• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1039-1041
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• 2000

To obtain a high performance in a vector controlled induction machine, it is essential to know the instantaneous position of the rotor flux which depends on the rotor time constant. But the rotor time constant mainly varies due to the temperature rise in the motor winding, so real time compensating algorithm is necessary. This paper proposes that it uses short duration pulses added to the constant flux command current and then resultant torque command current produced by speed controller is utilized for the rotor resistance estimation. This method has advantages with a low computational requirement and does not require voltage sensors. The proposed method is proved by simulations.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1909-1911
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• 2000

Recently many research activities on the diagnosis of stator winding insulation of large rotating machines have been reported. Capacitive couplers are widely used as sensors for on-line partial discharge (PD) measurement of high voltage rotating machines. This paper presents laboratory test to compare Stator Slot Coupler (SSC), Resistance Temperature Detector (RTD), 80 [pF] coupler and 500 [pF] coupler for on-line PD measurement of rotating machines.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.91-93
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• 1998

In this paper 30 kVA superconducting generator's transient-state electromagnetic analysis by FEM is described. The transient-state analysis by moving air gap technique was performed to analyze its 3 phase sudden short circuit characteristics. External circuit components were connected to generator model with end-winding resistance and inductance.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.949-951
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• 2000

In order to design thermally trigger controlled persistent current switch(PCS) for MRI magnet system, it is very important to know informations of applied adiabatic method and condition to get designed resistance and characteristics. Adiabatic part of PCS is consist of cotton-gummed tape and cryogenic stycast. This adiabatic method has the advantage of continuously winding superconducting and adiabatic part of PCS and reducing the time of manufacture. We experimentally derived averaged thermal conductivity on the assumption that shape of adiabatic part of PCS is that of pipe. In result, averaged thermal conductivity is about 0.29 W/m K and designed value is very satisfied with actual experimental data.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.696-698
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• 2000

A new high voltage generator is designed and basic performance analysis by 2D-FEA is performed. The new generator is able to supply electricity directly to the high voltage grid without the need for a step-up transformer. For the 2D-FEA analysis, the generator model is coupled to external circuit components with inductance and end-winding resistance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1123-1129
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• 2012

This paper presents the fast steady state analysis using time-stepping finite element method for a high power three-phase transformer. The high power transformer spends huge computational cost of the time-stepping finite element method. It is because that the high power transformer requires a lot of time to reach steady state by its large inductance component. In order to reduce computational cost, in this paper, the adaptive time-step control algorithm combined with the embedded 2nd 4th singly diagonally implicit Runge-Kutta method and the analysis strategy using variation of the winding resistance are studied, and their numerical results are compared with those from the typical time-stepping finite element method.

• 전기의세계
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• v.28 no.1
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• pp.59-66
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• 1979

The linearized models on per for mance dynamics of the pulse motor have been already proposed by many others. These models exhibit certain advantages of their own because of their simple formulation, but in many cases the models are proved to be inadequate for further accurate analysis of the motor dynamics, owing to impractical and rather rough assumptions in the derivation. In this study a dynamic state transition model is induced, using the equivalent circuit obtained from the operating principle of the variable reluctance pulse motor which turns out to be nonlinear equation. This nonlinear dynamic state equation is numerically analysed by the use of UNIVAC System/3(OS/3) digital computer at hand. In the course of the dynamic analysis of the performance characteristics of a testing motor, dependance of the inertia of rotor and load, the coefficient of viscous friction between rotor and housing, and the winding resistance of the stator is discussed and a comparative study of the machine constants is carried on as related to the design problem of the motor.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.754-756
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• 1996

In this paper, polymer housing arrester has very good characteristics in design versatility as well as excellent resistance to moist ingress and pollution performance. For the presented of the characteristics evaluation and technology of disk spring and knuckle structure of FRP to filament winding seems to protect the arrester elements from moisture absorption. The achievement in the research and technology will contribute to the showed very good characteristic in adhesion of terminal cap and FRP cylinder for outdoor arresters and domestic products of high voltage power distribution arrester.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.783-785
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• 2003

This test was performed to assess the insulation deterioration condition of the stator winding of 3.3kV class induction motors which have been in service for 15 years after being installed in 1988. The insulation diagnostic tests include resistance, polarization index(P.I). dissipation factor(${\Delta}tan{\delta}$) and maximum partial discharges(Qmax). The results of diagnostic tests were compared to the visual inspection in overhaul.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.221-230
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• 2007

This paper deals with analytical prediction for electromagnetic characteristics of a tubular linear actuator with Halbach array using transfer relations, namely, Melcher's methodology. Using transfer relations derived in terms of magnetic vector potential and a two-dimensional (2-d) cylindrical coordinate system, this paper derives analytical solutions for magnetic vector potential due to permanent magnets (PMs) and stator winding currents. On the basis of these analytical solutions, this paper also achieves analytical solutions for the magnetic fields distribution produced by PMs, stator windings current and axial thrust. The analytical results are validated extensively by finite element (FE) analyses. In particular, test results such as thrust measurements are given to confirm the analysis. Finally, this paper estimates control parameters using analytical solutions and test results such as thrust, back-emf, inductance and resistance measurements.