Estimation of the Temperature Rise in High-Speed Electrical Machines with Magnetic Bearings

The paper deals with the estimation of the temperature rise in high-speed electrical machines with active magnetic bearings. The calculation is based on a thermal network method. The input data for the model include the geometry, rotational speed, electrical power losses and cooling method of the motor and the bearings. The heat transfer coefficients and the friction losses are computed according to the input data. The developed thermal model was tested in the case of a 36 kW and 50 000 rpm high-speed air compressor equipped with conical-type active magnetic bearings. The model seems to have a reasonable good accuracy if the roughness in the stator is taken into account.