Soft switched single stage wireless power transfer
A control scheme and architecture for a wireless electrical energy transmission circuit employs two solid-state switches and a zero voltage switching (ZVS) topology to power an antenna network. The switches drive the antenna network at its resonant frequency and simultaneously energize a separate resonant circuit that has a resonant frequency lower than the antenna circuit. The resonant circuit creates out of phase voltage and current waveforms that enable the switches to operate with (ZVS).
1. A wireless power transmission circuit comprising:
a voltage source coupled to a power conversion circuit including first, second, third and fourth solid-state switches;
an antenna network driven at a first frequency by the first, second, third and fourth solid-state switches and configured to transmit electrical energy;
a resonant circuit coupled to the antenna network and configured to resonate at a second frequency that is different than the first frequency; and
a controller coupled to the first, second, third and fourth solid-state switches and configured to regulate power from the voltage source to the antenna network by changing a phase delay between a switch state of two or more of the first, second, third and fourth solid-state switches.
2. A method of operating a wireless power transmission circuit, the method comprising:
supplying power with a voltage source;
driving an antenna network at a first frequency with power supplied by the voltage source and regulated by a full-bridge circuit comprising a plurality of solid-state switches;
coupling the antenna network to a resonant circuit that resonates at a second frequency that is different than the first frequency;
regulating power to the antenna network with a controller configured to change the power supplied to the antenna network by changing a phase delay between a switch state of two or more of the plurality of solid-state switches.
3. The wireless power transmission circuit of claim 1 wherein the phase delay is changed between an on state of two or more of the first, second, third and fourth solid-state switches.
4. The wireless power transmission circuit of claim 1 wherein the phase delay is changed between an off state of two or more of the first, second, third and fourth solid-state switches.
5. A wireless power transmission circuit comprising:
a voltage source coupled to first, second, third and fourth solid-state switches;
an antenna network driven at a first frequency by the first, second, third and fourth solid-state switches and configured to transmit electrical energy;
a resonant circuit coupled to the antenna network and configured to resonate at a second frequency that is different than the first frequency; and
a controller coupled to the first, second, third and fourth solid-state switches and configured to regulate power from the voltage source to the antenna network by changing a phase delay between a switch state of two or more of the first, second, third and fourth solid-state switches.
6. The wireless power transmission circuit of claim 5 wherein the phase delay is changed between an off state of two or more of the first, second, third and fourth solid-state switches.
7. The wireless power transmission circuit of claim 1 wherein the first, second, third and fourth solid-state switches operate at a switching frequency in a range of 1-20 MHz.
8. The wireless power transmission circuit of claim 1 wherein the first, second, third and fourth solid-state switches are configured to operate with a voltage potential in the range of 50-1000 Volts DC.
9. The wireless power transmission circuit of claim 1 wherein the resonant circuit is coupled between the first switch node and the antenna network.
10. The wireless power transmission circuit of claim 9 further comprising an AC voltage divider circuit coupled to the resonant circuit and configured to reduce an AC voltage supplied to the antenna network.
11. The wireless power transmission circuit of claim 10 further comprising an impedance matching circuit coupled to the AC voltage divider circuit and configured to match an impedance of the antenna network.
12. The wireless power transmission circuit of claim 9 wherein the resonant circuit is a first resonant circuit and a second resonant circuit is coupled between the first switch node and the second output terminal; and
a third resonant circuit is coupled between the second switch node and the second output terminal.
13. The wireless power transmission circuit of claim 9 wherein the resonant circuit is a first resonant circuit and a second resonant circuit is coupled in parallel with the first resonant circuit.
14. The wireless power transmission circuit of claim 1 wherein switch state is an on state.
15. The wireless power transmission circuit of claim 1 wherein switch state is an off state.
16. The wireless power transmission circuit of claim 5 wherein the phase delay is changed between an on state of two or more of the first, second, third and fourth solid-state switches.
17. The wireless power transmission circuit of claim 16 wherein in a first portion of a switching cycle the first and second solid-state switches operate complementary and in a second portion of a switching cycle the third and fourth solid-state switches operate complementary.
18. The wireless power transmission circuit of claim 17 wherein zero voltage switching is performed in a deadtime located between the first portion of the switching cycle and the second portion of the switching cycle.
19. The wireless power transmission circuit of claim 16 wherein the first, second, third and fourth solid-state switches operate at a fixed duty cycle.
20. The wireless power transmission circuit of claim 19 wherein the fixed duty cycle is approximately 50 percent.
21. The wireless power transmission circuit of claim 16 wherein the phase delay is changed between the switch state of the first and the third solid-state switches.
22. The wireless power transmission circuit of claim 16 wherein the first, second, third and fourth solid-state switches change state with zero voltage switching.
23. The wireless power transmission circuit of claim 16 wherein switch state is an on state.
24. The wireless power transmission circuit of claim 16 wherein switch state is an off state.
25. A method of operating a wireless power transmission circuit, the method comprising:
supplying power with a voltage source;
driving the transmission circuit at a first frequency with power supplied by the voltage source and regulated by a plurality of solid-state switches;
coupling the transmission circuit to a resonant circuit that resonates at a second frequency that is different than the first frequency;
regulating power to the transmission circuit with a controller configured to change the power supplied to the transmission circuit by changing a phase delay between a switch state of two or more of the plurality of solid-state switches.
26. The method of claim 25 wherein in a first portion of a switching cycle first and second solid-state switches of the plurality of solid-state switches operate complementary and in a second portion of the switching cycle third and fourth solid-state switches of the plurality of solid-state switches operate complementary.
27. The method of claim 26 wherein zero voltage switching is performed in a deadtime located between the first portion of the switching cycle and the second portion of the switching cycle.
28. The method of claim 26 wherein the phase delay is changed between the first and the third solid-state switches.
29. The method of claim 25 wherein the plurality of solid-state switches operate at a fixed duty cycle.
30. The method of claim 29 wherein the fixed duty cycle is 50 percent.
31. The method of claim 25 wherein the plurality of solid-state switches change state with zero voltage switching.