A high torque dual 3-phase permanent magnet vernier machine with strong fault-tolerance

The field modulation effect has been proposed and investigated in various electric machine topologies.Among them,permanent magnet vernier machines(PMVMs)have attained intensive research due to the high torque density and simple structure.However,the performance of PMVMs in terms of fault tolerance is seldom mentioned.This article proposes a novel dual 3-phase fault-tolerant PMVM with segregated concentric windings.Benefiting from the field modulation effect,the PMVM can generate high torque with low PM flux.The low PM flux also implies small fault currents in the short-circuit case.Therefore,the PMVM exhibits inherent good fault-tolerant capability without sacrificing torque performance.Two independent 3-phase modular winding sets are adopted to improve redundancy.To realize the physical and electrical isolation,each winding set is controlled by a standard 3-phase inverter.The healthy performance and fault tolerance of the proposed machine are evaluated by finite element analysis and verified by experimental tests.The results infer its advantages in healthy conditions and various fault scenarios,including open-circuit,short-circuit,and interturn short-circuit conditions.

Analytical Solution of a Fractional-slot Double-layer-winding Open-slot Vernier Permanent Magnet Machine with Tooth Tips

An analytical solution(ANA)for a fractional-slot double-layer-winding open-slot vernier permanent magnet(VPM)machine with tooth tips is presented.Magnetic vector potential equations are analytically solved using the technique of variable separation in four subdomains in a two-dimensional polar coordinate system.Based on the solved magnetic vector potential,the flux density distribution,torque,flux linkage,inductance,electromotive force(EMF)and power factor are analytically developed.An 18-slot/32-rotor-pole prototype is analyzed,and the results match well with the finite element analysis(FEA),which validates that the ANA consumes less time than FEA.Therefore,the tooth tips are optimized using the ANA to improve the average torque.Moreover,the ANA can be used to evaluate the demagnetization withstand capabilities of permanent magnets.The material utilization,slot-filling factor,EMF,and torque are compared between the models with three and four subdomains.Finally,an experimental prototype is constructed and tested,and the results validate the ANA.

New Topologies of High Torque Density Machine Based on Magnetic Field Modulation Principle

With the increasing demand for high torque density in motors,more and more new topologies emerge.Furthermore,the magnetic field modulation principle is widely concerned and has evolved into an effective analysis method for studying the new motor topology.This paper introduces the principle of magnetic field modulation.And the research on high torque density in recent years is reviewed from the perspective of magnetic field modulation,including permanent magnet vernier machine(PMVM),flux reverse machine(FRM),flux switching machine(FSM),dual permanent magnet(DPM)machine,and DC biased machine.The principle of magnetic field modulation makes it possible to propose higher torque density topologies in the future.

Reduction of Unipolar Leakage Flux and Torque Ripple in Consequent-pole PM Vernier Machine

This paper proposes a new consequent-pole permanent magnet vernier machine(CPMVM),which can be regarded as a combination of two conventional CPMVM with opposite polarities.Based on the simplified axial magnetic circuit model,it is verified that the proposed CPMVM can reduce the unipolar leakage flux.In order to reduce the torque ripple of machine and improve the output torque of machine,the flux barrier is placed on the rotor of the proposed machine.Then,the parameters of the proposed CPMVM are optimized and determined.Moreover,the electromagnetic performance,including no-load air-gap flux density,average torque and torque ripple,flux linkage,back-electromotive force,cogging torque,average torque,torque ripple,power factor and loss,is compared with conventional surface-mounted permanent magnet vernier machine(SPMVM)and CPMVM.Finally,it is demonstrated that proposed CPMVM with flux barrier can effectively reduce the unipolar leakage flux and greatly reduce the torque ripple of machine.Also,compared with the SPMVM,the proposed CPMVM with flux barrier saves more than 45%of the permanent magnet material without reducing output torque.

Modeling and Analysis of Spoke-Type Permanent Magnet Vernier Machine Based on Equivalent Magnetic Network Method

In this paper,a new equivalent magnetic network(EMN)model is established for a spoke-type permanent magnet(PM)vernier(PMV)machine.Two different modeling methods are proposed for different parts of the PMV machine,considering that their magnetic field distributions are quite different.Hierarchical modeling method is proposed for the modeling of the rotor as the magnetic intensity of the rotor iron core presents gradient distribution along the radial direction.Mesh based reluctance network method is used for the modeling of flux modulation poles with irregular and unstable magnetic field distributions.Moreover,accurate PM leakage permeance calculation formulae are deduced to improve the simulation precision.The electromagnetic parameters,such as flux linkage,back electromagnetic force,electromagnetic torque and iron loss are predicted by the proposed EMN model.Finally,finite element analysis(FEA)and experimental results are given to verify the effectiveness of the proposed methods.

