Coupled-Inductor-Based Dual Active Bridge Converter With Soft Switching Capability and Low Component Count

Abstract

A coupled-inductor-based dual active bridge (DAB) converter with soft switching capability and low component count is proposed in this article. Under wide-input voltage range application, it only utilizes four active switches to achieve voltage regulation and can behave like the current-fed DAB (CF-DAB) converter. In addition, three magnetic components, including the input dc inductor, the transformer, and the leakage inductor, can all be integrated into one coupled inductor, thus reducing the magnetic component count. With the coupled-inductor structure, the voltage of the half bridge capacitor at the output side can be automatically changed according to different duty cycle. Consequently, the voltage matching at the two ports of the equivalent leakage inductor will always be satisfied by controlling the input capacitor voltage with the adopted pulsewidth modulation (PWM). Based on the detailed analysis of the working modes, power transfer characteristics, and zero-voltage switching (ZVS) conditions, full load range ZVS can be mathematically obtained, which shows that the full load range ZVS capability is an intrinsic feature of the proposed converter and is not related to the converter inductance values. Furthermore, the magnetic integration and parameter design are analyzed in detail. Finally, experimental results are provided to demonstrate the effectiveness of the proposed solution.