Wireless power transfer in-band communication system

• US 9,363,041 B2
• Filed: 10/25/2013
• Issued: 06/07/2016
• Est. Priority Date: 10/26/2012
• Status: Active Grant

• Current Assignee: MediaTek Singapore Pte. Ltd. (MediaTek, Inc.)
• Original Assignee: MediaTek Singapore Pte. Ltd. (MediaTek, Inc.)
• Inventors: Plumb, William, Wang, Zhen, Zvonar, Zoran, Riehl, Patrick Stanley, Satyamoorthy, Anand, Tustin, Philip Frank
• Primary Examiner(s): Fan, Chieh M
• Assistant Examiner(s): Cadeau, Wednel
• Application Number:
  US14/356,607
• Publication Number:
  US 20140314170A1
• Time in Patent Office: 956 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H02J 50/10 using inductive coupling
• 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 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 25/4904 using self-synchronising codes, e.g. split-phase codes
• CPC Class Codes: H04W 52/0261 managing power supply demand, e.g. depending on battery level

Abstract

A wireless charging in-band communication system includes a transmitter module that formats a message using CRC calculation and attaches the results of the CRC calculation to the message for message error detection. The transmitter includes channel encoding for message error correction. A modulation module performs biphase modulation for DC balanced signals and impedance switching to change reflected impedance seen by the source. A synchronization module prepending the message with a synchronization sequence having Golay complementary codes. Moreover, the in-band communication includes a receiver module that receives the message from the transmitter module. The receiver module includes an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module. The receiver module includes a front end filter used for pulse shaping and noise rejection. A preamble detection block includes a Golay complementary code correlator used for message detection, synchronization, and equalization coefficient estimation and selection. A decoding module performs biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding Also, the decoding module performs equalization, error correction channel decoding,and error detection (CRC).

Claims

1. A wireless charging in-band communication system, the wireless charging in-band communication system being used for performing communication between a load device and a source device, the wireless charging in-band communication system comprising:

a transmitter module that is positioned within the load device and formats a message using CRC calculation and attaches the results of the CRC calculation to the message for message error detection, the transmitter module includes a channel encoding module for message error correction, and a modulation module that performs biphase modulation for DC balanced signals and impedance switching to change reflected impedance seen by the source device, and a synchronization module that prepends the message with a synchronization sequence having Golay complementary codes; and

a receiver module that is positioned within the source device and receives the message from the transmitter module, the receiver module includes an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module, the receiver module includes a front end filter used for pulse shaping and noise rejection, a preamble detection block having a Golay complementary code correlator used for message detection, synchronization, and equalization coefficient estimation and selection, and a decoding module that performs biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding, the decoding module performs equalization, error correction channel decoding, and error detection (CRC);

wherein the message is transmitted outward by the transmitter module through changing the reflected impedance, and the message transmitted by the transmitter module is a message corresponding to usage related to power transfer, so as to affect power transfer control of the source device; and

the synchronization module provides a gap between the preamble and message, for timing adjustments in the receiver module.

2. The wireless charging in-band communication system of claim 1, wherein the front end filter comprises of downsampling and pulse shaping filters having a plurality of filters sections.

3. The wireless charging in-band communication system of claim 1, wherein an input signal from the impedance sensing circuit is oversampled and a plurality of downsampling and pulse shaping filters within the front end filter increase the number of effective bits.

4. The wireless charging in-band communication system of claim 1, wherein a plurality of pulse shaping filters within the front end filter utilizes a DC removal block to remove DC components of a message.

5. The wireless charging in-band communication system of claim 1, wherein the transmitter and receiver modules utilize BCH or Hamming code for developing a codeword.

6. The wireless charging in-band communication system of claim 1, wherein the transmitter module utilizes the modulation module to perform biphase modulation.

7. The wireless charging in-band communication system of claim 1, wherein the receiver module comprises a sliding window time correlator or a circular correlator.

8. The wireless charging in-band communication system of claim 1, wherein the preamble detection block comprises an Optimized Golay Correlator (OGC) with the noise estimation and DC offset estimation and removal.

9. The wireless charging in-band communication system of claim 1, wherein the synchronization module provides the gap between the preamble and message to allow timing adjustments done by the preamble detection block in the receiver module to take effect at the output of the front end filter in time for the message to be received.

10. The wireless charging in-band communication system of claim 1, wherein the biphase demodulation uses an inverted version of the correlation sequence to reduce the number of consecutive “

1”

s.

11. The wireless charging in-band communication system of claim 1, wherein the biphase demodulation comprises coarse DC offset removal as part of the front end filter and fine DC offset done digitally.

12. The wireless charging in-band communication system of claim 5, wherein the codeword comprises information bits and redundant bits.

