Dynamic tuning in wireless energy transfer systems

• US 10,651,689 B2
• Filed: 11/21/2018
• Issued: 05/12/2020
• Est. Priority Date: 10/22/2015
• Status: Active Grant

• Current Assignee: WiTricity Corporation
• Original Assignee: WiTricity Corporation
• Inventors: Karnstedt, Curt, Buenrostro, Christopher
• Primary Examiner(s): Sun, Pinping
• Assistant Examiner(s): Dhillon, Jagdeep S
• Application Number:
  US16/197,624
• Publication Number:
  US 20190109496A1
• Time in Patent Office: 538 Days
• Field of Search: 307104, 307149, 307 35, 307 43, 307 80, 307 82, 327116, 327117, 327119, 327156, 327158, 327451, 323283, 323235, 323293
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H03H 7/40 Automatic matching of load impedance to source impedance
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

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.

Claims

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.