Analysis and Design of a Dual-Frequency Capacitive Power Transfer System to Reduce Coupler Voltage Stress

Abstract

In a capacitive power transfer (CPT) system, the coupling capacitance formed between the coupling plates is very small only in the pF or nF range, which leads to high voltage stress among the coupling plates during energy transmission, which increases the risk of an electrical breakdown between the coupled plates. To solve this problem, a novel dual-frequency CPT system is proposed in this paper, which uses the “peak clipping” effect caused by the superposition of the fundamental wave and third harmonic wave to reduce the voltage stress of the coupled plates. Through the detailed analysis of the working principle of the CPT system, it is shown that the dual-frequency CPT system can indeed reduce the high voltage stress among the coupled plate to 84.3% of the equivalent single-frequency system and can also reduce the inverter conduction losses to 90%. A 200 W prototype is designed with the proposed scheme, and the experimental results confirm the correctness of the theoretical derivation.