A Coupled Inductor-Based Bidirectional DC-DC Converter with Step-Up Step-Down Operation for Electric Vehicle Applications

Abstract

A coupled-inductor-based high step-up high step-down DC-DC converter with bidirectional capability suitable for electric vehicle (EV) applications is proposed in this paper. The voltage gain in both step-up and step-down operations is increased by a two-winding coupled inductor. The current ripple in the low-voltage port is low making it suitable for renewable energy sources. In addition, the low number of components causes the efficiency of the proposed converter to be competitive with similar topologies in the literature. Due to the use of only three bidirectional switches with low voltage stress, the cost and volume of the converter are reduced. To demonstrate the performance of the proposed bidirectional converter, an analysis of the operation modes in the steady state is presented. Also, a comparison between the suggested converter and other similar converters in the literature is provided. The results of these comparisons show that the proposed converter has a lower number of components and higher efficiency than the others. In addition, lower voltage stress and noticeable voltage gain in comparison with others are further results of these comparisons. Eventually, the experimental results in step-up and step-down operations are presented. In step-up operation, the experimental prototype is tested under fs = 50 kHz, VLow = 20 V, VHigh = 110 V, rated power = 120 W, with 94.60% efficiency. Furthermore, VHigh is considered 100 V with VLow = 33 V and 94.43% efficiency at 50 W rated power in step-down mode operation.