• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.582-585
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• 2004

Most of hard disk drives currently employ fluid dynamic bearing (FDB) for their rotor support. Stiffness of the FDB is affected by many design factors such as bearing clearance, fluid viscosity, and rotational speed. For the high rotating speed HDDs stiffness of the rotor is normally high enough to accomodate load disturbances. However small form factor HDDs that are to be operated in low power consumption are often designed with low stiffness rotors. Although the low stiffness rotor clearly benefits low power operation, it could damage the entire motor structure or head disk interface even by a light mechanical load disturbance such as shock or vibration. In addition, since a single channel HDD does not provide gram load equilibrium in axial direction the rotor could be tilted and make a hard contact to stator. A non-symmetric groove pattern could successfully compensate the tilted rotor angle during operation.

• Journal of Advanced Marine Engineering and Technology
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• 제16권5호
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• pp.6-16
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• 1992

Since world-wide oil shock on 1970s, many large size-low speed diesel engines, instead of steam turbines, are used for the industrial electric power generating plants due to their economic advantage of low specific fuel consumption. But it is very important to control their electric power fluctuation problems for the purpose of smooth parallel operation with existing power plants. In this paper the fluctuation problem of KEPCO Nam-cheju No.1 generator driven by diesel ngine(B & W 7K 60MC, 13931x138.5RPM) is investigated with analysis of torsional vibration of which 4th harmonic component is related to its power fluctuation. The problem can be improved by modification of cylinder arrangement and flywheel position in reverse sequence, equalizing the combustion gas pressure of all cylinder and installation of torsional vibration damper enlarged 30%(Je=7287Kg.m$^{2}$) and high quality balancing of generator rotor.

• 동력기계공학회지
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• 제16권6호
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• pp.73-78
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• 2012

This paper investigates the restart performance of sensorlessly controlled IPMSM Fan motor free-running in middle or high speed range just after inverter power off. There could be some difficulties to extract exact position information by using conventional sensorless control for restarting the motor because of stopped inverter operation. To solve this problem, we proposes to use low cost hall sensor. Using a hall sensor with SMO (Sliding Mode Observer) give us a solution to facilitate rotor position information extraction. The algorithm in this paper shows a certain way of the restarting method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.479-481
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• 2006

This paper describes a 2.5V, 320MHz low-noise and low-power Phase Locked Loop(PLL) using a noise-rejected Voltage Controlled ring Oscillator(VCO) fabricated in a TSMC 0.25um CMOS technology. In order to improve the power consumption and oscillation frequency of the PLL, The VCO consist of three-stage fully differential delay cells that can obtain the characteristic of high speed, low power and low phase noise. The VCO operates at 7MHz -670MHz. The oscillator consumes l.58mA from a 320MHz frequency and 2.5V supply. When the PLL with fully-differential ring VCO is locked 320MHz, the jitter and phase noise measured 26ps (rms), 157ps (p-p) and -97.09dB at 100kHz offset. We introduce and analysis the conditions in which ring VCO can oscillate for low-power operation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 II
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• pp.979-982
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• 2003

Due to the differential transmission technique and low voltage swing, LVDS has been widely used for high speed transmission with low power consumption. This paper presents the design and implementation of interface circuits for 1.5Gb/s operation in 0.35um CMOS technology. The interface circuit ate fully compatible with the low-voltage differential signaling(LVDS) standard. The LVDS proposed in this paper utilizes a sense amplifiers instead of the conventional differential pre-amplifier, which provides a 1.5Gb/s transmission speed with further reduced driver output voltage. Furthermore, the reduced driver output voltage results in reducing the power consumption.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2110-2112
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• 1997

The induction motor drive for the spindle of machining center is required to do not only a constant torque operation in low speed region(below base rpm), but also a constant power operation in high speed region(beyond base rpm). Also, control voltage shortage due to high speed operation must be overcome. The vector controlled inverter system with input 3 phase pwm converter is designed for that kind of condition. We experimented the performance of the inverter system with spindle motor made by Hyosung industries co.