基于混合介质网格的表贴式永磁游标电机通用等效磁网络模型

为了更加快速准确地分析表贴式永磁游标电机的电磁特性与参数,提出一种通用等效磁网络模型。该模型的关键在于引入混合介质网格,可将调制齿区域沿周向剖分成相同大小的网格单元,实现对表贴式永磁游标电机调制齿区域的通用建模。同时,此通用等效磁网络模型还确定了定子和气隙的节点连接关系,避免传统等效磁网络模型因瞬态仿真导致的两者节点不规则连接问题,降低仿真误差。此外,考虑到定子极靴存在局部磁饱和现象,文中根据其拓扑结构和磁通密度分布,将定子极靴剖分成3个部分,并细分磁饱和区域,进一步提高模型精度。最后,利用此通用等效磁网络模型计算表贴式永磁游标电机的部分电磁性能,包括气隙磁密,磁链,反电势和转矩,并通过比较计算结果、有限元分析结果以及实验结果的误差,验证所提出模型的有效性和精确性。

环形和分布绕组永磁游标直线电机性能对比分析

针对分布绕组永磁游标直线电机端部重叠导致端部过长、质量过重、电机效率过低的问题,提出一种环形绕组永磁游标直线电机。首先,介绍了永磁游标直线电机的工作原理和基本结构;然后,基于有限元分析,将环形绕组永磁游标直线电机的平均推力、推重比、效率、功率因数等性能与分布绕组永磁游标直线电机进行比较;结果表明,相较于分布绕组,环形绕组永磁游标电机的绕组长度缩短了18.7%,端部漏抗降低了41.5%、推重比提高了19%,电机效率提高了4.2%,同时减少了电机铜耗与体积,更具有工程应用价值。

新能源农机用双永磁游标电机的模型预测电流控制

模块化双永磁游标电机兼具高转矩密度和低铁耗,适用于低速大转矩的直驱应用领域。针对新能源农机用模块化双永磁游标电机控制系统存在的转矩脉动大、电流谐波多和转速波动大等问题,提出一种基于改进式模型预测电流控制策略。相比于传统模型预测电流控制,提出的控制策略采用双矢量模型预测电流控制,在每个控制周期内可同时选择2个任意电压矢量组合作用,扩大了电压矢量的选择和幅值调节范围,可进行更准确的电流控制。同时,考虑系统延迟,在预测控制中加入电流延迟补偿环节。仿真结果表明,所提的控制策略可有效减小转矩脉动、电流谐波和转速波动,提升系统的控制性能。

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.

轮辐式游标永磁电机分析与多目标优化设计

为了削弱磁位波动效应对轮辐式游标永磁电机转矩性能的影响,首先研究磁位波动效应产生机理,基于等效磁路模型推导出空载气隙磁密的解析模型,分析其对气隙磁场调制效果的抑制作用,并利用有限元法验证了转子磁动势和气隙磁密解析模型的准确性。其次,提出了一种基于参数灵敏度分层的多目标优化设计方法,通过综合灵敏度分析法对设计变量空间进行分层降维,根据灵敏度层次选用针对性的优化设计方法,构建出具有高精度的电机性能代理模型。以此为基础,运用多目标遗传优化算法对电机转矩密度、齿槽转矩和转矩波动等进行综合优化设计。最终确定优选设计方案,并通过有限元法验算优化设计的有效性,结果显示,优化后齿槽转矩由28.5 mN·m降至10.3 mN·m,转矩波动由4.9%降至1.6%,平均转矩由0.68 N·m提升至0.83 N·m,电机的输出转矩性能与品质均得到有效提升。

