Wireless power transmission

Abstract

Wireless power transmission methods, wireless power transmitters, wireless power receiving method, and wireless power receivers are disclosed. Wireless power is transmitted using power signal comprising a multi-sine waveform within a bandwidth to drive a plurality of antennas. Beam-forming coefficients are generated and the relative phases of the power signal used to drive the antennas is controlled by the beam-forming coefficients.

1 . A wireless power transmission method, in a transmitter, the method comprising:
 receiving feedback information from a receiver, the feedback information comprising indications of signals received by antennas of the receiver from antennas of the transmitter;   generating a power signal using the feedback information, the power signal comprising a multi-sine waveform within a bandwidth;   generating beamforming coefficients indicating relative phases for a plurality of the antennas of the transmitter using the feedback information; and   driving the plurality of antennas of the transmitter with the power signal with relative phases of the plurality of antennas of the transmitter controlled according to the beamforming coefficients.   
     
     
         2 . A wireless power transmission method according to  claim 1 , wherein the feedback information comprises an indication of a charging rate of an energy storage device of the receiver. 
     
     
         3 . A method according to  claim 2 , wherein generating beamforming coefficients indicating relative phases for a plurality of the antennas of the transmitter using the feedback information comprises incrementally varying phase differences between the signals transmitted on the plurality of antennas to optimize the charging rate of the energy storage device of the receiver. 
     
     
         4 . A method according to  claim 1 , further comprising determining coefficients for the multi-sine waveform that optimize the power received by the receiver in a channel training procedure. 
     
     
         5 . A method according to  claim 4 , wherein the channel training procedure is initiated in response to a channel training initiation signal received from the receiver, the channel training initiation signal indicating a drop in a charging rate of an energy storage device of the receiver. 
     
     
         6 . A wireless power transmission method according to  claim 1 , further comprising selecting a frequency range as the bandwidth. 
     
     
         7 . A wireless power transmission method according to  claim 6 , wherein the frequency range is selected using the feedback information. 
     
     
         8 . A wireless power transmission method according to  claim 6 , wherein the frequency range is selected in response to a user input. 
     
     
         9 . A wireless power transmitter comprising:
 a plurality of power transmission antennas configured to wirelessly transmit power to a receiver;   a wireless communication module configured to receive feedback information from the receiver, the feedback information comprising indications of signals received by antennas of the receiver from the plurality of antennas of the transmitter;   a signal generator configured to generate a power signal comprising a multi-sine waveform within a bandwidth;   a power signal optimizer configured to control the signal generator using the feedback information;   a phase control logic configured to generate beamforming coefficients indicating relative phases for the plurality of the antennas of the transmitter using the feedback information;   a splitter configured to split the power signal into a plurality of antenna signals each corresponding to respective antennas of the plurality of antennas; and   a plurality of phase shifters configured to shift the relative phase of the antenna signals according to the beamforming coefficients such that the plurality of antennas of the transmitter are driven with the power signal with relative phases controlled according to the beamforming coefficients.   
     
     
         10 . A wireless power transmitter according to  claim 9 , wherein the feedback information comprises an indication of a charging rate of an energy storage device of the receiver. 
     
     
         11 . A wireless power transmitter according to  claim 10 , wherein the phase control logic is configured to generate the beamforming coefficients by incrementally varying phase differences between the signals transmitted on the plurality of antennas to optimize the charging rate of the energy storage device of the receiver. 
     
     
         12 . A wireless power transmitter according to  claim 9 , further comprising a channel estimator configured to estimate channel state information for channels between the plurality of antennas of the transmitter and antennas of the receiver and wherein the power signal optimizer is configured to determining coefficients for the multi-sine waveform that optimize the power received by the receiver. 
     
     
         13 . A wireless power transmitter according to  claim 12 , wherein the channel estimator is configured to initiate a channel training procedure in response to a channel training initiation signal received from the receiver, the channel training initiation signal indicating a drop in a charging rate of an energy storage device of the receiver. 
     
     
         14 . A wireless power transmitter according to  claim 13 , wherein the channel estimator is configured to determine if the drop in charging rate was due to a scheduled change in target receiver and to initiate the channel training procedure if the drop was not due to a scheduled change in target receiver. 
     
     
         15 . A wireless power transmitter according to  claim 9 , further comprising a frequency selector configured to select a frequency range as the bandwidth. 
     
     
         16 . A wireless power transmitter according to  claim 15 , wherein the frequency range is selected using the feedback information. 
     
     
         17 . A wireless power transmitter according to  claim 15 , wherein the frequency range is selected in response to a user input. 
     
     
         18 . A feedback method in a wireless power receiver, the method comprising:
 receiving a wireless power transmission signal from a transmitter at an antenna or a plurality of antennas of the wireless power receiver;   monitoring a charging rate in an energy storage device coupled to the antenna or plurality of antennas;   identifying a change in the charging rate; and   sending a channel training initiation signal to the transmitter.   
     
     
         19 . A wireless power receiver comprising
 a plurality of antennas configured to receive a wireless power transmission signal from a transmitter;   an energy storage device coupled to the plurality of antennas;   a monitoring unit configured to monitor a charging rate of the energy storage device;   a channel estimator configured to identify a drop in the charging rate of the energy storage device and generate a channel training initiation signal; and   a wireless communication module configured to send the channel training initiation signal to the transmitter.   
     
     
         20 . A wireless power receiver according to  claim 19 , wherein the channel estimator is further configured to cause the plurality of antennas to generate a pilot signal.