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 having first and second output terminals;
a first pair of complementary switches coupled in series and connected between the first and second output terminals, wherein a first switch node is positioned between the first pair of complementary switches;
a second pair of complementary switches coupled in series and connected between the first and second output terminals, wherein a second switch node is positioned between the second pair of complementary switches;
an antenna network coupled between the first switch node and the second switch node; and
a resonant circuit coupled to the antenna network and configured to resonate at a frequency that is different than a resonant frequency of the antenna network to create out of phase voltage and current signals that enable one or more switches of the first pair of complementary switches to operate with zero voltage switching (ZVS);
wherein power from the voltage source to the antenna network is regulated by changing a delay between an on-state of a solid-state switch of the first pair of complementary switches and an on-state of a solid-state switch of the second pair of complementary switches.
2. The wireless power transmission circuit of claim 1 wherein the first pair of complementary switches operate such that when a first switch of the first pair of complementary switches is off a second switch of the first pair of complementary switches is on and when the first switch of the first pair of complementary switches is on the second switch of the first pair of complementary switches is off.
3. The wireless power transmission circuit of claim 1 wherein the second pair of complementary switches operate such that when a first switch of the second pair of complementary switches is off a second switch of the second pair of complementary switches is on and when the first switch of the second pair of complementary switches is on the second switch of the second pair of complementary switches is off.
4. The wireless power transmission circuit of claim 1 wherein the first and second pairs of complementary switches operate with a fixed duty cycle.
5. The wireless power transmission circuit of claim 4 wherein the fixed duty cycle is fifty percent.
6. The wireless power transmission circuit of claim 1 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.
7. The wireless power transmission circuit of claim 1 wherein the resonant circuit is coupled between the first switch node and the antenna network.
8. The wireless power transmission circuit of claim 1 wherein the first and second pairs of complementary switches are Gallium-Nitride based devices.
9. The wireless power transmission circuit of claim 1 wherein the first and second pairs of complementary switches operate with zero voltage switching.
10. A wireless power transmission circuit comprising:
a voltage source having first and second output terminals;
a first pair of switches coupled in series and connected between the first and second output terminals,
a first switch node positioned between the first pair of switches;
a second pair of switches coupled in series and connected between the first and second output terminals;
a second switch node positioned between the second pair of switches;
an antenna network coupled between the first switch node and the second switch node; and
a resonant circuit coupled to the antenna network and configured to resonate at a frequency that is different than a resonant frequency of the antenna network to create out of phase voltage and current signals that enable one or more switches of the first pair of switches to operate with zero voltage switching (ZVS).
11. The wireless power transmission circuit of claim 10 wherein the first and second pairs of switches operate with a fixed duty cycle.
12. The wireless power transmission circuit of claim 11 wherein the fixed duty cycle is fifty percent.
13. The wireless power transmission circuit of claim 10 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.
14. The wireless power transmission circuit of claim 10 wherein the resonant circuit is coupled between the first switch node and the antenna network.
15. The wireless power transmission circuit of claim 10 further comprising an AC voltage divider circuit coupled to the resonant circuit and configured to reduce an AC voltage supplied to the antenna network.
16. The wireless power transmission circuit of claim 15 further comprising an impedance matching circuit coupled to the AC voltage divider circuit and configured to match an impedance of the antenna network.
17. The wireless power transmission circuit of claim 10 wherein the first and second pairs of switches operate with zero voltage switching.
18. The wireless power transmission circuit of claim 10 wherein the first and second pairs of switches are Gallium-Nitride based devices.