Reasearch On Three Dimensional Temperature Field And Shaft’s Dynamic Characteristics Of Submersible Permanent Magnet Motors

High-speed asynchronous motor submersible screw pump system has low efficiency and low operating safety in the exploitation of complex oil,also it is easy to get stuck.And in severe cases,the motor will be damaged or the system will be scrapped.Therefore,it is an inevitable requirement for the development of China’s crude oil industry to investigate energy-saving and environment-friendly high-power submersible permanent magnet motors with high output efficiency,good safety,and strong reliability.This paper aims to improve the efficiency of submersible permanent magnet motors,reduce output torque fluctuations,meet high temperature insulation requirements,improve the reliability of motor running,and optimize the design of motor structural parameters,so that designing an efficient submersible permanent magnet motor suitable for high-viscosity mixed oil wells has been developed.Firstly,the the submersible motor body design is carried out and the influence of motor parameter changes on motor performance is analyzed.According to the classification of the ploe-slot matching of the submersible permanent magnet motor,the electromagnetic performance indicators of the motors with different ploe-slot shapes and different pole slot matching schemes are compared.Based on the optimal pole arc coefficient method and the magnetic pole eccentricity,the rotor magnetic pole optimization design is carried out.The simulation results show that the waveform deviation factor of No-load back EMF and Air Gap Flux Density can be effectively reduced,which improves the motor performance and output sta bility.Secondly,the characteristics of the temperature field of the motor under steady-state operating conditions of the submersible motor is researched.Based on the theory of electromagnetic field,the loss of the motor is calculated and the location of the loss is analyzed.Then a three dimensional(3D)steady state temperature field model was established using a finite element simulation platform.The influence fluid velocity of and insulation material on the temperature rise of the motor was analyzed.The selection scheme of the insulation material and the limitation of the flow rate of the liquid were given,which can ensure the safe operation of the motor under high temperature conditions.Finally,according to the modal analysis of the dynamic characteristics of the motor shaft,the natural frequencies of the rotating shaft and the corresponding mode shapes are studied,and an improved shaft structure is designed.The influence of unilateral magnetic pull on the deflection of the motor shaft is anal yzed for the stress field of the motor shaft.Simulation results show that the improved shaft mechanical structure can effectively improve the low-order modal frequency of the shaft,avoid resonance loss,reduce the stress deformation of the motor shaft and achieve all the motor indicators.