The cooling of electric motors is a key challenge in the development and design process of electric powertrains, especially in the field of electromobility, where a high continuous power output is required in a limited installation space. Electric motorcycles set special standards here, as their compact design and the thermal losses of the motors make optimized cooling technology a prerequisite. This thesis investigates which factors contribute to the heating of a permanent magnet synchronous motor and assigns them to specific components. Based on this, prototypes with two different cooling systems are compared in terms of their heat dissipation capabilities. Based on the cooling performance measured, ways of optimizing the designs are then examined respectively. This is supported by research into the current state of the art. The first test sample uses a traditional jacket cooling on the stator housing, while the other test sample uses direct cooling by spraying coolant directly onto the winding heads. As the aim is to investigate the relative cooling performance of both systems and ultimately assess their suitability for use in competition motorcycles, the tests must be carried out under the exclusion of as many influencing factors as feasible. To achieve this, a step-by-step approach towards the actual cooling tests is carried out by first confirming the active parts´ behavior and then the temperature development with deactivated cooling systems. The findings are incorporated into the compensation of possible interference factors and finally the test series enables precise identification of the isolated cooling performance of the two systems. Direct cooling is clearly superior to jacket cooling in the current configuration in all test points. Encapsulation of the winding heads is evaluated on the basis of a measurement that identifies the heat transfer between the winding and housing as the core cause of this. Optimization points are also identified for the direct cooling system. These are mainly concerned with operational details such as the optimum coolant fill level. The results of this investigation not only contribute to the thermal optimization of these prototypes but also give direction for future development projects.
- Automotive Mechatronics and Management
Design of a High Performance Electric Motor Cooling System
Golombek, M. J. (Author). 2025
Student thesis: Master's Thesis