Numerical calculation of global temperature field during phase failure of small induction motor

Abstract

The open phase fault is one of the main factors affecting the stability of asynchronous motor. After the fault, the temperature of stator winding and rotor guide bar of induction motor increases sharply, which shortens the service life of the motor. In this study, a three-dimensional temperature field model of small induction motor was established, and the calculation formula of heat source of small induction motor was given. To solve the problem of complex heat exchange in stator groove, the concept of equivalent thermal conductivity was used. The heat dissipation coefficients of the important parts in the solution domain were listed. The heat transfer model was introduced to define the heat dissipation coefficient at the end of the iron core. The finite element model of 3D temperature field of prototype under nominal operation condition and open phase fault condition was established. The temperature distributions of stator, winding, guide bar, shell and equivalent insulation area during rated operation and after open phase fault were calculated. The effects of copper loss of stator winding and eddy current loss of rotor on the temperature of equivalent insulation area were analyzed. The effect of ribbed reinforcement on the temperature distributions of stator and shell was investigated. Finally, the temperature variation of each phase winding after phase break was summarized, which lays a theoretical foundation for the prediction of motor faults from the perspective of temperature field distribution.