• Proceedings of the KSME Conference
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• 2004.04a
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• pp.852-857
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• 2004

In this paper, an angular self-sensing algorithm is proposed and implemented to a Lorentz force type integrated motor-bearing system. It is based on the principle that the flux linkages of stator windings, calculated from the voltage and torque control current, are the functions of the rotor angle. The tracking angular position error is proven to vanish using the Lyapunov stability method, and the experimental results show that the initial error decays within about 5 seconds. It is found that the resolution of the algorithm remains about 1º over the speed range of 100 to 1000 rpm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.117-122
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• 2006

Maximum efficiency control scheme in a stator flux-oriented induction motor drive is proposed for minimizing input dc power. Flux level is decreased in steps for searching the minimum input dc power. In addition, Torque equation, slip angular frequency, and decoupling compensation current considering iron loss resistance is used. Simulation and experimental results verify the effectiveness of the proposed method.

• Steel and Composite Structures
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• v.18 no.4
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• pp.909-924
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• 2015

This paper investigates the vibration phenomenon of a nanobeam subjected to a time-dependent heat flux. Material properties of the nanobeam are assumed to be graded in the thickness direction according to a novel exponential distribution law in terms of the volume fractions of the metal and ceramic constituents. The upper surface of the functionally graded (FG) nanobeam is pure ceramic whereas the lower surface is pure metal. A nonlocal generalized thermoelasticity theory with dual-phase-lag (DPL) model is used to solve this problem. The theories of coupled thermoelasticity, generalized thermoelasticity with one relaxation time, and without energy dissipation can extracted as limited and special cases of the present model. An analytical technique based on Laplace transform is used to calculate the variation of deflection and temperature. The inverse of Laplace transforms are computed numerically using Fourier expansion techniques. The effects of the phase-lags (PLs), nonlocal parameter and the angular frequency of oscillation of the heat flux on the lateral vibration, the temperature, and the axial displacement of the nanobeam are studied.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.140-142
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• 2006

Cogging torque is often a principal source of vibration, noise and difficulty of control in permanent-magnet brushless DC motors. Cogging torque can be minimized by sinusoidal air-gap flux density waveform because it is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance. Therefore, this paper will present a design method of magnetization system of bonded isotropic neodynium-iron-boron(Nd-Fe-B) magnets in ring type with sinusoidal air-gap flux density distribution and low manufacturing cost. An analytical technique of magnetization makes use of two-dimensional finite element method(2D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation.

• Journal of Magnetics
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• v.22 no.2
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• pp.203-213
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• 2017

Magnetically suspended control & sensitive gyroscope (MSCSG) is a novel type of gyroscope with the integration of attitude control and attitude angular measurement. To improve the precision and reduce the power consumption of Lorentz Force-type Magnetic Bearing (LFMB), the air gap flux density distribution of LFMB has been studied. The uniformity of air gap flux density is defined to qualify the uniform degree of the air gap flux density distribution. Considering the consumption, the average value of flux density is defined as well. Some optimal designs and analyses of LFMB are carried out by finite element simulation. The strength of the permanent magnet is taken into consideration during the machining process. To verify the design and simulation, a high-precision instrument is employed to measure the 3-dimensional magnetic flux density of LFMB. After measurement and calculation, the uniform degree of magnetic flux density distribution reaches 0.978 and the average value of the flux density is 0.482T. Experimental results show that the optimal design is effective and some useful advice can be obtained for further research.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.292-294
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• 2006

• Progress in Superconductivity
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• v.9 no.2
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• pp.173-176
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• 2008

[ $MgB_2$ ] films grown by hybrid physical chemical vapor deposition under appropriate growth conditions commonly exhibit columnar grain structure. The grain boundaries between adjacent columnar grains have been reported to be good flux pinning centers. In this work, we measured the angular dependence of critical current density ($J_c$) and observed the enhanced flux pinning when an external magnetic field was aligned parallel to the columnar direction. This $J_c$ was almost comparable to the $J_c$ for intrinsic pinning case up to 1 T at low temperatures, indicating that grain boundary pinning is very effective. At high fields, however, $J_c$ decreased rapidly resulting from the fact that the density of flux pinning centers provided by grain boundaries was outnumbered by the flux density.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.1
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• pp.7-15
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• 2002

The paper proposes the characteristics analysis for a Transverse flux type Switched Reluctance Motor(TSRM) considering the nonlinear magnetic phenomena. To investigate the nonlinear parameters of magnetic equivalent circuit, the designed TSRM is analyzed by the 2D and 3D finite element method as functions of input current and angular displacement. On the base of FEM analysis results, the current, torque, back EMF and output power wave of TSRM are simulated from the motion equation by MATLAB/Simulink. The simulated performance characteristics for a 4-phase, 24-pole TSRM are verified by experimental results of a prototype TSRM.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.930-932
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• 2001

This paper is proposed the modeling and computational methods for estimating the steady and dynamic characteristics of a transverse flux type SRM. Prediction of the steady and dynamic characteristics state of a switched reluctance motor (SRM) drive can be quite involved because of complex interdependent influences between motor parameters and excitation. To obtain characteristics parameters of the transverse flux type SRM which is considered the magnetic non-linearity phenomena, the magnetic equivalent parameters of SRM are computed by the finite element method as functions of the input current and angular displacement. Dynamic characteristics of the designed transverse flux type SRM is simulated and estimated by Matlab/simlunk.

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.256-258
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• 2000

This paper is proposed the modeling and computational methods for estimating the steady and dynamic characteristics of a transverse flux type SRM. To obtain characteristics parameters of the transverse flux type SRM which is considered the magnetic non-linearity phenomena. the magnetic equivalent parameters of SRM are computed by the finite element method as functions of the input current and angular displacement. Dynamic characteristics of the designed transverse flux type SRM is simulated and estimated by Matlab/simlunk.