Three‐dimensional array of strong magnetic field by using cubic permanent magnets

The strong magnetic field arrays by using cubic permanent magnets are proposed as a magnetic field source. The magnets used two types of the magnetized directions: 6 and 18 directions. The array is three‐dimensional structure: cube consisting of three, five, seven, and nine cubic magnets on the side. There are two types of the structures: through‐hole and dead end in the center. For each cube magnet, the magnetic flux density of the center was calculated by the derived formulae, which are solved the area integral by the integral formulae. It is a feature that the calculations are fast. The directions in which the magnetic flux density of the z‐axis is maximized were selected, and the sum of their magnetic flux density was obtained. At the same time, each sum of the magnetic flux density of the x‐axis and y‐axis was selected to be zero. It was found that the obtained results are independent of the length of one side. Therefore, the structures can also be combined to cover the structures. Although the operating point of the magnet is not taken into account, it was able to find the arrangements of more than 2 T. It was confirmed that the array of 24 cubes was consistent with the experiment.     

基于操作功最优的永磁机构参数控制优化

以永磁机构分、合闸操作功与真空断路器开断性能要求匹配最优为目标,基于四连杆传动规律将12 kV真空断路器本体及传动机构的反力特性归算至永磁机构的运动部件动铁芯上,构建永磁机构操动特性数学模型。利用ANSYS-Maxwell仿真得到配永磁机构真空断路器的动铁芯位移、线圈电流、电容电压变化曲线等操动特性,计算出机构平均合闸速度、操作功等参数。以真空断路器操作功最优为目标函数,以线圈匝数、线径、操动电流为约束条件,在仿真的基础上建立正交回归实验,利用遗传算法对线圈参数进行优化设计,并通过实验进行验证。结果表明,在保证永磁机构操动特性满足真空断路器动作特性需求条件下,线圈优化设计后的永磁机构操作功从970.41 J降低到362.26 J,降低了动铁芯碰撞速度,提高了机构的稳定性。     

永磁机构在空气式断路器中可行性分析及其MATLAB仿真*

提出了一种新型的永磁机构(PMA)代替之前运用在空气式断路器(ACB)中弹簧机械机构的模型.通过有限元分析法分析永磁机构在开闸与合闸位置各种情况的磁场情况,然后根据仿真结果优化计算结果,并将计算好的电磁参数导入到以MATLAB为基础的仿真系统中.MATLAB联合仿真通过模拟PMA合闸与分闸过程,以及对仿真数据的分析,最后认可了PMA能够对空气式断路器的开合过程进行有效的控制,并且展现出了比传统弹簧机械结构更好的优越性.     

新型四线圈双稳态永磁操作机构的研究

为了解决大行程永磁操作机构设计时出现的分、合闸始动电流过大及刚分速度不满足要求的问题,本文首次提出了四线圈双稳态永磁操作机构的概念.理论分析和试验证明,这是一种可行的方法.关键在于要恰当设计分、合闸解锁线圈匝数的比例,不同的永磁操作机构需要的分、合闸解锁线圈匝数的比例是不同的.另外,本文提出了一种很容易实现的四线圈双稳态永磁操作机构的主回路控制方案.     

真空断路器永磁操作机构控制器保护电路元件参数优化设计

根据真空断路器双稳态双线圈永磁机构操作控制器的典型结构,给出了建立其归一化电路的方法.基于归一化参数的机构操作控制器主电路模型,分别讨论了缓冲电路的元件参数、续流回路的元件参数对电力电子开关器件电流、电压冲击的关系,得出了相关的计算曲线.以过电流、过电压倍数及其过渡过程时间为优化指标,针对实际样机,对其设计参数进行了电...     

