A Coupled Inductor-Based High Step-Down/ Step-Up DC-DC Nonisolated Bidirectional Converter With Reduced Ripple in Current and Voltage Stress

This article proposes a nonisolated hybrid bidirectional dc-dc converter (NHBC) with a high step-down/step-up voltage conversion ratio, reduced voltage and current stresses on semiconductor devices, and decreasing ripples in inductor currents. In particular, this article presents a novel transformer-less energy-efficient bidirectional converter for various bidirectional power flow applications, including batteries in electrified aviation power distribution systems. This NHBC consists of a bidirectional switch-diode capacitor (BSDC) and a bidirectional switch-diode coupled inductor (BSDCI) cells operating in the continuous conduction mode (CCM). Series-parallel transitions between identical capacitors of BSDC and coupled inductors of BSDCI cells modify voltage conversion ratios and reduce ripples in currents and voltage stresses of semiconductor devices of NHBC. Furthermore, the mutual inductance of coupled inductor in BSDCI also reduces ripple in inductor currents and NHBC volume. This study demonstrates steady-state operations, ripple, and efficiency analyses providing design insights into the proposed NHBC in both step-down/step-up modes. A 300-W laboratory prototype validates wide voltage conversion ratios and other objectives considering 48-V low voltage (LV) and 270-V high voltage (HV). The experimental results endorse the feasibility and effectiveness of the proposed topology.