1.5MW直驱永磁风力发电机性能研究

分析了极数、槽数和相数对直驱永磁风力发电机性能的影响,以及减小齿槽转矩和提高输出功率的极、槽配合和极弧系数的选取方法。运用等效电路模型设计额定功率为1.5 MW、78极324槽的直驱永磁风力发电机,基于ANSOFT有限元法,研究了直驱永磁风力发电机在额定、短路情况下的运行特点,并进行了发电机运行特性理论分析和实验研究,通过仿真和实验验证了所设计直驱永磁电机的可行性和实用性。     

直驱型多相永磁同步电机转矩脉动及损耗特性

与普通三相电机相比,直驱型多相永磁同步电机具有相数多、极槽匹配与绕组排布多样、中性点连接与PWM控制方式多样等特点,这使得电机绕组电流与磁场谐波含量极为复杂,电机性能也具有一定的特殊性。因此,有必要对其主要性能进行细致的研究:本文分析了电机转矩脉动及损耗与谐波磁场的关系;采用有限元软件Ansoft对目标电机进行建模,研究了直驱型多相永磁同步电机特有因素(相数与供电方式、中性点接法、极槽匹配与绕组排布)对电机转矩脉动及损耗的影响。研究结果表明,增加电机的相数和极槽数、合理的选择中性点连接方式,可以有效地减少电机磁场谐波含量,降低电机的转矩脉动及损耗。     

聚磁式场调制永磁风力发电机工作原理与静态特性

提出一种新型聚磁式场调制永磁(Flux-Concentrating Field-Modulated Permanent-Magnet,FCFMPM)电机,该电机外转子采用聚磁式永磁体结构改善气隙磁通密度,定子采用开口槽结构提高空间利用率.基于磁齿轮效应,定子齿对转子永磁磁场进行调制,产生极对数少、运行速度快的谐波磁场,由该谐波磁场作为有效励磁的FCFMPM电机具有低速、大转矩密度的特点.在深入分析电机工作原理的基础上,运用二维有限元方法计算了其静态特性,包括空载永磁磁链、空载感应电动势、电感、定位力矩和电磁转矩等.研制了一台5kW实验样机,并与商业化小型永磁直驱风力发电机做比较.仿真和实验结果表明,所提电机具有转矩密度大、定位力矩小、外特性硬等特点,特别适用于如风力发电等低速、直驱系统.     

低速永磁直驱同步电动机技术

分析和研究了低速永磁直驱同步电动机的设计及工艺技术。对传统工业系统的弊端及低速永磁直驱同步电动机的优点进行了阐述,对低速永磁直驱同步电动机的研究热点进行分析,其研究热点主要集中在转子磁路结构、定子绕组排布、齿槽转矩抑制、齿谐波消除、永磁体退磁等几个方面。     

直驱式永磁同步风力发电机性能研究

通过等效磁路法设计了额定功率1.5MW的直驱式永磁风力发电机;为了深入研究额定功率1.5MW的直驱式永磁风力发电机的运行特性,采用场路结合法分析了永磁风力发电机在空载、额定负载和短路情况下的运行特点,并验证了所设计永磁风力发电机的可行性;在此基础上,将极孤系数、负载变化对永磁同步发电机输出功率的影响进行了仿真;对比研究了每极每相槽数对永磁同步发电机性能的影响.结果表明:极槽匹配对直驱式风力永磁发电机性能有很大影响;通过合理选择极数、槽数以及极弧系数,可以减少输出电压谐波分量的影响,降低永磁材料的使用,节省成本,有助于直驱式风力永磁发电机获得良好的性能.     

