宽转子无轴承开关磁阻电机的计及磁饱和径向力模型

针对无轴承开关磁阻电机现有的基于无磁饱和假设的数学模型只适用于未磁饱和工况的缺点,为宽转子单绕组无轴承开关磁阻电机建立了一种可以计及磁饱和影响的全周期径向力数学模型。首先依据该电机的磁场有限元分析结果,基于麦克斯韦应力法求出了径向力关于气隙磁密的表达式;然后对铁心材料的非线性磁化特性进行拟合,再根据该电机的等效磁路计算了计及磁饱和影响的气隙磁密;之后建立了该电机的径向力模型,并在对比分析了边缘气隙磁密和主气隙磁密对径向力的影响后,对所建径向力模型进行简化,以减小计算量和复杂度。最后利用三维有限元分析进行验证,结果表明所建径向力模型对该电机未磁饱和、部分磁饱和以及完全磁饱和工况均适用。计及磁饱和的全周期径向力模型的建立,可以为电机运行特性分析、本体优化设计以及控制策略研究提供更准确的理论参考。     

基于麦克斯韦应力法的双绕组无轴承开关磁阻电机新型数学模型

现有的双绕组无轴承开关磁阻电机麦克斯韦应力法数学模型忽略了相互垂直方向上径向悬浮力的耦合,但当转子偏离定转子齿极中心对齐位置较大时存在较强的耦合,故现有模型难以满足高精确度稳定悬浮控制要求。选择一种计及相互垂直方向悬浮力耦合的新积分路径,建立了基于麦克斯韦应力法的双绕组无轴承开关磁阻电机新型数学模型,同时为计及电机磁路的饱和特性,采用最小二乘法对铁心材料的非线性磁化曲线进行拟合,求解考虑磁饱和的各气隙磁密。通过与有限元仿真结果对比,验证了所建模型不仅揭示了相互垂直方向上径向悬浮力的耦合关系,考虑了磁饱和特性,且具有精确度良好、计算量小等优点,为实现高精度稳定悬浮控制奠定了基础。     

无轴承开关磁阻电机径向电磁力模型

针对现有无轴承开关磁阻电机数学模型忽略磁饱和或对磁饱和考虑不充分的不足,将麦克斯韦张量法和磁路分析法结合起来,提出了一种计算无轴承开关磁阻电机径向电磁力的方法.该方法考虑了电机运行过程中磁饱和以及转子的偏心位移,能够准确的描述电机径向电磁力的特性,为电机运行状态的离线分析和电机的设计提供了更为可靠的理论依据;该模型同时为无轴承开关磁阻电机电磁振动和噪声的预测与控制提供了理论依据.以一台实验样机为例,建立了考虑磁饱和的无轴承开关磁电机有限元分析模型.仿真结果证明了该解析模型的有效性.     

新型无轴承开关磁阻电机双相导通数学模型

针对传统无轴承开关磁阻电机数学模型单相电流导通模式的局限性,提出了一种适用于单、双相导通的无轴承开关磁阻电机数学模型.在建立两相电流导通的等效磁路模型基础上,确定电感矩阵,推导出两相电流导通的径向悬浮力和电磁转矩的表达式.基于该数学模型的双相电流导通模式极大程度地拓宽了无轴承开关磁阻电机的工作区域,增加了其承受径向负载的能力.利用磁场分析法验证了该数学模型的正确性和优良的工作特性.     

