Short Circuit Fault Diagnosis for a Parallel Lithium-Ion Battery Pack in Electric Vehicles

Lithium-ion battery packs are widely deployed as power sources in transportation electrification solutions. To ensure safe and reliable operation of battery packs, it is of critical importance to monitor battery operation status and diagnose battery faults early. This paper proposes a soft short circuit (SC) fault detection method for a parallel battery pack. Since it is impractical to equip current sensors for all the cells in a parallel pack, a reconstructed state-space equation combining the electrical dynamic of a battery cell and the electrical characteristics of a parallel battery pack is designed for the cell current estimation. Then, the occurrence of an SC fault can be timely detected based on the difference between the measured and estimated branch current flowing through the first interconnected resistance. Simulations on a parallel-connected battery pack under a 10 Ω SC resistance are conducted to verify the effectiveness of the proposed method.