• Proceedings of the KIEE Conference
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• 2005.07e
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• pp.97-99
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• 2005

현장에서 사용중 고압전선에 고장이 발생한 6.6kV 건식변압기 고장의 원인분석을 위하여 설계와 제조방식이 동일하고 사용기간이 비슷한 건식변압기에 대한 전기적 열적 시험을 실시하였다. 전기적 시험으로서는 교류 및 충격 내전압시험, 부분방전시험을 실시하였고 열적시험으로는 단락법을 사용하여 온도를 상승시켰으며, 내부 및 외부권선표면의 온도분포와 열화상에 의한 온도분포를 측정하였다. 시험결과 부분방전특성이 기준치에 비하여 높게 나타났으며, 권선온도분포는 사용한계온도이하인 것으로 분석되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.217-220
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• 2011

본 연구에서는 경상북도 북부지역의 5개의 소수력발전 후보지점을 설정하였으며, 5개 후보지점에 대하여 설치가능한 소수력 발전시설은 지형학적 측면을 비롯하여 다양한 타당성 검토를 통하여 댐식 소수력 발전시설이 타당한 것으로 분석되었다. 5개 후보지점에서 설정된 유량지속곡선을 이용하여 발전용량을 산정하고 수차를 선정하였다. 따라서 산정된 발전 용량을 편익비용 분석법과 내부수익률 분석법을 이용하여 경제성분석을 실시하였다. 본 연구에서는 3개의 소수력발전 후보지점(경상북도 봉화군 명호면, 경상북도 영주시 문수면 권선리, 경상북도 예천군 형호리)이 B/C 비율이 1이상으로 경제성이 있는 것으로 분석되었으나, 설비용량 500kW 이상인 최적 개발후보지는 경상북도 영양군 입암면 후보지점인 것으로 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.476-482
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• 2019

Regulatory protocols such as the Convention on Climate Change and the regulation of greenhouse gas emissions act as catalysts for the development of high-efficiency energy equipment and the efficient use of energy. Among the fields where energy consumption is high, the electric heating equipment is not efficient. The electric boiler mainly uses a method of circulating water by contacting the heater. When the existing electric boiler is used, the water minerals are contacted with the high-temperature heater to be carbonized and adsorbed, thereby promoting the corrosion of the heater and lowering the efficiency of the heater. For this reason, an electric induction boiler, which has high energy efficiency and is applied to an induction heating system that can uniformly heat the object to be heated rather than conduction or convection heating, is in the limelight. This method induces a boiler pipe And it is recognized as an alternative that can solve the problem that occurs when heating is performed by direct heating. Despite the fact that research on induction heating has been conducted for a relatively long period of time, there have been few studies on the electrothermal technology using induction heating. Therefore, in this paper, to improve the heat efficiency of electric induction boiler, the influence of the cross sectional area, number of windings and winding layers is analyzed by finite element method through parametric study method. The method of finding the design point which maximizes the total loss is proposed by the alternating winding design method which can maximize the heat generation by analyzing copper and iron losses.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.94-105
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• 2010

To detect faults in an inverter-fed permanent magnet synchronous motor (PMSM) drive under the circumstance having faults in a stator winding and inverter switch, an on-line basis fault detecting scheme during operation is presented. The proposed scheme is achieved by monitoring the second-order harmonic component in q-axis current and the fault is detected by comparing these components with those in normal conditions. The linear interpolation method is employed to determine the harmonic data in normal operating conditions. As soon as the fault is detected, the operating mode is changed to identify a fault type using the phase current waveform. To verify the effectiveness of the proposed fault detecting scheme, a test motor to allow inter-turn short in the stator winding has been built. The entire control algorithm is implemented using DSP TMS320F28335. Without requiring an additional hardware, the fault can be effectively detected by the proposed scheme during operation so long as the steady-state condition is satisfied.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.37-41
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• 2008

Superconducting Electrodynamic suspension(EDS) system is generated by the interaction between the magnetic field made by the induced the eddy current in the ground conductor and the moving magnetic field made by onboard superconducting magnet. The levitation force of EDS system, which is proportional to the strength of the moving magnetic field, becomes saturated according to the increase of the velocity. Especially, the levitation force is influenced by the structure of HTS magnet and ground magnet. This paper deals with the optimal design condition for the HTS levitation magnet. The 3-D numerical analysis with FEM was used to find the distribution of the magnetic field, the optimal coil structure, and the calculation of the levitation force.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.434-440
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• 2023

