Calculation and Analysis of the Thermal State of the Frequency-Controlled Induction Motor Pump Unit

Abstract

The article presents the results of the application of a method for calculating the thermal state of a frequency-controlled induction motor of closed design in steady-state heating mode. The study analyzes the excess temperature of thermal bodies, particularly the stator winding of the frequency-controlled induction motor installed in the pumping unit. Previous studies on regulated electric drives based on induction motors have focused on low-voltage induction motor drives for general industrial purposes. However, high-voltage induction motors have distinct specific features in terms of design and operation. The study of thermal processes in such motor drives is mainly based on three research methods: the method of heating thermal parameters, the method of the temperature field, and the method of equivalent thermal circuits. The analysis of these methods of thermal calculation showed that the most acceptable method of thermal calculation of regulated high-voltage induction motors is the method of equivalent thermal circuits (ETC). Based on the analysis of the excess temperature of thermal bodies, in particular the stator winding of the frequency-controlled induction motor installed in the pumping unit, it is shown that the optimal frequency control range lies within 30-50 Hz, that is, the frequency reduction causes an increase in temperature in all thermal bodies of the engine.