Cell Open Circuit Fault Diagnostic for Series-Parallel Connected Li-ion Battery Pack

Abstract

Fault diagnosis has great significances for reducing the failures and improving the reliability of Li-ion battery systems. However, there are few researches on cell open circuit (COC) fault diagnostic for the series-parallel connected battery pack before. In this study, a voltage correlation coefficient-based method and a dual extended Kalman filter (DEKF) are proposed to detect the COC fault. Then, performances of these two methods are compared by taking several COC fault simulation experiment. Experiments with a 4S-3P battery pack under different operating conditions are used to verify two proposed diagnostic approaches. The experimental results demonstrate that the voltage correlation coefficient-based method with the merit of lower misdiagnosis rate, shorter diagnoses delay and low computational cost is more suitable for COC fault detection than DEKF-based method.