Innovated Approach of Predictive Thermal Management for High-Speed Propulsion Electric Machines in More Electric Aircraft

The thermal management system has significant impacts on the efficiency of propulsion electric machines in the more electric aircraft. This article proposes a predictive thermal management system by utilizing the thermal-magnetic coupling phenomenon to improve efficiency. There are three major innovated contributions. First, the theoretical mathematic model of the temperature and the electromagnetic energy conversion efficiency is studied, which provides analytical expressions to describe power loss at different motor operation statuses. Second, based on the model, a predictive thermal management system is proposed to actively adjust the cooling according to the efficiency at real-time temperature, maintaining an optimal high-efficiency status. Third, the energy consumption of the cooling system, such as the pump, is also optimized to improve the overall efficiency. Meanwhile, the cooling system is designed to prevent any excessive temperature rise to ensure thermal safety and insulation lifetime. A partial stator prototype is implemented and tested in a thermal chamber. Experiments show that the motor loss is reduced by up to 7%, the cooling system working time is reduced by 30%, and the total system loss is reduced by up to 9%, which validates the proposed predictive thermal management system.