| Due to the advantages of small size,high power density and high efficiency,permanent magnet synchronous motors(PMSM)have been widely used in locomotive traction,new energy vehicles and other industrial fields.Since the permanent magnet material of the PMSM is sensitive to temperature,the excessive temperature rise in the motor will weaken its performance,and even cause permanent demagnetization.In order to suppress the temperature rise of the motor,ensure its safe operation and improve its performance,there is important significance to calculate the temperature field of the PMSM and design reasonable cooling structure according to the temperature distribution.In this paper,numerical analysis is used to analyze the temperature field of a fully enclosed water-cooled permanent magnet synchronous motor(FEWC-PMSM),and the temperature field calculation results are compared with the measured data.The comparison results show that the numerical analysis method can accurately calculate the temperature field of the motor.Then the sensitivity analysis method is applied to study the influence of two factors(water flow rate,water temperature)on the cooling effects and the influence of other two factors(rotor loss,loss distribution uniformity)on the temperature field calculation results.From the analysis results,it is known that the rotor losses have great influence on the rotor temperature.To account for the influence of current harmonics on the rotor losses and its distribution,this paper collects the current of the motor during actual operation and uses it as the excitation in the numerical analysis to more accurately calculate the losses.Based on the temperature field calculation results,this paper proposes an internal-external dual-circulation cooling structure design method combining internal and external cooling manners.Under the premise of ensuring electromagnetic performance,the inner circulation cooling circuit of the motor is constructed by opening the rotor core axial venting hole,the stator core axial venting hole and adding the end fan,then Taguchi method is used to optimize the parameter of the inner circulation structure.The optimized design results show that the cooling structure can significantly reduce the internal temperature of the motor,which improves the reliability of the FEWC-PMSM at high speed.The design idea can provide reference for the internal cooling design of other motors. |
