High-Efficiency Asymmetrical Half-Bridge Converter With a New Coupled Inductor Rectifier (CIR)

• Published in: IEEE transactions on power electronics Vol. 34; no. 12; pp. 11541 - 11552
• Main Authors: Han, Jung-Kyu, Kim, Jong-Woo, Lee, Byoung-Hee, Lai, Jih-Sheng, Moon, Gun-Woo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Asymmetrical half-bridge (AHB) converter; Asymmetry; Capacitors; Conduction losses; Core loss; coupled inductor rectifier (CIR); dc-offset current; Diodes; Direct current; Efficiency; Electric bridges; Electric converters; Energy conversion efficiency; high efficiency; Inductors; Light emitting diodes; Power electronics; Rectifiers; Stress; Switches; Topology; Transformers; Zero voltage switching; zero-voltage switching (ZVS)
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2019.2906722

A conventional asymmetrical half-bridge (AHB) converter is one of the most promising topologies in low-power applications because of the zero-voltage switching (ZVS) of all switches and the small number of components. However, when it operates with an asymmetrical duty ratio, it has a large dc-offset current in the transformer, which increases the size and core loss of the transformer. Moreover, because the dc-offset current decreases ZVS energy for one of the half-bridge switches, it has low efficiency in a light load condition. In addition, because most of the output current is concentrated in high-voltage-rating diodes that have large forward voltage drops, large conduction loss occurs in the secondary rectifier. To solve these problems, a new AHB converter with a coupled inductor rectifier (CIR) is proposed in this paper. By adopting the CIR structure in the AHB converter, the proposed converter not only eliminates the dc-offset current in the transformer, but it also has equalized current stress in the rectifier diodes. As a result, the proposed converter achieves high efficiency in entire load condition, compared to an AHB converter with a full-bridge rectifier. The effectiveness and feasibility are verified with a 250-400 V input and 100 V/200 W output prototype.