A Soft-switching Bidirectional AC/DC Converter with MERS Turn-off Snubber Circuit and Discontinuous Current Mode

Abstract

With an increase in renewable energy source installations in the domestic field, bidirectional ac/dc converters are attracting attention. Efficiency, power density improvement and EMI reduction are necessary for converters in this field. Using high-frequency switching can reduce the size of passive components and help achieve a high-power-density converter; however, the switching losses and EMI can increase. In this study, we propose a new bidirectional ac/dc converter circuit topology that can reduce the switching losses and EMI with a soft-switching operation. The soft-switching operation is based on the DCM (discontinuous current mode) operation and a MERS (magnetic energy recovery switch)-type turn-off snubber. This paper focuses on a modulation technique applied to this converter. Experiments with a fabricated 1kW converter were conducted, and the principles of operation were confirmed. Loss analysis indicates that inductor design is the key design issue for the proposed converter.