An Extendable High-Voltage Gain Soft-Switching Bidirectional DC-DC Converter With Coupled Inductor

This article proposes a nonisolated extendable soft-switching bidirectional dc-dc converter that is suitable for high-voltage gain and high-power applications. The proposed converter adopts the structure of interleaved parallel at the low-voltage side (LVS) and series connection at the high-voltage side (HVS), which features low-voltage stresses of the switches and capacitors and current sharing. In addition, the converter can achieve soft-switching of all the switches at light and full load in a wide voltage range by combining coupled inductors with resonant tanks, and the leakage inductors' energy can be controlled. The operating principle, voltage stresses of devices, soft-switching conditions, and comparison analysis are discussed in detail. Furthermore, the parameter design of the proposed converter is presented. Finally, a 1-kW experimental prototype with 40-90 V LVS and 400 V HVS is constructed to verify the performance of the converter, and results show that its maximum efficiency reaches 97.9% in boost mode and 97.6% in buck mode.