This paper propose the method that measure the main system parameters for current control of a.c. motor adopting the vector control technique. The automatical method that tuning PI control gains for current control of servo motors are used frequently through the information of main system parameters, wire resistance and inductance. In this study, the techniques to measure these two system parameters through the control of 3-phase inverter are presented. These control and measuring method are implemented by measuring output phase current obtained as a results of the step current control using simple proportional feedback input. Moreover, this method use freewheeling current of inverter at special switching mode for measuring inductance. This analytic strategy is could measure and calculate the system parameters without the complex measurement algorithm and new additional measuring circuits. That is could measure the total resistance and total inductance including wiring resistance and conduction resistance of switching devices using real driving circuits to control the motors.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.297-299
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• 2002

To wind a HTS (High Temperature Superconductor) tape conductor on a bobbin, double pancake winding technique is widely used to reduce number of splicing contacts between conductor pieces. However, this makes some Ic (critical current) degradation on kink points which is unavoidable. This paper describes the two ways of winding; usual double pancake and soldered double pancake. Characteristics of the two windings are measured and compared.

• 전기의세계
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• v.38 no.11
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• pp.11-20
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• 1989

고압회전기의 고정자권선에는 열, 전기 및 기계적, 환경적 스트레스가 단독 또는 복합적으로 가해지며, 이러한 응력들은 기기의 크기, 정력, 동작상태 등에 따라서 변화된다. 따라서 주기적인 절연진단 시험을 통하여 절연상태를 평가하고 그 변화추이를 검토하여 잔여수명을 예측함으로써 보수 및 교체시기를 계획하여 절연파괴로 인한 대형사고를 예방하는 것이 가장 바람직하다. 본 논문에서는 대용량 회전기의 정지기간 동안 실시하는 진단시험 및 열화상태 판정법등에 관하여 서술하고자 한다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1193_1194
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• 2009

일반적으로 자기부상열차는 고속, 내구성, 안전성 등을 만족하는 가장 적합한 시스템 중 하나로 부각되고 있다. 300[km/h] 이하의 중저속 자기부상철도의 경우, 추진용으로 선형유도전동기가 사용되고 있으며, 초고속 자기부상철도의 경우, 선형유도전동기보다 고효율, 고출력의 특성을 가지는 선형동기전동기가 사용되고 있다. 한국철도기술연구원에서는 2008년도부터 700[km/h]급 초고속튜브열차용 선형동기전동기연구를 시작하였으며, 추진/부상 일체형 권선형 선형동기전동기연구를 수행하고 있다. 따라서 본 논문에서는 초고속튜브열차용 선형동기전동기 연구의 일환으로, 축소형 영구자석형 선형동기전동기(PM-LSM)의 수학적 방법에 의한 기본설계를 수행하였으며, 이를 이동자만을 고려한 자기등가회로법을 이용하여 권선형 선형동기전동기(EM-LSM)로 변환 설계를 수행하였다. 또한 설계된 PM-LSM과 EM-LSM 모델의 FEM 해석을 이용한 특성 분석을 통하여 본 논문에서 제안한 변환 설계기법의 정확도 검증 연구를 수행하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.73-81
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• 2002

This paper introduces a four-Pole Lorentz force type self-bearing motor in which a new winding configuration is proposed to enable the sing1e winding to function both as a synchronous PM motor and as a magnetic bearing. The Lorentz force type has some good points such as the linearity of control force, freedom from flux saturation, and high efficiency, unlike conventional self-bearing motors using a reluctance force. And also, compared with the previously proposed eight-pole type, this four-pole self-bearing motor is more profitable for high rotational speed. In this paper, mathematical expressions of torque and radial force in the proposed self-bearing motor are derived to show that they can be separately controlled regardless of rotational speed and time. For verification of the theory, a prototype is made, where a ring-shape outer rotor is actively controlled in two radial directions while the other motions are passively stable supposing the radial stability. Through some experiments. it is shown that the proposed scheme can provide high capability and feasibility for a small high-speed self-bearing motor.