13. The wireless charging in-band communication system of claim 5, wherein the codeword comprises 15 bits.

14. The wireless charging in-band communication system of claim 5, wherein the codeword comprises 13 bits.

15. A method of performing the operations of a wireless charging in-band communication system, the wireless charging in-band communication system being used for performing communication between a load device and a source device, the method comprising:

formatting a message using CRC calculation and attaching the results of the CRC calculation to the message for message error detection;

performing biphase modulation for DC balanced signals using a modulation module of a transmitter module, including impedance switching to change reflected impedance seen by the source device, wherein the transmitter module is positioned within the load device;

prepending the message with a synchronization sequence having Golay complementary codes using a synchronization module;

receiving the message from the transmitter module using a receiver module, wherein the receiver module is positioned within the source device;

providing an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module;

providing a front end filter used for pulse shaping and noise rejection;

using a Golay complementary code correlator for message detection, synchronization, and equalization coefficient estimation and selection;

performing biphase demodulation with error correction with a DC offset being estimated as the average value of the signal over the length of the message before channel decoding using a biphase demodulator module; and

performing equalization, error correction channel decoding, and error detection (CRC);

wherein the message is transmitted outward by the transmitter module through changing the reflected impedance, and the message transmitted by the transmitter module is a message corresponding to usage related to power transfer, so as to affect power transfer control of the source device; and

the synchronization module provides a gap between the preamble and message, for timing adjustments in the receiver module.

16. The method system of claim 15, wherein the front end filter comprises of downsampling and pulse shaping filters having a plurality of filters sections.

17. The method system of claim 15, wherein an input signal from the impedance sensing circuit is oversampled and a plurality of downsampling and pulse shaping filters within the front end filter increase the number of effective bits.

18. The method system of claim 15, wherein a plurality of pulse shaping filters within the front end filter utilizes a DC removal block to remove DC components of a message.

19. The method system of claim 15, wherein the transmitter and receiver modules utilize BCH or Hamming code for developing a codeword.

20. The method system of claim 15, wherein the transmitter module utilizes the modulation module to perform biphase modulation.

21. The method system of claim 15, wherein the receiver module comprises a sliding window time correlator or a circular correlator.

22. The method of claim 15, wherein the receiver module includes a preamble detection block having the Golay complementary code correlator;

and the preamble detection block comprises an Optimized Golay Correlator (OGC) with the noise estimation and DC offset estimation and removal.

23. The method of claim 15, wherein the receiver module includes a preamble detection block having the Golay complementary code correlator;

and the synchronization module provides the gap between the preamble and message to allow timing adjustments done by the preamble detection block in the receiver module to take effect at the output of the front end filter in time for the message to be received.

24. The method of claim 15, wherein the biphase demodulation uses an inverted version of the correlation sequence to reduce the number of consecutive “

1”

s.

25. The method of claim 15, wherein the biphase demodulation comprises coarse DC offset removal as part of the front end filter and fine DC offset.

26. The method system of claim 19, wherein the codeword comprises information bits and redundant bits.

27. The method system of claim 19, wherein the codeword comprises 15 bits.

28. The method of claim 19, wherein the codeword comprises 13 bits.

29. A transmitter module, used in a wireless charging system, for performing in-band communication with a receiver module in the wireless charging system to provide a message to the receiver module, the transmitter module comprising:

a check module, arranged for attaching check calculation results of the message to the message to generate an attached result, for message error detection;

an encoding module, arranged for performing channel encoding on the attached result to generate an encoded result;

a modulation module, arranged for performing modulation on the encoded result, including performing impedance switching to provide the message to the receiver module by changing reflected impedance seen by the receiver module; and

a synchronization module, arranged for prepending the message with a synchronization sequence having specific codes;

wherein the message is transmitted outward by the transmitter module through changing the reflected impedance, and the message transmitted by the transmitter module is a message corresponding to usage related to power transfer, so as to affect power transfer control of the receiver module; and

the synchronization module provides a gap between the preamble and message, for timing adjustments in the receiver module.

30. The transmitter module of claim 29, wherein the check module performs a CRC calculation on the message to generate the check calculation results.

