A ZVS-Based Non-Isolated High Step-Up DC–DC Converter With Low Voltage Stress for Renewable Applications

Abstract

A high gain soft switched step-up DC-DC converter is presented in this paper. High gain is achieved at lower duty and turns ratio with a pair of coupled inductors and a voltage multiplier. In addition, an active clamp is incorporated to reduce the voltage stress across the main switch. Hence, switches with lower on-state resistance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R_dson</i> ) and lower voltage ratings are employed, reducing both conduction losses and cost. It additionally helps in achieving zero voltage switching (ZVS) to both MOSFETs. By recycling the leakage energy of the coupled inductors, voltage gain is further increased. It also helps to accomplish zero current switching (ZCS) turn-on and off of diodes. This further reduces losses and increases further efficiency. Moreover, the reverse recovery problem of the diodes is also mitigated. The working principle, steady-state analysis, and design guidelines have been carried out. Finally, a 500 W hardware set up with an input voltage range of 20-24 V and output of 400 V at a switching frequency of 50 kHz is built to validate the performance of the proposed converter. The operating efficiency at full load is observed as 95.11%.