| Abstract |
A distributed switch matrix is proposed that enables balancing of series-connected groups of batterycells in a pack through dc-dc converters. The switch matrix is used to develop a multi-function electricvehicle Battery Management System (BMS) that features active cell balancing, online electrochemical impedance spectroscopy, and 12V auxiliary bus power supply. The BMS is designed for 6S2P,88Ah custom liquid-cooled modules. A prototype system is demonstrated using a 1S2P, 0.5mO nominalimpedance battery unit. Bidirectional active balancing operates at 2.5A while power is exchanged withthe auxiliary bus. The 88Ah battery impedance is measured from 11 to 2000Hz for a varying range oftemperatures. Based on a Monte-Carlo battery pack simulation under randomised cell capacity imbalance, an estimated 20\% average increase in usable pack capacity can be achieved with active balancingengaged. |
