Online Battery Impedance Identification Based on DC-DC Converter with Low Ripple

This paper provides an online battery impedance identification method based on two-phase interleaving DC/DC converter. Unlike the traditional offline method, the online method is more practical. Different from the previously proposed method with buck/boost converter, this method can reduce switching ripples, which will improve the preciseness of battery impedance identification. In addition, the use of cross-correlation algorithm can extract signal information at a specific frequency accurately and easily. The battery impedance is measured online by applying a duty cycle perturbation on the power converter. The low ripple of this converter is achieved by interleaving the currents of each phase. In this paper, the viability and rationality of this method are analyzed in theory. Then, an experimental prototype is constructed to verify the feasibility and effectiveness. Finally, the battery impedance results are obtained.