A multicell battery system design for electric and plug-in hybrid electric vehicles

The performance of electric vehicles (EVs) and plug-in hybrid electric vehicle (PHEVs) strongly relies on their battery storage system, which consists of multiple battery cells connected in series and parallel. However, cell state variations are commonly present, which reduces the energy conversion efficiency of the battery system. Furthermore, in a large battery system the risk of catastrophic faults of cells increases because a large numbers of cells are used. To solve these problems, this paper proposes a novel power electronics-enabled, self-X, multicell battery system design. The proposed battery system can self-heal from failures or abnormal operations of single or multiple cells and self-balance from cell state variations. These features are achieved by a cell switching circuit and a high-performance battery management system (BMS). The proposed design is validated by simulation studies in MATLAB Simulink for a battery system containing five modules connected in series, where each module consists of 6×3 cylindrical lithium-ion cells. The proposed design is scalable to large battery systems for EV/PHEV applications.