Review, Analysis, and Design of Four Basic CPT Topologies and the Application of High-Order Compensation Networks

This article reviews existing capacitive power transfer (CPT) systems and aims to provide a universal methodology to systematically construct CPT topologies with zero-phase angle (ZPA) and load-independent output property. There are three contributions. First, y, z, g, and h parameters of a two-port network are adopted to model the capacitive coupler for four basic CPT compensations, which facilitates the resonant circuit analysis by forming parallel or series LC resonance. Second, four basic CPT compensations, series-series (SS), series-parallel (SP), parallel-series, and parallel-parallel (PP), are developed and analyzed. ZPA frequencies are identified with a load-independent output, and a unified efficiency analysis is also provided. Third, by selectively deploying high-order T/Π-type LCL/CLC networks and the SS mutual inductance with basic CPT compensations, a universal CPT design methodology is provided. In total, 144 feasible CPT topologies are derived with ZPA property and constant-current (CC) or constant-voltage output, which not only summaries existing ones but also predicts new topologies. Considerations are provided to guide the topology selection, from which ten typical CPT topologies are elaborated and recommended. A 500-W LCL-PP-LCL compensated CPT circuit is implemented. Experiments validate the proposed methodology by a ZPA property and a load-independent CC output, and a peak dc-dc efficiency of 87.76% is also achieved at 478 W.