Charge equalization using quasi-resonant converters in battery string for medical power operated vehicle application

A systematic approach to the analysis and design of a soft-switching bidirectional converter for the battery charge equalization (BCE) control of a medical power operated vehicle is presented in this paper. The quasi-resonant (QR) converter circuit is designed to achieve the zero current switching (ZCS) for reducing the switching loss of the bidirectional converter. Results indicate that the switching loss and EMI emission can be improved by using the QR ZCS technology in the charging system with the proposed BCE. The validity of the battery equalization is further verified by using an experimental installation of a lead-acid battery string. Experimental results show that the proposed battery equalization scheme can not only achieve the bidirectional battery equalization performance, but also can reduce the switching loss and improve the EMI performance during the equalization period.