一种新型的无轴承开关磁阻电机数学模型

针对经典采用直线磁路和椭圆形磁路分割求取气隙磁导的无轴承开关磁阻电机数学模型的局限性，文中提出了一种基于直线磁路和改进的椭圆形磁路分割求取气隙磁导的新型无轴承开关磁阻电机数学模型，该数学模型不仅保证定、转级对中位置时电磁转矩的连续性，而且同时较为准确地描述了沿α和β方向径向悬浮力之间的耦合关系。不仅如此，基于该数学模型在一定程度上拓宽无轴承开关磁阻电机的有效工作区域，仿真分析验证了该数学模型的优良特性。     

横向磁场直线开关磁阻电机的数学建模

为了建立横向磁场直线开关磁阻电机(transverse flux linear switched reluctance motors,TFLSRM)的解析数学模型,首先分析TFLSRM的结构和磁路特点,建立TFLSRM的磁路等效模型,采用直线磁路和变椭圆系数的椭圆形磁路分割法推导等效磁路的气隙磁导解析式,确定以磁导表示的绕组电感和磁链,建立了推力和法向力的数学模型.有限元分析结果验证了所建数学模型的正确性,利用该模型分析了改变次级极宽和气隙长度对电机推力和法向力的影响,半实物仿真实验结果验证了所建模型的有效性.     

宽转子极无轴承开关磁阻电机径向力模型全周期拓展

针对单绕组宽转子极无轴承开关磁阻电机在定转子极非完全交叠区间的径向悬浮力模型空白、已有定转子极完全交叠区间径向悬浮力模型推导过程复杂且计算量大的不足,首先通过磁场有限元分析,分别确定了该电机在定转子非完全交叠区间和完全交叠区间的电磁场几何分布,计算了气隙磁密,再根据麦克斯韦应力法分别推导了这2个区间的径向力表达式,从而建立该电机在一个完整周期范围内的径向力数学模型,并通过与三维有限元计算结果的对比验证该模型的准确性。相比于利用等效磁路图推导径向力模型而言,该建模过程更简便,计算量也更小。全周期径向力模型的建立,不仅能为电机本体和控制器设计提供理论参考,还有助于提高该电机控制策略设计的灵活性,也可以提高与传统单绕组无轴承电机控制器的通用性。     

分块开关磁阻电机的研究现状及其新结构构想

分块开关磁阻电机通过分块的定子或转子结构,可获得较短的磁路以减小铁心损耗,圆柱形的转子可缩减风(油)阻,结构和电磁的隔离能增强电机可靠性及容错性.本文对现有的各型分块开关磁阻电机的结构和磁路进行了解析,在此基础上,提出了双极性励磁分块转子开关磁阻电机、环状绕组分块转子开关磁阻电机、C形分块定子开关磁阻电机、E形分块定子...     

盘式开关磁阻电机临界重叠位置磁化曲线计算

针对三维有限元方法分析轴向磁场盘式开关磁阻电机时计算机配置要求高、耗时长及不适于电机的优化设计和基于定转子极中心线对齐位置和定子极中心线和转子槽中心线对齐位置这两个关键位置的磁路法计算精确度不高等问题,对转子齿前沿和定子齿前沿重叠位置即临界重叠位置处磁化曲线进行解析计算.利用三相6/4极和12/8极轴向磁场盘式开关磁阻电机的有限元仿真结果及磁阻最小原理划分该位置处磁链并进行计算,推导出该种电机临界重叠位置处磁化曲线,并与三维有限元方法的计算结果进行对比.分析结果表明,此种解析法的计算精确度符合要求.计算结果验证了解析分析计算的正确性.     

一种新型双定子8/3极开关磁阻电机转矩模型

提出了一种新型双定子8/3极开关磁阻电机。在分析其结构和原理的基础上,建立等效磁路模型和磁路分割模型,得到了自感、互感和气隙磁导公式,进而推导出该电机的转矩数学模型。最后利用有限元分析软件,验证了该数学模型的正确性,并对比了双定子8/3极开关磁阻电机与双相励磁8/6极开关磁阻电机在转矩输出特性上的优缺点。结果表明双定子8/3极开关磁阻电机具有更加平稳的输出转矩。     

Novel Two-Phase Switched Reluctance Machine Using Common-Pole E-Core Structure: Concept, Analysis, and Experimental Verification

