Functional safety approach for thermal runaway in battery management systems

Abstract

Forecasting demand for autonomous power storage and supply systems for electric vehicles (EV) has become a key area of research. The rapid popularization of EVs is heavily based on the reliability and safety of rechargeable energy storage systems (ESSs), especially lithium-ion batteries (LIBs). Although these batteries offer high energy density and efficiency, they remain vulnerable to hazardous events such as thermal runaway, leading to severe consequences, including fire and explosion. This paper presents a methodology to fulfill the functional safety of BMS thermal runaway according to ISO 26262 standard. The approach integrates hazard analysis and risk assessment (HARA), the formulation of safety goals (SG), and the specification of functional and technical safety requirements (FSR and TSR). To strengthen assurance, safety contracts based on battery chemistry and specifications are established and linked to structured safety cases using Goal Structuring Notation (GSN). The proposed methodology is validated through simulations in MATLAB Simulink, demonstrating how dynamic safety assurance can detect deviations, trigger control actions, and update safety cases to prevent unsafe states. The results show that the framework effectively minimizes the risks related with over-current, over-voltage, and over-temperature conditions, thus contributing to regulatory compliance and increased confidence in the safety of EVs.