Novel Fitting Algorithm for Parametrization of Equivalent Circuit Model of Li-Ion Battery From Broadband Impedance Measurements

The impedance of lithium-ion (Li-ion) batteries contains information about the dynamics and state parameters battery. This can be utilized to improve performance safety battery application. is typically modeled by an equivalent-circuit-model (ECM), which provides dynamic In addition, variations in model used for estimation. A fitting algorithm required parametrize ECM due nonlinearity both ECM. However, conventional algorithms, such as complex-nonlinear-least-squares (CNLS) algorithm, often have a high computational burden require selection initial conditions, difficult obtain adaptively. article proposes novel parametrization based on geometric shape complex-plane. applied practical fast broadband pseudorandom sequence measurements carried out at various state-of-charges (SOC) temperatures lithium-iron-phosphate cell. method compared CNLS with different conditions. results show that proposed accurate fit low effort. Moreover, specific are found dependent SOC temperatures.