Tunable wireless energy transfer systems
View Patent ↗Described herein are improved configurations for a wireless power transfer. A power source for driving a resonator includes a switching amplifier. The duty cycle of the switching amplifier may be adjusted as well as optionally inductors and/or capacitors of the circuit to improve the efficiency of power transfer from the power source to the resonators when the parameters of the resonant load change.
1. In a system adapted for wireless power transfer, a tunable resonant amplifier circuit for driving an inductive load having a varying impedance, the circuit comprising:
a switching amplifier with a variable duty cycle, frequency and bus voltage;
an inductive load wirelessly coupled to at least one magnetic resonator;
a connection between the inductive load and the switching amplifier, the connection including at least one tunable component; and
a processing unit, comprising a wireless communications controller, used to control the at least one tunable component and the duty cycle of the amplifier;
wherein the processing unit adjusts the duty cycle of the amplifier and the at least one tunable component to maintain low loss operation of the amplifier, and to provide adequate power to the at least one magnetic resonator wirelessly coupled to the inductive load.
2. The circuit of claim 1 , wherein the at least one tunable component includes a tunable capacitor.
3. The circuit of claim 2 , wherein the tunable capacitor is in series with the inductive load.
4. The circuit of claim 2 , wherein the tunable capacitor is in parallel with the inductive load.
5. The circuit of claim 1 , wherein the connection between the inductive load and the switching amplifier includes more than one tunable component.
6. The circuit of claim 1 , wherein the switching amplifier uses a variable switching frequency.
7. The circuit of claim 1 , wherein a bus voltage of the switching amplifier is variable and is used to control an amount of power delivered to the inductive load.
8. The circuit of claim 1 , wherein the processor is configured to monitor an impedance at an output of the switching amplifier and to compute an adjustment to the variable duty cycle of the switching amplifier such that zero voltage switching is substantially maintained.
9. The circuit of claim 8 , wherein the processor is configured to compute a second adjustment to at least one tunable component such that zero current switching is substantially maintained.
10. The circuit of claim 1 , wherein the circuit is used as a source in a wireless power transmission system.
11. The circuit of claim 1 , wherein the communications controller supports a Bluetooth protocol.
12. The circuit of claim 1 , wherein the communications controller supports a Wifi protocol.
13. A method of tuning a resonant amplifier circuit in a wireless power transfer facility that includes a connection between a switching amplifier and an inductive load wirelessly coupled to at least one magnetic resonator and having a varying impedance, the method comprising the steps of:
measuring at least one parameter at an output of the switching amplifier;
wirelessly receiving control information from the at least one magnetic resonator;
adjusting a duty cycle of the switching amplifier; and
adjusting at least one tunable component in the connection between the switching amplifier and the inductive load;
wherein adjusting the duty cycle of the switching amplifier and adjusting at least one tunable component are controlled to maintain low loss operation of the switching amplifier and adequate power to the at least magnetic resonator coupled to the inductive load.
14. The method of claim 13 , wherein the at least one tunable component includes a tunable capacitor.
15. The method of claim 13 , wherein measuring at least one parameter includes measuring an impedance at the output of the switching amplifier.
16. The method of claim 15 , further comprising the steps of computing necessary adjustments to the duty cycle of the switching amplifier and adjustments to the at least one tunable component, based on the impedance, to maintain substantially zero voltage switching at the output of the switching amplifier.
17. The method of claim 15 , further comprising the steps of computing necessary adjustments to the duty cycle of the switching amplifier and adjustments to the at least one tunable component, based on the impedance, to maintain substantially zero current switching at the output of the switching amplifier.
18. The method of claim 17 , wherein the circuit is used as a source in a wireless power transmission system.
19. The method of claim 13 , wherein the wirelessly received control information is transmitted using a Bluetooth protocol.
20. The method of claim 13 , wherein the wirelessly received control information is transmitted using a WiFi protocol.