Communication demodulation in wireless charging system

Patent metadata

Field	Value
Publication number	US-11336117-B2
Application number	US-202016777777-A
Country	US
Kind code	B2
Filing date	Jan 30, 2020
Priority date	Apr 16, 2019
Publication date	May 17, 2022
Grant date	May 17, 2022

Abstract

A wireless charging system is configured to charge one or more receiver devices simultaneously. The wireless charging system includes multiple coils that may be driven independently based on a feedback system with one or more feedback channels. One of the feedback channels may be demodulated communication signals from the one or more receiver devices. The demodulation may be performed by a communication demodulation circuit with configurable gain. The demodulated communication signals are processed for error correction at a bit level and a packet level, which improves accuracy despite presence of multiple receiver devices and noisy conditions.

First claim

What is claimed is:

1. A demodulation circuit of a wireless charging system for demodulating a signal from a receiver device comprising:
a first scaling module configured to modify an amplitude of the signal;
a rectification module configured to rectify the signal from the first scaling module;
a second scaling module, the second scaling module including a plurality of stages, wherein each stage is configured to modify the amplitude of the rectified signal;
an integrator configured to determine an average amplitude of the rectified signal;
a controller configured to determine a gain for the first scaling module and for each stage of the second scaling module based in part on the average amplitude determined by the integrator; and
a comparator module configured to determine a state of the signal by comparing the amplitude of the signal from the second scaling module to a threshold value, wherein the signal corresponds to a first state when the amplitude is less than or equal to the threshold value and the signal corresponds to a second state when the amplitude is greater than the threshold value.

2. The demodulation circuit of claim 1 , further comprising:
a low pass filter configured to remove frequencies above a cut-off frequency associated with the low pass filter from the rectified signal.

3. The demodulation circuit of claim 1 , wherein the signal is determined based on a current through a coil of the wireless charging system.

4. A wireless charging system comprising:
a coil configured to transmit power to a receiver device;
a demodulation circuit of a wireless charging system for demodulating the signal from the receiver device comprising:
a first scaling module configured to modify an amplitude of the signal,
a rectification module configured to rectify the signal from the first scaling module,
a second scaling module, the second scaling module including a plurality of stages, wherein each stage is configured to modify the amplitude of the rectified signal,
an integrator configured to determine an average amplitude of the rectified signal,
a controller configured to determine a gain for the first scaling module and for each stage of the second scaling module based in part on the average amplitude determined by the integrator, and
a comparator module configured to determine a state of the signal by comparing the amplitude of the signal from the second scaling module to a threshold value, wherein the signal corresponds to a first state when the amplitude is less than or equal to the threshold value and wherein the signal corresponds to a second state when the amplitude is greater than the threshold value; and
a microcontroller configured to determine a byte representative of the demodulated signal from the demodulation circuit.

5. The wireless charging system of claim 4 , wherein the signal is according to Qi protocol.

6. The wireless charging system of claim 4 , wherein the signal is determined based on a current through the coil of the wireless charging system.

7. A method of demodulating a signal from a receiver device, comprising:
receiving the signal from the receiver device using a coil of a wireless charging system;
applying a first gain to the signal;
responsive to applying the first gain, performing a rectification on the signal;
applying a second gain to the rectified signal;
responsive to applying the second gain, comparing the signal to a predetermined value to determine whether the signal is at a high level or at a low level;
determining a byte representative of the signal based on the comparison, wherein a value of each bit in the byte is based on a number of transitions between the high level and the low level, wherein the bit corresponds to a predetermined time period; and
transmitting the byte to a controller of the wireless charging system configured to drive the coil for charging the receiver device.

8. The method of claim 7 , wherein the signal is received according to a Qi protocol.

9. The method of claim 7 , wherein receiving the signal from the receiver device using a coil comprises measuring a current through the coil.

10. The method of claim 9 , wherein the current through the coil is a function of a receiver load of the wireless charging system.

11. The method of claim 7 , wherein the first gain and the second gain are determined by the controller based in part on an average amplitude of the signal.

12. The method of claim 11 , wherein the average amplitude is determined by an integrator circuit.

13. The method of claim 7 , wherein determining the byte representative of the signal further comprises:
for each bit corresponding to a predetermined time period of the signal:
determining the number of transitions based on a number of times the signal changes from the high level to the low level or from the low level to the high level,
responsive to determining that the number of transitions is one, decoding a zero for the bit, and
responsive to determining that the number of transitions is two, decoding a one for the bit.

14. The method of claim 13 , wherein responsive to determining that the number of transitions is greater than two, updating the number of transitions by subtracting an even number of transitions with a spacing of less than a threshold duration.

15. The method of claim 14 , wherein responsive to the updated number of transitions being greater than two, flagging the bit as an undecodable bit.

16. The method of claim 7 , wherein the byte includes a parity bit, the parity bit configured to ensure that a parity of the byte adds up to odd.

17. The method of claim 7 , wherein the byte is one of a plurality of bytes of a packet, the packet including a checksum.

Assignees

• Aira Inc

Inventors

• Abajian William Paul
• Laffitte Jules Marie Xavier
• Macdonald John
• Shi Lixin
• Vander Ploeg Jake Lee
• Zhu Xiaoping

Classifications

• H02J50/40

  using two or more transmitting or receiving devices (H02J50/50 takes precedence) · CPC title

• H02J50/80

  involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices · CPC title

• H02J50/402

  the two or more transmitting or the two or more receiving devices being integrated in the same unit, e.g. power mats with several coils or antennas with several sub-antennas · CPC title

• H02J50/10 Primary

  using inductive coupling · CPC title

• H02J7/02

  for charging batteries from AC mains by converters · CPC title