Electrical and Thermal Performance Predictions in Inverter-Fed Squirrel-Cage Induction Motor Drives

The electrical, mechanical and thermal interactions in an induction motor are defined by coupling an electrical model with a thermal one. This is especially useful when the motor, fed by an inverter, works under variable load conditions. The electrical time domain model is capable of predicting precisely both steady state and transient behaviour. Derived from a thermal model based on node analysis, a new thermal model is presented, the parameters of which are identified automatically with respect to the rotor speed and airgap temperature if a set of test results is provided. Once identified this model can be used to study the temperature-rises and to localize the losses in the motor. Some simulation and experimental results show the validity of this method.