Reduction of Cogging Torque and Electromagnetic Vibration Based on Different Combination of Pole Arc Coefficient for Interior Permanent Magnet Synchronous Machine

Cogging torque and electromagnetic vibration are two important factors for evaluating permanent magnet synchronous machine(PMSM)and are key issues that must be considered and resolved in the design and manufacture of high-performance PMSM for electric vehicles.A fast and accurate magnetic field calculation model for interior permanent magnet synchronous machine(IPMSM)is proposed in this article.Based on the traditional magnetic potential permeance method,the stator cogging effect and complex boundary conditions of the IPMSM can be fully considered in this model,so as to realize the rapid calculation of equivalent magnetomotive force(MMF),air gap permeance,and other key electromagnetic properties.In this article,a 6-pole 36-slot IPMSM is taken as an example to establish its equivalent solution model,thereby the cogging torque is accurately calculated.And the validity of this model is verified by a variety of different magnetic pole structures,pole slot combinations machines,and prototype experiments.In addition,the improvement measure of the machine with different combination of pole arc coefficient is also studied based on this model.Cogging torque and electromagnetic vibration can be effectively weakened.Combined with the finite element model and multi-physics coupling model,the electromagnetic characteristics and vibration performance of this machine are comprehensively compared and analyzed.The analysis results have well verified its effectiveness.It can be extended to other structures or types of PMSM and has very important practical value and research significance.

Torque Characteristics of High Torque Density Partitioned PM Consequent Pole Flux Switching Machines With Flux Barriers

Unique double salient structure of Permanent Magnet Flux Switching Machines(PMFSM)with both Concentrated Armature inding(CAW)and Permanent Magnet(PM)on stator attract researcher's interest for high speed brushless application when high torque density(T den)and power density(P den)are the primal requirements.However,despite of stator leakage flux,high rare-earth PM usage,PMFSM is subjected to slot effects due to presence of both PM and CAW in stator and partial saturation due to double salient structure which generates cogging torque(T cog),torque ripples(Trip)and lower average torque(T avg).To overcomne aforesaid demerits,this paper presents Partitioned PM(PPM)Consequent Pole Flux Switching Machine(PPM-CPFSM)with flux barriers to enhance flux mnodulation,curtail PM usage and diminish stator leakage flux which reduces slotting effects and partial saturation to ultimately reduces T cog and Trip In comparison with the existing state of the art,proposed PPM-CPFSM reduces 46.5390 of the total PM volumne and offer Tavg higher up to 88.8%,suppress Trip naximun up to 24.8%,diminish Tcog up to 22.74%and offer 2.45 times Tden and Pden.Furthermore,torque characteristics of proposed PPM-CPFSM is investigated utilizing space harmonics injection i.e.inverse cosine,inverse cosine with 3rd harmonics and rotor pole shaping techniques i.e.,ecce ntric circle,chanfering and notching.Detailed electromagnetic perfornance analysis reveals that harmonics injection suppressed Tcog maximun up to 83.5%,Trip up to 40.72%at the cost of 4.71%Tavg.Finally,rotor mnechanical stress analysis is utilized for rotor withstand capability and 3D-FEA based Coupled Elctromagnetic Thermal Analysis(CETA)for thermal behavior of the developed PPM CPFSM.CETA reveals that open space along PPM act as cooling duct that inprove heat dissipation.

无磁轭分块电枢盘式电机齿槽转矩优化设计

为了满足定子无磁轭分块电枢(yokeless and segmented armature,YASA)轴向磁通永磁电机作为车用牵引电机时对输出转矩高平稳性的要求,提出一种基于永磁体径向均匀分段、分组同向偏移的方法来抑制YASA电机的齿槽转矩,以降低转矩脉动。应用三维有限元分析,分别研究了3种不同的永磁体分段方案对齿槽转矩的削弱效果,确定了磁极的最优偏转角度及其对电机综合性能的影响。仿真结果验证了该方法的可行性。YASA电机的齿槽转矩降低了92.62%,额定工况下转矩脉动下降了72.02%,永磁体涡流损耗降低91.28%,同时输出转矩下降不超过5.34%,提高了YASA电机的综合性能。

Magnets Shifting Design of Dual PM Excited Vernier Machine for High-torque Application

