Keywords: finite element method, FEM, induction motors, plugging, thermal analysis, transients, design performance, 2D heat flow, stator currents, braking
Computation of thermal condition in an induction motor during plugging
The problem of two–dimensional heat flow in the stator of induction motor is solved by use of a finite element formulation and arch–shaped elements in the r–θ plane of the cylindrical coordinate system. The shape functions and exact solution matrices are derived algebraically for utmost economy in computation. The temperature distribution has been determined considering convection from the stator frame and cylindrical air–gap surface. The model is applied to one squirrel cage totally enclosed fan cooled (TEFC) machine of 7.5 kW. Finally, the temperatures obtained by this two–dimensional approximation have been compared for different stator currents for a period of 10 seconds at time intervals of 1 sec during the transient in plugging method of braking.