12kV真空断路器半双稳态永磁机构的设计

应用于真空断路器的永磁操动机构一般分为双稳态和单稳态永磁机构。对于单稳态永磁机构,通过调整分闸弹簧在分闸位的预拉力,可以实现对分闸特性的调节。增大预拉力可以缩短分闸时间,降低分闸弹跳,但预拉力过大会导致合闸状态时的保持合力减小,可能造成合闸的不可靠,也会对合闸动态特性造成不利影响,如合闸时间增加等。本文提出了应用于12kV真空断路器的半双稳态永磁机构的设计方法,该机构在分闸状态由较小的永磁保持力和弹簧力共同实现分闸保持。分闸位保持力大有助于抑制分闸弹跳,同时永磁保持力在动铁芯离开分闸位置后迅速减小,对合闸保持以及合闸动态特性几乎没有不利影响。利用Ansoft Maxwell软件建立永磁机构模型,进行静态和动态的仿真。根据设计结果制作实际样机,对其进行测试,实验结果验证了设计与仿真的正确性。     

一种磁悬浮永磁直线电动机的电磁力特性

为消除直线电机数控机床进给系统的摩擦阻力,提出一种自身产生磁悬浮力的磁悬浮永磁直线同步电动机.从描述磁介质的分子环流假设出发,用毕奥-萨伐尔定理导出永磁体外部空间磁场分布的解析表达式,并基于由磁荷法和虚位移法给出的永磁体磁力数值积分公式,椎导出电机悬浮力波动的解析模型,说明斜极对电机悬浮力的影响.利用Maxwell 3D软件建立三维有限元瞬态分析模型,结果证明该磁悬浮永磁直线电动机自身可以产生独立并可控的推力和悬浮力.进一步建立斜极结构下电动机的三维有限元模型,分析结果表明采用斜极结构可以有效的减小电机推力和悬浮力的波动.     

智能真空断路器上的永磁操动机构静态保持力验证

在建立永磁操动机构数学模型的基础上，采用有限元分析方法对永磁操动机的保持力进行计算，并对其进行试验测量。对理论计算和试验测量的结果进行对比分析，可看出，有限元法能有效解决区域形状不规则的问题，可用统一的格式处理各种单元和不同的边界条件，并可编制出通用的计算程序，有限元法对于非线性问题及材料和结构参数复杂的问题均十分有效，使用该方法对永磁操动机构进行分析能为新产品设计提供有益的参考和依据。     

配永磁机构真空断路器操动时间分散性的预测模型与影响因素研究

针对现有模型存在的难以实现多场充分耦合的问题，提出了一种对配永磁机构真空断路器动作时间进行预测的新模型。该模型考虑励磁变化和运动部件速度效应带来的涡流影响，实现了永磁操动机构的复杂机械运动、电子瞬态电路与瞬态磁场的多场耦合分析。基于该模型，对某型号配永磁机构真空断路器的动作时间进行了预测，实验证明所提方法是正确的。在此基础上，利用模型分析了励磁电压、环境温度、铁心材料和励磁方式等因素对永磁操作机构动作时间分散性的影响，并研究了各因素对动作时间分散性的影响机理。     

Optimization of the magnetic system of a brushless DC motor with rare-earth permanent magnets

This article discusses the causes of cogging torque pulsations in a deenergized brushless dc motor (BLDC) with a tooth stator and magnetoelectricity stimulation. Based on the causes that we identify, we propose a method of reducing cogging torque pulsations in order to improve the rotation speed uniformity of a BLDC. The method is based on optimization of the number of stator slots, which determines the type of stator winding for a given number of poles in magneto-electric machines. For the maximum possible reduction of cogging torque pulsations, it is proposed to bevel the stator slots at an angle divisible by the main tooth harmonic period. All analytical calculations were performed with the use of numerical methods for mathematical modeling of the magnetic field in the magneto-electric machines with the use of Elcut specialized software. Based on the calculation results, recommendations for the design of a BLDC with a minimum level of cogging torque pulsations were elaborated. Our theoretical studies have been checked by experimental investigations of a DBM 142-18-3 motor and applied to the design of the BLDC (DBM series) manufactured by JSC Electroprivod, Kirov. Electric motors of DBM series are used as precision electric drives for metalworking equipment, where a high uniformity of rotation speed is a major requirement.     