In this study,a novel dual permanent magnet excited vernier machine(DPMEVM)with magnets shifting in stator is proposed.Compared with the conventional permanent magnet synchronous machine(PMSM),the DPMEVM based on the bidirectional field modulation effect can operate in a wider torque range.However,the torque ripple of a conventional DPMEVM is high because of the superposition of the torque generated by the stator-side and rotor-side PMs.Consequently,a novel DPMEVM with magnets shifting is proposed to further reduce the torque ripple.First,the topologies and working principles of the baseline machine and proposed machines are introduced.Second,the torque-contribution harmonics are analyzed and calculated using the Maxwell tensor method.The calculation results reveal that the DPMEVM,benefiting from multiple working harmonics,can offer an enhanced torque capability compared to the PMSM.In addition,the torque ripple characteristics of the proposed machines are analyzed.It is verified that the torque ripple can be significantly reduced through magnets shifting.Third,the performances of the baseline machine and proposed machines are analyzed and compared in terms of flux density,open-circuit back-EMF,and torque characteristics.In addition,the proposed principle can be extended to machines with the same unit motor.Finally,a 120s-110p prototype machine is manufactured for validation.

V型交替极永磁同步电机气隙磁场调制效应研究

与传统V型永磁(V-shaped permanent magnet,VPM)结构相邻N和S极永磁体形成一对极磁场不同,V型交替极永磁(V-shaped consequent-pole permanent magnet,VCPM)结构永磁体与相邻铁心形成一对极磁场。为进一步探究VPM和VCPM电机磁场分布的不同带来的转矩性能差异,首先通过麦克斯韦应力张量法确认,并量化分析VPM和VCPM电机气隙磁密各次谐波转矩贡献,揭示两种电机主谐波与调制谐波转矩贡献的差异性,进而阐明VCPM电机转矩提升的根本原因在于其显著增加的调制谐波贡献的转矩分量。然后,研究关键结构参数对VCPM电机气隙磁场调制效应的影响规律。最后,加工一台VCPM样机并开展试验研究,验证理论分析和有限元仿真结果的可靠性。

基于气隙磁场重构的永磁电机转矩脉动抑制研究

永磁电机的齿槽转矩引起转矩脉动,影响电机系统的低速性能和控制精度。该文建立齿槽转矩与气隙磁场谐波的模型,分析低次谐波磁场对齿槽转矩的影响规律,揭示齿槽转矩产生机理。通过部分磁极反余弦削极技术重构气隙磁场波形,抵消3、5、7次谐波磁场引起的齿槽转矩,实现电机齿槽转矩的抑制。与现有减小齿槽转矩的方法相比,所提方法通过间接控制气隙磁场减小齿槽转矩。通过有限元法对所提的方法进行验证,并研制1台12槽8极部分反余弦削极转子永磁电机,进行相关测试。

纯电动汽车传动系统-电机结构参数协同设计优化

提出一种纯电动汽车传动系统与电机结构参数协同设计优化方法,来提高纯电动汽车动力性与经济性,同时降低永磁同步电机齿槽转矩以降低电机的振动噪声。首先,以电机结构参数为输入,额定转矩与齿槽转矩为输出,开展了基于电机多参数仿真和不同机器学习预测模型精度的研究,并建立永磁同步电机额定转矩和齿槽转矩的高精度机器学习预测模型;其次,利用电机基本设计参数(额定转矩、峰值转矩、额定转速、峰值转速)以及峰值效率构建永磁同步电机效率map图的快速预估数学模型;再次,基于电机齿槽转矩预测模型以及电机效率map图的快速预估数学模型,建立电机结构参数与效率特性的映射关系;最后,以电机结构参数和传动比为优化变量,整车动力性、经济性以及电机齿槽转矩为优化目标,运用遗传算法进行多目标优化。仿真结果表明,相较于优化前,优化后的整车性能0-100 km/h加速时间缩短了27.3%,15 km/h最大爬坡度提高了40.5%,WLTC工况能耗减少了1.6%,电机齿槽转矩降低了42.2%。

高转矩性能多相组永磁电机及其关键技术综述

多相组永磁电机具有转矩密度高、转矩脉动小、容错能力强的优点,在航空航天、舰船推进等高转矩性能应用场合得到广泛的关注。首先,该文探讨多相组永磁电机的绕组拓扑特点,分析其转矩性能提升机理,归纳转矩性能最优的相移角设计规律。其次,总结了近年来国内外学者在多相组永磁电机领域已开展的工作,重点围绕槽极配比、拓扑结构、相组间联结方式等关键技术进行介绍。然后,基于电流谐波注入和永磁体谐波注削技术,进一步阐述了提高多相组永磁电机转矩性能的方法。针对多相组永磁电机高可靠设计技术,从短路电流抑制、相间独立性提高、绕组余度提升的层面进行了整理和归纳。最后,对高转矩性能多相组永磁电机进行总结与展望。