分数槽集中绕组永磁电动机的槽极选择与径向力分析

介绍了分数槽集中绕组永磁交流电动机槽极选择的主要依据。简要介绍了永磁电机径向力波分析的理论,重点分析了分数槽集中绕组永磁交流电动机的主要谐波类型。利用有限元分析方法计算了10极分数槽集中绕组永磁交流电动机的谐波磁场,进行了径向力波分析。综合对比不同槽数下电动机的绕组系数、低阶力波含量和齿槽转矩,选择出合适的槽极配合。     

低速大转矩永磁同步电动机设计

结合一台15kW抽油机用直驱式永磁同步电动机,研究了低速大转矩永磁同步电动机的一般设计方法和相关问题;为消除低速时的转矩脉动,采用了分数槽绕组、合理设计极弧系数、定子斜槽等措施;用Ansoft软件对气隙磁密波形、磁场分布、反电动势波形的仿真结果表明,这些措施可以有效消除气隙磁场的高次谐波,进而消除低速时的转矩脉动;实际...     

永磁直驱风力发电机不同极槽配比的磁场研究

永磁同步发电机运行时,永磁体和电枢铁心相互作用会产生齿槽转矩,引起转矩波动和噪声.应用Ansys设计分析软件中的有限元模块和磁路等效模块,研究了分数槽绕组外转子永磁直驱风力发电机在不同极槽配比情况下的齿槽转矩、磁场分布、气隙磁密谐波含量和电机效率的变化规律;对比分析了整数槽电机在直槽和斜槽2种设计方案下的电压及畸变率.仿真结果表明,分数槽和斜槽结构均能有效削弱电机的齿槽转矩,消除高次谐波电压,且整数斜槽结构的电机削弱齿槽转矩的效果更好一些.     

低速大转矩永磁直驱电机研究综述与展望

低速大转矩永磁直驱电机替代传统的感应电机加机械减速机构的传动模式具有明显的优势,受到越来越广泛的关注。转矩密度是衡量低速大转矩直驱电机的关键指标之一,本文主要从结构特点、应用现状和科研进展等方面,介绍了真分数槽集中绕组永磁电机、永磁游标电机、永磁盘式电机、横向磁通电机和双定子/双转子电机等几类高转矩密度低速大转矩永磁直驱电机。概述了转矩脉动、气隙偏心故障、机械强度和温度场研究等的必要性和方法。基于研究现状展望未来发展方向,为实现高性能低速大转矩永磁直驱电机提供参考。     

直驱型多相永磁同步电机定子磁动势与气隙磁密特性分析

直驱型多相永磁同步电机由于相数多、采用分数槽绕组结构、电机的中性点连接与PWM控制方式多样等特点,使得电机绕组电流与磁场谐波含量极为复杂,电机性能与普通三相电机相比有较大区别,因此,有必要对其电磁特性进行细致的研究。该文建立了直驱型多相永磁同步电机定子绕组磁动势数学分析模型,给出了详细推导过程。研究了电机绕组电流和磁动势的影响因素:相数与供电方式、中性点接法、极槽匹配与绕组分布。全面分析了以上因素对直驱型多相永磁同步电机电流及磁场的影响。研究结果表明,增加电机的相数和极槽数,合理的选择中性点连接方式,可以有效减少电机的谐波含量,提高电机的性能。     

A novel polyphase multipole square-wave permanent magnet motordrive for electric vehicles

A novel high-power-density permanent magnet (PM) motor drive for electric vehicles (EVs) is proposed. The motor is a polyphase multipole square-wave PM motor, which can be classified as a kind of PM brushless DC motor. The distinct features of the proposed motor as compared to those of the conventional PM brushless DC motor are as follows. First, the multipole magnetic circuit arrangement enables the minimization of the magnetic yoke, resulting in the reduction of motor volume and weight. Second, the coil span is purposely designed to be equal to one slot pitch, thus saving the amount of copper used. Third, by using a fractional number of slots per pole per phase, the arrangement of the numbers of poles and slots is so unique that the magnetic force between the stator and the rotor at any rotating position is uniform, hence eliminating the cogging torque that usually occurs in PM motors. Finally, the motor can be controlled to operate at a constant torque region and a constant power region with field weakening, thus both high starting torque and high cruising speed can be achieved. Therefore, as the proposed motor drive possesses the distinct advantages of high power density, high efficiency, and superior dynamic performance, it is very suitable for EV applications. A prototype of a five-phase 22-pole 5 kW motor drive has been designed for an experimental EV     

