Circuit and architecture for a demodulator for a wireless power transfer system and method therefor

• US 9,362,756 B2
• Filed: 09/30/2014
• Issued: 06/07/2016
• Est. Priority Date: 12/16/2013
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Khandelwal, Ashish, Su, Yipeng
• Primary Examiner(s): Tran, Tuan A
• Application Number:
  US14/502,378
• Publication Number:
  US 20150171932A1
• Time in Patent Office: 616 Days
• Field of Search: 455/41.1, 340/10.1, 340/10.3, 340/10.34, 340/10.4, 340/13.24, 340/13.25, 340/13.26
• US Class Current: 1/1
• CPC Class Codes: H02J 50/10 using inductive coupling
• 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: H03K 19/20 characterised by logic function, e.g. AND, OR, NOR, NOT circuits H03K19/003 - H03K19/01 take precedence
• CPC Class Codes: H03K 2005/00078 Fixed delay
• CPC Class Codes: H03K 5/1532 Peak detectors measuring characteristics of individual pulses G01R29/02
• CPC Class Codes: H03K 5/1536 Zero-crossing detectors in measuring circuits G01R19/175
• CPC Class Codes: H03K 5/24 the characteristic being amplitude
• CPC Class Codes: H04B 5/0093 with one coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/02 using transceiver
• CPC Class Codes: H04B 5/266 One coil at each side, e.g. with primary and secondary coils
• CPC Class Codes: H04B 5/48 Transceivers
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

A primary side wireless power transmitter inductively couplable to a secondary side wireless power receiver for receiving communications from the secondary side wireless power receiver through the inductive coupling having a primary side tank circuit receiving a signal from the secondary side wireless power receiver. A phase delay or time delay circuit generates a fixed delay clock signal from a signal utilized to excite the primary side tank circuit. A sample and hold circuit samples a tank circuit voltage utilizing the fixed phase or time delayed clock signal. A comparator is coupled to an output of the sample and hold circuit for extracting data or commands from the signal stream. A method of operating a primary side wireless transmitter inductively coupled to a secondary side wireless power receiver for supplying power to the wireless power receiver to power a load coupled to the receiver is also disclosed.

Claims

1. In a primary side wireless power transmitter for being inductively coupled to a secondary side wireless power receiver for supplying power to the wireless power receiver to power a load coupled to the wireless power receiver, a primary side control for receiving communications from the secondary side wireless power receiver through the inductive coupling, comprising:

a primary side tank circuit being excited into oscillation by excitation signal, the tank circuit receiving a signal stream from the secondary side wireless power receiver;

a delay circuit generating a fixed delay clock signal from the excitation signal;

a sample and hold circuit sampling a tank circuit voltage utilizing the fixed delayed clock signal; and

a comparator coupled to an output of the sample and hold circuit for extracting data or commands from the signal stream.

2. The controller of claim 1 wherein the delay circuit is a phase delay circuit generates a clock signal which has a phase delay of between 15°

and 75°

with respect to the excitation signal.

3. The controller of claim 2 wherein the output of the sample and hold circuit is filtered by a low pass filter.

4. The controller of claim 3 wherein output of the low pass filter is compared with an average value of the output of the low pass filter to detect data or commands from the secondary side power receiver.

5. The controller of claim 1 wherein the delay circuit that generates a clock is a time delay circuit.

6. The controller of claim 5 wherein the time delay is 250 ns to 1.2 μ

s.

7. The controller of claim 5 wherein the output of the sample and hold circuit is filtered by a low pass filter.

8. The controller of claim 7 wherein output of the low pass filter is compared with an average value of the output of the low pass filter to detect data or commands from the secondary side power receiver.

9. A method of operating a primary side wireless transmitter inductively coupled to a secondary side wireless power receiver for supplying power to the wireless power receiver to power a load coupled to the receiver comprising:

exciting a tank circuit into oscillation utilizing at excitation signal;

receiving a signal stream from the wireless power receiver in a primary side tank circuit;

generating a fixed delayed clock signal from the excitation signal;

sampling the tank circuit voltage utilizing the fixed delayed clock and holding the sampled value;

generating a threshold voltage signal from the signal stream signal; and

extracting data from the signal stream utilizing the threshold voltage signal.

10. The method of claim 9 wherein the fixed delay is a phase delayed clock that is generated at a fixed delay of between 15°

and 75°

with respect to the excitation signal.

11. The method of claim 10 wherein the delay circuit that generates a clock is a time delay circuit.

12. The method of claim 11 wherein the time delay is 250 ns to 1.2 μ

s.

13. The method of claim 11 further comprising low pass filtering the output of the sample and hold circuit.

14. The method of claim 13 further comprising comparing output of the low pass filter with an average value of the output of the low pass filter to detect data or commands from the secondary side receiver.

15. The method of claim 10 further comprising low pass filtering the output of the sample and hold circuit.

16. The method of claim 15 further comprising comparing output of the low pass filter with an average value of the output of the low pass filter to detect data or commands from the secondary side receiver.

17. A wireless power transfer system comprising:

a transmitter for transmitting electrical energy through a first inductive coil electromagnetically coupled to a second inductive coil in a receiver;

a circuit in the receiver coupling a resistor or capacitor across the second inductive coil to generate data or command signals in the first inductive coil;

a sample and hold circuit sampling a value of signal in the first inductive coil and holding the value, the sample being taken at a fixed delay from an excitation signal for the first coil; and

a comparator coupled to an output of the sample and hold circuit for extracting data or commands from a signal stream.

18. The wireless power transfer system of claim 17 wherein the fixed delay is a phase delay of between 15°

and 75°

with respect to the expectation signal.

19. The wireless power transfer system of claim 17 wherein the fixed delay circuit is a fixed time delay circuit.

20. The wireless power transfer system of claim 19 wherein the time delay is between 250 ns 1.2 μ

s.