• Journal of Institute of Convergence Technology
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• v.11 no.1
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• pp.7-12
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• 2021

The magnetic gear, which amplifies the torque by filtering the magnetic field generated by the low-speed permanent magnet with a modulator, can exclude gear contact and can be effectively applied when there are environmental restrictions. In this paper, we discuss the magnetic force characteristics of a magnetic gear using a magnetic focusing array that replaces a general permanent magnet array magnetized in a radial direction along the circumferential direction. The torque increasing effect of the discussed array, known as an arrangement that increases the principal component by focusing a radial magnetic field, is compared with that of a general magnetic gear. In particular, in a magnetic gear using such an array, the sensitivity of torque according to variables is analyzed to see how various variables known as factors affecting torque have an effect.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.1
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• pp.36-43
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• 2019

In this paper, the characteristics of the coaxial magnetic gear according to the shape of the same gear ratio are analyzed using the two - dimensional finite element analysis. The rotor shape is SMCMG, CPCMG and RCMG. After this we analyzed the characteristics according to three shapes. Also, the amount of permanent magnet used in each shape was compared. Next, characteristics analysis of the magnetic gear according to the shape at the same torque was performed. And the total weight and efficiency of the magnetic gears were compared and verified.

• Journal of Institute of Convergence Technology
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• v.10 no.1
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• pp.25-29
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• 2020

Magnetic gears of non-contact power type have great advantages in terms of maintenance and repair than mechanical gears, and are used in various ways. Harmonic gears can derive a higher gear ratio than conventional gears through power transmission through a unique rotation mechanism. Magnetic harmonic gears, in which the gear teeth of the harmonic gears are replaced with magnets, have the advantages of both gears, but are difficult to implement and practical, so many studies are being conducted. In this study, we check whether the results of various types of magnetic gears can be applied to harmonic gears. By applying the axial type magnetic gear to the harmonic gear, the characteristic analysis is conducted to see if the result comparable to the existing radial type magnetic harmonic gear is obtained.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.355-362
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• 2021

Since coaxial magnetic gears use non-contact power transmission, friction, wear, noise, and heat generated in the power transmission process of existing mechanical gears can be minimized. Currently, research for application to various industries is being actively conducted, but among the characteristics of coaxial magnetic gears, the problem of rapidly decreasing torque density at a high gear ratio was discussed. This paper proposes a direction for multiple gear combination using low gear ratio coaxial magnetic gears with high torque density. In order to confirm the effectiveness of the method, the torque density was compared with a single high gear ratio model, and the combination and design direction of multiple coaxial magnetic gears were shown.

• Journal of Institute of Convergence Technology
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• v.12 no.1
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• pp.7-12
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• 2022

The reduction ratio of the magnetic gear is determined by the ratio of the number of poles between the high-speed permanent magnet layer and the low-speed permanent magnet layer. In general, it is known that the greater the least common multiple of both poles, the smaller the torque ripple called by cogging of the magnetic force generated in the magnetic gear. However, little is known about the effect of the harmonic modulator that filters the magnetic field in the magnetic gear to magnetically couple the high-speed side and the low-speed side except for the number of poles. In this study, torque ripple characteristics according to changes in modulator shape such as opening ratio and tooth thickness are analyzed using a finite element analysis tool.

• Journal of Power Electronics
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• v.19 no.3
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• pp.794-802
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• 2019

Magnetic geared motors are driven using the same operating principle as conventional synchronous motors in which a magnetic gear is embedded. The magnetic geared motor is structurally similar to a magnetic gear. However, by applying currents to the stator coil, the high-speed rotor is rotated by a magnetic field and the low-speed rotor is rotated according to the gear ratio. In this paper, the operational principle of a magnetic geared motor and the magnetic flux density in its inner and outer air gaps are described. Then the magnetic flux density in the two air gaps is used to express a method for calculating the electrical and mechanical output. Results obtained with the analytical calculation method are compared with those of the finite element analysis. Finally, a prototype is used to verify the results of the analytical calculation and FEA.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.545-551
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• 2015

This paper deals with torque analysis of magnetic spur gear with radial magnetized permanent magnets based on analytical method. The analysis is implemented in three parts: First, on the basis of magnetic vector potential and a two-dimensional (2D) polar-coordinate system, the magnetic field solution due to permanent magnet of source gear are obtained. And by using derived magnetic field solutions, the analytical solutions for external magnetic field distribution which affects load gear are obtained. Second, by using coordinate conversion, external magnetic field which is on the primary coordinate system is converted to the secondary coordinate system. Finally, the load gear is reduced to equivalent current densities, and the torque is computed on these currents in the external field of the source magnet. These analytical results are validated by comparing with the 2-D finite element analysis (FEA).

• Journal of the Korean Society for Precision Engineering
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• v.31 no.6
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• pp.543-550
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• 2014

A magnet gear composed of two layers of permanent magnets repeated circumferentially can transmit the power without mechanical contact. In the topology called by the magnet shutter gear known as the most competitive concept among the existing concepts, the number of pole-pairs on the high speed rotor corresponds to that of low speed rotor through electric steel set functioning as a magnetic modulator. The methodology is classified into radial type and axial type according to its magnetic path as in the motor. However, the magnetic modulator has multiple poles located separately. So, it is very complicated to assemble each module of the magnet gear mechanically and to sustain a mechanical stiffness of the modulator. The practical trouble can be solved partially through reconfiguring the modules. This paper deals with the novel magnetic shutter gear topology varying the magnetic path and its effectiveness is verified through real hardware implementation.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.77-84
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• 2024

This paper introduces a study on an electromagnet magnetic gear designed for gear ratio conversion. In comparison to magnetic gears using permanent magnets, this electromagnet magnetic gear exhibits lower torque density, highlighting the need for torque density improvement. To address this, the research focuses on enhancing torque density by examining the consistent orientation of each rotor's magnetization during gear ratio conversion and attaching permanent magnets accordingly. However, an issue arises due to the uneven magnetic flux density caused by the non-uniform attachment of permanent magnets, leading to an increase in torque ripple. Therefore, building upon previous studies aimed at reducing torque ripple in electromagnet magnetic gears, this research explores the optimal methods, such as pole piece bridges and fillet configurations, to mitigate torque ripple even during gear ratio conversion.

• Journal of Magnetics
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• v.20 no.2
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• pp.186-192
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• 2015

This paper describes the electromagnetic and mechanical characteristics of coaxial magnetic gear (CMG) with a low gear ratio. The analysis models are restricted to a CMG with a gear ratio of less than 2. The electromagnetic characteristics including transmitted torque and iron losses are presented according to the variation of the gear ratio. The pole pairs of high speed rotor are chosen as 6, 8 and 10 by considering the torque capability. As the gear ratio approaches 1, both iron losses on the ferromagnetic materials and eddy current losses on the rotor permanent magnets are increased. The radial and tangential forces on the modulating pieces are calculated using the Maxwell stress tensor. When the maximum force is exerted on the modulating pieces, the mechanical characteristics including stress and deformation are derived by structural analysis. In CMG models with a low gear ratio, the maximum radial force acting on modulating pieces is larger than that in CMG models with a high gear ratio, and the normal stress and normal deformation are increased in a CMG with a low gear ratio. Therefore, modulating pieces should be designed to withstand larger radial forces in CMG with a low gear ratio compared to CMG with a high gear ratio.