Thermal Behavior Simulation of An Externally Cooled Electric Motor

Abstract

This paper presents the simulation results of the thermal behavior for an externally cooled asynchronous electric motor in both steady and transient states cases. For this purpose, a mathematical model based on the heat equation is first developed to determine internal thermal sources such as copper, mechanical and iron losses. Then, a computer program is developed to numerically simulate the proposed mathematical model. This program determines the radial distribution of steady and transient states temperatures, and predicts the effect of the ambient temperature on the transient and permanent temperature distributions. This makes it possible to calculate the specific speed of the motor as a function of its rotation speed, the airflow rate and the pressure dropping at the fan level. The obtained results show that the engine heating is mainly due to the elements that show thermal losses by Joule effect. The mitigation of these losses is strictly related with the specific speed, which makes it possible to select the right choice of the engine cooling system. Using the nodal numerical method to determine the distribution of the radial temperature in both steady and transient states cases under the effect of the ambient temperature. The obtained results are analyzed and discussed.