Novel Non-Isolated High Step-Up DC-DC Converter Topologies for Electric Vehicles

This paper presents three new non-isolated high step-up converters (NI-HSC) for electric vehicle charging applications. Higher duty ratios increase the overall gain of the step-up converter. However, this increases voltage and current stresses in the switching devices. This paper proposes three soft-switched high step-up converters (SS-HSC) improved with auxiliary cells, to reduce the switching losses and to improve the overall efficiency. The auxiliary cell provides soft-switching of the main MOSFETs. The zero voltage switching (ZVS) is achieved for all the MOSFETs during turn-on. Zero current switching (ZCS) turn-off is obtained for one main switch and the auxiliary switch. Principles of operation and simulation results are presented to evaluate the theoretical analysis. The designed converter systems are simulated with 100 V input voltage at 6 kW to obtain 600 V output voltage.