• 전기학회논문지
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• 제65권12호
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• pp.2008-2013
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• 2016

This paper proposes analysis and suppression method for reactive power vibration of the slave motor caused by back-EMF mismatch between the master and the slave motor and stator resistance during middle-low speed operation. The master and slave motors are parallel connected dual SPMSMs(Surface mounted Permanent Magnet Synchronous Motors) fed by a single inverter. To suppress vibration of reactive power, RPC(Reactive Power Compensator) proposed in this paper analyzes flux-axis current vibration of the slave motor that occurs in middle-low speed operation using a mathematical model of the fan motor. And RPC adds vibration components detected from flux-axis current of the slave motor to flux-axis current of the master motor. The results of experiment conducted verify the efficacy of the proposed method.

• 한국전자통신학회논문지
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• 제8권2호
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• pp.285-290
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• 2013

Slotless 선형 동기 전동기(Linear Synchronous Motor)는 가동자의 구조가 간단하고 1차측 철심의 슬롯을 제거하여 갭 중의 자기에너지를 균일화해 추력 변동을 억제할 수 있는 장점을 가지고 있다. 또한 고효율로 구동이 가능하고 제어성이 타 선형 전동기에 비해 뛰어나 반송장치의 적용이 확대 되고 있는 실정이다. 하지만 주거 환경 분야의 적용은 미흡한 실정이다. 따라서 본 논문에서는 Slotless 선형 동기 전동기의 주거 환경 분야 적용을 위해 위치 피드백 제어에 따른 구동 특성을 고찰하고 속도 진동의 최소화와 안정된 응답 특성을 얻기 위해 부하 탑재와 가속도를 변화시켜 위치 피드백 제어를 비교함으로써 제어기의 유용함을 입증한다.

• 소음진동
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• 제7권2호
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• pp.209-214
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• 1997

균열을 가진 회전축은 고조파성분이 진동에 나타나는 특징을 갖는다. 이 고조파성분을 균열탐지에 활용하기 위하여는 이들이 크게 발생되는 회전수를 이용할 필요가 있다. 2차고조파공진속도를 정의하여 이 속도에서의 균열과 불균형질량 방위각에 따른 고조파 진동 특성을 단순회전체에서 설명하였다. 이 특성을 이용하여 균열의 위치를 나타낼 수 있는 알고리즘을 만들고 수치실험을 하여 타당성을 보였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 추계학술대회 논문집
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• pp.607-610
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• 2009

The abnormal combustion in the running engine results to knocking which increases the pressure and temperature in the cylinder, thereby decreasing the generated power by reducing the thermal efficiency. When the temperature and pressure in the cylinder increased rapidly by knocking, abnormal combustion takes place and the engine power is decreased. To investigate the knocking phenomenon, accelerometers are installed in the cylinder head to monitor and diagnose the vibration signal. As method of signal analysis, the time-frequency analysis method was adapted for acquisition of vibration signal and analyzes engine combustion in the short time. In this experiment, after analyzing time data which is stored in the signal recorder in one unit work (4 strokes: 2 revolutions), the signal with frequency and Wavelet methods with extracted one engine combustion data was also analyzed. Then, normal condition with no knocking signal is analyzed at this time. Hereafter, the experiments made a standard for distinguishing normal and abnormal condition to be carried out in acquisition of vibration signal at all cylinders and extracting knocking signal. In addition, analyzing methods can be diverse with Symmetry Dot Patterns (SDP), Time Synchronous Average (TSA), Wigner-Ville Distribution (WVD), Wigner-Ville Spectrum (WVS) and Mean Instantaneous Power (MIP) in the cold test [2]. With signal processing of vibration from engine knocking sensor, the authors adapted a part of engine /rotor vibration analysis and monitoring system for marine vessels to prevent several problems due to engine knocking

• 한국소음진동공학회논문집
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• 제11권8호
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• pp.338-348
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• 2001

A hybrid self-hearing motor, which Is a functional combination of general permanent magnet (PM) motor and hybrid active magnetic bearing(AMB), was proposed a few years ago. In this paper the hybrid self-bearing motor is modified to a disk type, in which one of two magnetic hearings was substituted for a thin yoke to make the system more compact. An outer rotors in this self-hearing motor is actively controlled only in two radial directions while the ocher motions are passively salable owing to the disk-type structure. Main advantages of the proposed self-hearing motor are simple control mechanism, low power consumption and smart structure. Mathematical model for the magnetic force Is built wish consideration of the radial displacement of the rotor. The model helps us not only to design a levitation controller but also to expect the system performance. Some experimental results show good capability and feasibility of the Proposed self-bearing motor.

