• 한국정밀공학회지
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• 제15권8호
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• pp.11-16
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• 1998

Recently, the motor-integrated spindle systems have been used to simplify the machine tool structure, to improve the motion flexibility of machine tool, and to perform the high-speed machining. In this study, a static and dynamic analysis system for motor-integrated high-speed spindle systems is developed based on Timoshenko theory, finite element method and windows programming techniques. Since the system has various analysis modules related to static deformation analysis, modal analysis, frequency response analysis, unbalance response analysis and so on, it is useful in performing systematically the design and evaluation processes of motor-integrated high-speed spindle systems under windows GUI environment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.116-120
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• 2003

In general, industrial rotating machinery have been designed to have critical speed that is above operating speed. But nowadays, they should be operated more than the first critical speed as usual with the trend of high speed and high performance of rotating machinery. Therefore, it is important to predict the accuracy rotordynamic characteristics of the high speed rotating system in advance. In this paper, the results of rotordynamic analysis about FWP(Feed Water Pump) drive turbine rotor are showed. Because the FWP drive turbine analyzed is high speed machinery operated more than the operation speed of conventional FWP drive turbine, Seismic response analysis as well as unbalance response analysis is done in order to improve the reliability of the new turbine rotor-bearing system.

• 대한기계학회논문집
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• 제12권5호
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• pp.976-983
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• 1988

본 연구에서는 회전체 베어링계에 대한 불균형 응답 계산시 회전속도 의존성 을 손쉽게 고려할 수 있는 방법에 대해 논하고자 한다. 그 방법은 람다행렬(lamda matrix)을 도입하여, 회전속도 의존성을 지닌 고유치 문제를 회전속도 의존성이 없는 문제로 변환시킨 후 기존의 모우드 해석기법을 적용하여 불균형 응답특성을 알아내는 방법이다. 이때 베어링의 회전속도 의존성을 다항식(polynomial)으로 근사화할 수 있다는 기본 가정을 두었는데, 이러한 가정은 실제 베어링이 관심있는 회전수 영역에서 고차의 다항식으로 충분히 정확하게 근사화 될 수 있으므로 응용성을 크게 약화시키지 는 않는다. 특별히 회전속도 의존성이 자이로 효과(gyroscopic effect)에 의해서만 기인할 때는 여기서 제시하는 방법은 전혀 오차를 주지 않게 된다.

• 전력전자학회논문지
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• 제19권4호
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• pp.332-341
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• 2014

A cascaded H-bridge multi-level STATCOM(STATic synchronous COMpensator), which is composed of many cell inverters with independent dc-sources, generates inevitably dc-side voltage unbalance among phases when it compensates unbalanced load. It comes from the difference of flowing active power in each phase when this compensator makes negative-sequence current to eliminate the unbalance of source-side current. However, this unbalance can be controlled by injecting zero-sequence current which is decoupled with grid currents, so the compensator can work well during this balancing process. Both a feedback control algorithm, which produces zero-sequence current proportional to dc-side voltage unbalance within each phase, and a feedforward control algorithm, which makes zero-sequence current directly from the compensator's negative-sequence current, were proposed. The dc-side voltage of each phase can be controlled stably by these proposed algorithms in both steady-state and transient, so the compensator can have fast response to satisfy control performance under rapid changing load. These balancing controllers were implemented and verified via simulation and experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.67-69
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• 1999

This study deals with the unbalance response of a rotor of Switched Reluctance Motor(SRM) due to unbalanced mass. The method to analyze SRM with rotor-bearing system is based on an extension of the well-known Transfer Matrix Method(TMM). Most of the calculation results present the natural frequencies as a function of the speed of rotation which yields critical speeds and response to unbalanced mass.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.353.1-353
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• 2001

• 대한기계학회논문집
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• 제13권3호
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• pp.362-372
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• 1989

본 연구에서는 입형펌프를 회전체, 컬럼 및 배럴, 그리고 수윤활 베어링으로 기지된 3층 구조물로 하고 각 부분 상호간에 발생하는 유체력을 고려한 선형 수학모델을 작성하였다. 유체에 의한 압력효과를 Fritz의 제안식에 의해 물의 부가질량으로, 그리고 임펠러 및 라이너 링의 동적계수를 Yang의 식을 이용하여 산출하였다. 이를 이용하여 입형펌프의 고유치 해석과 불평형 진동응답 그리고 오부로부터 주기적인 외력이 가하여진 경우의 시간응답해석을 직접적분법인 Newmark-.betha.법을 이용하여 구하고 입형펌프의 동적응답특성을 명확히 하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.925-934
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• 2005

The dynamic response due to the unbalance and crack and the quasi-static response due to gravity are analytically derived based on the complex transfer matrix. The additional slope is expressed as function of the bending moment at crack position based on the fracture mechanics concept, and inversely the bending moment is expressed as function of the additional slope at the crack position. At each angle step during the shaft revolution, the additional slope and bending moment are calculated by an iterative method. The transient behavior is considered by introducing Fourier series expansion concept for the additional slope. Simulation is carried out for a simple rotor similar to those available in the literature and comparison of the basic crack behavior is shown. Using the additional slope, the cracked rotor behavior is explained with the crack depth increased: the magnitude of the additional slope increases and the closed crack duration during a revolution decreases as the crack depth increases. The direction of unbalance is also shown as a factor to affect the crack breathing. Whirl orbits are shown near the sub-critical speed ranges of the rotor.

• 한국소음진동공학회논문집
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• 제15권10호
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• pp.1137-1147
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• 2005

The dynamic response due to the unbalance and crack and the quasi-static response due to gravity are analytically derived based on the complex transfer matrix. The additional slope is expressed as function of the bending moment at crack position based on the fracture mechanics concept, and inversely the bending moment is expressed as function of the additional slope at the crack Position. At each angle step during the shaft revolution, the additional slope and bending moment are calculated by an iterativemethod. The transient behavior is considered by introducing Fourier series expansion concept for the additional slope. Simulation is carried out for a simple rotor similar to those available in the literature and comparison of the basic crack behavior is shown. Using the additional slope, the cracked rotor behavior is explained with the crack depth increased: the magnitude of the additional slope increases and the closed crack duration during a revolution decreases as the crack depth increases. The direction of unbalance is also shown as a factor to affect the crack breathing. Whirl orbits are shown near the sub-critical speed ranges of the rotor.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.714-719
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• 2000

This paper describes a transfer matrix approach to analyze the dynamics of a high sped flexible rotor system supported at 2 positions by five ceramic bearings. The rotor system is modelled as lumped parameters in which many factors are considered not only lumped inertia or mass, bending moment, shear force but also gyroscopic effect and unbalance. The equation of motion is derived in the transfer matrix form, from which the eigenvalues equation is also derived. The transfer natural frequencies and modes. The eigenvalues, eigenmodes, campbell diagram, whirling critical speed, whirling modes, and the response of unbalance are calculated and discussed.