A Nonisolated Bidirectional DC-DC Converter with High Voltage Conversion Ratio Based on Coupled Inductor and Switched Capacitor

In this article, a nonisolated bidirectional dc-dc converter is proposed based on coupled inductor (CL) and switched capacitor (SC). The converter can achieve a high voltage conversion ratio (VCR) by using CL and SC. The CL is operated not only as a filter inductor to regulate voltage but also as a transformer to improve the VCR. Furthermore, the voltage stresses of capacitors and switches are reduced by introducing SC structure. The pulsewidth modulation plus phase-shift control is employed, where the duty cycle is used to ensure that the voltages of two sides are matched and the phase-shift angle is used to control the direction and amount of power flow. In addition, all the switches can achieve zero voltage switching in both forward and backward modes under a wide operating range, which can improve the efficiency of power conversion. The operating principle and steady-state analysis are examined, and a 400-W prototype is designed to verify the validity of the proposed converter.