A temperature calculation and prediction of a three-phase induction motor with non sinusoidal voltage supply

This paper proposes an analysis and prediction of stator windings temperature for a 1 hp, 380 V, 50 Hz, 4-pole, three-phase induction motor fed by PWM inverter. The inverter produces nonsinusoidal source at fundamental frequency of 50 Hz while the switching frequencies of the inverter are 1 kHz, 5 kHz, and 10 kHz. The experimental results are compared with those supplied by sinusoidal source at the same load. The power losses in any level of harmonics distortion can be calculated by using the method of induction motor equivalent circuit. The nonlinear relation in polynomial equation of heat collection rate and temperature, together with heat transfer theory are applied in order to increase the accuracy of temperature calculation. Then the temperatures obtained from the proposed procedure are compared with those obtained from the testing.