Development of a Thermal Model for an Inner Stator Type Reluctance Motor

Abstract

Thermal modeling is an important aspect of electric motor design. Numerous techniques exist to predict the temperatures in a motor, and they can be incorporated in the design of a thermal model for a new type of electric motor. This work discusses the available modeling techniques and determines which methods are applicable for medium-sized motors with either natural convection or forced convective cooling over irregular geometry. A time-dependant thermal model, with thermal transport parameters based upon geometric and simplified air flow information, is developed based on a discrete lumped parameter model with several modifications to improve accuracy. The model was completed with the aid of nine experiments, and the result is a thermal model that exhibits an absolute error of less than 6.1°C for the nine test runs at three different currents between 8.4 A rms and 28.2 A rms and three cooling levels, natural, 10.7 CFM and 24.4 CFM.