Testing and Prediction of Temperature of Three-Phase Induction Motor with PWM Inverter Supply

Abstract

This paper presents the study of electrical power losses, the thermal behavior, the design of mathematicalmodel and prediction of temperature of an induction motor supplied by a 3-phase PWM inverter.The purpose of this research was to determine the criterions about loading, protection of damaged motorfrom overheat of an Insulator. The 3-phase PWM inverter operated the fundamental frequencies varyingbetween 15-50 Hz.While a constant switching frequency is of 15 kHz, the motor torque was maintainedconstant at 5 N.m . A storage oscilloscope was used to measure the voltages and currents at the output of theinverter. In addition, a thermocouple was used to measure the winding temperature and anemometer wasused to measure speed of ventilating fan.

The results of tests revealed that the values of the electrical power input and power output variedaccording to the frequencies of inverter and the values of the winding temperature was inverse with thefrequencies of inverter, the test results are shown that the winding temperature by the prediction is nearlythe same that by the experiment.

The advantage of this research is that it enables modified motor structure, implementation of ventilatingfan and planning for motor loading when supplied by a 3-phase PWM inverter.

Keywords : PWM Inverter / Electrical Power Loss / Winding Temperature / Harmonic /Induction Motor