• Journal of Advanced Marine Engineering and Technology
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• 제10권4호
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• pp.31-40
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• 1986

With the tendency toward high speed and high pressure in centrifugal pumps, the problem of sub-synchronous vibration has arisen, caused by the hydraulic forces of the working fluid, such as wearring, balance piston, impeller, etc.. These forces can drastically alter the rotor critical speeds and stability characteristics, and can be acted significant destabilizing forces. For preventing such self-excited vibration, the desing of the rotor system needs, which would secure the stability of the machine. In this paper, a procedure is presented for dynamic modeling of rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter finite rotor elements and discrete bearings, seals and impellers. A finite element model including the effects of rotatory inertia and gyroscopic moments is developed using the consistent matrix approach. The technique of dynamic matrix reduction is applied to the shaft matrices to reduce them to a set of matrices of dynamic of significantly fewer degrees of freedom. The representation of bearing, seal and impeller elements is in term of linearized stiffness and damping matrices by reasonably small perturbations from equilibrium. The stability behavior of a typical double suction centrifugal pump is presented. Results show the influence of clearance and flow conditions on running speeds and stability characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.726-727
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• 2015

본 논문은 IPMSM(Interior Permanent Magnetic - Synchronous Motor) 구동 시에 나타나는 전자기력의 기본파 성분의 진동을 분석하였다. 대상 전동기로는 크기가 같고 동일 출력을 내는 14극 12슬롯, 14극 18슬롯 IPMSM을 선정하였다. 두 전동기의 Vibration Order를 수식적으로 검토한 결과 14극 12슬롯 전동기가 14극 18슬롯 전동기에 비해 전자기력의 기본파 성분이 진동에 취약함을 확인하였고, 이를 유한요소해석(FEA)을 통해 검증하였다. 검토결과를 바탕으로 전자기력의 기본파 성분 진동저감을 위한 극 수 슬롯 수 조합에 대해서 분석하였다.

• Journal of Electrical Engineering and Technology
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• 제6권3호
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• pp.356-363
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• 2011

Vibrations and noise in electrical machines are directly related to the characteristics of the radial forces on one hand, and mechanical behavior on the other [1, 4]. The characteristics of these forces depend on the air gap flux density, which is also influenced by other factors, such as stator slots and poles, saturation level, winding type, and certain faults. The aim of this work is to investigate the effect of eccentricity and demagnetization faults on electromagnetic noise generated by the external surface of Permanent Magnet Synchronous Machine [PMSM]. For this purpose, an analytical electromagnetic vibroacoustic model is developed. The results confirm the effect of eccentricity and demagnetization fault in generating some low modes radial forces.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2594-2599
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• 2008

This study deals with the development of PMSM(Permanent Magnet Synchronous Motor) for automotive EDC(Electric Drive Compressor). We have already developed the previous version of PMSM. It showed the characteristics of small size and high efficiency. But noise and vibration levels were higher than target values, so it was impossible to apply. So, in order to reduce noise and vibration levels, many parameters like the numbers of slots, the numbers of winding turns, and slot open width were changed. As a result, noise level of newly developed PMSM was decreased about 36.9% at maximum operating frequency (8600 rpm), and was reduced about 37.7% at rated frequency (6000 rpm) with the same sized and more efficient PMSM.

• Structural Engineering and Mechanics
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• 제34권5호
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• pp.549-561
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• 2010

In this paper, free vibration analyses of a parallel placed twin pipe system simulated by simply supported-simply supported and fixed-fixed Euler-Bernoulli beams resting on Winkler elastic soil are presented. The motion of the system is described by a homogenous set of two partial differential equations, which is solved by a simulation method called the Differential Transform Method (DTM). Free vibrations of an elastically connected twin pipe system are realized by synchronous and asynchronous deflections. The results of the presented theoretical analyses for simply supported Euler-Bernoulli beams are compared with existing ones in open literature and very good agreement is demonstrated.