基于联合仿真的表贴式永磁游标电机性能分析

表贴式永磁游标电机内部电磁参数复杂多变,MATLAB/Simulink不能精确反映不同运行工况下电机的实际电磁性能。将交叉耦合理论应用于表贴式永磁游标电机的磁链、电感和转矩模型的研究中,分析计算了交叉耦合对表贴式永磁游标电机磁链、电感和转矩的影响。基于ANSYS Maxwell、Simplorer及MATLAB/Simulink软件建立了场路联合仿真的电机驱动控制系统模型,测试了电机的驱动性能,并与MATLAB/Simulink定参数仿真结果进行了对比。理论分析和仿真结果表明,因电机内部电磁状态的实时变化,采用联合仿真分析方法的计算结果具有更高的准确性。

永磁游标电机转矩特性研究

永磁游标电机具有转矩密度高、结构简单等优点,在电动船舶、风力发电等低速大转矩驱动领域应用广泛。为进一步提高永磁游标电机的转矩密度,采用气隙磁场调制理论研究永磁游标电机的转矩特性。通过分析永磁磁场和电枢反应磁场谐波的有效耦合过程,揭示永磁游标电机转矩产生机理。根据电机结构参数与磁动势、磁导分布的关系,确定待优化参数,结合响应面法和遗传算法对电机转矩性能进行多目标优化设计。采用麦克斯韦应力张量法定量分析气隙磁场各次谐波对电磁转矩的贡献。结果表明,永磁游标电机电磁转矩仅由单一气隙磁场工作谐波产生。在此基础上,研究关键结构参数对气隙磁场调制效应和电机转矩性能的影响,为该类电机的拓扑结构创新及其转矩性能提升提供了理论依据。

表贴式永磁游标电机电磁特性和实验验证

为验证表贴式永磁游标电机高转矩密度的基本原理,基于表贴式永磁游标电机基本方程的分析,研究了电机关键参数对转矩的影响。设计了电机参数,给出了结构示意图,根据定子槽数和极对数,分析了槽电动势星形图,并给出了绕组连接图。基于二维有限元模型深入分析了电机的电磁特性,包括空载磁链、空载电动势、两种励磁源单独作用时的气隙磁密、齿槽转矩和电磁转矩。制作了永磁游标电机实验样机,对其空载反电势进行了测试。仿真和实验结果验证了理论分析的正确性和二维有限元模型的准确性,为永磁游标电机的精确控制提供了有力支撑。

V型游标永磁电机功率因数内在机理及其提升方法

基于功率因数内在机理的研究,提出一种提升游标永磁电机(VPM)功率因数的设计方法,该方法采用分层优化,对影响电机功率因数的主要因素,即永磁磁链和同步电感,分别进行了理论推导和优化分析。该文首先对永磁磁链进行了优化设计,利用气隙谐波作为电机结构设计与电机电磁性能之间的中间桥梁,一方面,气隙谐波作为电机参数的设计目标,另一方面,也作为电机功率因数和其他相关电磁性能的设计变量。基于永磁磁链的分析,进一步优化相关参数对同步电感的影响,从而最终确定了VPM电机的优化设计方案。此外,为了验证该方法的有效性,对优化前后电机的电磁性能进行了分析评估。最后对优化后的电机进行了加工和实验测试,理论分析和实验结果表明所提出的VPM电机功率因数优化设计方法的有效性和合理性,提升了VPM电机在轮毂电机直接转矩驱动系统中的应用潜力。

混合励磁交替极永磁电机多谐波调磁技术研究

高磁能永磁材料是电机实现高转矩/功率密度的前提条件,但其高矫顽力等特性导致电机弱磁困难,限制其在航空航天等高速场合的应用。针对此问题,该文提出一种混合励磁交替极永磁游标电机(hybrid excited consequent pole permanent magnet vernier machine,HE-CPPMVM)。该电机的转子采用CPPM结构,定子齿上同时绕有集中电枢绕组和直流励磁绕组。无励磁电流时,旋转的永磁场经定子齿的调制后与电枢反应谐波相互作用实现机电能量转换;施加励磁电流时,定子励磁绕组通电后可产生静止励磁磁场,经CPPM转子凸极铁芯调制后与电枢反应谐波相互作用可灵活调节电机磁场。该文介绍该电机的结构特征,建立交替极永磁场、励磁磁场和定转子磁导模型,阐述工作谐波特性,揭示其多谐波工作调磁原理。加工原理样机并进行测试,验证调磁原理的有效性。

