Analysis Of The Influence Of Rotor Axial Ventilation Holes On The Performance Of Medium-sized And High-voltage Induction Motors

The large and medium forced air cooling motor cooling scheme using the axial ventilation hole of the rotor is being paid more and more attention,but the majority of domestic and foreign researchers only analyzed the influence of ventilation structure on the temperature of the motor.There is little specific analysis of rotor axial ventilation holes on the electromagnetic properties of the motor effects.Through the test found in the rotor yoke is provided with an axial ventilation hole after which the key parts of the temperature rise of the motor is greatly reduced.However,the power factor of the motor under the same specification is lower and the core loss becomes higher after adopting the axial ventilation hole.Moreover,the traditional magnetic circuit algorithm has a great error compared with the test value in the core loss,power factor,current and so on.In this paper,based on the finite element method of field road motion multi physics field coupling analysis,the physical nature of the influence of the axial ventilation hole of the rotor on the performance of the motor is revealed.Taking YKK355-4?355k W and YXKK355-4?400k W medium-sized and high-voltage induction motors as an example,the solution field model of the motor are set up by using the electromagnetic theory of motor and the specific size of the motor.According to the electromagnetic theory of the motor and the specific size of the motor provided by the enterprise,the physical model and mathematical model of the motor solution are set up.By comparing the changes of the magnetic field before and after the opening,the limitation of the traditional magnetic circuit algorithm and the reasons for the influence of the axial ventilation hole on the electromagnetic performance are discussed.Using the above method,the influence of the axial ventilation hole on the harmonic magnetic field of the motor and the typical position of the motor in the motor is analyzed.On this basis,a method based on finite element for calculating the iron core loss of motor is provided,and the iron core loss in the whole area of motor is calculated,and the 3-D distribution diagram of iron core loss in a motor is obtained,and the result is close to the test prototype.Through the results of comprehensive analysis,the number,position and shape of the axial ventilation hole are changed,and the improvement scheme is given.Finally,the improvement scheme is analyzed and verified from the angle of electromagnetictemperature-mechanical strength,which will provide theoretical support for the design of the high voltage motor of the rotor core opening axial ventilation hole in the future.