Analysis and control of S/SP compensation contactless resonant converter with constant voltage gain

A novel S/SP type compensation contactless resonant converter is proposed in this paper, which features the advantage of constant gain intersection point with zero phase angle of input impedance. Different from S/P compensation, the constant gain value is not only independent of load change but also independent of transformer's coupling coefficient change causing by the change of gap or misalignment. The characteristic analysis of the proposed resonant converter is performed in this paper. It is also found that with the proposed S/SP compensation the output voltage gain is not sensitive to the parameter change around the gain intersection point. Therefore, both phase locking control and fixed-frequency control can be employed for the proposed converter. A 60W prototype with PLL control and a 1.5kW prototype with constant frequency control are built to verify the analysis. Experimental results testify the theoretical analysis very well. The efficiency of the fabricated prototype reaches 95.2% with 1.5kW output at 10 cm gap.