• 전기학회논문지
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• 제58권12호
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• pp.2391-2395
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• 2009

Active control schemes which modify the excitation to correct for any of the nonideal characteristics of the SPMSM is described. Especially, because of design limitations(size and cost) in automobile, the back-EMF of SPMSM can't be perfectly designed with sinusoidal wave and iron core of stator is saturated so that torque ripple is unavoidable. An active cancellation method of the pulsating torque components which would otherwise be generated using the classic sinusoidal current excitation is illustrated.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2274-2277
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• 2003

A cylindrical permanent magnet inside the four-phase permanent magnet (PM) stepping motor is employed as the rotor. The stator has four teeth around, which its coils are wound. The mode of excitation can be classified into 3 modes: single-phase excitation, two-phase excitation and ministep excitation. The ministep drive is a method to subdivide one step into several small steps by means of electronics. The paper presents the programmable ministep technique drive. This technique decodes the results obtained from the counter to locate the data in Read Only Memory (ROM). The Sinusoidal Pulse Width Modulation (SPWM) is transformed to binary file and saved to the ROM. The experiment is performed with the four-phase PM stepping motor and drives from a two-phase programmable sinusoidal ministep signal, instead of square wave. The results show that the performances of the proposed programmable ministep technique drive have high efficiency, smooth step motion, and high speed response. Moreover, the resolution of sinusoidal ministep signal can be controlled by the input frequency (f command).

• 한국공작기계학회논문집
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• 제11권2호
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• pp.71-79
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• 2002

In this paper, an oil hydraulic pipeline is terminated by both rotary sinusoidal flow generator at upstream oriffice at down stream. The pulsating pressure wave from generated by the rotary sinusoidal flow generator, is measured by using sensor. In the analysis of this paper, a component of the fundamental frequency is obtained by using Laplace transformation.. The experimental and analytical results make clear that (1) viscosity is significant role in hydraulic pipe. (2) When pulsating frequency is matched with the natural frequency, resonance frequency occured periodically. According to the study proposed here, dynamic pressure in a circular oil pipe is expressed in propagation of pressure wave with respect to frequency and Bessel function. The resonance at oil temperature $20^{\circ}$$0^{\circ}C$ in this study. The abrupt change of gain value is due to effect of resonance frequency. The results of experiment are compared with the calculated results, and agreement of both results is fairly good.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.126-128
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• 1993

Rectifiers of power conversion system are widely used condenser at input to be cheap and to be simple construction. But this method is produced harmonics of pulse at peak value of input AC voltage. The main circuit which make input current of a sinusoidal wave and improve power-factor is almost taken step-up converter. This paper is able to obtain high power-factor and efficiency because the input current is made sinusoidal wave in single phase alternating current(AC) source. Also the proposed converter is able to minimize switching loss by ZVCS(zero voltage switching and zero current switching).

• 산업기술연구
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• 제27권A호
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• pp.149-155
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• 2007

The counter emf(electromotive forces) of a permanent magnet multi-phase brushless motor is generally a non-sinusoidal wave or a non-ideal trapezoid. So, conventional modeling using a sinusoidal wave or an ideal trapezoid counter emf can result in errors. In order to reduce modeling errors for simulation and analysis the properties of a multi-phase brushless AC motor, this paper proposes a phase variable model that is a mixed modeling technique using both Finite Element Analysis(FEA) based circuits and motor voltage equations. The phase model parameters including the counter emf voltage waveform are obtained by using of FEA, and the mixed modeling technique based on circuits and equations is used to implement a simulation model for multi-phase brushless AC motors with any counter emf voltage waveforms. Adequacy of the proposed model is established from the simulation and experimental results for a seven-phase brushless motor.

• 조명전기설비학회논문지
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• 제24권1호
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• pp.78-84
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• 2010

단상유도전동기의 효율을 높이기 위한 강화 코일형(RC형)을 개발하여 기존의 코일과 비교하였을 때, 코일의 길이, 굵기, 종류 등이 같은 동일조건에서 전류를 흘려 자속을 발생시키는 코일은 (1) 전체자속발생량이 증가하고, (2) 자속의 공간분포가 정현파에 가깝고, (3) 자속흐름이 고유방향성을 유지할 때, 코일을 내장한 시스템의 성능이 개선된다. 강화코일(RC: Reinforced Coil)은 코일의 원래영역을 갖는 바깥코일(OC: Outer Coil)과 중앙부위 자속을 강화하기 위한 안쪽코일(IC: Inner Coil)을 매턴마다 양방향으로 원점대칭이 되도록 결합함으로써 정현근접성은 물론 영역친근성을 높여 고유방향성을 동시에 구현할 수 있다. 따라서 강화코일형(RC형)은 코일 좌우의 자속량과 중앙부위의 자속량이 정현파에 가깝도록 순수 바깥코일(OC)과 강화코일(RC)의 적정 턴수를 직렬 연결함으로써 얻어진다. 강화코일을 단상유도전동기에 적용하여 효율을 높일 수 있는 유용성에 대한 것을 실험을 통하여 확인하였다.