永磁力矩电机三相绕组不对称性改进方法研究

由于力矩电机多作为驱动电机使用,且电机对低速平稳性要求很高,所以选用了一种特殊的极槽配合方式。12极39槽的选择使得电机齿槽转矩较小的同时导致电机三相绕组不对称。降低绕组不对称对电机低速平稳性的影响,对提高绕组的对称性的方法研究有着重要的意义。以一台采用12极39槽的力矩电机为例,提出了一种绕组不对称性的改进方法,通过改变绕组的排列方式提高了绕组的对称性,且保证了电机的低速平稳性。最终通过理论研究与仿真分析验证了不对称性改进方法的有效性。     

Cogging torque investigation of PM motors resulting from asymmetry property of magnetic poles: Influence of performance variation between permanent magnets

This paper examines the cogging torque of a permanent magnet (PM) motor resulting from the asymmetry property of magnetic poles, which comes from the performance variation between magnets. A PM motor with 32 poles (= 16 pole pairs) and 36 slots is selected for verification, because the motor whose pole/slot ratio is 8/9 is sensitive to the performance variation between permanent magnets. Assuming that two different magnetization levels of magnets are mixed together in one rotor, the amplitude of the 2.25th and 4.5th components of cogging torque, which show 36 (= 2.25 × 16) and 72 (= 4.5 × 16) times of pulsation per rotation respectively and both of which result from the asymmetry property of the magnetic poles, are evaluated. As a result, it is clarified that the cogging torque characteristics depend on the alignment pattern of the two kinds of magnets. The amplitudes of the 2.25th and 4.5th components of cogging torque are proportional respectively to the amplitude of the 36th and 72nd order harmonics of the squared magnetic flux density around the rotor which is set in the space without stator. Using the proportional constants found from the finite element analyses in some alignment patterns, the cogging torque amplitudes of the motors with other alignment patterns can be predicted by calculating the squared magnetic flux density around the rotor only. The predicted cogging torque amplitudes correspond to the actually calculated results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(3): 57– 67, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20669     

Low-speed high-torque drive system applying vernier motor torque

The application of the direct drive system is increasing in the field of robot and factory automation because of controllability with high accuracy. However, it requires the motor high torque at low speed. Although the vernier motor presented by Lee in 1963 could produce the reluctance torque in low speed, it involved many problems to be solved. This paper studies the reluctance torque of the vernier motor using the finite-element field analysis. Since the increase of rotor slot number is effective in producing high torque, in the model here, there are not only winding slots but also small slots on the stator teeth surfaces. Also, the rotor slots are provided in the periphery of the core more than the total number of stator slots by the pole number. The calculated torques have agreed very well with the experimental results. A prominent feature of the control scheme is to control the armature current phase based on the detected rotor slot position. Thus there is no problem such as pull-in or pull-out in Lee's vernier motor. Then the instantaneous torque is controlled by the amplitude of armature current. The experimental results on both the speed control and the position control also are shown in this paper.     

可调速异步盘式磁力联轴器的转矩计算及其影响因素分析

为研究可调速异步盘式磁力联轴器的参数对转矩的影响,采用有限元方法进行三维磁场数值计算,得出了磁力联轴器在静态和瞬态下气隙的三维磁场分布.并对影响磁力联轴器转矩的关键参数如气隙长度、永磁体厚度、磁极数、从动盘的槽数、槽深以及主动转速等进行了分析.研究结果表明:当在一定的外形尺寸下,取磁极数为18,槽数为16,槽深为15mm时其转矩最大为20N·m左右.另外,增加气隙长度会降低联轴器的转矩;在一定的范围内,转矩随着磁极数、从动盘的槽数、槽深的增大先增大后减小,且槽数不能与磁极数相等;转矩随着主动转速先增大后减小,其变化曲线类似于电机的机械特性曲线,可为选择相应的电机转速和磁力联轴器调速提供依据.     

