• Title/Summary/Keyword: Speed Improvement

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A Study on the Improvement of Combustion Stability for SI Engine at Idle Operation (SI 기관의 공회전시 연소 안정성 향상에 관한 연구)

  • Lee, J.S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.6 no.6
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    • pp.259-266
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    • 1998
  • In the SI engine, the improvement of combustion stability is important not only for the fuel consumption rate but also for the emission control at idling of engine. Thus the engine speed fluctuation at idle operation mainly comes from cyclic variation of combustion in the SI engine. In this syudy, the improvement of combustion stability for the SI engine at idle condition by the cooling water temperature, duty ratio of ISC, spark ignition timing as well as the reducement of the harmful exhaust gas emission was discussed.

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A Study on Speed Regulations in Accordance with Speed-up for Tilting Train (틸팅차량 속도 향상에 따른 규정(안) 연구)

  • Chung Jong-Duk;Kim Jeongguk;Hong Yong-Ki;Kim Weon-Kyung;Pyun Jang-Sik
    • Proceedings of the KSR Conference
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    • 2004.06a
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    • pp.837-841
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    • 2004
  • In order to improve the speed of railway, several parameters and/or technical issues, which are affecting speed improvement negatively, need to be considered in addition to the enhancement of physical performance of the railway system such as maximum speed, speed at curve, and speed at turnout track. The parameters under complicated situation of railway system are from the areas of rolling stocks, track, power system, signalling, etc. In general, two different aspects of technical issues can be evaluated; Technical issues in the hardware aspect and technical issues in the software aspect. The hardware parameters include running performance, braking performance, and power performance, while the software factors are rules, regulations, and riding quality. In this investigation, a comparison study between hardware and software aspects in technical issues was conducted to provide technical information on the amendment of railway speed-up regulations.

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Effect of workpiece speed in ultra high speed cylindrical plunge grinding (초고속 원통 플런지연삭에서 공작물속도의 영향)

  • 주종길;박규열
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1997.10a
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    • pp.961-964
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    • 1997
  • In this paper, grinding characteristics of ultra high speed cylindrical plunge grinding was investigated by use of vitrified CBN wheel. From the experimental result, it was convinced that grinding power is decreased according to the increase of wheel and workpiece speed due to changing of grinding mechanism which decreases depth of cut and length of contact curve according to increment of wheel speed. And also, stock removal reduction of each gram lead to improvement of surface roughness by increasing the wheel speed.

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Sensorless Induction Motor Vector Control Using Stator Current-based MRAC (고정자 전류 기반의 모델 기준 적응 제어를 애용한 유도전동기의 센서리스 벡터제어)

  • 박철우;최병태;권우현
    • Journal of Institute of Control, Robotics and Systems
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    • v.9 no.9
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    • pp.692-699
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    • 2003
  • A novel rotor speed estimation method using Model Reference Adaptive Control(MRAC) is proposed to improve the performance of a sensorless vector controller. In the proposed mettled, the stator current is used as the model variable for estimating the speed. In conventional MRAC methods, the relation between the two model errors and the speed estmation error is unclear. Yet, in the proposed method, the stator current error is represented as a function of the first degree for the error value in the speed estimation. Therefore, the proposed method can produce a fast speed estimation and is robust to the parameters error In addition, the proposed method of offers a considerable improvement in the performance of a sensorless vector controller at a low speed. The superiority of the proposed method is verified by simulation and experiment in a low speed region and at a zero-speed.

New Speed Detection Method for the Improvement of the Speed Detection Characteristics in the Low Speed Region (저속영역의 속도검출특성 개선을 위한 새로운 속도검출방법)

  • Baek, S.K.;Min, J.J.;Lee, J.W.
    • Proceedings of the KIEE Conference
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    • 1997.11a
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    • pp.476-478
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    • 1997
  • A new speed detection method using low resolution incremental encoders, especially excellent in the low speed region and in the transient state, is proposed. The half period error of an incremental encoder is greater than the period error. So it's not recommended to quadruple the number of pulses per revolution, because it increase the ripple of speed. To overcome this restriction a speed detection, method has been proposed. But it requires so many latch circuits. Therefore we propose a new speed detection method that has different concept and has fewer latch circuits.

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A Study on the Characteristics Improvement of Electro-Hydraulic Servo System Controlled by High Speed Solenoid Valve (고속전자밸브로 제어되는 전기.유압 서보시스템의 특성 개선에 관한 연구)

  • Park, Seong-Hwan;Lee, Jin-Geol
    • Journal of Institute of Control, Robotics and Systems
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    • v.7 no.4
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    • pp.288-294
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    • 2001
  • In this study, a new PWM method considering the actuation delay of high speed solenoid valves is proposed to improve the response characteristics of electro hydraulic servo systems controlled by high speed solenoid valves. In addition, the decision method for the system gain, the basic period of PWM, and the sampling time is proposed, Since the conventional system controlled by high speed solenoid valves is too slow to apply this method, a high speed driving circuit(Quick-Drive) which enables rapid switching of the high speed solenoid valve at a high speed sampling mode is applied to realize this method. The experimental result shows that it is possible to achieve precision and quiet control without occurrence of limit cycle and wide range dead band.

