Capacitive Coupling Wireless Power Transfer Circuit with a Compensated L for High Voltage Gain and Soft Switching

Abstract

A Capacitive coupling wireless power transfer (WPT) circuit with a compensated L is proposed. Two pairs of small area metal electrodes are used to produce two coupling capacitors and a resonant inductor is employed for the capacitive coupling wireless power transfer. By adding one parallel inductor to the series resonant circuit, an output voltage gain greater than 1 can be achieved. In addition, zero voltage switching (ZVS), zero current switching (ZCS), and higher output voltage can be obtained using the compensated inductor even at high frequency operation. A 6.3W Capacitive coupling WPT system is implemented with an approximately 700pF coupling capacitance by two 108cm2 copper plates and 6.78MHz operation for charging a small power electric device. The experimental results confirm the ZVS and ZCS operation, higher efficiency, and larger output voltage.