Dynamic tuning in wireless energy transfer systems

Patent metadata

Field	Value
Publication number	US-10651688-B2
Application number	US-201816197619-A
Country	US
Kind code	B2
Filing date	Nov 21, 2018
Priority date	Oct 22, 2015
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for dynamically tuning circuit elements. One aspect includes a variable capacitance device. The device includes a first capacitor, a first switch, a second capacitor, a second switch, and control circuitry. The control circuitry is configured to adjust respective capacitances of the first and second capacitors by causing a first control signal to be applied to the first-switch control terminal for a duration of time in response to detecting a zero voltage condition across the first switch, and by causing a second control signal to be applied to the second-switch control terminal for the duration of time in response to detecting a zero voltage condition across the second switch.

First claim

What is claimed is:

1. A variable capacitance device comprising:
a first capacitor comprising a first-capacitor first terminal and a first-capacitor second terminal, the first-capacitor first terminal electrically connected to a ground;
a first switch comprising a first-switch first terminal, a first-switch second terminal, and a first-switch control terminal, the first-switch first terminal electrically connected to the first-capacitor first terminal, and the first-switch second terminal electrically connected to the first-capacitor second terminal;
a second capacitor comprising a second-capacitor first terminal and a second-capacitor second terminal, the second-capacitor first terminal electrically connected to the ground;
a second switch comprising a second-switch first terminal, a second-switch second terminal, and a second-switch a control terminal, the second-switch first terminal electrically connected to the second-capacitor first terminal, and the second-switch second terminal electrically connected to the second-capacitor second terminal; and
control circuitry coupled with the first-switch control terminal and with the second-switch control terminal,
wherein the control circuitry is configured to adjust respective capacitances of the first and second capacitors by:
in response to detecting a zero voltage condition across the first switch, causing a first control signal to be applied to the first-switch control terminal for a duration of time, wherein the first control signal causes the first switch to close; and
in response to detecting a zero voltage condition across the second switch, causing a second control signal to be applied to the second-switch control terminal for the duration of time, wherein the second control signal causes the second switch to close.

2. The variable capacitance device of claim 1 , wherein a capacitance of the device depends on the duration of time for which the first and second control signals are applied to the respective first-switch control terminal and second-switch control terminal.

3. The variable capacitance device of claim 1 , wherein the first switch is a first transistor and the second switch is a second transistor.

4. The variable capacitance device of claim 1 , wherein the control circuitry is configured to receive an input signal and, in response to receiving the input signal, change the duration of time for which the first and second control signals are applied to the respective first-switch control terminal and second-switch control terminal.

5. A wireless energy transfer system comprising:
a split coil resonator comprising a first winding magnetically coupled with a second winding; and
a variable capacitance device comprising:
a first capacitor comprising a first-capacitor first terminal and a first-capacitor second terminal, the first-capacitor first terminal electrically connected to a ground, and the first-capacitor second terminal electrically connected to a first-winding terminal of the first winding of the split coil resonator;
a first switch comprising a first-switch first terminal, a first-switch second terminal, and a first-switch control terminal, the first-switch first terminal electrically connected to the first-capacitor first terminal, and the first-switch second terminal electrically connected to the first-capacitor second terminal;
a second capacitor comprising a second-capacitor first terminal and a second-capacitor second terminal, the second-capacitor first terminal electrically connected to the ground, and the second-capacitor second terminal electrically connected to a second-winding terminal of the second winding of the split coil resonator;
a second switch comprising a second-switch first terminal, a second-switch second terminal, and a second-switch a control terminal, the second-switch first terminal electrically connected to the second-capacitor first terminal, and the second-switch second terminal electrically connected to the second-capacitor second terminal; and
control circuitry coupled with the first-switch control terminal and with the second-switch control terminal,
wherein the control circuitry is configured to adjust respective capacitances of the first and second capacitors by:
in response to detecting a zero voltage condition across the first switch, causing a first control signal to be applied to the first-switch control terminal for a duration of time, wherein the first control signal causes the first switch to close; and
in response to detecting a zero voltage condition across the second switch, causing a second control signal to be applied to the second-switch control terminal for the duration of time, wherein the second control signal causes the second switch to close.

6. The wireless energy transfer system of claim 5 , further comprising:
a third capacitor comprising a third-capacitor first terminal and a third-capacitor second terminal, the third-capacitor first terminal electrically connected to the first-winding terminal, and the third-capacitor second terminal electrically connected to the first-capacitor second terminal; and
a fourth capacitor comprising a fourth-capacitor first terminal and a fourth-capacitor second terminal, the fourth-capacitor first terminal electrically connected to the second-winding terminal, and the fourth-capacitor second terminal electrically connected to the second-capacitor second terminal.

7. The wireless energy transfer system of claim 5 , further comprising a third capacitor comprising a third-capacitor first terminal and a third-capacitor second terminal, the third-capacitor first terminal electrically connected to the first-winding terminal, and the third-capacitor second terminal electrically connected to the second-winding terminal.

8. The wireless energy transfer system of claim 5 , wherein a capacitance of the variable capacitance device depends on the duration of time for which the first and second control signals are applied to the respective first-switch control terminal and second-switch control terminal.

9. A wireless power transfer system comprising an impedance matching circuit, the impedance matching circuit including a variable capacitance device comprising:
a first capacitor comprising a first-capacitor first terminal and a first-capacitor second terminal, the first-capacitor first terminal electrically connected to a ground;
a first switch comprising a first-switch first terminal, a first-switch second terminal, and a first-switch control terminal, the first-switch first terminal electrically connected to the first-capacitor first terminal, and the first-switch second terminal electrically connected to the first-capacitor second terminal;
a second capacitor comprising a second-capacitor first terminal and a second-capacitor second terminal, the second-capacitor first terminal electrically connected to the ground;
a second switch comprising a second-switch first terminal, a second-switch second terminal, and a second-switch a control terminal, the second-switch first terminal electrically connected to the second-capacitor first terminal, and the second-switch second terminal electrically connected to the second-capacitor second terminal; and
control circuitry coupled with the first-switch control terminal and with the second-switch control terminal,
wherein the control circuitry is configured to adjust respective capacitances of the first and second capacitors by:
in response to detecting a zero voltage condition across the first switch, causing a first control signal to be applied to the first-switch control terminal for a duration of time, wherein the first control signal causes the first switch to close; and
in response to detecting a zero voltage condition acro

Assignees

• Witricity Corp

Inventors

• Karnstedt Curt
• Buenrostro Christopher

Classifications

• H03H7/40

  Automatic matching of load impedance to source impedance · CPC title

• H02J50/12 Primary

  of the resonant type · CPC title

• H02J50/90

  involving detection or optimisation of position, e.g. alignment · CPC title

• H02J50/60

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title

• H04B5/0037

  Electricity · mapped topic