A method of determining the advanced angle of square-wave currentsin a bearingless switched reluctance motor

Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. These motors have combined the characteristics of switched reluctance motors and magnetic bearings. This paper proposes a method of determining the advanced angle of square-wave currents in a bearingless switched reluctance motor. Under any torque condition, from no load to full load, stable operation is realized by controlling the advanced angle of square-wave currents with the proposed method. It is shown experimentally that the proposed method is effective in realizing stable operation     

Improved analysis of a bearingless switched reluctance motor

Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. Bearingless switched reluctance motors have combined characteristics of switched reluctance motors and magnetic bearings. Production of radial force for rotor shaft magnetic suspension is explained with differential stator windings. Mathematical relations between motor currents and radial force are derived by considering cross coupling and fringing fluxes. Theoretical relationships are verified with experimental results at partial overlap positions     

Torque and suspension force in a bearingless switched reluctance motor

Bearingless switched reluctance motors, which can control rotor radial positions with magnetic force, have been proposed. The bearingless switched reluctance motors are characterized by integration of switched reluctance motors and magnetic bearings. These motors have two kinds of stator windings composed of motor main windings and suspension windings in the same stator in order to produce suspension force that can realize rotor shaft suspension without mechanical contacts or lubrication. For successful stable operation, accurate theoretical formulas of instantaneous torque and suspension force are necessary to a rotational speed controller and a rotor radial position controller. This paper derives the theoretical formulas of the instantaneous torque and the suspension force from an assumption of simple permeance distribution. This derivation process makes an assumption that fringing fluxes are distributed on elliptical lines. It is shown with experimental results that the derived theoretical formulas are very accurate in terms of practical application. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(2): 72–82, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20157     

无轴承开关磁阻电机麦克斯韦应力法数学模型

针对已有基于虚位移法的无轴承开关磁阻电机数学模型推导复杂的缺限,从麦克斯韦应力法角度出发,建立了考虑电机磁饱和特性的数学模型。在大电流饱和状态下,该模型有效地描述了电机产生的径向悬浮力和电磁转矩。利用有限元分析的方法验证了该模型的优良特性。试验结果显示利用该模型能够很好地实现电机稳定悬浮,表明采用麦克斯韦应力法建模的正确性和可行性。该方法的应用为研究无轴承开关磁阻电机电磁力分布提供了新的思路。     

无轴承开关磁阻电机磁饱和特性的电磁场分析

阐述了无轴承开关磁阻电机径向悬浮力产生的原理,考虑电机内复杂的磁场饱和情况,定性分析了主、副绕组电流大小对悬浮力的影响.计及磁场饱和,建立了无轴承开关磁阻电机的有限元分析模型,以一台3kW样机为例计算了各种主、副绕组电流组合时的转矩与悬浮力.数值计算结果验证了定性分析所得结果,表明无轴承开关磁阻电机在运行中存在比传统开关磁阻电机更加复杂的磁饱和现象,磁饱和使得电机悬浮力与绕组电流关系严重非线性,而且悬浮力大小并非总是随绕组电流的增加而增加,存在随电流增加悬浮力减小的情况,这必然给稳定悬浮控制带来困难.     

开关磁阻轮毂电机非线性建模及驱动控制仿真

针对开关磁阻轮毂电机气隙偏心产生的不平衡径向力对车辆平顺性造成的不利影响,提出一种基于电流斩波的脉冲调制控制（PWM）的方法抑制开关磁阻轮毂电机不平衡径向力,从根本上改善车辆平顺性。首先通过Ansoft Maxwell 对一台8/6极四相开关磁阻电机进行有限元分析,在获取电机特殊位置电感数据的基础上,采用傅里叶级数拟合的方法建立开关磁阻电机非线性模型,并与有限元分析结果做对比验证了该模型的准确性。在此基础上建立开关磁阻轮毂电机驱动模型和轮毂电机驱动电动汽车机电耦合一体化模型,将所提出基于电流斩波的PWM控制方法与传统电流斩波控制方法对车辆平顺性影响做对比,仿真结果显示基于电流斩波的PWM控制方法能有效降低开关磁阻轮毂电机不平衡径向力的大小,在提高电机输出转矩的同时改善轮毂电机驱动电动汽车平顺性。     

