Development of a heat pipe-based battery thermal management system for hybrid electric vehicles

Enhanced battery pack cooling remains an open thermal management challenge in hybrid electric vehicle applications. A robust cooling system should maintain the battery pack core temperature within a prescribed operating range to improve system performance, durability, and reliability while minimizing power consumption. This paper proposes a smart battery thermal management system utilizing heat pipes as a thermal bus to efficiently remove heat. The system couples a standard air conditioning system with traditional ambient air ventilation. The two loops can run independently or in tandem to achieve the desired control. A nonlinear model predictive controller was developed to maintain the battery core temperature within a designated range using the compressor and fan speeds as the control inputs. A mathematical battery thermal model was developed to estimate the core and surface temperatures. The system performance and power requirements were evaluated for various driving cycles and ambient conditions. Numerical results showed that the proposed cooling system can regulate the battery core temperature within the desired temperature range (maximum tracking error of 2.1 degrees C) while compensating for ambient temperature conditions using a suitable cooling strategy. The simulation results showed the ability to remove up to 1135 kJ of heat. The simulation also presents the power consumed by system components under varying modes and ambient conditions.