Electrochemical impedance spectroscopy state of charge measurement for batteries using power converter modulation

This paper will demonstrate the concept of a new, low-cost, on-line technique for monitoring battery state of health (SOH) and state of charge (SOC) using electrochemical impedance spectroscopy (EIS). A particular focus will be electric vehicles (EVs), where the SOC accuracy over existing battery management systems (BMS) will improve range prediction accuracy, although the proposed technique is also applicable to other electrochemical energy storage devices. While currently there exist few methods to measure the battery state of charge online, these methods are generally categorized as “indirect” methods which are prone to errors due to environmental changes and require additional hardware/costs for implementation. In this paper the EIS excitation signal will be generated by the system's existing power converter without requiring extra hardware but only requires software upgrade. The main objective of the proposed method is to minimize the impact on the main operation of the power converter in the syste