Numerical analysis of stator-rotor coupled transient thermal field in induction motors with blocked rotor

An analysis method for electromagnetic-thermal coupling field is proposed, and the whole region transient thermal field in an induction motor with rotor blocked is calculated. The equivalent thermal model of the mush stator windings is established, by means of which the calculation of the motor thermal field is easier and less time is need. Then the two dimensional numerical analysis models of the cross section in a squirrel-cage induction motor for electromagnetic and thermal field are developed. Loss distribution which was obtained from electromagnetic field analysis is taken as the heart source of transient thermal field calculation. By this method, the transient thermal process with application of full voltage during 10s rotor blocked, during 10 min disconnection of motor and during repeated next 10s rotor blocked is calculated and the heart transfer relationship between stator and rotor is analyzed, as well as the temperature change on rotor out surface. Calculation results show good agreement with experimental data and the correctness of the calculation could be verified. It could supply a helpful theory reference for induction motor thermal analysis.