Modeling and Simulation of Impedance Measurement for Battery Energy Storage Systems with Multi-Frequency Perturbation Signals

This paper aims to address the challenge of identifying early-stage short-circuit faults in lithium-ion battery modules through conventional voltage and current signals. The perturbation injection method is employed to inject low-amplitude AC disturbances into battery circuits under constant-current charging cases. By synchronously capturing voltage and current responses and performing frequency-domain analysis, the system achieves real-time impedance spectrum acquisition. A comparative analysis is given based on linear frequency-modulated signals and multiple sine wave signals. The results demonstrate superior performance in wide-band impedance measurement regarding spectral distribution and measurement accuracy. A MATLAB/Simulink-based impedance measurement model including individual cells and battery modules is developed. Simulation results show that within the 1~1000 Hz frequency range, the maximum impedance amplitude errors are 0.0129 Ω for individual cells and 0.077 Ω for battery modules. Further experiments utilizing parallel short-circuit resistors with varying values verify that increased short-circuit severity can lead to reduced impedance amplitude and expanded phase angle. It also validates that module impedance characteristics are closely correlated to the number and spatial distribution of short-circuited cells. These results validate the feasibility and effectiveness of the proposed method in detecting short-circuit faults in battery modules.