Design Of Cooling System For Interior Permanent Magnet Synchronous Motor

The interior permanent magnet synchronous motor has the advantages of simple structure,high power density and high efficiency,and has been used more and more widely in the field of electric drive.The cooling system design of permanent magnet synchronous motor is one of the key technologies of motor design.The interior permanent magnet synchronous motor has a compact structure and poor cooling environment of permanent magnet.Therefore,the design of its cooling system is particularly important and has great significance for the temperature rise distribution of the motor.In this thesis,a 50 k W interior permanent magnet synchronous motor is taken as an example to study the calculation of the temperature rise of the motor and the design of the cooling system.The temperature field distribution of the motor is analyzed and calculated,and the design of the cooling structure of the waterway and its influencing factors are discussed.Firstly,based on the basic theory of electromagnetic field,the finite element magnetic field analysis model of interior permanent magnet synchronous motor is established.The magnetic field distribution and component loss value of permanent magnet synchronous motor during steady-state operation are calculated.The physical model and calculation model of three-dimensional temperature field of permanent magnet synchronous motor are established.The heat generation rate,heat transfer coefficient and material properties of main components of permanent magnet synchronous motor are calculated.According to the calculated parameters,the finite element method is used to calculate the temperature field of the motor under the condition of natural heat dissipation,and the temperature rise distribution of main components of the motor is analyzed,which provides numerical basis for the design of the motor cooling structure.Secondly,by analyzing the structure,heat source,temperature rise and existing water cooling structure of permanent magnet synchronous motor,four kinds of water cooling structures are designed,including unilateral axial Z-shaped structure,bilateral axial Z-shaped structure,unilateral circumferential Z-shaped cooling structure and bilateral circumferential Z-shaped cooling structure.The fluid-solid thermal coupling models of four kinds of water-cooled structures and interior permanent magnet synchronous motors were established respectively,and the numerical simulation was carried out.The temperature,flow rate,pressure and temperature distribution were analyzed,and it was determined that the bilateral circumferential Z-shaped cooling structure was better.Finally,the bilateral circumferential Z-shaped cooling runner was further optimized,and analyzed from the aspects of the number of runner,inlet velocity,housing material and different spoiler heights.The temperature rise before and after the cooling structure is compared and analyzed when the permanent magnet synchronous motor runs steady-state at rated operating conditions,and the cooling effect of the proposed water cooling structure on the permanent magnet synchronous motor is verified.