Ventilation Structure Optimization Of Air-Air Cooled Asynchronous Motor Based On Calculation Of Fluid And Temperature Rise

Air-air cooled asynchronous motors are widely used in industries,railway traction and other fields,but with the continuous increase of motor power density and the constraints of the overall size of the motor,the heat dissipation problem has become an important factor restricting the increase of the power density of the motor.In order to improve the cooling performance of air-air cooled asynchronous motors,the YKK450-4 500 k W asynchronous motor is taken as the research object.First,according to the basic structure and ventilation method of the motor,a three-dimensional flow-heat coupling solution model of the motor is established.Based on the theory of fluid mechanics and heat transfer,the finite volume method is used to carry out the numerical simulation of the fluid field and temperature field of the motor,and the fluid flow velocity changes in the stator and rotor radial ventilation ditches,air gaps and other areas of the motor,as well as the temperature distribution of the main components of the motor under rated load operation are obtained.Simultaneously,the calculated results are compared with the experimental data to verify the correctness of the motor flow-heat coupling solution model and the accuracy of the calculation results.Secondly,in view of the eddy current phenomenon that hinders fluid flow at the distal end of the stator radial ventilation ditch,on the basis of the constant circumferential effective length of the stator ventilation channel,starting from the bottom of the stator slot,the distal shaft end of the ventilation channel is deflected respectively counterclockwise by 10°,15°,20°,25°,30°,and then recalculated and analyzed to explore the influence of the deflection of the angle of the distal shaft end of the ventilation channel on the fluid flow and heat transfer in the radial ventilation ditch.Through comparative analysis,it is concluded that 20° is the optimal deflection angle.The results show that the eddy current phenomenon in the radial ventilation ditch is significantly weakened after optimization,the average value of the convective heat transfer coefficient on the surface of the ventilation channel is increased compared with that before optimization,and the hottest spot temperature of the stator winding and the temperature of the rotor core are reduced.Finally,the simulation calculation of the fluid flow characteristics and heat transfer performance of the inner and outer air passages of the electric motor air cooler is carried out.On the basis of fully considering the flow distribution and the interaction of various cooling factors,the number of wind deflectors and the position of the wind baffles are comprehensively optimized.At the same time,by calculating the intersection of the flow-pressure relationship curves of the internal fan and its driving wind resistance,the inlet boundary conditions after comprehensive optimization are substituted into the recalculation.The calculation results show that the outlet temperature of the internal air duct of the cooler is decreased by 2.1% after comprehensive optimization.The research results provide a certain reference value for the analysis and optimization of the cooling system of medium-sized high-voltage asynchronous motors.