Multipulse HPPC for Current-Scheduled ECM Parameterization and SoC Estimation in EV Batteries

Accurate state-of-charge (SoC) estimation is central to safe and efficient Battery Management Systems (BMS) in electric vehicles. This study evaluates a multipulse Hybrid Pulse Power Characterization (HPPC) protocol using three discharge rates (0.5 C, 1 C, and 2.5 C) and two regenerative-charge rates (−0.5 C and −0.4 C). Three discharge-derived first-order RC parameter sets are scheduled within an extended Kalman filter according to instantaneous current magnitude and tested on a 54.6 V, 20.8 Ah NMC battery pack. A matched-input dynamic record is used to compare the single-pulse and multipulse HPPC-derived estimators. Because the reference SoC is nominal-capacity Coulomb counting using the same measured current, the reported SoC errors quantify agreement with that trajectory rather than independently measured ground-truth SoC. The multipulse parameterization reduced SoC RMSE from 2.1354% to 1.4065%, MAE from 1.7001% to 1.1138%, and MaxAE from 3.8951% to 3.6014%, while R2 increased from 0.98882 to 0.99515. For voltage estimation, RMSE decreased from 0.3145 V to 0.2409 V and MAE from 0.2379 V to 0.1532 V, but MaxAE increased from 1.7800 V to 2.1770 V. The results therefore show lower aggregate estimation error on the shared dynamic record without establishing independent absolute SoC accuracy or universal ECM fidelity.