盘式永磁Halbach悬浮装置的磁场和力特性分析

针对电磁式(EMS)磁悬浮实现稳定悬浮需要复杂的闭环控制和悬浮气隙较小等问题,提出的盘式永磁Halbach悬浮装置是一种电动式(EDS)磁悬浮系统,具有悬浮气隙大和不需要复杂的闭环控制即可实现稳定的悬浮等优点.盘式永磁Halbach悬浮装置通过永磁体和导体板上感应出的涡流相互作用产生悬浮力和转矩.从电磁场理论出发建立悬浮装置的分环电磁模型,采用拉普拉斯分离变量方法进行磁场分布求解,并直接利用磁场分析所得的磁场分布结果求解次级悬浮力和水平转矩,给出磁悬浮装置的力特性与其参数的关系,证明在一定的相对速度下,装置可以输出足够大的悬浮力.建立有限元模型,通过分析得出系统的磁场分布以及电磁力等的分析结果;搭建实验平台对永磁电动式系统的基本特性进行研究,主要是悬浮力和转矩的测试;利用有限元计算和样机实验验证理论分析和计算结果的正确性.     

A salient‐pole synchronous generator with permanent magnets between the field poles

In this paper, a new salient‐pole synchronous generator (SG) termed the PMa‐SG is presented. In the PMa‐SG, permanent magnets (PMs) are placed between the pole shoes to reduce the magnetic saturation in the field poles. By using finite element analysis (FEA), the internal magnetic fields and basic characteristics of a 2.8‐MVA PMa‐SG are compared with those of a conventional SG of the same size, and the reduction effect of the magnetic saturation of the PMs is examined. The FEA simulations are also validated by experiments on a 2.0‐kVA prototype machine. The PMs placed between the pole shoes reduce the magnetic saturation in the pole bodies and pole tips and effectively increase the terminal voltage and output power. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 174(4): 58–67, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21132     

Formulation and mixing conditions of magnetic composite materials used for magnetic wedges in an interior permanent magnet synchronous motor

An interior permanent magnet synchronous motor (IPMSM) is characterized by its high efficiency. However, torque ripple and loss occur because of the spatial harmonics generated by air-gap permeance fluctuations. This study clarified that slot harmonic components can be suppressed by inserting magnetic wedges made of magnetic composite material in the slot opening of an IPMSM. First, the authors examined the torque and loss characteristics by varying relative permeability and saturation magnetic flux density of magnetic wedges using finite element analysis (FEA). Results indicated that the torque ripple and loss could be suppressed when the relative permeability of the magnetic wedge was μ_r = 10 to 22 and the saturation magnetic flux density was B_s = 0.5 to 0.75 T. Furthermore, the authors produced magnetic composite materials made of various soft magnetic material powders and examined their magnetic properties and viscosities. Results showed that a magnetic composite material with optimal magnetic properties and injectable viscosity could be manufactured using Fe-Si-Al with a low volume fraction.     

Analytical and numerical computation of air-gap magnetic fields in brushless motors with surface permanent magnets

This paper extends the theory of the air-gap magnetic field in permanent-magnet (PM) brushless motors. Scalar and vector potential solutions to the field equations are brought together to unify many of the important practical methods already in use. The theory admits a more general representation of the magnetization vector than has been previously assumed, including both the radial and tangential components, and variation with radius. The work is applied in the design of PM motors where there is a requirement to minimize noise and torque ripple, and maximize efficiency, and a continuing need for improvements in the accuracy and rigor of design calculations. The air-gap flux-density distribution is at the heart of the design process, and it is desirable to study different magnetization patterns, including imperfections in the magnetization, for a wide range of magnet shapes. This paper shows the application of the analytical solutions in comparison with a new finite-element procedure, with test results on a prototype motor, and with simpler, older methods of calculation based on magnetic equivalent circuits. The comparison brings out many interesting points in relation to the accuracy and the speed and practicality of the various methods.     

