Resonant wireless charging system and method for electric toothbrush

1. A system for charging one or more electric devices, the system comprising:

a charging station comprising:

an input node configured to receive a power input;

a boost converter coupled to the input node and configured to step up the power input to a boosted voltage level;

a sensing circuit coupled to the boost converter and configured to detect an electronic device at a receiver side after the power input has been stepped up by the boost converter;

a power amplifier coupled to the sensing circuit, and a switch coupled to the power amplifier to turn on and off the power amplifier intermittently to allow a detection of the electronic device at the receiver side, wherein the boost converter is configured to provide a range of DC voltage to the power amplifier, and the electronic device is detected by the sensing circuit; and

a transmitter resonant circuit coupled to the power amplifier and including a transmitter coupling coil configured to oscillate at a resonant frequency; and

the one or more electric devices to be placed at the receiver side, comprising:

a receiver resonant circuit including a receiver coupling coil configured to be wirelessly coupled to the transmitter coupling coil; and

a DC voltage charger configured to charge one or more batteries in the electric device.

2. The system of claim 1 , wherein the resonant frequency is between 1 to 10 MHz.

3. The system of claim 2 , wherein:

the transmitter resonant circuit is coupled to the receiver resonant circuit with a corresponding coupling efficiency smaller than 0.1.

4. The system of claim 1 , wherein the charging station further comprises a holder configured to hold the one or more electric devices at free positions covering an adjustable distance and an adjustable angle with respect to the transmitter coupling coil.

5. The system of claim 4 , wherein the wireless transmitter resonant circuit is on a plate separate from a base of the holder.

6. The system of claim 1 , wherein the power input is a fixed input DC voltage supplied to the input node using a USB port.

7. The system of claim 4 , wherein turning on and off the power amplifier intermittently to allow a detection of the electronic device at a receiver side comprises:

providing, by the sensing circuit, a detection result to an open loop controller; and

turning on and off the power amplifier intermittently by the open loop controller.

8. The system of claim 1 , wherein the one or more electric devices comprises a rectifier coupled to the receiver resonant circuit and at least one of:

a back to back transient voltage suppression diode placed before the rectifier; or

a Zener diode placed after the rectifier.

9. A method for charging one or more electric devices, the method comprising:

receiving a power input by a charging station;

stepping up, by a boost converter, the power input to a boosted voltage;

amplifying the boosted voltage through a power amplifier, wherein the boost converter is configured to provide a range of DC voltage to the power amplifier;

turning on and off the power amplifier intermittently to allow a detection of an electronic device at a receiver side, wherein the electronic device is detected by a sensing circuit;

if one or more electronic device is detected at the receiver side, oscillating a transmitter resonant circuit of the charging station at a resonant frequency; and

wirelessly coupling the transmitter resonant circuit to a receiver resonant circuit of the one or more electric devices.

10. The method of claim 9 , wherein the resonant frequency is between 1 to 10 MHz.

11. The method of claim 10 , wherein:

the transmitter resonant circuit is coupled to the receiver resonant circuit with a corresponding coupling efficiency smaller than 0.1.

12. The method of claim 9 , further comprising holding the one or more electric devices in a holder of the charging station at free positions covering an adjustable distance and an adjustable angle with respect to the transmitter resonant circuit.

13. The method of claim 12 , wherein the wireless transmitter resonant circuit is on a plate separate from a base of the holder.

14. The method of claim 9 , further comprising supplying a fixed input DC voltage using a USB port as the power input.

15. The method of claim 12 , wherein turning on and off the power amplifier intermittently to allow a detection of an electronic device at a receiver side comprises:

providing, by the sensing circuit, a detection result to an open loop controller;

turning on and off the power amplifier intermittently by the open loop controller.

16. The method of claim 9 , wherein the receiver resonant circuit comprises a rectifier and at least one of a back to back transient voltage suppression diode before the rectifier or a Zener diode after the rectifier.