Wide-range ZVS asymmetric half-bridge converter with clamping switches for small DC offset current

Abstract

In this paper, a new wide range zero-voltage switching asymmetric half-bridge (AHB) converter with clamping switches for small DC offset current is proposed. Since the hold-up time requirement makes the conventional AHB converter operates asymmetrically in nominal state, a large DC offset current degrades the performance of AHB converters. In order to overcome this problem, the proposed AHB converter operates symmetrically in nominal state and two clamp switches that replace the clamp diodes, operate in hold-up state for additional gain. From the results, it can reduce the DC offset current of transformer and relieves the drawbacks that caused by asymmetric operation. In addition, a large external inductor of the proposed converter makes the wider zero-voltage switching (ZVS) range. Therefore, the proposed converter achieves the high overall efficiency and the smaller DC offset current than the conventional AHB converter. To verify these advantages of the proposed converter, the experiment was implemented with 340~400V input voltage, 500W (12V/41.67A) output power system at 100 kHz.