Novel Bidirectional Multiple-Input Multiple-Output Converter for Simultaneous Direct Battery Module Balancing

Charge balancers are needed to equalize the energy stored in battery cells connected in series to increase the usable capacity and lifetime of the entire stack. A multiple-input multiple-output DC/DC converter for battery module balancing, based on flux additivity, is proposed. It allows bidirectional, simultaneous and direct charge transfer. A prototype converter with two bidirectional channels has successfully been built-up and tested. First experimental results are presented to verify the feasibility of the charge balancer. A time averaged model is derived considering the influence of the common multiwinding transformer voltage.