集成压缩机用双定子磁通切换电机的设计及优化

针对轴流压缩机系统体积大、冷却难的问题,基于6/4双定子磁通切换永磁电机,提出一种新型集成压缩机用磁通切换永磁电机(FSPMM)。首先,推导了考虑转子斜极影响的齿槽转矩解析表达,建立了气体流量轨迹模型。其次,设计E型槽FSPMM和C型槽FSPMM结构并建立有限元仿真模型,对其磁密分布、反电动势、齿槽转矩、电磁转矩及波动等电磁特性进行了计算和对比分析,结果表明E型槽FSPMM的电磁性能明显优于C型槽FSPMM的电磁性能。最后,综合考虑电磁性能和流体影响,对E型槽FSPMM的转子结构进行了优化,优化后的6/4双E型槽FSPMM的转矩波动下降了15.25%,出口流速提高到113.27 m/s,适用于多级轴流压缩机系统。

A New Technique:Research and industrial application of a novel compound permanent magnet synchronous machine

We propose a novel kind of compound permanent magnet synchronous machine (CPMSM), which is applicable in low-speed and high-torque situations. We first explain the structure of the CPMSM. Based on theoretically deducing the calculation formulae of the CPMSM electromagnetic parameters, we analyze the operating characteristics of the CPMSM, and obtain the power-angle curves and working curves. The no-load magnetic field distribution and the cogging torque are analyzed by applying the finite element method of three-dimensional (3D) magnetic fields, to determine the no-load leakage coefficient and the waveform of the cogging torque. Furthermore, the optimal parameters of the permanent magnet for reducing the cogging torque are determined. An important application target of the CPMSM is in directdrive pumping units. We have installed and tested a direct- drive pumping unit in an existing oil well. Test results show that the power consumption of the direct-drive pumping unit driven by CPMSM is 61.1% of that of the beam-pumping unit, and that the floor space and weight are only 50% of those of a beam-pumping unit. The noise output does not exceed 58 dB in a range of 1 m around the machine when the machine is 1.5 m from the ground.

磁极偏移削弱永磁电机齿槽转矩方法

研究了永磁电机磁极偏移对齿槽转矩的影响,发现当每极槽数不为整数时,磁极偏移会引入新的齿槽转矩谐波。因此要通过磁极偏移减小齿槽转矩,除了减小永磁体对称时存在的齿槽转矩谐波外,还要减小新引入的低次谐波。为解决现有的永磁体偏移角度计算方法存在的不足,本文推导了磁极偏移时齿槽转矩的表达式,提出了确定永磁体偏转角度的新方法。有限元计算结果表明:与现有的方法相比,本文提出的磁极偏移角度计算方法得到的偏转角度对原有齿槽转矩谐波以及新引入的低次谐波都有较好的削弱作用,因此能较好地减小齿槽转矩。

基于槽口偏移的永磁电机齿槽转矩削弱方法

齿槽转矩是永磁同步电机设计研究的一个重要方面。本文运用傅里叶级数的方法分析了齿槽转矩的表达式,电机的齿槽转矩为电机各槽产生齿槽转矩的叠加,以此为基础对单个槽产生齿槽转矩的叠加规律进行了研究,提出了一种基于槽口偏移削弱齿槽转矩的方法。研究表明,通过本文方法将电机的槽口偏移适当角度,可以抵消电机齿槽转矩中的某次或者几次谐波,给出了具体槽口偏移角度的确定公式。最后通过计算实例运用有限元仿真进行验证,结果表明该方法可有效地削弱永磁电机齿槽转矩,本文的结论正确有效。

基于电流谐波注入的磁通切换永磁电机定位力矩补偿方法

磁通切换永磁电机具有功率密度高、输出转矩大、反电动势正弦等优点,而较高的气隙磁密与定转子双凸极结构会产生较大的定位力矩。定位力矩会引起电机运行时的转矩脉动、振动和噪声问题,从而限制了磁通切换永磁电机的应用。从控制角度出发,提出一种新型的采用电流谐波注入法补偿定位力矩的控制策略,即通过注入谐波电流产生的转矩抵消定位力矩中的基波与二次谐波分量,从而达到补偿的目的。通过半实物仿真平台dSPACE实现了该控制算法,并在一台2kW磁通切换永磁电机的驱动系统上验证了所提出补偿控制方法的有效性。该控制方法也可拓展应用到其它反电动势为正弦且定位力矩较大的永磁电机驱动系统。

