A novel battery active equalization-based internal short circuit fault diagnosis method for lithium-ion batteries

The thermal runaway caused by internal short circuit (ISC) faults is the main safety issue of lithium-ion batteries. The diagnosis of ISC faults is the key but suffering problems including high complexity, inaccurate results, and even failure during battery balancing. To address these issues, an ISC fault diagnosis method based on active battery balancing is proposed, which only requires the balanced energy information. Diagnosis and quantification of ISC faults can be realized with extremely low computational complexity. An equalization topology structure based on flyback transformation is adopted, and an online internal resistance compensation method combining driving mode and charging mode is developed. Through the proposed method, the ISC resistance is quantitatively analyzed. Finally, a series of test results validate the effectiveness of the proposed method. The experimental results show that the diagnosis of ISC faults can be completed in the shortest time of 4801 s, and the ISC resistance estimation error is mostly within 2 %.