• 전력전자학회논문지
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• 제5권6호
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• pp.610-619
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• 2000

본 논문에서는 현재 전력저장시스템으로써 가장 많이 사용하고 있는 배터리를 대체할 목적의 5MB (Superconductive Magnetic Bearing)를 이용한 off-line UPS에 관해 연구하였다 영구자석의 덩어리형 고온 초전도 체위에서의 부상득성을 이용하여 베어링 문제의 해결방안에 접근함으로써 고효율의 FES찰 구성하여 단상 off-line UPS에 적용하였으며 제어회로에는 80C 1 96KC 마이크로프로세서를 사용하였고 빠픈 응답윤 요구하는 부분 은 아날로그회로를 사용하여 구성하였다. 에너지 저장모드에서 컨버터 입력천류는 전원전압과 동상의 정현파로 제어하였으며 에너지 회생모드에서는 출력잔압윤 정현파로 제어하기위해 필터커패시터전류릎 직접 제어하였다. 시작 품제작을 통해 시스템의 안장된 동작특성을 확인함으로써 제안된 FES가 Off-line UPS 에서의 에너지 저장매체로써 우수함을 입증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1416-1418
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• 1994

Expressions for the displacement of a bimorph, one end fixed and the other free, has been introduced when sinusoidal inputs were applied to the ceramic plates on a thin metal plate. Maximum displacements at the free end and strains at the position of strain gage attached were measured when various wave forms, voltages, and frequencies were applied to the bimorph whose length is 6.6[cm], width 2.5[cm], and thickness 0.0365[cm]. Under the constant voltage ( $70[V_{peak}]$ ), the strains and the displacements at the free end were larger than the case of the sinusoidal input when the square wave was applied and were smaller when triangular wave. It was shown that the displacements at the free end and the strains of the gage position were increased as the applied voltage in the range of $30-90[V_{peak}]$ and effective length were increased. And it was also found that the resonant frequency of a bimorph was decreased as its effective length was increased, and that the displacements and the strains were maximum at the resonant frequency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.443-445
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• 1995

Since the residential load is an AC load, while the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell and must provide the sinusoidal wave current and voltage with unity power factor in the case of driving to Interact with utility line. It is always necessary for the output of solar cell to operate in the vicinity of maximum power point, since it is greatly fluctuated by insolation. This paper treats that we will constitute a single phase PWM voltage source inverter and trace the modulation index which always maximize the output of solar cell in propotion to insolation variation and prove it by simulation that we can provide current wave, which is nearly sinusoidal wave with unity power factor, for load and utility line.

• 대한전자공학회논문지
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• 제12권2호
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• pp.43-46
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• 1975

쵸퍼형DC증폭기의 AC증폭기의 인력신호는 일련의 단형연이다. 따라서 이 때의 AC증폭기의 동작은 정장파신호에 대한 그것과 큰 차이가 있다. 본 논문은 단형파에 대한 AC증폭기의 각단에서의 파형의 찌그러짐에 대한 해석을 하여 쵸퍼용AC증폭기의 설계상의 문제점을 고찰한 것이다. 각증폭단의 시정수가 동일한 경우에는 각단의 신호파형은 모두 지수감쇠속형파로 되며, 시정수가 다를 경우에는 여러개의 지수감쇠구형파의 합성파로 된다. In a chopper amplifier the input signal of the AC amplifier is a train of square-waves. In the rase of square-wave the operatiom of AC amplifier is much different from that of ordinary sinusoidal wave. In this paper for the purpose of contributing to the design of chopper amplifier destortions of waveforms in the amplifier were investigated. When the time constant of each stage is equal the waveform in each stave apppears as square wave whose top is exponentially decaying. And when each stave has different time constant the waveform in n-th stage is composed of n-square waves whose tops are exponentially decaying.