• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권3호
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• pp.130-140
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• 2001

This paper presents the performance of a parallel active power filter(PT) system in unbalanced load condition. The unbalanced load leads to negative sequence of current, and makes 120Hz ripple in the DC-link voltage forcing large capacitance and increases the rating of APF. thus, the separation of negative sequence is performed in synchronous reference frame and controlled to flow into supply network. The validity of the scheme is investigated through simulation and the experimental results for a prototype active power filter system rated at 10kVA.

• 전기학회논문지P
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• 제57권2호
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• pp.160-163
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• 2008

In this paper, an auto-diagnosis method of the stator winding fault for small induction motor is suggested. 3-phase stator currents are sampled, filtered, and transformed with Park's vector transformation. After then Park's vector patterns are obtained. To detect the stator winding fault automatically, a distortion ratio is newly defined and compared with the one of healthy motor, and the threshold levels of distortion ratio are suggested. The 2-turn, 4-turn, 8-turn winding fault are tested with no load, 25%, 50%, 75%, and 100% rated load. The distortion ratio of the Park's vector patterns are increased as the increase of the faulted turns, but are same as the increase of the load.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권8호
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• pp.417-425
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• 1999

This paper presents an effective control scheme with the voltage-fed half-bridge series resonant inverter for induction heating system, which is based upon a load-adaptive tuned frequency tracking control strategy using PLL(Phase Locked Loop) and its peripheral control circuits. The proposed control strategy ensures a stable operation characteristics of overall inverter system and ZVS(Zero Voltage Switching) irrespective of sensitive load parameter variations, specially in the non-magnetic materials as well as power regulation. The detail operation principle and the characteristics of inverter system with the proposed control scheme are described and its validity is verified by the simulation and the experimental results for a prototype induction cooking system rated at 1.2kW.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2301-2303
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• 2003

A steam turnine in thermal/nuclear power plant drives generator and maintains it at rated speed using high temperature and high pressure steam energy. After synchronization in parallel with the power system, generator output increases according as the governor, that is the controller, increases steam flow into turbine. By the way, as the steam flow into turbine can not be reduced fast even though the electrical load is lost, the turbine gets into dangerous situation due to the increase of its speed. At this time, the duty of the turbine governor is to limit the speed to its overspeed trip setpoint by stopping the steam flow as soon as possible, the test of which is called load rejection test. It is introduced in this paper for a simulation test of generator load rejection to be implemented on the turbine governor in a 600MW nuclear power plant before its startup.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.358-360
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• 2007

In this paper, an auto-diagnosis method of the stator winding fault for small induction motor is suggested. 3-phase stator currents are sampled, filtered, and transformed with Park's vector transformation. After then Park's vector patterns are obtained. To detect the stator winding fault automatically, a distortion ratio (id/iq) is newly defined and compared with the one of healthy motor, and the threshold levels are suggested. The 2-turn, 4-turn, 8-turn winding fault are tested with no load, 25%, 50%, 75%, and 100% rated load. The distortion ratio of the Park's vector patterns are increased as the increase of the faulted turns, but are same as the increase of the load.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.255-257
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• 1994

The V/F slip frequency constant control methods are used for driving induction motor with load commutated current source inverter, that is. constant V/F and slip frequency driving is used to load commutate the inverter below the critical frequency, while constant voltage and variable frequency and slip frequency driving are used in above the critical region. In order to applicate the load commutated current source inverter to the general use, speed control range of induction noter is selected to two times at rated frequency. Therefore, economical application is possible because of the maximum reduction of the condenser of the inverter output port. The use of the proposed force commutated circuit improves the false operation of force commutated circuit and inverter commutation failure which are produced by the influence of the lower-order harmonics of the conventional load commutated current source inverter at starting.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.190-193
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• 2003

This paper Proposes 40 [KVA] rated SIV(Static Inverter) system for Light Rail Transit. The SIV Provide power of a fluorescent light in the car, Air-conditioner. and other equipments. To control output voltage it is used voltage control loop for constant voltage control and simultaneously used current control loop for instantaneous control at load changing. The Performance of SIV system will be verified by experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 추계학술대회 논문집 학회본부
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• pp.271-273
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• 1995

This paper proposes the efficiency improvement method of vvcf-induction motor drives, which operates always at rated speed, regardless of load conditions, with counter emf estimation. The counter emf is estimated by detecting the fundamental component of motor input current, which is employed in speed control algorithm through the comparison with the actual counter emf during the nonconduction interval. The input power reduction by speed control is confirmed through simulations and experimental results.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 추계학술대회 논문집(I)
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• pp.522-527
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• 2002

This paper proposes 40 [KVA] rated SW(Static Inverter) system for Light Rail Transit. The SIV provide power of a fluorescent light in the car, Air-conditioner, and other equipments. To control output voltage it is used voltage control loop for constant voltage control and simultaneously used current control loop for instantaneous control at load changing. The performance of SW system will be verified by experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 전력전자학술대회
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• pp.1-2
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• 2017

In this paper a method is proposed to optimize the inductor design of PFC boost converter with maximum efficiency at rated load. The variables of switching frequency, the number of turns, core size and permeability are selected to improve the efficiency. The experimental result shows the proposed inductor design method can lead a higher efficiency when compared with the typical inductor design method.