High conversion ratio DC-DC converter with isolated transformer and switched-clamp capacitor for Taiwan photon source

A new high step-up voltage converter that combines a switch capacitor and isolated transformer, together with a passive clamp circuit, is employed to reduce voltage stress on the main power switch. The voltage stress of the power switch should be clamped to 1/4 V_o, and the proposed converter can achieve high step-up voltage gain with appropriate duty ratio. The energy of the leakage inductor can be recycled by the clamp capacitor because of the passive clamp circuit, and low On-state resistance R_DS(on) of the power switch can be adopted to reduce the conduction loss. In this paper, several mathematical derivations are presented, CCM and DCM operating principle are discussed, and experimental results are provided to verify the effectiveness of converter topology. Finally, a 24-V-input voltage to 200-V-output voltage and a 150 W output power prototype converter are fabricated in the laboratory.