Design And Optimization Of Hybrid Permanent Magnet Vernier Motor For Top Dive Dilling

As a key component of oil drilling platform,the performance of top drive motor is directly related to the efficiency of drilling.In order to solve the problems of low torque density and large volume in traditional top-drive motor,based on the multi-harmonic characteristics of permanent magnet vernier motor itself,this thesis designs a surface-mounted permanent magnet vernier motor and makes a prototype according to the requirements of top-drive motor with low speed,high torque and certain overload capacity.At the same time,in order to satisfy the efficient operation of the motor under different speed control conditions,a hybrid permanent magnet vernier motor with a new series magnetic circuit is proposed.By adjusting the current of the magnetic winding,the magnetization state of the low-coercive permanent magnet is changed,thus the gap magnetic flux of the motor is adjusted,which solves the problems of high magnetic weakness loss and large inverter capacity of the traditional top-drive motor.The main research contents are as follows:(1)According to the basic structure of the surface-mounted permanent magnet vernier motor,the working principle of the magnetic field modulation of the motor is analyzed in detail by using the equivalent magnetic circuit method.The essence of its low-speed and high-torque characteristics is that the fundamental magnetic field and the modulated harmonic magnetic field participate in the electromechanical energy conversion together.By comparing with the traditional permanent magnet synchronous motor,it shows that the application of this kind of motor in the top drive unit has the advantage of omitting the variable speed gearbox and improving the torque density of the device.(2)Based on the operating condition of the top drive unit,the design index of the vernier motor is formulated,and the relationship between the motor’s torque and main dimensions is deduced,which provides the theoretical basis for the main parameters of the motor.Based on the finite element method,the influence of pole ratio and pole groove fit on magnetic leakage is explored,and the relationships between parameters such as crack ratio,tooth width,slot depth,permanent magnet thickness and pole arc factor and torque,no-load back potential are analyzed.The main structure dimensions are optimized with the output torque as the target.On this basis,an experimental prototype is made,and the experimental results verify the correctness of the design scheme.(3)A new series magnetic circuit hybrid permanent magnet vernier motor is presented.The variation of air gap flux is analyzed when the magnetic regulating winding is used to charge and demagnetize the low-coercive permanent magnet.The size of low-coercive permanent magnet is optimized by using the finite element method.The electromagnetic characteristics of the low-coercive permanent magnet under weak magnetic condition are analyzed and compared with the original one to verify the rationality of air gap flux adjustment.This thesis carries out the research work based on the new permanent magnet vernier motor,which provides a new selection scheme for improving the performance of the top drive unit,and provides reference basis for other low-speed and high-torque power drive and direct-drive power generation system design,which has certain practical value.