transfer systems increase power transfer density without a reduced risk of arcing.
11. The capacitive wireless power transfer system of claim 1 wherein the capacitive wireless power transfer system comprises an electric vehicle (EV) capacitive wireless power transfer system.
12. The capacitive wireless power transfer system of claim 1 wherein the capacitive wireless power transfer system comprises an inverter coupled to the first matching network and a rectifier coupled to the second matching network.
13. The capacitive wireless power transfer system of claim 12 wherein the inverter comprises a full-bridge inverter.
14. The capacitive wireless power transfer system of claim 12 wherein the rectifier comprises a full-bridge rectifier.
15. A capacitive wireless power transfer system comprising:
two pair of coupled conducting plates;
a first matching network coupled to the first pair of conducting plates; and
a second matching network coupled to the second pair of conducting plates,
wherein at least one of the first and second matching networks comprises an inductor having inductance value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system, at least one of the first and second matching networks comprises a multi-stage matching network, and at least one stage of the multi-stage matching network uses parasitic capacitances to augment or replace discrete capacitances.
16. The capacitive wireless power transfer system of claim 15 wherein the at least one of the first and second matching networks comprising a multi-stage matching network comprises a stage coupled to one of the first and second coupled conducting plates comprises an inductor having inductance value selected based on a parasitic capacitance value of the capacitive wireless power transfer system.
17. A method of designing a capacitive wireless power transfer system comprising:
determining a parasitic capacitance value of a capacitive wireless power transfer system comprising:
two pair of coupled conducting plates;
a first matching network coupled to a first pair of the conducting plates; and
a second matching network coupled to a second pair of the conducting plates; and
determining an inductance value of an inductor of at least one of the first and second matching network having a value selected based on a capacitance value of at least one parasitic capacitor formed by a parasitic interaction between any two conducting plates of the two pair of coupled conducting plates of the capacitive wireless power transfer system.
18. The method of claim 17 wherein the operation of determining the inductance value comprises using a model of the capacitive wireless power transfer system.
19. The method of claim 18 wherein the model comprises using a four-capacitance and/or three-capacitance equivalent circuit model of a capacitive wireless power transfer system.
20. The method of claim 17 wherein the first and second matching networks comprise at least one matching network stage comprising capacitance solely or partially attributable to a parasitic capacitance of the capacitive wireless power transfer system.
21. The method of claim 17 wherein each of the first and second matching networks comprise at least one matching network stage comprising a capacitance value based upon a parasitic capacitance of the wireless power transfer system.