Design process of traction motor having tooth coil windings

Abstract

A traction motor design process is described. Not only the application but also the control and the converter hardware set their own boundaries for the machine design. In traction applications the driving speed often varies from low speeds up to deep field weakening at high speed. As electrical drives are utilized in hybrid or full electric working machines or vehicles to improve their energy efficiency the electric drive efficiency should be high over the machine's whole operating speed range. To achieve high enough acceleration the low speed torque demand is usually set high which can be challenging from the electric machine design point of view. In the low speed area a high torque is needed and all the current reserves of the converter hardware are often used to achieve the highest possible torque. At high speeds the iron losses rise proportionally to the square of the speed. Losses in the permanent magnets depend both on the armature current and frequency. As an example different traction motor versions with the rated power of 110 kW, 2.5 p.u. starting torque and maximum 2.5 p.u. speed will be studied in the paper.