• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.208-210
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• 1994

In this paper, the design sensitivity evaluation based on the 2-dimensional finite clement discretization is presented for the voltage source and eddy current problem. And it is applied to the two shape design problems of the rotor slot of 3-phase squirrel cage induction motors. The first is to increase the starting torque while keeping the rated torque fixed. The other is only to increase the torque at the rated speed while keeping the starting torque fixed. As an optimization method, the Gradient Projection method is used to control casily the torques for various speeds of rotor. One fourth of rotor is analyzed by using a semi-periodic boundary condition. Because the shape of rotor slot has much influence on the slip torque characteristic, the 10 design parameters are taken on the interface between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal typo with rounding corners.

• 전력전자학회논문지
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• 제6권6호
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• pp.506-513
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• 2001

SRM의 토크는 상전류와 인덕턱스의 기울기에 따라 달라진다. 그러나 자기회로의 포화로 인하여 원하는 토크를 제어하기 어렵다. 원하는 토크를 발생시키기 위해 SRM 드라이브는 스위치-온각, 스위치-오프각 그리고 인가 접압에 의해 제어된다. 스위치-온, 오프 각 에의해 원하는 전류와 토크를 제어할수있다. 본 논문은 스위치 온, 오프각을 제어하는 최적제어방식을 제안하였다. 스위치 오프 각은 시뮬레이션과 실험을 통하여 효율을 기준으로 결정하였으며, 스위치 온각은 부하에 의해 결정되었다. 도통각은 토크제어와 속도제어를 위해 GA-신경회로망을 이용하여 제어하였다.

• 대한금속재료학회지
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• 제50권2호
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• pp.129-135
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• 2012

High speed casting technology is an attractive method to increase the productivity of continuous casting. However, high speed casting causes flow instability of molten steel in a mold. In this study, Large Eddy Simulation (LES) has been performed to identify the characteristics of mold flow for various shapes of submerged entry nozzles. The LES code has been newly developed to efficiently compute the two-phase flow by using the Fractional Step Method (FSM) combined with the Volume of Fluid (VOF) method. The Immersed Boundary Method was used to implement the shape of the submerged entry nozzle. Three cases of discharge angle of the submerged entry nozzle were computed and compared. The current results shed light on improving shape design of a submerged entry nozzle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.363-365
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• 1994

In switched reluctance motors(SRM), shaft position sensing is essential in order to synchronize the excitation pulse of a pertinent phase to the rotor position. This paper describes the operation of SRM drive using a simple position sensor of low cost. The position sensor is composed of a slotted disk similar to the rotor core shape of a prototype 6/4 SRM and three opto-interrupters disposed at an angle of 30 degrees. The phase current waveforms measured at several rotor speeds in experiment arc compared with those obtained through the computer simulation.

• Journal of Power Electronics
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• 제14권6호
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• pp.1243-1253
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• 2014

The phase inductance of a switch reluctance motor (SRM) is significantly nonlinear. With different saturation conditions, the phase inductance shape is clearly changed. This study focuses on the relationship between coefficient and current in an inductance model with ignored harmonics above the order of 3. A position estimation method based on the variable coefficient inductance model is proposed in this paper. A four-quadrant sensorless control system of the SRM drive is constructed based on the relationship between variable coefficient inductance and rotor position. The proposed algorithms are implemented in an experimental SRM test setup. Experimental results show that the proposed method estimates position accurately in operating two/four-quadrants. The entire system also has good static and dynamic performance.

• Journal of Magnetics
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• 제17권2호
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• pp.100-108
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• 2012

Flux concentrated permanent magnet transverse flux machines, FCPM-TFMs, with segmented stators require multi-turn concentric saddle coils to replace the ring coils, which are normally utilized in conventional layeredphase TFM constructions. In this paper, we investigate the influence of the shape of saddle phase windings and their parameter variations on the output torque productivity. Non-meshed coils evaluated via a finite element method (FEM) to examine the effect of the coil's location within one phase on machine performance. By using meshed coils, the analysis can be extended to inspect the distributions of magnetic field strength as well as current density in the coils. Throughout the study, the influence of design parameters on the output torque for two stator structures, i.e., a laminated and soft magnetic composite (SMC), are evaluated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.974-976
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• 1993

A design method of three phase induction motors that have characteristics of low starting current and high starting torque is proposed. This design method is based on the traditional theory related to the skin effect and the gap saturation effect. The starting performances and the analysis method are explained in short. Finally, comparison of example design data on electric hoist motor with standard motor is shown.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.924-926
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• 2001

This paper presents the characteristics of current harmonics and torque ripple of Brushless DC motor, which is developed the fan blower of vehicles, according to permanent magnet shape input voltage wave form. To investigate the torque ripple and the phase current harmonics, these characteristics is analysed and compared the experimental results. In the process of analysis, FEM is introduced and computed a transient state torque of BLDC with a sinusoidal and a PWM wave voltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.122-124
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• 2001

In this paper, the influence of electrical parameters such as the turn-on and turn-off angle on the torque and force characteristics is investigated for the reduction of the torque ripple which is main source of vibration and noise in switched reluctance motor (SRM). The four different types of the turn-on angle are set to the section of rising inductance profile respectively. The optimum turn-on angle is proposed for the acquisition of the flat current shape minimizing the torque ripple. 2D finite element method (FEM) considering the iron saturation and the actual switching circuit of the SRM drive is applied for the dynamic analysis. The simulation results of phase current and torque are also compared to the experimental results.

• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.75-81
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• 2014

A simulation of eddy current testing has been utilized for predicting the signal characteristics to the various defects and developing the probes. Especially, CIVA which is a simulation tool dedicated to nondestructive testing has a good accuracy and speed, and provides a three-dimensional graphical user interface for improved visualization and familiar data displays consistent with NDE technique. Although internal validations have been performed by the CIVA software development specialists, an independent validation study is necessary for the accuracy assessment of the software prior to practical use. For this purpose, in this study, eddy current testing signals of ASME FBH calibration standard tube for bobbin probe were simulated using CIVA and the results were compared to the experimental inspected signals based on the relationship between each flaw signal in terms of amplitude and phase, and the shape of the Lissajous curve. And then we verified the accuracy of the simulated signals and the possible range for simulation. Overall, there is a good qualitative agreement between the CIVA simulated and experimental results in the absolute and differential modes at the two inspection frequencies.