An Isolated Bidirectional Soft-Switching DC-DC Converter for Wide Input/Output Voltage Range

Abstract

This paper presents the analysis and design of an isolated bidirectional DC-DC converter for applications where both input and output voltages may vary in a wide range. The proposed topology is derived from the integration of an isolated Current-Fed Dual-Active-Bridge (CF-DAB) stage with a Four-Switch Buck-Boost cell (4SBB), sharing one switching leg. Detailed design procedures are outlined for both CF-DAB and 4SBB stages, allowing to achieve Zero-Voltage turn-on of all devices while minimizing the inductor current RMS values. An optimized design of the CF-DAB coupled inductors allowed to achieve the desired leakage inductance value without the need for an additional magnetic component. Experimental results taken on a 5 kW prototype interfacing two voltage ports with VL ∈ [42 V, 72 V], VH ∈ [225 V, 435 V] validate the proposed design procedure.

Keywords

• isolated DC-DC converters
• current-fed dual-active-bridge
• four-switch buck-boost