宽转子无轴承开关磁阻电机的转子极形优化

为了解决宽转子无轴承开关磁阻电机由于开关型供电方式以及双凸极铁心结构在运行过程中容易导致转矩脉动很大的问题,本文对其转子极结构进行改进,提出在转子极两侧开槽的优化设计方案。旨在通过增大开槽处的气隙磁阻,提高用于产生转矩的切向分量的气隙磁密,从而降低转矩脉动。对所开槽进行参数化处理,使用控制变量法分析各开槽参数对转矩性能的影响,以性能指标最优为目标确定开槽参数。利用场路耦合的方法将电机有限元分析模型和直接瞬时转矩控制电路模型结合起来,实现电机系统的动态运行。仿真结果表明转子极开槽后能够有效降低宽转子无轴承开关磁阻电机的转矩脉动,提升平均转矩,并且对径向悬浮力的影响很小。     

一种无轴承开关磁阻电机独立控制策略

基于无轴承开关磁阻电机中平均转矩和径向悬浮力之间独立控制的思想,研究了一种新型的控制策略。其中主绕组电流单、双相交替工作,悬浮绕组电流固定开关角轮流导通15°,实现无轴承电机转矩和悬浮的独立控制并建立该控制策略下的瞬时转矩、平均转矩和径向悬浮力的计算公式,阐述电机控制参数和控制依据,分析了该控制策略的工作区域。仿真和实验结果均证实了理论分析的正确性和可行性。     

磁悬浮开关磁阻电动机转子径向偏心时的仿真

磁悬浮开关磁阻电动机结合了开关磁阻电动机和磁轴承的特点,通过电磁力控制转子径向位置。分析了磁悬浮开关磁阻电动机悬浮力和旋转力的产生原理。基于开关磁阻电动机转子的四个特殊位置,利用二维有限元方法分析了转子位于中心位置与有径向偏心时的电机内部磁场,给出了磁场分布图、径向悬浮力与径向偏心矩的关系曲线、旋转力与径向偏心矩的关系曲线,为进一步描述磁悬浮开关磁阻电动机悬浮力与旋转力的模型提供了依据。     

Radial Force Analytic Modeling for a Novel Bearingless Switched Reluctance Motor When Considering Rotor Eccentricity

Abstract—Analytic modeling of radial forces is proposed for the novel bearingless switched reluctance motor, where the rotor eccentricity is taken into account. The novel bearingless switched reluctance motor's model is never disclosed, even though there are many advantages, such as fewer suspension windings and simpler control circuit and algorithm, when compared to the conventional bearingless switched reluctance motor. The analytic model of radial forces is very important to achieve this new bearingless switched reluctance motor's suspension control. The rotor eccentricity is a key cause to affect the radial forces. This article calculates the air-gap permeances through considering rotor eccentricity. The self-inductance and mutual-inductance expressions of the motor torque windings and the suspension windings are derived by using the magnetic equivalent circuit method. The derived radial force model discloses the effects of winding currents, rotor position angle, and rotor eccentricity displacement. The finite-element analysis based results verify the built model.     

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.     

Unbalanced Magnetic Force Mitigation and Torque Ripple Reduction in Eccentric Switched Reluctance Motors Using Flux Leakages

Abstract—In this article, a comprehensive method is introduced to redress eccentricity fault consequences. Two main effects of eccentricity faults include considerable increase in unbalanced magnetic force and torque ripple. Dependency of unbalanced magnetic force and torque ripple on eccentricity fault level is shown, and the possibility of compensating them via controlling currents in facing poles is proved. These objectives are accomplished through a novel converter that controls currents in poles of every phase such that one pole is responsible for nullifying unbalanced magnetic force and the facing pole is in charge of torque ripple reducing. The control algorithm is analyzed in details and through finite-element method and MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA) is implemented on a 6/4 switched reluctance motor with 30% eccentricity fault level. The proposed strategy samples the flux leakage as the index both for occurrence and criterion for compensation of unbalanced magnetic force. The suggested method is designed such that there is no need to detect eccentricity fault direction, location, and type, which makes it cost effective and practical for a wide range of switched reluctance motors and applications.     

