Challenges and Potential Solutions for Reduced Unbalance of Permanent Magnet Rotors for Electric Traction Motors

The growing demand for highly efficient and power dense electric traction motors increases the complexity and amount of technical challenges in the production of permanent magnet rotors. For instance, rotors designed for particularly high power densities must withstand rotational speeds of up to 18 000rpm and temperatures of up to 180°C, but need to be manufactured at minimum unit costs and cycle times. Especially initial unbalances and changes of unbalance during operation can be a challenge to rotor manufacturers. Thus, a profound knowledge of technical challenges and potential solutions for reduced unbalance is required for the economically viable and resource-saving production of highly efficient motors. Therefore, this paper presents an overview of technical challenges and potential solutions for unbalance reduction in the production of permanent magnet rotors for electric traction motors according to the current state of research and development. The summarized challenges and approaches are subsequently prioritized by experimental investigations as well as FE-simulations following a design of experiments. They are finally complemented by further concepts in order to present optimization potentials for reduction of unbalance along the production of permanent magnet rotors. In future, these can be implemented in industry and research in order to enable a sustainable electrification of individual mobility.