Fast battery impedance measurement based on discrete Fourier transform and S transform with discrete interval binary sequence

Accurate estimation of battery states is critical for monitoring safety. Impedance has emerged as a powerful parameter for precisely estimating key states of batteries. However, fast battery impedance measurements always require high generation frequency hardware, which limit their practical applications. The objective of this paper is to decrease the generation frequency while keeping short measurement time. In this paper, the discrete interval binary sequence (DIBS) is used with enhanced low-frequency component. Meanwhile, impedance of low-frequency region is calculated by discrete Fourier transform (DFT), and impedance of high-frequency region is calculated by S transform (ST) through averaging eight edges. The experimental results confirm effectiveness of this method. With only 3 Hz generation frequency, precise impedance measurements within the range of 0.1 Hz–1000 Hz are achieved in just 10.33 s. Verification is conducted with different battery states. The normalized root mean square errors (NRMSEs) and mean absolute percentage errors (MAPEs) of the measurements are below 2.32 % and 2.03 %, respectively.