Enhanced battery thermal management systems with optimal charge control for electric vehicles

Thermal management systems play an important role in maintaining the required operating conditions of batteries in electric and hybrid vehicles. These systems consume energy and operate based on the temperature variations measured in the battery pack. Various types of such systems exist and can be classified as an active or a passive system, however, these systems could be limited in its ability to handle the entire heat load from the battery in an optimal way. This work explores the benefit of powertrain control for electric vehicles in supporting the battery thermal management. The developed strategy restricts the charging power to the battery during regenerative braking and at plug-in fast charging stations along the operating trajectory. The optimal control problem is approached as a power split between regenerative and friction braking and is solved using Pontryagin's Minimum Principle. Simulation results demonstrate the capability of this control law by operating an electric bus over a fixed trajectory, while maintaining the battery temperature within a defined safe operating range.