A Single-Stage AC-DC Converter Based on Semi Dual-Active-Bridge With Decoupled Inductor Current Modulation Strategy

In this article, a novel decoupled inductor current modulation strategy for a single-stage ac-dc converter based on a semi dual-active-bridge is proposed, which helps minimize the total harmonic distortion (THD) and improve the conversion efficiency. The transformer turns ratio is designed in an optimized manner for higher conversion efficiency. Only two control variables are used. And the converter could achieve a wider output voltage range and a high power factor without the mandatory current-tracking loop and look-up tables. In addition, comparisons of losses, THD, and backflow power between the decoupled inductor current and the optimal peak current modulation are presented. The power transfer capability, mode transition mechanism, soft-switching range, mode operation region, and parameter design are analyzed. The switches can achieve zero-voltage-switching within a wide operating range, and rectifier diodes can achieve zero-current-switching off in all operation situations. Besides, a 1-kW experimental prototype was built to verify the effectiveness of the proposed control strategy.