磁性磨具光整加工中基于Halbach Array的磁场设计与实验研究

目的提高磁性磨具表面光整加工技术对30CrMnSi高强度结构钢表面的加工效率,解决以往永磁式磁性磨具光整加工中磁场强度弱、磁能利用率低的问题。方法首先对30CrMnSi导磁工件的材料去除机理进行分析,探讨了磁感应强度B对工件材料去除的重要性。然后基于海尔贝克阵列(Halbach Array)进行了磁场的设计,通过理论计算和仿真分析,确定了永磁单元尺寸和磁场布置方案。最后以自制粘接性磁性磨料,对30CrMnSi板材进行单因素光整加工实验。结果根据磁场计算和仿真结果,确定了Halbach Array永磁阵列两个周期为最佳的磁场布置方案,并获得了理想的磁场强度和最佳的磁场分布。对30CrMnSi板材的加工实验表明,粗糙度下降百分比(%ΔRa)随着磁极转速和磨粒目数的增大而增大;磁性磨料中铁磁相与磨粒相质量比为3∶1、磁极转速为500 r/min、磨粒目数为240目时,加工效果最好,获得了Ra=0.129μm的表面,粗糙度最大下降百分比为90.74%。结论使用HalbachArray的方法对永磁场进行设计,可以增大加工区域的磁场强度并改善磁场分布,从而提高对30CrMnSi高强度结构钢表面的加工效率。

Characteristics Investigation of Single-Sided Ironless PMLSM Based on Halbach Array for Medium-Speed Maglev Train

This paper investigates characteristics of ironless permanent magnet linear synchronous motor(PMLSM)based on Halbach array used for medium-speed(200km/h)maglev train.Long primary ironless coil is laid in the middle of track and the Halbach permanent magnet array is attached to the bottom of each bogie as a source of traction,U-shape electromagnets at the both sides of the train for levitation.Two dimensional analytical model of single-sided ironless PMLSM based on Halbach array is established,using linear overlay method,the no-load air gap magnetic field is calculated firstly,winding current density distribution is obtained for calculating the characteristics of thrust and normal force against power angle,including force characteristics with equal and unequal pole pitch,the influence of steel sleeper,etc.Besides,the mathematical model for this type motor is built by 3D finite element method,the traction characteristics of medium-speed maglev under maximum speed 200km/h are calculated.The characteristics of this type motor are satisfactory owing to there is no detent force in the motor and thrust force reach maximum meanwhile normal force can be eliminated.Calculation method is verified by comparing finite element results,experimental result on a 200kW type motor further validates the accuracy of calculation and some important conclusions are obtained.

Magnetic field of mathematical modeling and simulation of 3D magnetic pole array spherical actuator

In this paper a new spherical actuator is designed and its advantages are compared to an existing spherical actuator, which function is limited by several design bottlenecks. First the output torque is too small. Second, the attitude is difficult to be accurately detected. The new three-dimen- sional magnetic pole array can solve these major problems. The new actuator features an outer rotor with multiple permanent magnet （PM） poles. Using an analytical solution and the finite element so- lution simulation, the feasibility of the approach is verified. A prototype was developed, tested, and experiments were conducted to obtain the practical value of the magnetic flux density.

基于永久磁铁的直线运动单元设计

以最大程度的降低直线运动单元在运动中的摩擦磨损为研究目的,设计了一种基于永久磁铁的新型直线运动单元。直线运动单元采用海尔贝克磁铁新型结构,利用永久磁铁的引力和斥力共同作用的方式实现运动运动单元的稳定悬浮。所设计的新型运动单元实现了运动过程中的零损耗和超低噪声,提高了运动单元的运动精度和可靠性,具有广阔的实际应用前景。

Loss Analysis of Magnetic Gear with Slotted in Magnetic Modulation Ring

In order to improve the operation efficiency of coaxial magnetic gear(CMG),in this paper,a CMG model with slotted in magnetic modulation ring is proposed.In this model,the permanent magnets(PMs)of internal and external rotors are distributed in Halbach array,the inner rotor PMs are equally divided into 3 small pieces,and the outer rotor PMs are equally divided into 2 small pieces.At the same time,the static magnetic modulation ring iron blocks are slotted,each iron block has 3 slots,the width of the slot is 0.4°,and the depth of the single side slot is 1mm.Finally,a two-dimensional model is established,and the eddy current loss and iron loss of the model are optimized,compared with the conventional CMG model,it is found that the changed pattern can increase the internal and external output torque by 4%and 4.12%,respectively.The eddy current loss is reduced by 66.57%,and the iron loss is reduced by 8.9%,which significantly improve the operation efficiency of the CMG.

Design of a PCB stator coreless axial flux permanent magnet synchronous motor based on a novel topology Halbach array

A novel topology Halbach permanent magnet array is proposed and applied to the design of a printed circuit board(PCB) axial flux permanent magnet(AFPM) motor. Compared with the traditional coreless AFPM motor, this novel topology for a Halbach permanent magnet array PCB stator AFPM motor has larger air-gap magnetic flux density and air-gap flux per pole. The magnetic flux leakage is effectively reduced, and the air-gap magnetic density is close to the sine wave. Results of the finite element analysis and prototype experiments verify the feasibility and effectiveness of the novel Halbach permanent magnet array PCB stator motor. A reference basis and practical value for the design of the PCB AFPM motor are provided.

