Optimizing Battery Cooling System for a Range Extended Electric Truck

Battery packs used in electrified automotive powertrains support heavy electrical loads resulting in significant heat generation within them. Cooling systems are used to regulate the battery pack temperatures, helping to slow down battery aging. Vehicle-level energy consumption simulations serve as a first step for determining the specifications of a battery cooling system based on the duty cycle and interactions with the rest of the powertrain. This paper presents the development of a battery model that takes into account the energy impact of heating in the battery and demonstrates its use in a vehicle-level energy consumption simulator to set the specifications of a suitable cooling system for a vehicle application. The vehicle application used in this paper is a Class 6 Pickup and Delivery commercial vehicle with a Range-Extended Electric Vehicle (REEV) powertrain configuration. The battery model, consisting of a State-of-Charge estimator and a thermal model for the battery pack's bulk temperature, is calibrated on the vehicle simulator based on bench test data for a passive cooling system. A model for an active liquid-cooling system is then developed, and its performance specifications are determined based on a chosen battery temperature increase target. The vehicle simulation results obtained with the two cooling systems demonstrate that although the active cooling system consumes slightly more energy due to the additional accessories that are needed to operate it, the battery temperature remains within tighter limits.