Improved motor intergrated permanent magnet gear for traction applications

Abstract

This paper presents a new demonstrator of a motor integrated permanent magnet gear for traction applications. The main purpose of the new demonstrator is to reduce rotational losses, which in the first version were too high. To mitigate the high rotational losses several aspects are improved in the design such as lower diameter/length ratio, imbedded and segmented magnet design, dummy slots etc. Also, improvements in the mechanical and thermal layout are addressed by using the central segmented cylinder as output and adding liquid cooling. The calculated rotational loss is reduced with more than a factor “8” resulting in a simulated efficiency above 95% in a broad torque-speed range. The 2D FEA calculated torque density of the new demonstrator is 107 kNm/m3 compared to 113 kNm/m3 from the first version. I.e. the loss reduction has not been a compromise with torque density. Various manufactured parts are presented together with some initial measurements.