取向磁场和磁粉种类对塑料粘结磁体磁性能的影响

将聚酰胺12(PA12)基体分别与体积分数为50%的各向异性锶铁氧体磁粉(SrFeO)和钐钴磁粉(Sm2Co17)用双螺杆挤出机熔融混合并造粒,使用注塑成型机在内置取向磁场的模具中注塑成型,制备粘结磁体.结果表明,对于由各向异性磁粉制作的塑料粘结磁体,取向磁场对试样的磁性有明显的影响,取向磁场增高,试样的剩磁明显增大....     

利用场路结合方法分析磁轴承悬浮力

针对磁轴承悬浮力分析比较复杂的问题,提出利用场路结合分析磁轴承悬浮力的方法.基于磁路法推导了径向磁轴承悬浮力的线性化模型,针对具体的磁轴承系统,利用有限元法分析了磁轴承能够满足线性化模型的偏置电流选择范围和磁轴承转子偏移范围,通过最小二乘法修正了线性化模型的电流刚度系数和位移刚度系数,并对超出线性化模型范围的悬浮力进行...     

Reluctance control magnetic suspension system—suspension system with permanent magnet and linear actuator

A new type of magnetic suspension system is proposed which uses a permanent magnet. In this system, the attractive force is adjusted by controlling the reluctance of the magnetic circuit. Since no electromagnet is necessary, this system is effective for saving energy and avoiding heat generation. The composition of this paper is as follows. First, the principle of this suspension system is explained and various types of magnetic circuits are introduced for reluctance control. Second, the possibility of one of them is examined from the viewpoint of linear control theory. Third, an experimental device is developed based on the proposed suspension method. The reluctance of this device is controlled by the air gap which is between the magnet and the suspended object, and which is adjusted by driving a permanent magnet by piezoelectric actuator. Experimental results support the theoretical predictions well.     

轴向电磁轴承多自由度承载力理论与实验研究

为了实现磁悬浮轴承系统的微型化,对轴向电磁轴承的多自由度承载力进行理论与实验研究。基于轴向磁轴承气隙磁通空间分布,利用分割磁场法建立磁路模型,由虚位移法得到轴向和径向承载力的数学表达式。借助有限元仿真软件,得到轴向磁轴承气隙磁感应强度与磁场空间分布。在搭建的磁轴承三维力学测量平台上,实验测量了轴向磁轴承的轴向与径向承载力,分析总结了多自由度承载力随电流、轴向位移和径向位移的变化规律,结合理论与仿真结果,分析了结构参数变化导致气隙磁场分布变化,进而改变轴向与径向承载力的物理机理,为轴向磁轴承实现多自由度悬浮研究提供了参考依据。     

磁场热处理对Sm_2Co_(17)磁体磁性能及微结构的影响

2:17型SmCo永磁体由于其优异的高温特性,而作为高温磁体广泛应用于航空航天、能源、医疗等高科技领域,而新技术的发展对于2:17型SmCo永磁体的磁性能提出了更高的要求,磁场热处理是一种改善磁体磁性能的有效方法。研究了磁场热处理温度及时间对2:17型SmCo永磁体磁性能和微结构的影响,并考察了相应的磁畴和微观结构。实验结果表明,当磁场热处理的温度为400℃、热处理时间为1 h时,并在磁场中冷却,磁体的综合性能最好,剩磁Br为10.99 kG,提高了5.17%,矫顽力Hcj为1545.04 kA/m,提高了16.93%,最大磁能积(BH)max为223.84 kJ/m~3,提高了10.19%,并且磁畴尺寸细化变窄,矫顽力有显著提高。