Electrochemical Impedance Spectroscopy: A Novel High-Power Measurement Technique for Onboard Batteries Using Full-Bridge Conversion

Electrochemical impedance spectroscopy (EIS) has received extensive attention because it can reflect the electrochemical mechanism of a battery and is one of the important references for evaluating the health status of a battery. EIS is usually obtained by sinusoidal scanning in the laboratory through professional equipment, making it hardly accessible in the actual vehicle application. This study presents a high-power impedance test system based on a full-bridge converter capable of being compatible with a battery management system (BMS). The experimental results show that the developed test system can accurately measure the EIS of a cylindrical 18650 battery with a capacity of 3.5 Ah, a pouch battery with a capacity of 10 Ah, and a prismatic battery with a capacity of 50 Ah over the frequency range of 0.1-800 Hz. Their overall measurement error is less than 3%. The hardware implementation of the test system is simple, which can provide a feasible on-board impedance measurement. In addition, the test system shows good adaptability and accuracy for the EIS measurement of battery packs.