• Journal of Magnetics
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• v.18 no.2
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• pp.95-104
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• 2013

This paper presents a general analytical method for predicting the magnetic fields of different Halbach magnet arrays with or without back iron mounted on slotless permanent magnet (PM) linear machines. By using Fourier decomposition, the magnetization components of four typical Halbach magnet arrays are determined. By applying special synthetic boundary conditions on the PM surfaces, the expressions of their magnetic field distributions are derived based on the magnetic scalar potential (MSP), which are simpler than those based on the magnetic vector potential (MVP). The correctness of the method is validated by finite element analysis. The harmonics of airgap flux density waveforms of these Halbach magnet arrays with or without back iron are also compared and optimized.

• Journal of Magnetics
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• v.21 no.3
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• pp.364-373
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• 2016

The article presents the results and findings obtained through the assembly of opposing linear Halbach arrays from two magnet layers using large magnetic blocks from permanent NdFeB magnets, especially concerning the distribution of magnetic induction in an air gap. The use of these large blocks has led to a significant expansion of the area of magnetic field with a substantially higher value of magnetic induction in comparison with similar linear Halbach arrays composed of small magnets. The paper also discusses the determined dependences of magnetic induction on the parameters of the x, y, z coordinate system and indicates the possibilities of achieving an even stronger magnetic field in a larger volume of an air gap for application for instance in equipment for magnetic separation of raw materials, in instrument technologies and in other areas.

• Journal of Magnetics
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• v.18 no.3
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• pp.276-282
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• 2013

In this paper, magnetic flux distributions of several permanent magnet arrays, including Halbach array, are analyzed and compared. Also, braking force characteristics on a moving solid conductor in the eddy current brake systems with such magnet arrays are analyzed. Then, a new performance index taking into account the maximum braking force and the volume of the magnet is introduced for the comparison and case study of permanent magnet arrays. By changing the lengths, magnetization directions and the height of the permanent magnet arrays, a higher braking force per volume of the magnet can be achieved.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1679-1685
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• 2015

This paper examines the effect of the magnetization pattern on the partial demagnetization of a permanent magnet (PM) machine that uses a ferrite magnet. Although the use of halbach-magnetized PM (HMPM) arrays in PM machines has been dramatically increasing because of their attractive features, the demagnetization characteristics of HMPM arrays have not yet been examined. In this study, two analyses of the demagnetization characteristics of HMPM arrays and parallel magnetized PMs (PMPMs) are performed, with the demagnetization characteristics being analyzed using a finite element method. According to our results, partial demagnetization occurred dramatically in the HMPM arrays. Thus, it is important to consider the vulnerability of HMPM arrays when designing PM machines.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.4
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• pp.353-358
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• 2011

In this paper, we describe a process for optimally designing a ring-type permanent magnet thrust bearing. The bearing consists of two sets of permanent magnet rings. One set is located inside the other set. An axial offset between the two sets creates axial force, which results in a thrust bearing function. In order to realize an optimal design of the bearing where the required load capacity of the bearing is achieved with the least magnet volume, we derived analytical design equations by adopting the equivalent current sheet (ECS) method. We considered the following two types of magnet arrays: axial arrays and Halbach arrays. These two types of arrays are optimized using the analytical design equations. The results of the optimization are verified using three dimensional (3D) finite element analyses (FEA). The results show that the Halbach array can achieve the required load capacity with less amount of permanent magnet than the axial array does. The efficacy of the ECS method is also verified by using 3D FEA. It is found that the accuracy of ECS method is more sensitive to the underlying assumptions for the Halbach array than for the axial array.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.72-74
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• 2001

This paper deals with a dynamic analysis and a position control for air-core type linear synchronous motor with Halbach array (HA) permanent magnet mover. The primary coils are designed to be air-cored, so the HA-PMLSM don't exist the detent force. The secondary HA array of PMs does not require any ferro-magnetic yoke and excites stronger magnetic flux density and closer to the sinusoids than a conventional PM array.

• Journal of Magnetics
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• v.22 no.2
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• pp.250-256
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• 2017

The article presents the principle of a relatively small device that makes it possible to generate a strong magnetic field in an air gap without electrical energy consumption. It describes the implemented design of this device, the method of the assembly of opposing linear arrays from two NdFeB magnet layers, its advantages, the possible ways of increasing the parameters further and its application in various areas.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.78-80
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• 2001

This paper deals with a comparison between the secondary Halbach array and conventional array of permanent magnets(PMs) in air-core type linear synchronous motor(LSM). Two types of PMLSM are analyzed and compared, with reference to the following parameters as variables: magnetic field, thrust and back emf.

• Journal of Electrical Engineering and Technology
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• v.7 no.4
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• pp.558-563
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• 2012

In this paper, a novel planar type magnetic levitation system without other assistant devices is proposed and it can move with 6 degree of freedom (X, Y, Z, ${\theta}_X$, ${\theta}_Y$, ${\theta}_Z$) in wafer size as well as in nano scale positioning.The mover is composed with 2-D Halbach permanent magnet array and the stator is composed with $10{\times}10$ coil arrays.It was composed in laboratory and tested with short stroke (4 [mm]) and long stroke (160 [mm])movements. The errors of short movement test is [X, Y, Z, ${\theta}_X$, ${\theta}_Y$, ${\theta}_Z$]${\leq}$ [${\pm}200nm$, ${\pm}200nm$, ${\pm}250nm$, ${\pm}3urad$, ${\pm}2urad$, ${\pm}1urad$]The errors of long stroke movement test is [X, Y, Z, ${\theta}_X$, ${\theta}_Y$, ${\theta}_Z$]${\leq}$ [${\pm}200nm$, ${\pm}200nm$, ${\pm}250nm$, ${\pm}1.5urad$, ${\pm}2urad$, ${\pm}0.5urad$].

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.2
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• pp.237-244
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• 2014

In this paper, we presented a study on the design of permanent magnet rotor for exterior rotor type brushless direct current(BLDC) motor. To reduce the cogging torque and torque ripple, the specific shape and magnetization pattern of permanent magnets in BLDC motors are suggested. Firstly, four permanent magnet models with different shapes and magnetization arrays are presented. The results from the finite element method(FEM), the most effective model for reducing cogging torque and torque ripple was presented. In addition, to confirm the steady state performance, the torque-speed characteristic analysis has been performed with variable speed and load. Finally, the best permanent magnet model for reducing cogging torque and torque ripple with appropriate torque-speed performance was selected through the comparison according to the device volume.