In situ calibration of rotating sensor coils for magnet testing

An in situ procedure for calibrating equivalent magnetic area and rotation radius of rotating coils is proposed for testing accelerator magnets shorter than the measuring coil. The procedure exploits measurements of magnetic field and mechanical displacement inside a reference quadrupole magnet. In a quadrupole field, an offset between the magnet and coil rotation axes gives rise to a dipole component in the field series expansion. The measurements of the focusing strength, the displacement, and the resulting dipole term allow the equivalent area and radius of the coil to be determined analytically. The procedure improves the accuracy of coils with large geometrical irregularities in the winding. This is essential for short magnets where the coil dimensions constrain the measurement accuracy. Experimental results on different coils measuring small-aperture permanent magnets are shown.     

Performance of a fast digital integrator in on-field magnetic measurements for particle accelerators

The fast digital integrator has been conceived to face most demanding magnet test requirements with a resolution of 10 ppm, a signal-to-noise ratio of 105 dB at 20 kHz, a time resolution of 50?ns, an offset of 10 ppm, and on-line processing. In this paper, the on-field achievements of the fast digital integrator are assessed by a specific measurement campaign at the European Organization for Nuclear Research (CERN). At first, the architecture and the metrological specifications of the instrument are reported. Then, the recent on-field achievements of (i) ±10 ppm of uncertainty in the measurement of the main field for superconducting magnets characterization, (ii) ±0.02 % of field uncertainty in quality assessment of small-aperture permanent magnets, and (iii) ±0.15 % of drift, in an excitation current measurement of 600 s under cryogenic conditions, are presented and discussed.     

Position and orientation detection of capsule endoscopes in spiral motion

In this paper, a position and orientation detection method for the capsule endoscopes devised to move through the human digestive organs in spiral motion, is introduced. The capsule is equipped with internal magnets and flexible threads on their outer shell. It is forced to rotate by an external rotating magnetic field that produces a spiral motion. As the external magnetic field is generated by rotating a permanent magnet, the 3-axes Cartesian coordinate position and 3-axes orientation of the capsule endoscopes can be measured by using only 3 hall-effect sensors orthogonally installed inside the capsule. However, in this study, an additional hall-effect sensor is employed along the rotating axis at a symmetrical position inside the capsule body to enhance measurement accuracy. In this way, the largest position detection error appearing along the rotating axis of the permanent magnet could be reduced to less than 15mm, when the relative position of the capsule endoscope to the permanent magnet is changed from 0mm to 50mm in the X-direction, from −50mm to +50mm in the Y-direction and from 200mm to 300mm in the Z-direction. The maximum error of the orientation detection appearing in the pitching direction ranged between −4° and +15°.     

在线铁谱仪磁场的优化设计

提出了一种适用于在线铁谱仪磁场的优化设计方法。首先建立结合永磁体与电磁铁的混合磁铁模式,然后设计一种以磨粒所受磁力为依据的衡量磁场性能的目标函数,再采用改进遗传算法和有限元方法对混合磁铁进行了优化设计。以优化结果为依据研制了混合磁铁,并进行了实验测试。结果表明,与磁感应强度相比,所提出的目标函数更适合判断铁谱仪磁场的性能;混合磁铁满足在线铁谱仪的功能要求,体积只有电磁铁的1/3。     

外加磁场对磁流体润滑油膜轴承的影响

为了研究磁流体润滑油膜轴承内磁场的分布情况,分别通过永磁铁、螺线管及亥姆赫兹线圈对其施加3种不同形式的外磁场。通过磁场二维实体有限元模型的数值仿真,分析在3种模型下磁流体润滑油膜轴承的磁场分布特性,并比较磁场在油膜区的分布情况。结果表明,永磁铁模型的磁场主要分布在永磁铁、油膜、轴承座以及靠近磁铁的轧辊部分,螺线管模型的磁场主要分布在油膜、轴承座以及靠近磁铁的轧辊部分,亥姆霍兹线圈模型的磁场主要分布在线圈以及油膜的端部;3种模型在油膜区磁场分布沿轴向均呈现中间小、两端大的不均匀现象,且具有端部效应;永磁铁模型和螺线管模型在油膜区磁场沿径向分布均匀,亥姆霍兹线圈模型沿径向分布不均匀。     