Characteristic and Thermal Analysis of Permanent Magnet Eddy Current Brake

In this paper,the subdomain analysis model of the eddy current brake(ECB)is established.By comparing with the finite element method,the accuracies of the subdomain model and the finite element model are verified.Furthermore,the resistance characteristics of radial,axial,andHalbach arrays under impact load are calculated and compared.The axial array has a large braking force coefficient but low critical velocity.The radial array has a low braking force coefficient but high critical velocity.The Halbach array has the advantages of the first two arrays.Not only the braking force coefficient is large,but also the critical speed is high.The parameter analysis of the Halbach array is further carried out.The inner tube thickness and air gap length are the sensitive factors of resistance characteristics.The demagnetization effect is significantly enhanced by the increase of the inner tube thickness.In order to ensure that the ECB does not overheat,the electromagnetic-thermal coupling model is established based on the heat transfer theory.The temperature rise of the inner tube is obvious while that of the permanentmagnet is small.The temperature rise of the inner tube is more than 20 K each time,and that of the permanent magnet is less than 1 K each time.

Analysis of the Comprehensive Physical Field for a New Flywheel Energy Storage Motor/Generator on Ships

A novel flywheel energy storage （FES） motor/generator （M/G） was proposed for marine systems. The purpose was to improve the power quality of a marine power system （MPS） and strengthen the energy recycle. Two structures including the magnetic or non-magnetic inner-rotor were contrasted in the magnetostatic field by using finite element analysis （FEA）. By optimally designing the size parameters, the average speed of FEA results of was 17 200 r/m, and the current was controlled between 62 and 68 A in the transient field. The electrical machine electromagnetism design was further optimized by the FEA in the temperature field, to find the local overheating point under the normal operation condition and provide guidance for the cooling system. Finally, it can be concluded from the comprehensive physical field analysis that the novel redundant structure M/G can improve the efficiency of the M/G and maintain the stability of the MPS.

Study on a New High Frequency Moving Coil Permanent Magnet Linear Motor

In order to improve the characteristics of a conventional moving coil permanent magnet linear motor （MCPMLM）, such as weak points on export force, response time, response speed, we studied a permanent magnet （PM） structure that is a key component of MCPMLM. Different magnetization techniques of single PM and differ- ent array structures of multiple PMs are compared, and a new MCPMLM magnetized along the external field force lines wing eight pieces of a tegular Halbach magnet array with air gaps is proposed as well. The analysis on magnetic field and experimental results of MCPMLM demonstrates that the force between the coil and the PM increases by more than 40%. The simulation frequeney is close to 350 Hz at -3 dB , and the response time is O. 005 s. In addition, the experiment frequency reaches 300 Hz at -3 dB and the response time is 0. 004 s, which agrees well with the simulation results. It means that the developed MCPMLM enjoys advantages in high frequency and rapid response, and can satisfy the requirements of a high speed electro-hydraulic proportional valve.

Assembling and Test of a Halbach Array Magnet System for Lorentz Forece Velocimetry in Electrolytes

The paper presents a Halbach array magnet system(HAMS)for the application within a very first Lorentz force velocimetry(LFV)experiment for electrolytic flows.Here the design,assembling procedure and characterization method are presented under consideration of the strict limited weight of the system.HAMS increase the Lorentz force outcome by a factor of three compared to the currently used simple magnet systems.Furthermore the fluid profile influence on a LFV measurement on electrolytes is investigated numerically-directly on the planned test setup-and presented for the first time.Here the Lorentz forces,generated by the HAMS,decreases by 8%comparing an ideal plug-like profile at the inlet with a semi-parabolic profile arising near the outlet of the experiment.

Localization of rare earth ions in an inhomogeneous magnetic field toward their magnetic separation

Efficient extraction and recycling methods are an important issue for rare earth elements(REE). The significant differences in their magnetic moments make magnetic separation a promising step. Although the magnetic field gradient manipulation of ions seemed to be impossible, the robust enrichment of some paramagnetic RE ions was found in the vicinity of the magnet. The studies in recent years resolved the physical paradox of why, despite the Brownian motion of the ions, there is a reproducible enrichment of RE ions in magnetic field gradients. The existence of trigger process and energy barrier was proved.However, these studies usually used only high paramagnetic ions, e.g., Dy(Ⅲ) or Ho(Ⅲ). This work verifies the theory of the possible magnetic separation for 8 different rare earth ions, respectively. For this purpose, concentration distribution in rare earth chloride solutions were measured using a MachZehnder interferometer. The magnetic field was assured by a Halbach configuration to enhance the effect. The results show the classification of RE solutions into 2 classes: Class I contains the REs with low magnetic moment, whereas Class II includes the REs of high magnetic moment. Only the latter group shows the enrichment of ions in the vicinity of the magnet which encourages the implementation of magnetic separation into existing hydrometallurgical technology to enhance the selectivity of REE.