Research Of NdFeB Permanent Magnet Synchronous Submersible Motor For Screw Pump

The screw pump is one of the valid equipments to exploit crude oil which has high viscosity and contains a lot of sand. The screw pump can only work effectively at low speed and its best rotational speed is around 100-500r/min normally. The existing submersible motors can not be applied to screw pumps directly because of its high rotational speed. Therefore, the development of low-speed and high-torque permanent magnet synchronous submersible motor (PMSSM) for screw pump has become one of the currently significant tasks.PMSSM for screw pump is a vertical three-phase induction motor. It adopts lathy structure of subsection of stator and rotor: each subsection of stator combines with non-magnetic substance and each subsection of rotor combines with rotor bearing. There is full of appropriative lubricating oil between stator and rotor. And there are permanent magnets in the PMSSM rotor.This paper researches on the influence of PMSSM characteristic which is subsection of stator and rotor and filled with the lubricant upon motor performances according to its special structure. The prototype has ten poles and thirty-six stator slots and adopts fractional winding slot. Stator inner diameter dimension of the motor is difficult to define because the range of slenderness ratio is very large. A new method is adopted to calculate stator inner diameter dimension in this paper. And how temperature influences the performance of the motor is presented. Through analysis, how to calculate the motor end leakage is obtained. Simple method of mechanical loss is gained by traditional experiential calculation formula. In this paper, how to select and arrange permanent magnets are discussed. Moreover, The MATLAB is used to program and design the prototype. And, the computer simulation results, such as wave shape of air-gap magnetic field and wave shape of no-load back electromotive force are shown by ANSOFT according to its model. Besides, the isolated magnetic bridge width influences on the motor performance parameters are given. Experiment data approves that the prototype has high performance. The prototype efficiency is higher 12.4% than induction submersible motor's for screw pump. And, the maximum torque multiple of the prototype increases to 2.42 from 1.67 of original induction motor. Contrasting experiment data and design calculation results show that the method and program developed in this paper are correct and feasible convenient in use as well. The research work in this paper is very important to improve the design method of permanent magnet synchronous motor.