Effective Capacitive Power Transfer

Capacitive power transfer (CPT) systems have up to date been used for very low power delivery due to a number of limitations. A fundamental treatment of the problem is carried out and a CPT system is presented that achieves many times higher power throughput into low-impedance loads than traditional systems with the same interface capacitance and frequency of operation and with reasonable ratings for the switching devices. The development and analysis of the system is based well on the parameters of the capacitive interface and a design procedure is provided. The validity of the concept has been verified by an experimental CPT system that delivered more than 25W through a combined interface capacitance of 100 pF, at an operating frequency of only 1 MHz, with efficiency exceeding 80%.