Dynamic tuning in wireless energy transfer systems
Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for dynamically tuning circuit elements. One aspect includes a zero voltage switching device including a switch, a first comparator, a second comparator and a controller. The switch includes a first terminal, a second terminal, and a control terminal. The first comparator includes a first input terminal electrically connected to the second terminal of the switch and a second input terminal electrically connected to the first terminal of the switch. The second comparator includes a first input terminal electrically connected to a reference voltage and a second input terminal electrically connected to the control terminal of the switch. The controller is configured to: detect a zero voltage condition across the switch, and, in response, cause a control signal to be applied to the control terminal of the switch.
1. A zero voltage switching device comprising:
a switch comprising a first terminal, a second terminal, and a control terminal;
a first comparator comprising a first-comparator output terminal and a first-comparator first input terminal electrically connected to the first terminal of the switch;
a second comparator comprising a second-comparator output terminal, a second-comparator first input terminal electrically connected to a first reference voltage, and a second-comparator second input terminal electrically connected to the control terminal of the switch; and
control circuitry coupled with the first-comparator output terminal and the second-comparator output terminal, the control circuitry comprising:
a phase detection circuit coupled with the first-comparator output terminal and the second-comparator output terminal;
an integrator circuit coupled with the phase detection circuit;
a third comparator comprising a third-comparator output terminal, a third-comparator first input terminal electrically connected to the first terminal of the switch, and a third-comparator second input terminal coupled with the integrator circuit;
a flip-flop comprising a reset terminal, a clock terminal electrically connected to the third-comparator output terminal, and an output terminal electrically connected to the control terminal of the switch; and
a controller coupled with the reset terminal of the flip-flop and configured to provide a reset signal to the flip-flop, and
wherein the control circuitry is configured to:
determine a phase difference between a first-comparator output signal and a second-comparator output signal,
generate a second reference voltage based the phase difference, and
cause a control signal to be applied to the control terminal of the switch upon detecting that a voltage signal at one of the first terminal or second terminal of the switch has crossed a voltage value equal to the second reference voltage.
2. The zero voltage switching device of claim 1 , wherein the controller is configured to provide the reset signal to turn the switch OFF after a switch ON duration.
3. The zero voltage switching device of claim 1 , wherein the switch is a field effect transistor, the control terminal is a gate of the transistor, the first terminal is one of a source or a drain of the transistor, and the second terminal is the other of the source or the drain of the transistor.
4. The zero voltage switching device of claim 3 , wherein the first reference voltage is selected based on a threshold voltage of the transistor.
5. The zero voltage switching device of claim 1 , wherein the control circuitry comprises one or more of: a microcontroller, a computer processor, or an application specific integrated circuit (ASIC).
6. The zero voltage switching device of claim 1 , wherein one of the first terminal of the switch or the second terminal of the switch is connected to an electrical ground.
7. The zero voltage switching device of claim 1 , further comprising a split coil resonator electrically coupled with one of the first terminal of the switch or the second terminal of the switch.