Steady State Temperature Field Analysis And Cooling Structure Design Optimization Of Vehicle Permanent Magnet Synchronous Motor

Permanent magnet synchronous motors have obvious advantages suitable for electric vehicles,such as higher power density,higher efficiency,and higher control system stability,making them the focus of most automotive manufacturers and university researchers.Since the electric vehicle will increase its power density as much as possible during the design of the motor,if an unreasonable motor cooling system is used,the temperature rise problem of the motor will be very serious.Excessive motor temperature rise will shorten the winding insulation life and cause permanent magnet demagnetization,which will affect the life of electric vehicles and even cause safety problems.Therefore,an effective motor cooling structure is necessary to ensure the safety of electric vehicles.In this thesis,the loss,temperature field and cooling system of 35 k W permanent magnet synchronous motor in rated conditions are studied.Based on the basic theory of electromagnetic field,establish a two-dimensional numerical analysis model of permanent magnet synchronous motor,and based on the finite element method to obtain the loss value of the main components of the motor.According to the basic theory of heat transfer,establish a permanent magnet synchronous motor physical model and numerical calculation model,and calculate the heat generation rate,heat transfer coefficient and material properties of the motor.According to the various thermal parameters obtained,the temperature field distribution of the permanent magnet synchronous motor under natural cooling is calculated based on the finite element method,and the parts that are susceptible to temperature are analyzed to provide a comparison basis for the design of the motor cooling system.According to the stator structure of permanent magnet synchronous motor,the basic theory of fluid mechanics,and the temperature distribution of permanent magnet synchronous motor under natural cooling,four cooling structures of water channels are designed,namely,circumferential spiral water channel,axial Z-shaped water channel,and circumferential Z-shaped Type water channel and circumferential parallel water channel,and calculate and analyze the cooling effect of the four water channels,and determine that the circumferential Z-shaped water channel structure type is better.Based on the theory of waterway structure design,the circumferential Z-shaped waterway structure was further optimized in terms of the number of waterways,the flow rate of the water inlet and the material of the casing.For the optimized water-cooling heat dissipation system,simulate and analyze the motor temperature rise under rated operating conditions,and compare it with the motor temperature rise under natural cooling to verify the cooling effect,and analyze the winding insulation of the motor using the water-cooled heat dissipation system and the temperature rise of the permanent magnet.