Research On Cooling System And Temperature Rise Of Permanent Magnet Synchronous Motor For Electric Vehicle

The characteristics of permanent magnet synchronous motors for electric vehicles,such as large power density,small size,and closed working environment,cause serious heat problems.Motor heat dissipation has become an important part of motor structure design,and additional cooling channels are required to force convection heat dissipation to ensure the reliability of motor operation.Based on the analysis of domestic and foreign scholars’ analysis of motor heat generation,motor cooling system and temperature field,a 60 k W permanent magnet synchronous motor for electric vehicle is taken as the research object to study the steady-state temperature field of the motor and the cooling performance of the cooling system.Based on the motor magnetic field theory and Maxwell simulation calculation,the loss value of the internal heat source of a certain type of motor is obtained,and the heat generation rate of each part of the motor is obtained,which lays the foundation for the simulation analysis of the motor temperature field,fluid field and pressure field.Based on the equivalent treatment of the thermal conductivity of the copper winding and the insulating layer,a model for solving the motor temperature field is established.Based on the related theories of heat transfer and computational fluid mechanics,the boundary conditions required for motor simulation are analyzed and calculated,and the fluid-solid thermal simulation of the motor is performed.In the case of the determination of the electromagnetic structure,considering the improvement of the motor cooling channel type,the cooling efficiency of the motor is improved,and a variety of channel structures are designed,that is,the axial z-channel,the circumferential channel,the spiral channel and the Four structural styles of font flow channel.Through theoretical calculations and CFD temperature field simulation calculations of motor models with different cooling structures,the heat dissipation characteristics of various cooling systems are analyzed,the heat dissipation effect of the motor and the power consumption of external water supply devices are comprehensively considered,and the preliminary cooling system scheme is determined.The influence of the number of flow channels on the heat dissipation performance of the motor was further studied.The multi-disciplinary optimization method was used to optimize the flow channel cross-sectional parameters of the preliminary cooling system to obtain the final flow channel cross-sectional parameters(inlet coolant flow rate,flow channel cross-sectional width and flow Road section height)optimization results.