A novel two-phase switched reluctance machine (SRM) with a stator composed of E-core structure having minimum stator core iron is proposed. The E-core stator has three poles with two poles at the ends having windings and a center pole containing no copper windings. The center stator pole in the E-core is shared by both phases during operation. The air gap around the common stator pole has constant and minimum reluctance irrespective of rotor position by its unique design, and the two remaining stator poles at the ends experience variable reluctance with respect to rotor position. The stator is constructed with two independent and physically separate E-cores, and the rotor is composed of ten poles. Other pole combinations are possible. Phase excitation in the novel SRM gives short flux paths, hence reducing the magnetomotive force required to drive the machine, resulting in significant reduction of copper wire and core losses compared to existing two-phase SRMs with flux paths that traverse the entire stator back iron. The concept and principle of operation of this novel SRM and its comparison to existing two-phase SRMs are detailed in this paper. Comparison between finite-element simulations and magnetic equivalent circuit (MEC) analysis for inductance are made and compared to experimentally measured characteristics. Furthermore, comparisons between a conventional two-phase SRM and the novel SRM are made in terms of its weight and output torque. Manufacturability and cost savings of the unique SRM structure are presented. It is shown that the E-core SRM using common stator pole has 50% less iron in the magnetic path compared to a conventional two-phase SRM.      

Initial rotor position estimation of a SRM drive installed in an electric vehicle

In this paper an estimation method of the initial rotor position at a stand still condition for switched reluctance motor (SRM) drives is proposed. In the SRM, a rotor shaft is connected to an incremental encoder, thus, only an initial position should be detected to realize smooth start up operation. The proposed method is injecting voltage pulses to all windings and detecting the current and estimating the position based on a simple relation between inductance profile and phase current. With an accurate estimated rotor position, the motor can start smoothly under heavy load. The proposed method is implemented in a 6‐stator‐pole and 4‐rotor‐pole, 1.5 kW switched reluctance motor installed in an electric vehicle. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

New pole tip shapes mitigating torque ripple in short pitched and fully pitched switched reluctance motors

High torque ripple is one of the major disadvantages of switched reluctance motor (SRM). Although there are several publications in the literature addressing the full or partial solution to the problem for conventional SRM, no publication exists for the torque ripple reduction of recently emerging fully pitched SRM. This paper deals with finding best dimension set for a particular stator and rotor pole tip shape aiming to reduce torque ripple in both short pitched and fully pitched SRMs. Five new stator and rotor pole tip structures have been investigated and compared with conventional pole tip. Analyses have been performed with the finite element (FE) models of 6/43-phase short pitched and fully pitched SRM with unipolar excitation. With the proposed pole tips, torque ripple is reduced by 24.1% in short pitched SRM for 10 A phase current and by 22.6% in fully pitched SRM for 5.59 A phase current.     

双凸极永磁电机斜极转子设计和绕组换流模式研究

本文首先分析了双凸极永磁电机转子极弧宽度对自定位转矩的影响,提出了双凸极永磁电机等极弧半极宽斜极转子的设计思想;在此基础上,通过对绕组磁链的分析,率先将六状态换流模式引入到双凸极永磁电机的控制系统中,改善了双凸极永磁电机的换流特性,有效减小了转矩脉动,同时简化了系统控制参数,提高了控制的可靠性.数字仿真和试验结果验证了这些设计思想的正确性.     

直驱式多转子极电励磁双凸极风力发电机

针对如何提高低速直驱双凸极发电机效率的问题,研究了一种多转子极电励磁双凸极发电机新结构,推导了该发电机定子极数与转子极数配合关系,给出了多转子极DSEM定子极宽与定子极距之比的取值,并在此基础上建立了有限元分析模型,在发电机转速、每相串联匝数、转子极数和主要尺寸相同的条件下对比分析了24/16、12/16和6/16极电励磁双凸极发电机的磁链、电动势、电感、定位力矩、效率和重量.分析结果表明本文所提多转子极DSEG发电机结构的合理性.     

