Reliable transformerless battery energy storage systems based on cascade dual‐boost/buck converters

Abstract

In this study, the cascade dual‐boost/buck half‐bridge and full‐bridge bidirectional ac–dc converters are proposed for grid‐tie transformerless battery energy storage systems (BESSs). The proposed converter contains the advantages of the traditional cascade H‐bridge (CHB) converter. However, compared with CHB converter, there is no shoot‐through issue in the proposed converter, which is more reliable for BESS. In addition, a unified control scheme is proposed for active‐power control and individual state‐of‐charge‐balancing control of BESS, which is very modular and easy to implement. At the end, a laboratory BESS is constructed and tested combining a cascade two‐unit dual‐boost/buck half‐bridge converter with nine lead–acid series‐connected battery units. Experimental results obtained from the laboratory system verified the feasibility and effectiveness of the proposed BESS and unified control scheme.