胶囊机器人磁驱动力建模与测量

可吞式无线磁驱胶囊机器人在胃肠道内的诊疗效果与机器人受到的外部磁驱动力密切相关。本文建立了外部磁驱动力的理论模型,基于等效磁荷模型推导了两径向充磁环形永磁体相互作用的数学表达式,采用自适应递归式计算方法开展了数值计算。此外,发展了环形永磁体间磁力实时测量方法,并开发了磁力-间距同步测量仪器开展实验研究,且建立了3D环形永磁体有限元仿真模型。实验测量磁力-间距关系曲线与理论计算和有限元仿真结果吻合较好,误差小于4%,验证了理论模型和有限元仿真模型的准确性和可靠性。通过参数分析,揭示了胶囊机器人内置永磁体长度、厚度和体积对磁力的影响规律。研究结果为精准驱动胶囊机器人在胃肠道内运动奠定了理论基础。     

材料自蔓延合成磁场环境的产生方法及强磁体研制

为了研究磁场环境对自蔓延高温合成的影响,从而利用磁场环境合成出所需材料,本文设计和制作了用于开展磁场环境下自蔓延高温合成(SHS)材料试验的强磁体。通过永磁铁磁场和通电线圈产生磁场的叠加,在实验区域产生特斯拉级强度。其中的关键技术有:同时改变永磁铁磁场方向或通电线圈中电流大小,实现连续改变实验区磁场强度(0~1 T),采用蓄电池供给短时间大电流。与同等强度的传统磁体比较,该磁体重量和成本降低1/10。     

永磁体形性特征对磁水复合支撑式艉轴承润滑特性的影响

螺旋桨重力会导致船舶推进轴系发生挠曲,造成艉轴承边缘润滑状态恶劣。采用一种磁水复合支撑形式的艉轴承,通过引入永磁体磁力作用,改善桨重因素对艉轴承边缘润滑状态的不利影响;构建永磁体三维磁力特性分析方法,探究不同永磁体材料磁性质和布置形式对磁力承载性能的影响规律;基于艉轴承弹性流体动压润滑分析方法,获取永磁体形性特征对润滑特性的影响规律。结果表明：磁承载力受永磁体材料剩磁的影响明显,材料剩磁越大,永磁体承载力越大,轴承润滑状态相对越好;沿周向增加磁块数目或增加永磁块轴向长度可以增大永磁体的承载力,但永磁体承载效率可能下降,设计时需综合考虑;磁体的布置形式也对磁力承载性能和润滑性能影响显著,在永磁体体积相同的情况下,更为合理的布置形式可使永磁体承载力与艉轴承最小水膜厚度明显增大。     

永磁型磁流变液联轴器的磁路设计及性能研究

采用永磁体作为磁流变液联轴器的磁源,设计出一种新型的永磁型磁流变液极限联轴器。磁流变液的工作间隙尺寸远小于永磁体的轴向尺寸,可忽略端部效应,将磁流变液联轴器的磁场求解简化为二维平面磁场。基于磁路设计的基本原理,采用有限元分析软件,对永磁型磁流变液联轴器的磁场分布进行模拟,并研究了不同工作间隙对磁场分布及磁流变液剪切应力的影响,推导出永磁型磁流变液联轴器传递的极限力矩与相关设计参数的关系。     

Measuring the magnetic parameters of the multipole magnets for the specialized MLS source of synchrotron radiation

A metrology light source (MLS) is currently being constructed at the Physikalisch-Technische Bundesanstalt State Metrology Institute (Germany) for work in the range from IR to far UV radiation. The MLS system is composed of a storage ring with a circumference of 48 m for electrons with energies of up to 600 MeV and a 100-MeV microtron. The magnetic system of the storage ring contains 8 dipole magnets, 24 quadrupole magnets, 24 sextupole magnets, and 4 octupole magnets, all designed and produced by the Budker Institute of Nuclear Physics. The radial rotating coil method has been used in magnetic measurements of the multipole magnets. The measuring system is described, and the experimental results are presented.     

