Constant Output Voltage Three-Phase Capacitive-Power-Transfer Converters With Phase Expansion and Design Methods

Capacitive power transfer (CPT) has attracted attention for its merits of light coupler structure, low cost, and minimal eddy current loss. However, constrained by high operating frequencies and device current/voltage ratings, conventional class D/E, half-bridge, and full-bridge CPT topologies can no longer meet the requirements of high-power applications. To address this, based on the phase expansion concept, a three-phase CPT topology with constant voltage output and an associated parameter design method are proposed. Firstly, a simplified equivalent circuit model of the three-phase CPT is established, and the AC-DC conversion relationship between the load and voltage is derived. Secondly, the output characteristics and operational constraints of various third-order compensation networks are analyzed based on the two-port network theory. Then, taking the LCL-CLC compensation network as an example, sensitivity and operational efficiency models are developed, and a parameter design method for the three-phase CPT is proposed. Finally, the effectiveness of the proposed three-phase CPT topology and its design method is validated through simulations and experiments.