Analysis Of Ventilation And Heat Transfer Of Induction Motor Under Different Driving Conditions

In recent years, ship is more and more important to the rapid economicdevelopment, and the requirements of driving capability are demanded than eversince. Induction motors are widely used in ship domain due to several advantages,such as strong overload capacity, high dynamic response speed, and work underfrequency control to satisfy the practical needs. However, high power density andtorque density may cause thermal load increasing which leads temperature rise ofpartial motor to be too high with motors working in narrow space, even hightemperature rise threatens stability and safety of motors. Therefore, it issignificant to analyze fluid-heat coupled field under frequency control andrelatively sensitivities of temperature rise in the process of operation.A55kW induction driving motor was taken as an example. A mathematicalmodel and a three dimensional fluid-heat coupled model with motor encapsulatedin air region were established according to cooling structure, based on thecomputational fluid dynamics and the numerical heat transfer. For research of thetemperature rise distribution of motor under different modulation ratios controlby PWM and the fluid flow characteristics according to the complex structureand cooling air flowing on the basis of fundamental assumptions, the temperatureand fluid field of induction driving motor under rated condition and differentmodulation ratios control by PWM were calculated numerically by addingboundary conditions and using the finite volume method. The comparison oftemperature text and results of simulation verifies the correctness of solutionmethod and the rationality of the model. The analysis for air velocity insidemotor and fluid flow outside motor was done. The comparison of temperaturerise of main parts can be done in detail under different modulation ratios control by PWM. And the analysis of relatively sensitivities of temperature rise inprocess of operation under modulation ratio0.8(M=0.8), such as insulation aging,was done.The cooling effect caused by fan at end of rotor and the fan in the coveroutside motor is analyzed based on the results of calculation, which can verifythe rationality of cooling structure design. The temperature rise distribution canbe shown when motor is operating under different modulation ratios control byPWM and relatively sensitivities of temperature rise change. These can verify therationality of motor and provide reference for the cooling system design of smalland medium induction motor.