高精度DY稳恒磁场测试仪的研制及应用

本文首次将霍尔效应与锁相技术结合起来，制成高精度稳恒磁场测试仪，并采用回归分析法，成功地用于监视器偏转线圈，特别是各种永磁校正元件的磁场分布的测量及分析，能对优化偏转线圈的结构，永磁校正元件的设计工作提供实际的指导。     

整体双层盘式永磁涡流联轴器及其转矩特性分析

基于对传统单层盘式永磁体涡流联轴器的磁路分析,设计了一种整体双层盘式永磁体涡流联轴器。该联轴器将两个单层盘式永磁涡流联轴器的永磁体以N-S对应的方式安装到一块背铁的正反面上,减小了背铁磁阻在磁路中带来的损耗,提高了永磁体的磁能利用率,增大了转矩。通过等效磁路法建立该结构的数学模型,并与有限元法仿真模型相结合,综合分析了其转矩特性。搭建了该永磁涡流联轴器的样机,通过实验验证了上述分析的可靠性。结果表明：所建数学模型准确,并且该联轴器的转矩相对于传统永磁涡流联轴器转矩有较大提高。     

Selecting the Rotor’s Magnetic System in Electromechanical Energy Converters with Highly Coercive Permanent Magnets

The selection of the optimal magnetic system for a quadrupole electromechanical energy converter with highly coercive permanent magnets is considered, in the case of nonsteady operation in generator mode. The type of magnetic system corresponding to different optimality criteria is identified. The eddy-current losses in the highly coercive permanent magnets are analyzed.     

Development of an optimised magnetic field source for flowmeter applications

Sensitivity of a magnetic flowmeter relies on many factors like magnetic field strength, gap between electrodes, material properties, magnet temperature etc. For a given measuring conditions, a strong magnetic field source can produce highest sensitivity for the flowmeter. An economic design of magnetic field source would be to produce the strongest magnetic field from a given amount of magnetic material. In this paper, various magnet configurations are analyzed using FEM and the flowmeter sensitivity using such magnet configurations are compared. It is observed that magnets arranged in a Halbach fashion produce the highest sensitivity for the flowmeter using a given amount of magnetic material. The major challenge for the development of such a magnetic field source is its fabrication from its constituent magnets, combatting their huge attractive/repulsive forces (∼2500 N for our case). Therefore, a specific mechanical tool has been designed for assembling the magnetic field source and a robust assembly technique has been devised using numerical computations. The designed magnetic field source produces a peak magnetic field of 0.78 T in the pole cross section of 50 mm × 50 mm.     

永磁电机退磁电流的仿真与测试

受外磁场、温度场、化学反应、机械振动等因素的影响,永磁电机在运输或工作过程中可能发生不可逆退磁.论文以样机为例,通过有限元的计算和分析,给出了电机退磁电流的计算方法,仿真结果可以以图表或图形等多种方式给出,直观、简洁、易于理解.另外论文还介绍了一种退磁电流的测试方法,结合磁场的有限元分析对永磁电机的退磁电流进行分析,通过验证试验结果与有限元分析非常吻合.为了保证电机在生命周期内的正常运转,在电机设计时应保证永磁体在最严酷的工作环境中各部分的最大去磁工作点应高于拐点位置.     

