Optimal Control for Thermal Management of Li-ion Batteries via Temperature-Responsive Coolant Flow

Abstract

A Battery Thermal Management system (BTMS) is responsible for cooling, heating, insulation, and ventilation of the battery pack to ensure safe, reliable, and long-lasting operation of the battery pack under controlled optimal conditions. Cold plates are one of the most popular active thermal control methods used in BTMS. Most cold plate-based cooling strategies use a constant coolant flow rate. A possible method to improve this could be a temperature-responsive coolant flow strategy. This paper focuses on the optimal control of coolant flow for an active hydraulic BTMS with mini-channel cooling plates. An appropriate cost function was formulated to optimise the coolant flow, capturing the trade-off between thermal degradation and pumping power. A software framework was created to obtain the optimal solution for flow rate as a function of time. The results obtained after optimisation showed that an optimal cooling strategy for high heat dissipation generally has three phases -i) increasing flow rate, ii) saturated flow rate, and iii) decreasing flow rate, which gives a lesser cost when compared to a constant flow rate.