ABSTRACT

Temperature rise ofthe most useful industrial work icon is ofmuch concern in the short and long term operations of asynchronous motor. The main aim of the thesis was to develop a thermal model for the asynchronous motor and to analyze the steady state and transient state behavior of the induction motor. The system’s thermal network is developed, using thermal resistances, capacitances and power losses, the algebraic and differential equations for the proposed models are solved so as to ascertain the thermal performances of the machine under steady and transient conditions using the lumped parameter thermal method. To analyze the thermal process, a 7.5kW machine was divided geometrically into seven lumped components, each component having a bulk thermal storage and heat generation and interconnections to adjacent components through a linear mesh of thermal impedances. The lumped parameters were derived entirely from dimensional information, the thermal properties of the materials used in the design, and constant heat transfer coefficients. The thermal circuit in steady-state condition consists of thermal resistances and heat sources connected between the components nodes while for transient analysis, the thermal capacitances were used additionally to take into account the change in internal energy of the body with time. MATLAB programs were developed and used to solve the steady and transient state mathematical model ofthe machine to obtain the curve response ofthe temperature rise for the asynchronous motor core parts. The resulting predicted temperature values for Frame-43.53°C, Stator Lamination-44.23°C, Stator Winding-50.10°C, Rotor Iron42.89°C, Rotor bar-42.81°C, EndwindingL—48.33°C and EndwindingR-32.58°C when compared with other result in Induction machine, shows that this work can appropriately be employed to predict the temperature distribution in induction machine and also provide useful information to designers and industries on the thermal characteristics ofthe induction machine.