Design of a Double-Sided LCLC-Compensated Capacitive Power Transfer System With Predesigned Coupler Plate Voltage Stresses

A high-performance capacitive power transfer (CPT) system is expected to achieve the load-independent constant output, near-zero reactive power, and soft switching of power switches simultaneously, resulting in a reduced power stage, simple control circuitry, and minimum component ratings. However, a well-compensated CPT system still suffers very-high-voltage stresses among not only the main coupled plates but also the leakage coupled plates due to the small coupling and edge emission, which increases the risk of air breakdown and deteriorate the electromagnetic interference (EMI) issue. To solve this problem, the voltage stresses among such coupler plates should be predesigned at an acceptable level. This article systematically analyzes the characteristics of a double-sided $LCLC$ -compensated CPT converter that is proven to have enough design freedom providing predesigned voltage stresses for two kinds of coupled plates. Also, three operating frequencies with load-independent constant current (CC) output and input zero-phase angle (ZPA) are found. Without reactive power in the circuit, a parameter design method is proposed for the double-sided $LCLC$ -compensated CPT converter at each frequency to satisfy the desired CC output and the predesigned voltage limitations. In this way, the breakdown and EMI issues can be well mitigated by the intended design, and this method can also be extended to other CPT circuits. Finally, a CPT prototype is built to verify the theoretical analysis with the predesigned voltage stresses among the coupler plates.