• Tribology and Lubricants
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• v.28 no.5
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• pp.197-202
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• 2012

In this study, with the purpose of fundamentally improving the unbalance response vibration of a large PRT motor-generator rotor by design, a performance improvement design analysis is carried-out by retrofitting tilting pad bearings, replacing the plain partial journal bearings that were originally applied for operation at a rated speed of 1,800 rpm. In this process, a goal of the design analysis is to obtain a design solution for maximizing the direct stiffness of the bearings while satisfying the key basic lubrication performance requirements such as the minimum lift-off speed and maximum oil-film temperature. The results show that with a careful design application of tilting pad journal bearings for operation at such a relatively low speed of 1,800 rpm, direct stiffness increment of the bearings by about two times can be effectively achieved. Prevention of pad unloading is also considered in the analysis. Moreover, the designs of elliptical and offset half journal bearings are also analyzed and reviewed.

• The KSFM Journal of Fluid Machinery
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• v.20 no.1
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• pp.48-52
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• 2017

Small-scale motor-generator sets have been used in laboratories for verification of real large wind turbines whose rated power are more than 1 MW. In this paper, a result of designing a small-scale motor-generator system, which is composed of motor, gear box, flywheel, and generator, is presented in the aspect of speed response. Design objective is to make a small-scale motor-generator system have the same time constant and optimal tip speed ratio region as a real MW wind turbine. A small-scale 3.5 kW motor-generator system for emulating response of a 2 MW wind turbine is considered and designed.

• Tribology and Lubricants
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• v.28 no.6
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• pp.265-271
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• 2012

In the preceding Part I study, for improving the unbalance response vibration of a large PRT motor-generator rotor fundamentally by design, a series of design analyses were carried out for bearing improvement by retrofitting from original plain partial journal bearings, applied for operation at a rated speed of 1,800 rpm, to final tilting pad journal bearings. To satisfy evenly key basic lubrication performances such as the minimum lift-off speed and maximum oil-film temperature, a design solution of 5-pad tilting pad journal bearings and maximizing the direct stiffness by about two times has been achieved. In this Part II study, a detailed rotordynamic analysis of the large PRT motor-generator rotor-bearing system will be performed, applying both the original plain partial journal bearings and the retrofitted tilting pad journal bearings, to confirm the effect of rotordynamic vibration improvement after retrofitting. The results show that the rotor unbalance response vibrations with the tilting pad journal bearings are greatly reduced by as much as about one ninth of those with the plain partial journal bearings. In addition, for the tilting pad journal bearings there exist no critical speed up to the rated speed and just one instance of a concerned critical speed around the rated speed, whereas for the plain partial journal bearings there exist one instance of a critical speed up to the rated speed and two instances of concerned critical speeds around the rated speed.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.835-836
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• 2006

최근의 선박 추진시스템은 기존의 엔진, 터빈 등의 구동 원에서 선박의 발전기로부터 선체 외부의 프로펠러와 일체형으로 구성된 모터를 구동하여 추진하는 전기추진식으로 변화되고 있다. 특히, 히토류계 영구자석재질의 발달로 인하여 대형 선박의 추진을 위한 대용량 자석계자형 BLDC와 영구자석형 동기전동기의 설계가 가능해 졌으며, 이에 대한 연구구도 활발히 이루어지고 있다. 그러나 이도 중 소형 선박기기에 한정되어 있으며, MW급 이상의 대형기기의 설계 연구도 일부 선진국에서만 진행 되고 있는 실정이다. 이에 본 연구에서는 5MW, 150rpm급 대용량 추진전동기 설계에 관한 연구를 하였다. 본 설계 모델은 오랜 기간 해양 운행을 해야 하는 선박특성 상 중요한 부분인 에너지 효율을 높이기 위하여 인버터를 전동기 내부에 배치한 구조로 부피와 중량을 줄이고, 더불어 속도에 따라 인버터를 커플링하여 상변환이 가능한 전동기를 설계하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.69-74
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• 2018

Large industrial motors require a large area because of the high risk of shutdown accidents and large industrial accidents due to the lowering of the dielectric strength of the armature windings and overheating problems. Therefore, there is a demand for a large-capacity motor that has small size, light weight, and excellent dielectric strength compared with conventional motors. Superconducting motors have advantages of high efficiency and output power, low size, low weight, and improved stability. This results from greatly increasing the magnetic field generation by using superconductive field coils in rotating machines such as generators and motors. It is very important to design and analyze the cooling system to lower the critical temperature of the wires to achieve superconducting performance. In this study, a field loss analysis and low-temperature heat transfer analysis of the cooling system were performed through the conceptual design of a 100-HP high-temperature superconducting synchronous motor. The field loss analysis shows that a uniform pore magnetic flux density appears when high-temperature superconducting wire is used. The low-temperature heat transfer analysis for gaseous neon and liquid neon showed that a flow rate of 1 kg/min of liquid neon is suitable for maintaining low-temperature stability of the high-temperature superconducting wire.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.47-49
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• 2005

최근의 선박 추진시스템은 기존의 엔진, 터빈 둥의 구동 원에서 선박의 발전기로부터 선체 외부의 프로펠러와 일체형으로 구성된 모터를 구동하여 추진하는 전기추진식으로 변화되고 있다. 특히, 히토류계 영구자석재질의 발달로 인하여 대형선박의 추진을 위한 대용량 자석계자형 BLDC와 영구자석형 동기전동기의 설계 연구가 활발히 이루어지고 있다. 그러나 여전히 MW급 대용량 BLDC 추진전동기의 설계 연구는 미흡한 실정이다. 이에 본 연구에서는 5MW급 대용량 BLDC 추진전동기 설계 연구를 진행하였으며, 그 결과 슬롯 수에 의한 고정자 형상이 다른 3가지 타입의 인버터 내장형 MW급 모델을 설계하였다. 그리고 이들 모델들을 정자계 유한요소법을 이용하여 해석함으로써 고정자 형상에 따른 회전특성을 분석하였고, 이를 바탕으로 본 설계 조건에 적합한 고정자 형상 설계 방향을 제시하였다.