【作者】 陈政；

【导师】 王晋；

【作者基本信息】 华中科技大学 ， 电气工程， 2021， 硕士

【摘要】 井下电动钻具钻井效率高,可显著降低油气开采成本,是实现深井油气资源高效低成本开发的重要途径,具有良好的应用前景。井下潜油电机作为电动钻具的核心部件,需具备高转矩密度和高可靠性等特性。永磁游标电机结构简单、转矩密度高,但传统的表贴式永磁游标电机存在功率因数偏低以及转子结构可靠性较差等问题。低功率因数会导致变频器容量加大从而增加成本,而表贴式转子在装配和运行过程中存在永磁体破碎或脱落隐患,其可靠性难以保证。本文以电动钻具为应用背景,提出采用交替极永磁游标电机作为井下电动钻具电机,并围绕其槽极配合、绕组型式选择以及定转子尺寸优化等方面开展系统深入的设计研究。首先,阐述了交替极永磁游标电机的结构和工作原理,通过与传统表贴式永磁游标电机的对比,揭示了交替极永磁游标电机结构更为可靠、永磁体用量更少和极间漏磁更少等优势。根据磁动势和磁导简化磁路模型,推导了交替极永磁游标电机的磁动势、气隙比磁导、气隙磁密、反电势以及电磁转矩的解析表达式。与传统表贴式永磁游标电机相比,交替极永磁游标电机磁动势含有偶次谐波,且气隙磁导和磁密谐波含量更高。进一步对两者的气隙磁密、空载反电势、电磁转矩和功率因数等电磁特性进行对比研究。结果显示交替极永磁游标电机在减少一半永磁体用量情况下可以获得与表贴式方案相同的转矩性能,但功率因数会变得更低。然后,针对交替极永磁游标电机功率因数低和结构可靠性的问题,开展进一步的电磁设计和优化。在综合考虑转矩和功率因数性能的条件下选择槽极配合和绕组型式,并分析定子主要尺寸对电磁性能的影响。在此基础上,对三种不同结构的交替极转子分别进行设计与优化。针对内置式交替极转子中永磁体外围极靴漏磁大的问题,提出非导磁极靴转子的设计方案,有效提高了输出转矩。通过对三种优化后的交替极转子方案进行综合性能对比研究,发现在同样输出转矩条件下,采用内置式交替极转子结构,可靠性最高,而且电机功率因数相比传统表贴式永磁游标电机提高了约12%,满足井下电动钻具电机性能要求。最后,设计并研制了一台定子18槽4对极、转子14对极的内置式交替极永磁游标小型样机,通过空载和负载实验分别测试了样机的空载反电势、输出转矩、功率因数和效率,并与有限元仿真结果进行了对比分析,验证了所提出的内置式转子交替极永磁游标电机方案的可行性以及电磁设计的准确性。更多还原

【Abstract】 The downhole electric drilling system has high drilling efficiency,can significantly reduce the oil and gas production cost,is an important means to realize the high-efficiency and lowcost development of oil and gas resources in deep wells,and has a good application prospect.As the core component of electric drilling system,downhole submersible motor needs high torque density and high reliability.Permanent magnet vernier motor has simple structure and high torque density,but the traditional surface mounted permanent magnet vernier motor(SPMVM)has some problems such as low power factor and poor reliability of rotor structure.Low power factor will lead to an increase in the capacity of the frequency converter,which will increase the cost.However,there is a hidden danger of permanent magnet breakage or falling off during the assembly and operation of the surface-mounted rotor,and its reliability is difficult to guarantee.In this paper,based on the application background of electric drilling tools,the consequent pole permanent magnet vernier motor(CPMVM)is proposed to be used as the motor of downhole electric drilling tools,and systematic and in-depth design research is carried out around its slot pole matching,winding type selection and stator and rotor size optimization.Firstly,the structure and working principle of the CPMVM are expounded.By comparing with the traditional SPMVM,the advantages of CPMVM such as more reliable structure,less permanent magnet consumption and less inter-pole magnetic leakage are revealed.According to the simplified magnetic circuit model of magnetomotive force and permeance,the analytical expressions of magnetomotive force,air gap specific permeance,air gap magnetic density,back emf and electromagnetic torque of CPMVM are derived.Compared with the traditional SPMVM,the magnetomotive force of CPMVM contains even harmonics,and the harmonic content of air-gap permeability and magnetic density is higher.The electromagnetic characteristics of the air gap magnetic density,no-load back EMF,electromagnetic torque and power factor of the two are further compared.The results show that the CPMVM can achieve the same torque performance as the surface-mounted scheme with half of the permanent magnet consumption,but the power factor will become lower.Secondly,aiming at the problems of low power factor and structural reliability of CPMVM,further electromagnetic design and optimization are carried out.Under the condition of comprehensive consideration of torque and power factor performance,slot-pole matching and winding type are selected,and the influence of main stator dimensions on electromagnetic performance is analyzed.On this basis,the consequent pole rotors with three different structures are designed and optimized respectively.In order to solve the problem of large magnetic leakage of permanent magnet peripheral pole shoes in built-in consequent pole rotor,a design scheme of rotor with non-conductive pole shoes is proposed,which effectively improves the output torque.By comparing the comprehensive performance of three optimized consequent pole rotor schemes,it is found that under the same output torque condition,the built-in consequent pole rotor structure has the highest reliability,and the power factor of the motor is increased by about 12% compared with the traditional surface-mounted structure,which meets the performance requirements of the downhole electric drilling tool motor.Finally,a small prototype of built-in CPMVM with 18 slots and 4 poles of stator and 14 poles of rotor was designed and developed.The no-load back EMF,output torque,power factor and efficiency of the prototype were tested through no-load and load experiments,and compared with the finite element simulation results,which verified the feasibility of the proposed built-in CPMVM and the accuracy of electromagnetic design.更多还原