New BMS Topology with Active Cell Balancing Between Electric Vehicles’ Traction and Auxiliary Batteries

This paper proposes a new topology for a battery management system (BMS) with active cell balancing capable of exchanging energy between an electric vehicle’s traction and auxiliary batteries. This topology facilitates energy exchange between any cell in the traction battery pack and with the auxiliary battery. The proposed topology allows both the selection of the cells involved in the balancing process and the charging of the auxiliary battery, eliminating the need for a dedicated dc-dc isolated power converter. The flexibility of this topology allows the adoption of different balancing strategies, which can be used to improve balancing efficiency. The proposed topology was first analyzed through computer simulations, and a laboratory BMS prototype was developed. The results from the simulation and experimental tests validate the topology operation and its performance in transferring energy between the cells and the auxiliary battery.