A Normalized Coupler Model of Capacitive Power Transfer Systems under Positional Offset of Plates

Capacitive power transfer (CPT) is considered a promising wireless power transfer technique due to its ability to eliminate eddy current losses and use of magnetic materials. However, current analytical coupler models face significant challenges in accurately characterizing the transmission characteristics when a positional offset exists between the capacitive plate pairs. This paper proposes a normalized coupler model considering positional offset conditions to analyze CPT systems’ power and efficiency characteristics. By employing modulation techniques in the transmitter, negative impedance characteristics are realized at its AC output, enabling system operation in the self-resonant mode. The output powers and efficiencies of the CPT system are tested and verified under different x-positional offset conditions using a 100W experimental prototype. Achieving analyzable output power and efficiency under positional offset conditions will significantly enhance the systematic and predictable analysis of CPT systems, with promising potential for applications in consumer electronics and mobile wireless equipment powering.