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Vibration reduction of the high-speed EMU for improvement of ride comfort (승차감 향상을 위한 동력분산형 고속전철의 진동저감)

  • Baek, Seung-Guk;Lee, Rae-Min;Shin, Bum-Sik;Lee, Sang-Won;Koo, Ja-Choon;Choi, Yeon-Sun
    • Proceedings of the KSR Conference
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    • 2008.11b
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    • pp.1435-1440
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    • 2008
  • High-speed train under development is a type of EMU(electric multiple units). Since power sources like motors and gears are distributed in the high-speed EMU, the high-speed EMU generates vibration and sound more than the articulated high-speed train. Vibration of vehicle, vibration between rails and wheels, hunting of bogie and snake motion reduce ride comfort. In this paper, to decrease the vibration of the articulated high-speed train, improvements were presented using an analytical model and a simulation model. The simulation model of the high-speed EMU was designed on the basis of the korean high-speed train and the design parameters for ride comfort were showed and the dynamic characteristics of the vehicle was understood. To consider the characteristics of the vehicle suspension, the analytical model was designed and the simulation model was verified with it.

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Improvement of ALINEA Model Using Speed (속도를 이용한 ALINEA 모델 보완에 관한 연구)

  • Cho, Han-Seon;Lee, Jun;Lee, Ho-Won;Kim, Eun-Mi
    • Journal of Korean Society of Transportation
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    • v.26 no.5
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    • pp.73-80
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    • 2008
  • ALINEA algorithm, which is one of the best on-ramp metering algorithms, was designed to control the traffic volume from on-ramp in order to maintain the optimal occupancy rate of the detectors installed downstream of the merge area. But, the reliability of occupancy rate estimated from the loop detectors, which are used most commonly in Korea, is relatively lower than other parameters such as speed and volume. Moreover, because occupancy rate depends on the length of loop detectors and site, lots of calibration work is required whenever they are installed in order to estimate the occupancy rate. Therefore, there exists room for improvement of ALINEA algorithm because only occupancy rate having some problems is considered as a control parameter in ALINEA algorithm. Practically it is difficult to measure or perceive the occupancy rate for traffic engineers and drivers. On the other hand, speed can be good alternative which can overcome the defect induced by using occupancy. In this study, occupancy based ALINEA algorithm is converted to speed based ALINEA assuming the linear relationship between density and speed.

Thrust Performance Improvement through Position Signal Compensation and Estimation in Super Speed Maglev (위치신호 보상 및 추정을 통한 초고속 자기부상철도 추력 성능 향상)

  • Lee, Jin-Ho;Jo, Jeong-Min;Han, Young-Jae;Lee, Chang-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.10
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    • pp.4739-4746
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    • 2013
  • In position detection for super speed maglev propulsion control, the influence of position signal delay and transmit cycle on propulsion power degradation is investigated analytically and validated by test bed experiments. As a solution to the problem caused by signal transmit, position signal compensation and estimation method is proposed and applied to the test bed. Through experiments, it is confirmed that by adapting the proposed method, the propulsion power is increased remarkably, which results in acceleration and velocity performance improvement. This method could be effectively applied to position detection system of Korean super speed maglev which is under development.

Design of a Fuzzy-Sliding Observer for improvement of low speed operation of DC Servo Motor (직류 서보전동기 저속운전 성능개선을 위한 퍼지-슬라이딩 관측기설계)

  • 고봉운;김상훈;김낙교
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2004.04a
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    • pp.153-156
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    • 2004
  • This Paper deals with speed control of DC servo motor using a Fuzzy-Sliding observer. Speed sensor detect a speed of rotor continuously. But It have a limit as a driving speed to detect speed precisely. So it is problem to improve the performance of the driving system To solve the problem, it is studied to detect a speed of DC motor without sensor In particular, study on the method to estimate the speed using the observer is performed a lot. In this parer, the gain of the observer is properly set up using the fuzzy control and sliding observer that have a superior transient characteristic and is easy to implement compared the exist ing method is designed. It estimate the derivative of the armature current directly using the armature current measured in the DC motor. It estimate the speed of the rotor using the differentiation. It is Proposed speed sensor less control method using the estimated speed. Optimal gain of Luenberger observer is set up using the fuzzy control and adapted speed control of DC servo motor. It is proved excellence and feasibility of the presented observer from the comparison tested a case with a speed sensor and a case without a speed sensor which used a highly efficient drive and 200W DC servo motor start ing system.

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