面贴式异向旋转双转子永磁电机的磁场解析计算

采用解析法分析了面贴式异向旋转双转子永磁电机的空载磁场分布。模型在二维极坐标下建立,考虑了径向/平行充磁,内永磁/外永磁转子结构。为了准确计算磁场分布和齿槽转矩,不同于之前的引入相对磁导函数或复数保角变换方法,而是直接利用边界条件来考虑定子槽的影响。在气隙和槽区域内采用拉普拉斯方程,在永磁体区域采用泊松方程求解,并且认为永磁体的相对磁导率是不为1的常数。通过傅里叶变换和分离变量法得出各部分磁通密度的径向、切向分量。通过转子转动,得出槽口区域磁场变化,同时准确估计该种电机的齿槽转矩和反感电动势。与有限元法计算结果比较,两者吻合很好,肯定了该解析法的计算精度。

轴向磁场磁通切换型永磁电机齿槽转矩抑制

轴向磁场磁通切换型永磁(Axial Field Flux-Switching Permanent Magnet Machine,AFFSPM)电机是一种高功率密度、高效率的新型永磁电机,但由于其定、转子的双凸极结构引起的聚磁效应,同传统的永磁电机相比,该结构电机的齿槽转矩较大。为了减小齿槽转矩,进一步提高电机性能,本文对AFFSPM电机的齿槽转矩进行了分析,首先推导了齿槽转矩的解析表达式,然后对转子齿面开辅助槽法进行了研究,采用实验设计(DOE)方法得到了齿槽转矩与辅助槽槽宽、槽深和槽扇形角之间的数学模型,计算出使齿槽转矩最小的辅助槽槽宽、槽深和槽扇形角的最优组合,并通过三维有限元法(FEM)验证了所得结果的正确性。结果表明,转子齿开辅助槽可以有效地削减齿槽转矩,转子齿面开两个辅助槽,优化辅助槽口宽度、槽口深度和槽口形状为3°、1.79mm和1.62°,齿槽转矩最大可以减小约44.3%。

永磁电机齿槽转矩的研究分析

研究了永磁电机齿槽转矩产生的机理和降低齿槽转矩的一些措施.以4极、48槽表面式稀土永磁同步电动机为例,利用二维有限元法分析了极弧系数、磁极偏移和开辅助槽对永磁电机齿槽转矩的影响.将理论分析得到的齿槽转矩结果与样机的齿槽转矩测试结果进行了比较,两者基本吻合.研究表明:通过选择合理的方法能够有效地降低齿槽转矩.

基于重复单元削弱永磁风力发电机齿槽转矩

齿槽转矩是永磁同步风力发电机研究的重要内容之一。为了削弱永磁电机的齿槽转矩,运用傅里叶级数的方法分析了齿槽转矩的表达式,提出了一种重复单元的概念,发现电机的齿槽转矩为各重复单元产生齿槽转矩的同相叠加,将两个或几个重复单元相对偏移适当角度,可以消除它们产生的齿槽转矩中的某次谐波。由此提出了一种基于重复单元的偏移磁极削弱齿槽转矩的方法,给出了磁极偏移角度的确定公式,最后进行有限元仿真。结果表明,与现有方法相比,本文提出的磁极偏移角度计算方法简单,对电机齿槽转矩有显著的削弱效果,且不会引起新的低次谐波。

永磁同步电机转子磁极优化技术综述

永磁同步电机的电磁转矩、转矩波动、电磁振动与噪声等电机性能与气隙磁密波形密切相关。减小气隙磁密中的谐波含量能够有效地削弱齿槽转矩、抑制转矩脉动,减小电机振动,提升电机的整体性能。对表贴式和内置式永磁同步电机来说,可以分别通过优化永磁体形状和转子表面铁心形状(统称为转子磁极优化技术)来减小气隙磁密中的谐波含量。该文回顾并总结了近年来国内外学者在永磁同步电机转子磁极优化技术方面所进行的研究工作,将不同的转子磁极优化技术进行归类,比较其优缺点。最后探讨了转子磁极优化技术尚存在的一些问题和未来发展的主要方向。

多相聚磁式横磁通永磁电机的自定位力矩研究

横磁通永磁电机研究日益得到广泛关注,然而其自定位力矩造成的机械震动、噪音污染不容忽视。该文在总结现有横磁通永磁电机结构特点的基础上,提出一种多相聚磁式组合定子横磁通永磁电机拓扑,并采用三维等效磁网络法进行了样机磁场分析和性能计算,结果证明在轴向和径向进行多相合成设计可以在提高电机输出功率的同时使部分自定位力矩相互抵消,有效抑制转矩脉动,适宜在低速、大功率、直接驱动的工业和军事领域推广应用。并基于分析结果研制了一台四相TFPM样机,实验测量和仿真结果的一致性证明了设计方法的正确性和有效性。