• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권3호
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• pp.168-174
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• 2004

On-line monitoring system(OMS) has been developed for the pumped storage generator/motor The OMS is applied to diagnosis of the PD(partial discharge) activity of stator insulation, the shorted-turn of rotor winding and the variation of the air-gap between stator and rotor. The OMS consists of DAS(data acquisition system), main server system, gateway and display PC. The DAS measures the PD, the shorted-turn and air-gap from three sensors installed on the generator/motor. The gateway controls the data which sent by DAS. The main server system saves the data, analyzes the data and conducts the diagnostic algorithm. The display PC shows the diagnostic results of partial discharge, shorted-turn and air-gap. Field tests were conducted using PDA(partial discharge analyzer). The results of the OMS and PDA measurements can be directly correlated with normalized quantity number(NQN), PD magnitude(Qm) and PD pattern.

• 한국항공우주학회지
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• 제30권4호
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• pp.99-105
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• 2002

본 연구에서는 정익과 동익간의 축방향 간격을 달리하여 축류형 터빈에서의 성능시험을 수행하였다. 실험에 사용된 터빈은 저압저속터빈으로써 평균반경에서 반동도가 0.373이며 축류형 3차원 단단터빈이다. 터빈의 평균반경 직경은 257.56mm이며 평균반경에서 동익의 익현은 28.2mm이다. 성능시험을 위한 공기력 입력장치로는 풍동이 사용되었으며 풍동의 터보블로워 동력은 30kW로써 290mmAq의 정압력에서 $340m^3$/min의 공기량을 보낼 수 있다. 터빈에서의 회전수 및 출력은 터빈 축에 직결식으로 연결된 다이나모메터에서 제어되었다. 실험에서 축방향 간격조정은 평균반경에서의 정익 축방향 익현의 1/4에서 3배까지 변경하여 총 9개의 성능시험을 수행하였다. 같은 무차원 유량과 RPM에서 축방향의 간격에 따른 효율의 변화는 최대 8%이내지만 최고효율을 얻게되는 축방향 간격은 1.6-1.9Cx 였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.129-131
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• 1994

Rectangular type hybrid step motor is designed to generate thirty percents higher torque than existing step motors. The torque for the motor is generated by the electromagnetic force at the air gap between the stator and rotor. The generating torque is proportioned to the rotor volume, i. e. rotor diameter. The main idea in this study is that the diameter of rotor is increased to generate more torque for the same overall motor size. This motors are manufactured by varying the shape of the teeth width of the stator and rotor. The optimum shape of the teeth is selected from the standpoint as smaller step angular accuracy.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.315-325
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• 2018

This paper investigates optimum air-gap flux distribution with third harmonic rotor flux orientation adjustment for five-phase induction motor. The technique of objective is to generate a nearly rectangular air-gap flux, and it improves iron utilization under variation loading conditions. The proportional relations between third harmonic and fundamental plane currents is usually adopted in the conventional method. However, misalignment between fundamental and third harmonic component occurs with variation loading. The iron of stator teeth is saturated due to this misalignment. This problem is solved by third harmonic rotor flux orientation adjustment simultaneously, and direction and amplitude are changed with mechanical load variation. The proposed method ensures that the air-gap flux density is near rectangular for a maximum value from no load to rated load. It is confirmed that the proposed method guarantees complete both planes decoupling with third harmonic flux orientation adjustment. The effectiveness of the proposed technique is validated experimentally.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권5호
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• pp.320-326
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• 2000

The canned motor of 3-phase induction is used for main coolant pump(MCP). The type of motor is canned-motor that stator and rotor are welded by sealed can. So, cooling water flows in the air gap of the canned motor as an independent cycling cooling system from the air gap to yoke of the motor to prevent high temperature of stator can and to lubricate bearing. Heat exchange is occurred between cooling water in the air gap and cooling water from the exterior pump to prevent rising of temperature in the motor. I has to analyze the characteristics of can exactly because the loss and the heat in the can are very important to design MCP. Therefore, thermal analysis is studied considering the effect of eddy-current los induced in the can.

• 대한전기학회논문지
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• 제31권8호
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• pp.46-53
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• 1982

When an induction motor is lightly loaded, the efficiency can be very substantially improved by controlling the air gap flux. Thus in the system which requires constant speed under either normal load or light load, it is possible to save energy by means of controlling the air gap flux. In this paper, the required relationships between stator current and rotor slip frequency for optimal efficiency control is derived and the improved control loop is suggested.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.9-11
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• 2008

When a squirrel cage induction motor is loaded, the electromagnetic noise can increase depending on the load current. It is due to the air gap harmonic fluxes from the rotor current induced during loading. This unfavorable noise can be anticipated by calculating the radial force waves in the air gap, vibration mode shapes of them, and stator core natural frequencies of each mode. With the experimental tests with the different rotor slot numbers, the variation of electromagnetic noise is studied between on-loaded and loaded running.

• Transactions on Electrical and Electronic Materials
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• 제7권2호
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• pp.90-95
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• 2006

An on-line diagnostic test has been studied and performed for the pumped storage generator/motor. This study aims at reducing the diagnostic cost, minimizing the technical dependency on third party manufactures. Further design of on-line diagnostic system such as shorted-turn of rotor winding, partial discharge (PD) of stator winding and air-gap between stator and rotor for pumped storage generator/motor has been verified. In addition, it needs to be validated on site performance of the developed continuous on-line monitoring system for corresponding tasks for the improvement of the availability & reliability during operation.

• 한국항행학회논문지
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• 제27권1호
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• pp.96-101
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• 2023

본 연구에서는, 회전하는 축계에서 무선센서 시스템 응용을 위해 에너지 하베스터(EH, energy harvester)를 제안되었다. 무선 센서 시스템(WSS)에 지속적으로 전원을 공급하기 위해 EH를 직경 20 cm의 샤프트에 설계 및 구현되었다. 로터에는 샤프트에 부착된 7개의 U자형 코어에 코일이 쌍으로 감겨 있다. 고정자는 8개의 I-코어에 부착된 8쌍의 자석으로 구성되며 외부 고정 장치에 고정되었다. EH의 발전 전력은 회전자와 고정자 사이의 공기 공극, 코일의 권수, 그리고 축의 회전속도에 따라 조사되었다. 제작된 EH는 300 rpm 및 3 mm 공기 공극에서 최대 2.87 W의 전력을 생산하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.388-394
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• 1998

In this paper, we propose a speed sensorless control of the saturated induction motor using the zero sequence third harmonic voltages and a compensation method of the stator resistance variations. The air-gap flux of the saturated induction motor contains the space harmonic components rorating synchronous frequency. As a function of the air-gap flux saturation, the dominant third harmonic voltage is used to compensate the non-linear variations of the mutual inductance depending on the saturation level of the motor. and also the stator resistance variations can be measured with the phase angle between the voltage vector and the zero sequencial voltages. The validity of the proposed compensation scheme in the speed sensorless control using rotor flux observer is verified by simulations.