Analysis and Design of Load-Independent ZPA Operation for P/S, PS/S, P/SP, and PS/SP Tank Networks in IPT Applications

The zero-phase-angle (ZPA) operation at inverter output of parallel-compensated inductive power transfer (IPT) topologies is frequently reported to be load dependent. Therefore, either the operating inverter switching frequency or the compensation capacitors are modified dynamically with load variation to reach new ZPA point. This letter proposes a novel design technique of compensation capacitors for several IPT topologies to obtain load-independent ZPA. The proposed method is based on the passive selection of tank network parameters; therefore, it obviates the requirement of dynamic tuning and complexities associated with it. A detailed mathematical analysis is reported, and experimental results obtained from a 1-kW lab-prototype are demonstrated to verify the analysis and performance.