Fast Charging Strategy of Lithium-ion Batteries with Thermal Safety Margin Based on Model Predictive Control

The tradeoff between efficiency and safety is unavoidable when designing charging strategies for batteries. This paper proposes an optimal fast charging strategy of Lithium-ion batteries taking account of charging efficiency and thermal safety based on model predictive control (MPC). Firstly, a polynomial function is introduced to approximate thermal safe boundary of Li-ion batteries, which reveals relationships between thermal-runaway initial temperature and state of charge (SOC). Then, based on an electric-thermal coupling model, fast and safe charging problem is formulated as an optimal output regulator problem accompanied with the thermal safety margin constraints. Finally, MPC algorithm is developed to solve the constrained optimization problem. Simulation result illustrates that the method enhances the charging efficiency while keeps the core temperature of batteries under a specified level.