Comparison of Four Resonant Topologies Based on Unified Design Procedure for Capacitive Power Transfer

This study analyzes and evaluates four transmission characteristics of the capacitive power transfer (CPT) with resonance coupling. A constant voltage source is used under all conditions. The target compensation topologies for the investigation are series-series (SS), series-parallel (SP), parallel-series (PS) and parallel-parallel (PP) topologies. The analysis results under the unified conditions describe the five transmission characteristics: (a) the equivalent maximum efficiency in four topologies, (b) the squared lower output power of the coupling coefficient of PS and PP topologies compared with those of SS and SP topologies, (c) the squared lower optimal loads of the coupling coefficient of SS and PS topologies compared with those of SP and PP topologies, (d) the constant unit power factor (CUPF) characteristics from the source in four topologies, (e) the constant current (CC) characteristics in SS and PP topologies, and the constant voltage (CV) characteristics in SP and PS topologies at the load variation around the optimal load. From these evaluations, both SS and SP topologies, which are superior in terms of the output power, are recommended when using the voltage source. Finally, the powering experiment in SS and SP topologies shows the effectiveness of these evaluations.