Battery lumped fractional-order hysteresis thermoelectric coupling model for state of charge estimation adaptive to time-varying core temperature conditions

As electric vehicles become more common, there is increasing concern regarding their battery reliability and safety. The estimation accuracy is strongly correlated with the performance of the battery model. The lumped fractional-order hysteresis thermoelectric coupling model (LFHTCM), considering temperature and hysteresis effects, is established in this paper. Firstly, the fractional-order hysteresis sub-model is established based on the Grunwald-Letnikov (G-L) fractional calculus principle and the recursive model of hysteresis voltage. Then, the thermal sub-model is established by integrating the Bernardi heating mechanism and the heat transfer model. The fractional-order sub-model provides voltage to the thermal sub-model for heat generation calculation. The thermal sub-model provides temperature to the fractional-order model for parameter correction. Finally, the fractional-order unscented Kalman filtering (FOUKF) algorithm was developed to estimate the state of charge (SOC) of the battery. Experimental results confirmed the effectiveness of the model, with its estimation enhancing the utilization, operational optimization, and calibration of batteries in practical applications.