Wireless power transfer in-band communication system

Abstract

A transmitter module is used in a wireless charging system, and is used 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 has a matching network, a rectifier and an impedance component. The matching network has at least one input terminal coupled to a coil of the transmitter module and at least one output terminal. The rectifier is coupled to the output terminal of the matching network. The impedance component is selectively coupled to the output terminal of the matching network to vary a reflected impedance of the transmitter module seen by the receiver module. By varying the reflected impedance of the transmitter module seen by the receiver module, the transmitter module communicates with the receiver module to provide power control commands, status and/or foreign object detection information.

What is claimed is: 
     
         1 . 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 matching network, having at least one input terminal coupled to a coil of the transmitter module and at least one output terminal;   a rectifier, coupled to the output terminal of the matching network; and   an impedance component, selectively coupled to the output terminal of the matching network to vary a reflected impedance of the transmitter module seen by the receiver module;   wherein by varying the reflected impedance of the transmitter module seen by the receiver module, the transmitter module communicate with the receiver module to provide power control commands, status and/or foreign object detection information.   
     
     
         2 . The transmitter module of  claim 1 , further comprising a switch for coupling and decoupling the impedance component to and from the matching network. 
     
     
         3 . The transmitter of  claim 1 , wherein the impedance component is capacitive or resistive. 
     
     
         4 . The transmitter module of  claim 1 , wherein a signal on a transmitted power waveform is modulated to facilitate the communication between the transmitter module and the receiver module. 
     
     
         5 . The transmitter module of  claim 4 , further comprising CRC calculation and attachment and channel encoding before the modulation. 
     
     
         6 . 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 from the transmitter module, the receiver module comprising:
 a matching network, having at least one input terminal coupled to a coil of the receiver module and at least one output terminal;   an amplifier, coupled to the output terminal of the matching network; and   an impedance sensing circuit, coupled to the amplifier, for detecting changes in a reflected impedance of the transmitter module seen by the receiver module;   wherein by detecting changes in the reflected impedance of the transmitter module seen by the receiver module, the receiver module communicate with the transmitter module to receive power control commands, status and/or foreign object detection information.   
     
     
         7 . The receiver module of  claim 6 , further comprising a front end filter, coupled to the impedance sensing circuit, for pulse shaping and noise rejection. 
     
     
         8 . The receiver module of  claim 7 , wherein the front end filter comprises an analog anti-aliasing filter and an analog-to-digital converter (ADC). 
     
     
         9 . The receiver module of  claim 7 , further comprising a preamble detection block, coupled to the front end filter, for message detection, synchronization, and equalization coefficient estimation. 
     
     
         10 . The receiver module of  claim 9 , further comprising a decoding module, coupled to the preamble detection block and the front end filter, for equalization, demodulation, decoding and CRC check. 
     
     
         11 . The receiver module of  claim 6 , wherein the impedance sensing circuit includes a current sensor for load sensing.