Double-input high-gain bidirectional DC-DC converter for hybrid energy storage systems in DC-micro grid

Novel double input non-isolated high gain bidirectional DC-DC converter is presented for hybrid battery and super-capacitor energy storage system. Coupled inductor has been used for achieving high gain in single input converters, but it has been rarely used in multi-input bidirectional high gain converters. The proposed converter can achieve ZVS operation for all of the switches, with the combination of quasi resonant and active clamp techniques. The proposed converter does not utilize transformer for achieving high gain, hence the number of switches is decreased in comparison to its counterparts. Therefore, it has better reliability and it is more cost effective. Furthermore, proposed converter utilizes just four switches in each mode, hence the conduction loss is decreased considerably. Also unlike its isolated counterparts which use phase shift technique, it has excellent voltage matching. Accordingly, the circulating current that causes current stress and loss in isolated converters naturally does not exist. The switching strategy of the converter is presented and simulations for different modes of the converter is carried out to demonstrate the performance of converter in different modes. The simulation results and efficiency calculations show the effects of the proposed converter.