新型Halbach阵列永磁游标电机结构优化设计

为提高永磁游标电机(PMVM)的输出转矩,发挥Halbach永磁体阵列的聚磁优势,提出转子侧Halbach阵列永磁体游标电机。采用解析分析法和有限元法,对比分析PMVM和Halbach永磁体阵列A型结构永磁游标电机(HPMVMA),结果显示采用Halbach永磁体阵列后提高了电机的空载反电势和输出转矩,减少了永磁体用量,但也带来了电机转矩脉动的增加。因此,在HPMVMA调制齿之间加入永磁体,构成新型Halbach永磁体阵列B型结构永磁游标电机(HPMVMB),对HPMVMB进行了永磁体、调制齿、定子齿宽等结构参数的优化,经过运行性能和经济指标对比分析,结果表明,与HPMVMA相比,HPMVMB永磁体用量增加20%的情况下,永磁体利用率和电机转矩密度分别提高了40.8%和69.01%,而转矩脉动下降了11.74%。通过有限元仿真验证了电机理论的有效性,并为游标电机的设计与优化提供了一定思路。

实心转子铁心式永磁游标电机涡流损耗抑制研究

针对实心转子铁心式永磁游标电机在运行过程中,转子铁心产生的涡流损耗远大于常规永磁电机的问题,对实心钢转子铁心中的涡流损耗产生机理进行了研究,并提出一种能够有效减小其涡流损耗的转子结构。首先,从永磁游标电机(VPM)的磁场特性和涡流损耗产生机理出发,对比了采用实心钢转子铁心的传统永磁电机和VPM电机,得出VPM电机具有更大的转子涡流损耗,并分析了其产生原因;随后,提出一种转子开槽的新型VPM电机结构,该结构可以在保证电机转矩基本不变的情况下,大幅减小转子涡流损耗;最后,通过三维有限元计算,验证了所提结构的有效性。结果表明:实心转子铁心式VPM电机的转子铁心涡流损耗是传统永磁电机的26.85倍;采用文中所提的电机结构,可以在输出转矩下降不到5%的情况下,转子涡流损耗减小达到67.2%。研究结果可为VPM电机的工业应用和推广提供参考。

基于田口法的分裂齿式永磁游标电机转矩优化设计

油田用抽油机驱动电机需在低速下具有较大的输出转矩和较小的转矩波动。以24 kW分裂齿式永磁游标电机为例,通过选择合适的极槽配合,初步确定电机模型;在初始设计参数的基础上,确定电机的参数选择范围。采用基于田口法的多目标优化方法分析电机的结构参数,选择最优的结构参数方案。针对优化前后的目标参数变化用有限元分析进行验证,证明该方法的合理性,得出能够指导工程实践的有益结论。

高温超导双定子永磁游标电机的优化与特性分析

双定子永磁游标电机可以在提高电机调制磁场的同时降低电枢主电感,具有高转矩密度和高功率因数的优势,然而其漏磁严重的缺陷影响了此类电机的推广应用。针对此问题,通过在内定子侧引入高温超导块材料,在改善磁通调制效果的同时有效降低了漏磁。首先,建立11对极12槽的二维电机模型并进行有限元分析,明确了电流超前角对负载转矩的影响作用。其次,利用参数化分析对电机主要结构尺寸进行优化,并综合考虑工艺设计,确定了高温超导块材料的最优尺寸选择。然后,对比分析了优化前后双定子永磁游标电机(Dual-stator permanent magnet vernier machine,DSPMVM)的电磁性能,结果表明在引入高温超导块材料后可显著提高电机功率密度和永磁体的利用率,较好地解决了因双气隙结构导致的漏磁问题。

双定子同极内嵌永磁游标电机转子永磁体极弧系数优化

进一步对双定子同极内嵌永磁游标电机(DS-CP-PMVM)进行讨论,旨在优化同极内嵌永磁转子结构,以保证转子永磁体用量减少的情况下,不降低电机的转矩能力。分析了DS-CP-PMVM的磁力线分布,提出当转子内外侧永磁体中心轴线夹角与内外定子A相轴线夹角相同时,转矩能力最优;讨论了永磁体极弧系数对转矩的影响,当转子内外侧永磁体极弧系数分别为0.62和0.66时,输出转矩最大,与相同永磁体厚度的表贴式结构相比,在定子电流为6 A时,转矩提高了6.4%。