无轴承开关磁阻电机磁场及力特性的分析

分析了无轴承开关磁阻电机(SRM)径向悬浮力产生原理.考虑磁饱和,以非线性磁化曲线为基础,建立了无轴承SRM的ANSYS有限元二维模型,对一台原理样机进行了电磁场分析,计算了转矩与悬浮力特性.将计算结果与采用线性磁化曲线时的有限元结果进行了比较,结果显示出考虑磁饱和的必要性,同时为样机的有效控制奠定了基础.     

一种新型定子齿极结构的开关磁阻电机电磁分析

给出了一种新型定子齿极结构的开关磁阻电机(SRM)的设计,利用径向力、电磁转矩的解析计算公式,完成了外圆弧形定子磁极结构SRM电磁力特性的计算.计算结果表明,新型结构的定子设计在保证定子极和转子极间切向电磁力基本不变的情况下,大大减小了径向电磁力,这对优化设计SRM结构参数,降低电机运行噪声,延长了电机寿命方面有重大的指导意义.     

新型混合励磁磁悬浮开关磁阻电机基础研究

为了实现磁悬浮开关磁阻电机(BSRM)转矩和悬浮力的自然解耦,提出了一种新型混合励磁磁悬浮开关磁阻电机(HEBSRM)。新型HEBSRM由12/14极BSRM、环形永磁体和径向磁轴承三部分组成。12/14极BSRM的转矩极和悬浮极之间嵌有隔磁环,使转矩磁通路径完全独立于悬浮磁通路径,从而在结构上实现转矩与悬浮力解耦。此外,详细推导了电机径向悬浮力的数学模型,并且通过有限元分析验证了新型HEBSRM结构的合理性。     

径向力激发噪声最小的开关磁阻电动机开关角优化

开关磁阻电机噪声主要是其径向力波使二阶振型模态产生偏移引发的.针对开关角是开关磁阻电机中两个最为重要的控制参数的特点,提出了开关磁阻电机电压PWM控制方式下开关角的两次在线寻优方法.寻优原理以径向力激发的二阶振型模态最高噪声声级最小为目标,并依据寻优步长不同实行两次优化搜索.仿真结果表明,两次在线寻优的开关角能使开关磁阻电机运行时激发的二阶振型模态最高噪声声级显著降低,从而使得整体噪声减小.     

基于神经网络逆系统的磁悬浮开关磁阻电动机的解耦控制

磁悬浮开关磁阻电动机作为一个多变量、非线性和强耦合的系统,其控制系统的设计非常复杂.对于磁悬浮开关磁阻电动机来说,得到径向力和平均转矩的先验知识是实现电机闭环控制的基本条件.基于基本电磁场理论,论文给出磁悬浮开关磁阻电动机的径向力模型,对该模型进行可逆性分析,证明该系统可逆,应用神经网络逆系统方法实现径向力的动态解耦,以便达到高性能的控制目的,仿真结果验证了方法的可行性.     

磁悬浮开关磁阻电机多目标优化设计

研究了一种基于极限学习机(extreme learning machine,ELM)与带精英策略非支配排序遗传算法(improved non-dominated sorting genetic algorithm,NSGA-II)的单绕组磁悬浮开关磁阻电机(single winding bearingless switched reluctance motor,SWBSRM)多目标优化设计方法。结合有限元分析(finite element analysis,FEA),分析了SWBSRM悬浮力、转矩随各结构参数变化的一般规律,得到ELM非参数模型。针对该训练模型并结合NSGA-II进行全局寻优,获得使悬浮力、转矩同时更优的结构参数数值组合。通过对比优化前后电机输出悬浮力、转矩大小,验证了以ELM、NSGA-II为基础的SWBSRM结构多目标优化设计的有效性。     

基于有限元法的磁悬浮开关磁阻电机数学模型

当电机高速运行时，为避免机械磨损，采用电磁力进行悬浮支撑，而磁轴承占用轴向空间，限制临界转速。磁悬浮开关磁阻电机利用电机定子与轴承机械结构的相似性，在原有的电机定子绕组上附加一套径向力绕组，通过一定的控制策略，同时实现电机的旋转和悬浮。该文在利用有限元软件Ansoft/ Maxwell 2D分析磁悬浮开关磁阻电机磁场的基础上，结合等效磁回路法并根据虚位移定理，推导出磁悬浮开关磁阻电机在考虑a、b轴方向径向偏移及其耦合时的径向力和转矩的数学模型，并用有限元分析结果验证了该模型的正确性和有效性。     

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.