Induction Motor Temperature Sensitivity Factor Analysis And Optimization

The complicated maritime environment requires military ships to have a more stable and efficient totally enclosed fan-cooled cage induction motor. Heating source of high density and small work space in the engine compartment results in poor motor cooling, however, in motor designing, in order to reduce cost and improve efficiency, high electromagnetic load is mostly adopted, which led to a higher temperature rise. Since temperature rise distributions of induction motor are directly related to its operating efficiency and output,it is necessary to make rational analysis,accurate calculation of temperature field and rational design ventilating structure inside the motor to promote efficiency and reduce energy.Taking 55 kW cage type of totally enclosed fan-cooled induction motor as an example in this paper, according to its structural features, a 3-dimensional semi-field physical model was built and rational basic hypothesis and boundary conditions were proposed, combined with the fundamentals of numerical heat transfer and computational fluid mechanics. The whole distribution of temperature rise and rheological properties inside and outside the motor were figured out by numerical solution of temperature field and fluid field. Experiments are given to verify the rationality and accuracy of the calculation method of temperature field simultaneously.According to the result of fluid field numerical calculation, the effect of self-reliance fan on stator end winding temperature rise and friction loss was analyzed in the motor, and the relationship among the characteristic length of self-reliance fan, stator end winding temperature rise and friction loss was explored,therefore, the characteristic length of self-reliance fan was obtained to equilibrate temperature rise of stator end winding and air friction loss.On the basis of the result by temperature field calculation, the sensitive factors of temperature rise distribution to the characteristic structure of chassis are analyzed,and three structural optimization programs were presented and computed bytemperature field and fluid field numerical calculation under the same situation of basic assumption and boundary conditions. By comparing the original program and the three optimization programs, the optimal ventilating structure program is determined.