A Novel Multisinusoidal PWM Excitation for Online Battery Impedance Spectroscopy Identification and Implementation by Reconfigurable Battery Systems

Electrochemical impedance spectroscopy (EIS) is a widely employed noninvasive detection technique for battery state estimation and fault diagnosis. This article introduces a novel multisinusoidal pulse width modulation (MSPWM) excitation for the purpose of online battery impedance spectroscopy identification. The introduced excitation is a unique form of broadband binary excitation that enables precise design of the amplitude and phase for every fundamental component, which can meet customized measurement requirements. Furthermore, the article proposes a method to inject the MSPWM excitation into cells and conduct online EIS measurements using reconfigurable battery systems (RBSs). Through modulation of the battery pack's charging or discharging current during regular operations, without the need for an additional external programmable power supply, the MSPWM excitation can be injected into the RBS cells, facilitating impedance measurement without interrupting the normal operation of the system. To validate the proposed method, a dc RBS consisting of 16 lithium-ion battery cells was constructed. The experimental results show strong consistency between the EIS measurements conducted using the proposed method and those obtained from a commercial electrochemical workstation.