Wide voltage range and low current ripple bidirectional DC/DC converter

Along with the prosperous growth of battery energy storage system being applied in renewable energy system, wide voltage range regulation and low current ripple bidirectional DC/DC converters attract much attention of researchers. Based on a basic boost-buck converter and voltage multiplying unit (VMU), this article proposes a two-stage DC/DC converter. The front stage is an input parallel output serial connected boost-buck converter and the back stage contains a dual-coupled inductors VMU. The storage inductors of the front stage aremagnetically coupled with those in back stage. Employing dual coupled inductors VMU can increase voltage gain while not increasing main switch voltage stress during step-up mode, which can widen the application scenarios. During step-down mode, a fully controlled method can obtain a greater step-down voltage ratio. Due to the interleaving control mode of the main switches, the current ripple of the battery side is lower when the converter works bidirectionally. The proposed converter has the advantages of widening voltage range regulation and lowering current ripple while avoiding extreme switch duty cycle. This article discusses theoretical step-up and step-down work mode of the proposed converter. Experimental results sampled from a 12 V/115 V prototype are presented to verify the analysis of the proposed converter.