31. The transmitter module of claim 29, wherein the channel encoding comprises BCH or Hamming encoding.

32. The transmitter module of claim 29, wherein the modulation module performs biphase modulation.

33. The transmitter module of claim 29, wherein the specific codes comprise Golay complementary codes.

34. A receiver module, used in a wireless charging system, for performing in-band communication with a transmitter module in the wireless charging system to receive a message provided by the transmitter module, the receiver module comprising:

an impedance sensing circuit, arranged for detecting changes in the reflected impedance of the transmitter module, wherein the message is included by the changes in the reflected impedance;

a front end filter, coupled to the impedance sensing circuit, arranged for performing pulse shaping and noise rejection;

a preamble detection block, coupled to the front end filter, arranged for performing message detection, synchronization, and equalization coefficient estimation; and

a decoding module, coupled to the front end filter, arranged for performing equalization, decoding, and error detection;

wherein the message is transmitted outward by the transmitter module through changing the reflected impedance, and the message transmitted by the transmitter module is a message corresponding to usage related to power transfer, so as to affect power transfer control of the receiver module; and

wherein a synchronization module in the transmitter module prepends the message with a synchronization sequence having specific codes, and the preamble detection block adjusts timing during a gap between the preamble and message.

35. The receiver module of claim 34, wherein the front end filter comprises of downsampling and pulse shaping filters having a plurality of filters sections.

36. The receiver module of claim 34, wherein the front end filter utilizes a DC removal block to remove DC components of a message.

37. The receiver module of claim 34, wherein the decoding comprises BCH or Hamming decoding.

38. The receiver module of claim 34, wherein the decoding module performs biphase demodulation with error correction.

39. The receiver module of claim 34, further comprising:

a sliding window time correlator or a circular correlator.

40. The receiver module of claim 34, wherein the preamble detection block comprises an Optimized Golay Correlator (OGC) with the noise estimation and DC offset estimation and removal.

41. The receiver module of claim 34, wherein the preamble detection block completes timing adjustments during the gap between the preamble and message to allow the receiver module to receive the message correctly.

42. The receiver module of claim 34, wherein a DC offset of the message is coarsely removed at an analog side of the front end filter and is fine removed at a digital side of the decoding module.

43. A method of performing the operations of a transmitter module in a wireless charging in-band communication system, wherein the wireless charging in-band communication system comprises the transmitter module and a receiver module, the transmitter module performs in-band communication with the receiver module to provide a message to the receiver module, and the method comprises:

attaching check calculation results of the message to the message to generate an attached result, for message error detection;

utilizing a modulation module to perform modulation according to the attached result, including performing impedance switching to provide the message to the receiver module by changing reflected impedance seen by the receiver module; and

utilizing a synchronization module to prepend the message with a synchronization sequence having specific codes;

wherein the message is transmitted outward by the transmitter module through changing the reflected impedance, and the message transmitted by the transmitter module is a message corresponding to usage related to power transfer, so as to affect power transfer control of the receiver module; and

the synchronization module provides a gap between the preamble and message, for timing adjustments in the receiver module.

44. The method of claim 43, wherein the check calculation results are generated by performing a CRC calculation on the message.

45. The method of claim 43, further comprising:

performing BCH or Hamming encoding on the attached result.

46. The method of claim 43, wherein the modulation module performs biphase modulation.

47. The method of claim 43, wherein the specific codes comprise Golay complementary codes. prepending the message with a synchronization sequence.

48. A method of performing the operations of a receiver module in a wireless charging in-band communication system, wherein the wireless charging in-band communication system comprises a transmitter module and the receiver module, the receiver module performs in-band communication with the transmitter module to receive a message provided by the receiver module, and the method comprises:

providing an impedance sensing circuit to detect changes in the reflected impedance of the transmitter module, wherein the message is included by the changes in the reflected impedance;

providing a front end filter to perform pulse shaping and noise rejection;

performing message detection, synchronization, and equalization coefficient estimation, comprising adjusting timing during a gap between the preamble and message; and

performing equalization, channel decoding, and error detection;

wherein the message is transmitted outward by the transmitter module through changing the reflected impedance, and the message transmitted by the transmitter module is a message corresponding to usage related to power transfer, so as to affect power transfer control of the receiver module; and

a synchronization module in the transmitter module prepends the message with a synchronization sequence having specific codes, and provides a gap between the preamble and message.

49. The method of claim 48, wherein the front end filter comprises of downsampling and pulse shaping filters having a plurality of filters sections.

50. The method of claim 48, wherein the front end filter utilizes a DC removal block to remove DC components of a message.

51. The method of claim 48, wherein the channel decoding comprises BCH or Hamming decoding.

52. The method of claim 48, further comprising:

performing biphase demodulation with error correction.

53. The method of claim 48, wherein the step of performing message detection, synchronization, and equalization coefficient estimation further comprises:

performing noise estimation and DC offset estimation and removal.

54. The method of claim 48, wherein the step of performing message detection, synchronization, and equalization coefficient estimation further comprises:

completing timing adjustments during the gap between the preamble and message to allow the receiver module to receive the message correctly.

55. The method of claim 48, wherein a DC offset of the message is coarsely removed at an analog side of the receiver module and is fine removed at a digital side of the receiver module.