• 전기의세계
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• 제15권5호
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• pp.32-39
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• 1966

This voltage Regulator, which regulates voltage in different way from the conventional regulator, is constructed by circular-plate core type stators and controllers (are similar to rotor of conventional). The principle of this Voltage Regulator is based on the rotating magnetic field theory including peculiar homopolar and heteropolar concept. Comparing with the conventional induction regulator, this regulator need not to have short windings and can cancel armature reaction. Moreover, it is able to decrease the machine noise and control the phase of it freely. And it's efficiency can become more than 95% which almost the same as that of transformer's. By increasing numbers of cores of the same size, the output power can be increased, the insulation can be decreased and high Voltage can directly be connected because applied voltage is distributed to each core. This Voltage Regulator can be also used as a current regulator, a starter a induction motor and a phase transformer etc.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1976-1977
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• 2007

This paper introduce the electrical quantities of a three-phase-connected wind induction generator (WIG) under sudden connection of static loads. An intelligent power-system recorder/monitor is employed to measure threephase voltages and currents of the studied system at WIG's terminals and load's terminals for 5 minutes. A laboratory 300 W wound-rotor induction machine driven by a blushless DC motor is utilized as the studied WIG. Since the generated harmonic currents are randomly varied, total harmonic distortion (THD) of current using cumulative probability density function is employed to determine the penetration of harmonic distortion. The results show that the harmonic currents generated by the studied WIG may be severely amplified to a high level by the connected self-excited capacitance at the stator's terminals.

• 전력전자학회논문지
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• 제5권6호
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• pp.620-631
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• 2000

본 논문에서는 인버터의 스위칭 주파수가 0.5-1kHz로 제한되는 3레벨 인버터로 구동되는 고전압 대용량 유도 전동기 직접토크제어의 토크리플 저감법을 제안한다. 기존의 토크리플 저감법은 인버터 스위칭 주파수가 비교적 높은 2-3kHz에서 동작하는 알고리즘으로 1kHz이하의 낮은 인버터 스위칭 주파수의 시스템에 적용하면 만족할만한 토크 라플 저감 성능블 얻을 수 없다. 새로운 직접토크제어 기법은 특히 낮은 스위칭 주파수를 갖는 시스템에 적용하기 위한 것이며, 모든 동작 속도 구간에서 토크리플 저감 성능을 나티낸다. 시뮬레이션과 실험을 통해 세안한 알고리즘의 타당성을 입증한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.817-820
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• 2002

Since a squirrel cage induction motor by NEMA Design types is designed to withstand full-voltage starting, direct starting method can be the most economical one. Starting a squirrel cage motor from standstill by connecting it directly across the line may allow inush currents of approximately 500-600% of rated current at lagging power factor of 35-50%. For many of the large motors, the starting inrush current may be great enough to cause voltage dips, which may adversely affect the building's lighting system. Electric utilities also have restrictions on starting currents, so that voltage fluctuations can be held to prescribed limits. Therefore the need for choosing the most appropriate method of motor starting is quite essential. In this paper, we proposed a plan for the selection of the most appropriate motor starting method, first by way of numeric simulation using manufacturer's data and second by way of actual experience. So far, more often than not, the selection of motor starting method has been accomplished only as regards to the capacity of the motor and the frequency of starting and stopping. But nowadays such high-tech apparatus as soft starters are being developed, and we are on the position to give more attention to clarify the way of selection of the motor starting method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.905-911
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• 2009

The viscosity drive method by the wheel which is widely used in the conventional railway systems needs a large friction force between the wheel and the guide-rail, which brings on a thrust force for a quick acceleration and a high-speed travelling. In addition, the viscosity drive method needs an increase of the vehicle weight for a large friction force. However, a maglev train is possible to be driven by the electro-magnet instead of the wheel, which produces a levitation and thrust force without any contact. In general, low-speed maglev train uses a linear induction motor(LIM) for propulsion that is operated under 300[km/h] due to the power-collecting and end-effect problems of LIM. In case of high-speed maglev train, a linear synchronous motor(LSM) is more suitable than LIM because of a high-efficiency and high-output properties. LSM has a driving principle as same as a conventional rotary synchronous motor(RSM), and the torque of RSM becomes the thrust force of LSM. A conventional LSM has relatively large air-gap compared with a conventional RSM. So, it must be achieved a design that is considered normal force by finite-asymmetric structure, end-effect on the entry and exit part, and support structure of a moving part. Therefore, in this research, authors accomplish a conceptualizing and basic design of a small-scaled LSM, and characteristics analysis using FEM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.313-316
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• 1989

A steady state analysis of a load commutated current source inverter which is widely used in high voltage - high power induction motor drive systems at present is presented and its related results are discussed. This analysis proposes a method by which we can determine the output capacitor playing a dominant role on the performance of the system. It is shown that the capacitance of output capacitors is mainly dependent on the range of frequencies that the inverter is operated in the load commutated state.

• 에너지공학
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• 제12권2호
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• pp.118-123
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• 2003

유도전동기는 단일기기로서 가장 많은 전력을 사용하고 있는 부하로서, 우리나라의 전력사용량 중 약 40%를 소비하고 있다. 따라서 유도전동기의 고효율화는 시급한 국가적 과제이다. 본 논문에서는 고효율유도 전동기의 보급에 있어서 가장 큰 장애요인인 초기구입비 상승에 따른 구매기피를 극복하기 위한 여러 방안 중 가장 효과적인 방법으로 알려진 고효율유도전동기 리베이트제도의 시행방안을 수립하고 이의 경제성을 평가한다. 그리고 리베이트제도로 전환된 고효율유도전동기의 시장을 유지하기 위한 강제규정으로서 최저효율제와의 연계방안을 수립한다.

• 전기학회논문지
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• 제60권6호
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• pp.1079-1085
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• 2011

To supply electrical power with high quality, the power system must be optimized in many ways such as planning, control and management. In order to optimize the power system, the analysis of the power system is necessary. The elements of the power system require an accurate model to analysis of the power system. The components of the power systems such as generators, transformers and transmission lines have been studied and researched a lot in their modeling and very sophisticated models have been proposed. However, in case of load in-depth studies on the exact model are required. In this paper, measurement-based load modeling method using real-time measured data is proposed in various methods to reflect the characteristics of the load. To prove the validity of the proposed method, PSCAD/EMTDC program is used to configure the power system and measurement data according to the various failures are used to study on load modeling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.369-371
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• 1999

A torque ripple minimization technique is proposed for high power induction motors driven by 3-level inverters with switching frequency of inverter switching elements limited around 500Hz level. It is noted that conventional DTC algorithms with torque ripple minimization scheme are devised for applications with relatively high switching frequency above 2-3kHz. A new DTC algorithm, especially for low switching frequency inverter system, illustrates relatively reduced torque ripple characteristics all over the operating speed region. Simulation results show effectiveness of the proposed control algorithm, and associated experimental works will be presented in the final paper.

• 한국정밀공학회지
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• 제16권1호통권94호
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• pp.219-225
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• 1999

Monitoring of the cutting force signals in cutting process has been well emphasized in machine tool communities. Although the cutting force can be directly measured by a tool dynamometer, this method is not always feasible because of high cost and limitations in setup. In this paper an indirect cutting force monitoring system is developed so that the cutting force in turning process is estimated based on a AC spindle drive model. This monitoring system considers the cutting force as a disturbance input to the spindle drive and estimates the cutting force based on the inverse dynamic model. The inverse dynamic model represents the dynamic relation between the cutting force, the motor torque and the motor power. The proposed monitoring system is realized on a CNC lathe and its estimation performance is evaluated experimentally.