High Performance Cooling Traction Brushless Machine Design for Mass Production

Licentiate thesis, 2019

In the last few years electric vehicles (EVs) are coming on the market. The shift from niche market to main stream is challenging. It took many years to reach the current internal combustion engine quality in the manufacturing process. However, a much faster process is needed for the electric drive-train if sustainability goals about CO2 emissions are to be met.

It is extremely important to think about the manufacturing process during the design of a piece of hardware if this is meant for mass production. In a few years from now, traction electric motors for EVs will be produced with the rate of millions per year and ensuring a simple, effective and reliable manufacturing process is key in the success of the electric vehicle industry.

This thesis presents an innovative brushless machine design meant for mass production. The machine is designed to achieve high power density and high reliability thanks to a novel cooling concept. The machine selected has a tooth coil winding, also defined as non-overlapping fractional slot concentrated winding. This winding concept is state of the art for many applications with high volumes and powers below 10 kW. Also, these have been proven successful in high power applications such as wind power generators. In this thesis the ambition is to show that this technology is promising as well for traction machines and it presents certain unique advantages when it comes to manufacturing and cooling.

The traction machine in this work is designed for a small two-seater electric vehicle but could as well be used in a parallel hybrid.