Analysis Of Temperature Field And Cooling System Of Roots Vacuum Pump Induction Motor

In recent years,roots vacuum pumps have been widely used in many fields,including pharmaceutical,aerospace,chemical,film and semiconductor industries,and play an important role in the national economy.As a core component of the vacuum pump,the shielded motor is difficult to dissipate heat due to the isolation of the shield sleeve,which leads to an increase in the temperature rise of the motor.Excessive temperature rise will cause problems such as failure of the insulation material of the motor,which in turn affects the reliability of vacuum pump operation.Therefore,the analysis of the temperature field and cooling system of the vacuum pump drive motor is particularly important.In this article,the asynchronous motor used in roots vacuum pump is taken as the research object,and its temperature rise and cooling are studied.First,based on the related theoretical basis of electromagnetic fields,an electromagnetic field simulation model was established,and the magnetic field line distribution of the motor,the stator current curve,the stator iron loss,the rotor iron loss,the copper loss,the stator shield eddy current loss,and the rotor shield sleeve eddy current loss were obtained using the finite element method simulation at the rated operating conditions,and which provides heat source data for the subsequent motor temperature field simulation and cooling system analysis.Then,after determining the thermal performance parameters of each part of the motor,a three-dimensional mathematical model was established,and the thermal network program of the asynchronous motor for the roots vacuum pump was compiled.The steady-state temperature field of the motor was calculated using the finite element method and the equivalent thermal network method.The comparative analysis of the simulation results provides a basis for the design of the cooling system.Afterwards,based on the theory of fluid mechanics and heat transfer,four cooling structures: circumferential spiral,circumferential circular,circumferential foldback and axial foldback are designed for the motor.Models are established and simulated using software to calculate distribution of motor fluid field and temperature field at different depth of water channels,different number of water channels,different inlet flow rates,different inlet temperatures,and different overload multiples.By comparing the flow velocity of the water channel,the pressure difference between the inlet and outlet,and the temperature rise of each component of the motor,the optimal channel depth,the optimal number of channels,the economical inlet flow rate,and the appropriate cooling water inlet temperature are obtained.Finally,the prototype motors with two cooling structures,namely a circumferential spiral type and an axial fold-back type were developed,and a roots vacuum pump drive motor test platform was set up to conduct temperature rise tests at different inlet water temperatures and different overload times.The experiments verified the simulation results of the finite element method and equivalent thermal network method in Chapter 3,and the simulation results of the cooling water inlet water temperature on the motor cooling effect in Chapter 4,and the correctness of the laws.