Constant capacitive wireless power transfer at variable coupling

Capacitive wireless power transfer uses the varying electric field for wireless power transfer from a transmitter plate to a receiver plate. The amount of power transferred to the load and the system efficiency are dependent of the coupling between transmitter and receiver. However, by changing the operating frequency, it is possible to achieve constant power transfer and efficiency, even at variable coupling. In this work, the analytical expressions for the three different gains of a general capacitive wireless power transfer system are calculated. Based on the gains, an analytical solution is determined for achieving constant power transfer and efficiency at variable coupling. The analytical results are validated by circuital simulation in SPICE.