An active clamp ZVT converter with input-parallel and output-series configuration

A novel converter is proposed in this paper to satisfy the high power, high step-up and isolated conversion requirements. In the proposed converter, the input-parallel configuration is adopted to share the large input current and reduce the conduction losses, while the output-series configuration is adopted to get a high voltage gain. Consequently, a transformer with a low turns ratio can be applied, which makes the transformer optimized easier. Moreover, the active clamp circuits are employed here to reduce the voltage stress of the switches and recycle the energy stored in the leakage inductance, and ZVT is achieved during the whole switching transition for all the active switches, so the switching losses can be reduced greatly. Furthermore, the diode reverse-recovery problem is partly solved due to the leakage inductance. Finally, a 40 V-input 400 V-output 1 kW prototype is built to demonstrate the theoretical analysis, and the maximum efficiency of 94.9% and 93.3% at full load are achieved.