Temperature rise determination of an induction motor under blocked rotor conditions

This paper presents an efficient approach for calculating the temperature field of a high voltage three phase induction machine. The procedure is based on a three dimensional (3D) transient thermal finite element (FE) simulation coupled to a two dimensional (2D) electromagnetic harmonic FE simulation. In each time step of the transient thermal simulation, the losses in the stator and rotor windings are updated with the results of the electromagnetic simulation in the frequency domain. The transient calculation is stopped when steady-state temperature is reached. Thus the overall time-variant temperature distribution in the induction motor is obtained and the hot spots at positions within the machine, which may be not accessible to a sensor, are determined. On the basis of this method, a comparison of temperature independent versus temperature dependent anisotropic values for the thermal conductivity is carried out.