Compact Drive Circuit for Capacitive Wireless Power Transfer System Utilizing Leakage-Enhanced Transformer

In capacitively-coupled wireless power transmission (C-WPT), drive circuit topologies with various impedance matching or compensation techniques have been widely investigated in conventional studies, but they tend to increase the circuit complexity and thus offset the simplicity of the energy link structure which is a unique advantage over the inductively-coupled power transmission. In this paper, through systematic considerations on various matching schemes, a compact drive circuit with leakage-enhanced transformer is proposed in order to minimize the circuit volume for the capacitive power transfer system. In the proposed topology, the integrated transformer handles quality factor control as well as reactive compensation. Consequently, it reduces the number of components, the overall system volume, and the voltage stress of the energy link capacitor. The optimal design guideline of the leakage-enhanced transformer is also presented. Comparisons with the conventional method considering the circuit volume and component stress show the advantage of the proposed scheme, and feasibility of the new topology is verified with 10 W prototype hardware.