• 한국자동차공학회논문집
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• 제11권6호
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• pp.21-29
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• 2003

Boosting of engine power by using Turbo- or Super-charger is a solution to comply with $CO_2$-regulation in Europe. Turbo-charger is now playing a major role in the field of charging system thank to its technical advantages such as no demand of operation power from engine. A mechanically driven Super-charger, however, is now popular due to quick speed response to change of the driving mode-high engine torque even at low engine speed. Since Super-charger needs operation power from engine, it is difficult to improve its relatively higher fuel consumption than that of Turbo-charger. This negative point is still an obstacle to the wide use of Super-charger. This study aims to develop power control concept to achieve the minimization of operation power when it is not necessary to charge at idling or part load driving condition. A screw type Super-charger was modified in design partially and adapted an internal bypass valve and a bypass tube to control charging pressure at part load. The various control concepts show a possibility to reduce operation power of Super-charger and result in improvement of fuel consumption.

• 전력전자학회논문지
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• 제9권1호
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• pp.17-24
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• 2004

터보 제너레이터의 시동기는 터보 샤프트 발전 시스템 시동기의 구성인 기어박스, DC 전동기, 저 전압 축전지를 대신하여 고속 발전기, 인버터 그리고 승압기로 구성된다. 터보 제너레이터는 시동 시 고속 회전이 요구되어 고속발전기는 수십 $\mu$Η의 낮은 누설 인덕턴스를 가지며, 인버터는 높은 전압의 DC link 전압이 필요하다. 본 연구에서는 시동기 구현을 위해 축전지 전압을 높은 전압으로 승압하는 대 용량 승압기를 개발하였다. 그리고 낮은 누설 인덕턴스를 갖는 전동기 권선에 높은 주파수의 전류 제어를 위해 정밀 고속 연산을 수행하는 인버터 드라이버의 설계와 안정된 점화를 위한 터보 제너레이터의 시동 알고리즘을 제안하였다. 또한 개발한 시동기로 터보 제너레이터의 시동을 수행하여 성능을 확인하였다.

• 전기전자학회논문지
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• 제20권3호
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• pp.285-290
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• 2016

고속 인터페이스에서 채널 대역폭에 의해 생기는 ISI는 최대 데이터 전송속도를 제한한다. ISI를 제거하는 가장 보편적인 기술로 DFE가 있다. 빠른 데이터 송수신을 위해서는 DFE가 효과적으로 ISI를 제거하는 것도 중요하지만 피드백 지연 등을 완화시켜 회로 자체의 최대 동작 주파수도 증가시켜야 한다. 또한, 싱글 엔디드 시그널링에서는 DFE가 ISI뿐만이 아닌 고주파 잡음도 효과적으로 제거하여야 한다. 한편, 데이터 전송 속도가 올라감에 따라 늘어 나는 ISI 및 고주파 잡음을 제거하기위한 DFE 구성품의 수가 증가한다. 이는 곧 추가의 전력소모를 야기하므로 고속 동작뿐만 아니라 저전력 동작도 주목할 필요가 있다. 본 논문에서는 ISI와 고주파 잡음을 효과적으로 제거하는 고속 DFE 및 저전력으로 동작하는 DFE의 동작 방식과 이들이 갖고 있는 장단점을 소개한다.

• Journal of Power Electronics
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• 제16권6호
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• pp.2173-2181
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• 2016

Permanent magnet synchronous motors (PMSMs) have higher torque and superior output power per volume than other types of AC motors. They are commonly used for applications that require a large output power and a wide range of speed. For precise control of PMSMs, knowing the accurate position of the rotor is essential, and normally position sensors such as a resolver or an encoder are employed. On the other hand, the position sensors make the driving system expensive and unstable if the attached sensor malfunctions. Therefore, sensorless algorithms are widely researched nowadays, to reduce the cost and cope with sensor failure. This paper proposes a sensorless algorithm that can be applied to a wide range of speed. The proposed method features a robust operation at low-speed as well as high-speed ranges by employing a gain adjustment scheme and intermittent voltage pulse injection method. In the proposed scheme the position estimation gain is tuned by a closed loop manner to have stable operation in tough driving environment. The proposed algorithm is fully verified by various experiments done with a 1 kW outer rotor-type PMSM.