Precise High-Frequency Impedance Measurements of Electric Vehicle Cylindrical Battery Cells Under Bias Current and at Various Temperatures

Characterization of battery cells and the creation of measurement-based models is a key step in the design process of battery packs for electric vehicles (EVs). Simulations of such models allow optimization of a battery pack design to minimize safety and functional errors that might appear late in the design stage and increase development time and cost. This paper demonstrates a method for measuring battery cell impedance with a vector network analyzer (VNA) under switch-controlled pulsed charge and discharge bias current and presents the resulting impact on the inductance of the cell at 108 MHz. The battery cell inductance under bias current at temperatures from -20°C to 40°C is presented. Finally, the bias current and temperature impact on the battery cell are shown.