磁力齿轮内转子护套过盈量计算及其应力分析

针对磁力齿轮中转子在旋转时产生的离心力容易导致表贴式永磁体损坏的问题,将一个高强度过盈配合的保护套应用到永磁体的保护中。对内转子保护套与永磁体间的过盈配合量及其应力的计算方法进行了分析,对一台内转子速度为56 r/min,传动比为8的磁力齿轮,计算了内转子护套和永磁体的应力值以及护套的过盈量,并根据计算出的过盈量利用ANSYS Workbench15.0分析了护套和永磁体的应力,通过建立试验平台对稳定运行一段时间的样机进行了拆分,观察护套效果。研究结果表明:仿真结果接近理论计算值,内转子护套表面光滑无凸起,证明数值计算的准确性,该护套可用于保护永磁体。     

一种基于光纤光栅的非接触式转速测量方法

提出了一种基于光纤光栅的非接触式转速测量方法。将永磁体与磁性材料之间距离-磁力的关系应用于转速传感中从而实现了非接触式转速测量,使用光纤光栅作为传感器件克服了电子类和光学类转速传感器抗电磁干扰能力差、对测量环境要求高的缺点。实验证明该方法是可行的。     

混合式永磁同步电机弱磁性能的研究

针对传统永磁同步电机弱磁性能不佳的问题,提出了应用混合式结构来改善永磁同步电机弱磁性能。研究了传统永磁同步电机的结构,得出了传统永磁同步电机弱磁困难的原因是电枢磁势和转子励磁磁势的不对等。分析了混合式永磁同步电机的结构,得出了其转子永磁体用量少,励磁磁势较小;气隙很小同步电感大,短路电流与额定电流的比值小。介绍了应用短路电流与额定电流的比值来判断永磁同步电机弱磁性能的方法,分析得出了混合式结构弱磁性能要好于传统永磁同步电机。采用了基于直轴电流负向控制的附加闭环方法进行弱磁控制,对传统永磁同步电机和混合式永磁同步电机的弱磁性能进行了对比实验,混合式结构的弱磁扩速倍数为传统式结构的2.63倍。研究结果表明,混合式结构可以有效提升永磁同步电机弱磁性能。     

Quadrupole lenses on the basis of permanent magnets for a PRIOR proton microscope prototype

Four quadrupole lenses based on permanent magnets of the NdFeB material (PMQ) were developed for the imaging section for forming images of the ion-optical system of the PRIOR proton microscope prototype: the effective length of two of them is 144 mm, and the other two are 288 mm long. The field induction at the radius of the lens aperture is 1.77 Т, and the aperture is 30 mm in size. The modular design of the PMQ makes it possible to vary the length of the lenses, compensate for the offset of the magnetic axis from the ion optical axis of the microscope channel, and decrease the variation of the angular position of the magnetic medians. The PMQ magnetic field was adjusted, scanned, and its main characteristics were determined. The 3D mathematical models of the magnetic-field distribution that are obtained as a result of PMQ measurements are intended for the use in calculations of the beam dynamics during adjustment of the ion-optical system of the proton microscope and for attaining the highest spatial resolution. The developed lenses were used in the first experiments on the PRIOR facility.     

基于杂散磁场感知与NBCNN-LSTM-Attention深度回归建模的永磁直线电机气隙磁密测量研究

本文提出一种基于隧道磁阻(TMR)传感器和噪声注入卷积神经网络(NBCNN)、长短期记忆网络(LSTM)、注意力机制动态集成神经网络预测模型(NBCNN-LSTM-Attention)的双边永磁同步直线电机气隙磁密新型非侵入式测量方法。首先，建立直线电机气隙磁场的解析模型和有限元模型作为数据基础，探寻直线电机的外部空间杂散磁场和内部中心气隙磁场存在非线性映射关系。其次，引入TMR传感器测量直线电机外部杂散磁场信号，并对传感器的安装位置进行优化，将内外一维磁密信号进行相似度特征匹配，以获取传感器最优测量位置。然后，将电机外部杂散磁场数据作为输入，内部气隙磁场数据作为输出，建立NBCNN-LSTM-Attention网络的内外磁场高精度映射模型，实现“用外代内”的非侵入式气隙磁密高精密测量。最后，搭建直线电机气隙磁密测量实验平台和高斯计对比测量实验平台，验证了本文所提方法的先进性和优越性。