磁极径向组合轴向磁场永磁电机转矩品质分析与优化设计

为了实现轴向磁场永磁(axial field permanent magnet,AFPM)电机大转矩惯量比、低转矩脉动等高品质转矩输出,提出磁极径向组合式的AFPM电机,采用传统表贴永磁与Halbach永磁阵列沿径向排列的转子结构。分析电机运行原理,推导电机功率尺寸方程;通过有限元方法对比分析该结构与传统表贴式结构的磁场分布、转矩、转矩脉动、反电动势及电感等电磁特性。在此基础上,基于响应面分析,构建多目标遗传优化设计方法,对电机转矩、齿槽转矩、反电动势和转矩脉动进行优化设计。最后,基于优选参数加工制造样机,并进行实验研究,验证了该电机结构的有效性和分析的正确性。     

电动自行车用磁通切换电机研究

针对电动自行车用磁通切换电机齿槽转矩大的问题，依据槽极配合原理，设计并对比了12槽10极和12槽11极2台电机。有限元仿真结果表明，12槽11极电机的转矩脉动仅为12槽10极的16.6%，通过转子分段斜极方式进一步减小其齿槽转矩，同时分析转子斜极角度对电机转矩性能的影响。研究结果表明，斜极优化后的12槽11极磁通切换电机转矩脉动仅有2%，且输出转矩能够满足电动自行车日常行驶动力需求。     

极槽数相近配合的永磁低速同步电动机

根据实际工程问题需要设计一台极槽数相近配合的低速永磁同步电动机。利用有限元法对电机磁场进行分析,并通过时步有限元法对其性能进行了仿真。分析与仿真结果表明：尽管电机的气隙磁场远非正弦分布,但绕组的感应电动势很接近正弦,电磁转矩的脉动以及齿槽转矩较小。     

TORQUE CALCULATION OF MACHINES WITH PERMANENT MAGNET MATERIALS

ABSTRACT

The prediction of torque in permanent magnet motors is essential for both their design and control. Most literature in the area uses the Lorenz equation for the force on a conductor in a magnetic field. This implies a model consisting of a slotless armature with the conductors distributed in the airgap. This is clearly not the case for the great majority of motors. In addition, this model is incapable of predicting such effects as cogging torque. A more fundamental approach is to use the energy transfer relationship, but this requires knowledge of the energy density of permanent magnet materials. There is surprisingly little agreement on the calculation of this energy.

This paper uses an expression for energy density derived using a simple theoretical model, to develop an expression for torque for a permanent magnet machine with one slot per pole per phase. The expression for torque is then compared with the theoretical results from the conventional approach. The analysis is confined to the linear region of operation. The model is then generalised for any number of slots and phases using the Discrete Fourier Transform (DFT), and a general expression is developed for useful torque. This DFT model will be most appropriate for machines with a low number of slots per pole since the discrete nature of the machine is most apparent for these cases. Cogging and useful torques of a laboratory servo motor is predicted using the model and compared with measured values.     

Dual stator winding induction machine drive

A new dual stator winding induction machine drive is described in this paper. The proposed induction machine consists of a standard squirrel-cage rotor and a stator with two separate windings wound for a dissimilar number of poles. Each stator winding is fed from an independent variable-frequency variable-voltage inverter. The proposed drive offers such advantages as speed sensorless operation, better reliability, and more flexibility to manipulate the resultant torque-speed curve of the motor. In the proposed drive, zero-speed operation is achieved by independently controlling the two sets of stator currents, hence, maintaining a minimum electrical frequency independent of the mechanical speed. This feature is especially important to minimize the negative impact of the stator resistance influence at low-speed operation and it greatly simplifies the implementation of speed sensorless control schemes. The drive is well suited for either constant volts per hertz or field-oriented (FO) operation. Circulating harmonic currents, common to most dual stator machines, are eliminated by the dissimilar pole number in each stator winding