Discrimination and screening method for a Li-Ion cell based on discrete wavelet transform (DWT)

Differences in electrochemical characteristics among Li-Ion cells inevitably result in voltage/state-of-charge (SOC) imbalances in the Li-Ion battery pack. Therefore, this paper investigates a new approach based on the discrete wavelet transform (DWT) that suitable for analyzing and evaluating discharging/charging voltage signal (DCVS) for discrimination and screening method of a Li-Ion cell. The Daubechies wavelet (dB) is used as mother wavelet for the analysis of the DCVS with a non-stationary and transients. By using the wavelet de-composition including the multi-resolution analysis (MRA), the information on the electrochemical characteristic of a cell can be extracted from a signal over a wide frequency range. By the proposed approach, the cells that have similar electrochemical characteristics are finally selected and used for stable configuration of a Li-Ion battery pack. Experimental results validated the effectiveness DWT-based proposed approach.