High gain, high efficiency bi-directional DC-DC converter for battery charging applications in stand-alone Photo-Voltaic systems

A bi-directional dc-dc converter is a vital part of standalone solar Photo-Voltaic (PV) systems for interfacing the battery. The converter proposed in this paper is a high gain, high efficiency bi-directional dc-dc converter pertinent to PV applications. The converter consists of one coupled inductor, one simple inductor, two power switches and four diodes. The circuit is operated in such a way that one switch, one coupled inductor and three diodes are used for step-up operation to boost the voltage of the battery to match the high voltage dc bus. The other switch, remaining diode and simple inductor are used for step down operation to charge the battery from the surplus PV energy. The high efficiency of the converter is achieved by optimizing components used for each step. The efficiency of the converter is as high as 98% for both step up and step down operations. Simulation of the converter has been performed for a 40V/400V, 200W system. Analysis and simulation results are presented in the paper to verify its feasibility.