Review and Analysis of a Coupled Inductor Based Bidirectional DC-DC Converter

ABSTRACT In this paper, a bidirectional DC-DC converter has been presented and analysed. Bidirectional DC-DC converters are used for transferring the power, between any two DC sources in any forward or reverse direction. This bi-directional dc-dc converter, is capable of bilateral power flow, providing the functionality of two uni-directional converters in a single converter unit. These type of converters are widely used in applications like Hybrid Electric Vehicle energy systems, fuel-cell hybrid power systems, Uninterrupted Power Supply systems, Photo-Voltaic hybrid power systems, and battery chargers. Different topologies of bidirectional dc-dc converters are studied for reference and finally the selected topology is analysed here. This paper describes the operating principles and steady-state analysis for the step-up and step-down modes of such bidirectional dc-dc converter. This converter has higher step-up and step-down voltage gains than the conventional bidirectional DC-DC boost/buck converter. The special element of such a bidirectional dc-dc converter is the coupled inductor employed here which has same number of winding turns at the primary and secondary sides. In order to analyze the steady-state characteristics of such proposed converter, some conditions are assumed as: 1) The ON-state resistance RDS(ON) of the switches and the equivalent series resistances of the coupled inductor and capacitors are ignored. 2) The capacitor is sufficiently large, and the voltages across the capacitor can be treated as constant.