Evolutionary computation based multi-objective pole shape optimization of switched reluctance machine

This paper presents the application of elitist Non-dominated Sorting Genetic Algorithm version II (NSGA-II) to determine optimum pole shape design for performance enhancement of Switched Reluctance Machine (SRM). In SRM, torque output and torque ripple are sensitive to stator and rotor pole arcs and their selection is a vital part of SRM design process. The problem of determining optimal pole arc is formulated as a multi-objective optimization problem with the objective of maximizing average torque, minimizing torque ripple and copper loss. In order to account for the geometry as well as for the nonlinearity of material utilized, the Finite Element Method (FEM) is used to determine the performance of the machine. The proposed optimization technique is applied to determine optimal pole shape of an 8/6, four-phase, 5 HP, 1500 rpm SRM. The results show the effectiveness of the proposed approach and confirm the application of NSGA-II as a promising tool for solving SRM design problems. The results obtained by NSGA-II are compared and validated with classical multi-objective approach based on weighted sum method using Differential Evolution (DE) algorithm.     

真空干泵用横向磁通开关磁阻电机对比分析

为了解决真空泵用电机工作在真空环境中,转子不易散热的问题,需要严格控制真空泵用电机的温升,从而提高系统运行的稳定性。开关磁阻电机（SRM）转子无绕组,转子损耗较小,整体温升较低,对于提升真空泵用驱动电机的性能具有重要意义。在传统SRM的基础上,设计了一款真空泵用横向磁通SRM,由于定子绕组空间较大,有利于电机散热,进一步减少了定子的损耗,从而降低了电机的整体温升。最后,对同功率、同体积的异步电机、径向SRM和横向磁通SRM进行了温度场、轴承的热应力和热形变的对比分析。结果表明,横向磁通SRM的温升、轴承的热应力和热形变均最小,说明横向磁通SRM作为真空泵用驱动电机的可行性。     

Characteristics of a hybrid‐type switched reluctance motor with salient pole stator

In this paper, we propose a new hybrid‐type switched reluctance motor (SRM) with salient pole stator, which has a pair of permanent magnets attached symmetrically between the iron poles of the rotor. We describe experimental results not only on the basic characteristics of the hybrid SRM, but also characteristics with a current control loop under optimized advanced firing angle and cutoff angle control. Considerable improvement of machine performance, especially in the efficiency and power factor, for the hybrid SRM over the conventional VR‐type SRM is confirmed. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 147(3): 72–79, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10285     

EXPERIENCE WITH DIRECT AND INDIRECT SEARCH METHODS APPLIED TO CAGE INDUCTION MOTOR DESIGN OPTIMIZATION

Abstract

In the present paper low cost cage induction motor design problem is approached using direct search methods, which do not require to calculate the derivatives of the function, and indirect method-a penalty function approach. Induction motor design is considered as a nonlinear, multivariable constrained optimisation problem with ampere conductors per meter, ratios stack length to pole pitch and stator slot depth to width, stator core depth, average air-gap flux density, and stator and rotor winding current densities as variables. The constraints are imposed on the thermal ratings of the machine and on performance indices- Results for same capacity motor with different optimization techniques are tabulated and compared.     

Design Method for Improving Motor Efficiency of Switched Reluctance Motor

The motor efficiencies of switched reluctance motors (SRMs) are inferior to those of permanent magnet synchronous motors. This paper describes a design procedure for an SRM to obtain a higher motor efficiency. The first step in the design procedure makes clear the principle for improving the motor efficiency. The cross‐sectional and axial shapes of the rotor and stator cores are designed by magnetic field analysis with the two‐dimensional (2D) and 3D finite element method. A high‐efficiency SRM with 12 stator poles and eight rotor poles is designed. The designed SRM was produced experimentally, and was tested to verify its performance. The motor efficiency was improved in comparison to the standard SRM with six stator poles and four rotor poles.