High-Efficiency Bidirectional Converter for Power Sources With Great Voltage Diversity

This study focuses on the development of a high-efficiency bidirectional converter for power sources with large voltage diversity. In conventional bidirectional converters, transformer-based circuit topologies are commonly employed and soft-switching techniques including zero-voltage-switching (ZVS) or zero-current-switching (ZCS) are frequently applied to mitigate corresponding switching losses. Unfortunately, switches of four and upward in these transformer-based schemes increase production costs and reduce conversion efficiency. In this study, a coupled-inductor bidirectional converter scheme utilizes only three power switches to fulfill the objective of bidirectional current control. The high step-up and step-down ratios enable a battery module with a low voltage to be injected into a high-voltage dc bus for subsequent utilization. Some experimental results are given to verify the effectiveness of the proposed bidirectional converter. Since the techniques of voltage clamping, synchronous rectification and soft switching are exploited in this circuit topology, and the corresponding device specifications are adequately fulfilled, it can provide high-efficiency bidirectional power conversion for power sources with large voltage diversity.