Patent ID: 9627915
Date: 2017-04-18
CPC Classifications: H02J,H02M,H04B

Claim:
1. A power transmission pad for wireless power transmission comprising: a. a coil; b. a power transmitter having a sweep frequency generator coupled to the coil to provide a frequency varying signal through the coil, thereby generating a variable magnetic field; and c. a controller coupled to the coil and to the sweep frequency generator, wherein when a plurality of portable electronic devices to be charged are positioned within the variable magnetic field a handshake protocol is performed between each of the portable electronic devices and the power transmission pad, wherein the power transmission pad is configured to determine the number of portable electronic devices positioned within the variable magnetic field by counting a number of handshake protocols and to adjust a power transmission level of a power transmission signal according to the determined number, wherein the power transmission pad is further configured to determine an optimal device frequency from the frequency varying signal for each portable electronic device where the optimal device frequency corresponds to a frequency where a maximum energy transfer occurs from the power transmission pad to the portable electronic device, and to determine an optimal system frequency of the power transmission signal using the determined optimal device frequency of each portable electronic device, wherein the optimal system frequency is an average of the determined optimal device frequency for each portable electronic device.