All-climate state-of-charge estimation and equilibrium management for lithium-ion batteries based on diffusion equivalent model

All-climate application of lithium-ion batteries is of crucial importance for future promotion on transportation and energy storage, which is still suffering from the unprecise model and algorithms. In this article, a coupled diffusion-equivalent circuit model is proposed for solving the problems of all-climate and multi-conditional battery modeling, which is developed based on simplified electrochemical theories. And the simplex sphereradial particle filter is introduced for delivering the precise method on the estimation for state of charge according to rigorous mathematical demonstration. Moreover, the equilibrium system is established based on original battery management system, and both cell-level and module-level experiments are carried out for validating the effectiveness and precision of proposed method. Maximum error of no more than 3% can be observed both for all-climate (between -20 degrees C-45 degrees C) and large depth of discharging, and 1% inconsistency can be achieved within sufficient balancing. The satisfactory results confirm that the proposed method can perform an accurate and robust solution for online state of charge estimation, and deliver great potential on future promotion for energy storage system or remote cloud-controlling system.

Automated summary

This article proposes a coupled diffusion-equivalent circuit model based on simplified electrochemical theories for all-climate and multi-conditional battery modeling. The simplex sphereradial particle filter is introduced for precise estimation of state of charge. Experimental results demonstrate the effectiveness and precision of the proposed method, with a maximum error of no more than 3% for all-climate conditions and large depth of discharging. The proposed method shows great potential for accurate and robust online state of charge estimation, and for future promotion of energy storage systems or remote cloud-controlling systems.