• Title/Summary/Keyword: signal control scheme

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A Study on a Digital Amplifier.Controller for Proportional Control Valve (비례제어밸브용 디지털 앰프.컨트롤러에 대한 연구)

  • Lee, J.C.;Koh, J.U.;Kwon, T.H.;Shin, H.B.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.8 no.1
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    • pp.19-25
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    • 2011
  • This study presents the design of digital amplifier.controller for a proportional control valve and the development of PID discrete control scheme by using RCP(Rapid Controller Prototyping) system. RCP system is the device to embed the control code developed in PC into the microcontroller on-site. Ramp input test using the digital amplifier.controller developed in this study was carried out for the proportional control valve of domestic production and Bosch Rexroth respectively. The instability problem occurred around maximum displacement of localized valve spool at ramp input test was solved by supplementing offset current to the duty ratio of PWM(Pulse Width Modulation) driving signal to the solenoid. The comparison of test results between localized proportional control valve and Bosch Rexroth's product shows that the characteristics obtained by ramp input test and static flow gains are alike each other. Two valves are about the same in dead bands and hysteresis characteristics.

Elimination of the State-of-Charge Errors for Distributed Battery Energy Storage Devices in Islanded Droop-controlled Microgrids

  • Wang, Weixin;Wu, Fengjiang;Zhao, Ke;Sun, Li;Duan, Jiandong;Sun, Dongyang
    • Journal of Power Electronics
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    • v.15 no.4
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    • pp.1105-1118
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    • 2015
  • Battery energy storage devices (ESDs) have become more and more commonplace to maintain the stability of islanded power systems. Considering the limitation in inverter capacity and the requirement of flexibility in the ESD, the droop control was implemented in paralleled ESDs for higher capacity and autonomous operation. Under the conventional droop control, state-of-charge (SoC) errors between paralleled ESDs is inevitable in the discharging operation. Thus, some ESDs cease operation earlier than expected. This paper proposes an adaptive accelerating parameter to improve the performance of the SoC error eliminating droop controller under the constraints of a microgrid. The SoC of a battery ESD is employed in the active power droop coefficient, which could eliminate the SoC error during the discharging process. In addition, to expedite the process of SoC error elimination, an adaptive accelerating parameter is dedicated to weaken the adverse effect of the constraints due to the requirement of the system running. Moreover, the stability and feasibility of the proposed control strategy are confirmed by small-signal analysis. The effectiveness of the control scheme is validated by simulation and experiment results.

Design of pole-assignment self-tuning controller for steam generator water level in nuclear power plants (원전 증기 발생기 수위 제어를 위한 자기 동조 제어기 설계)

  • Choi, Byung-Jae;No, Hee-Cheon;Kim, Byung-Kook
    • Journal of Institute of Control, Robotics and Systems
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    • v.2 no.4
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    • pp.306-311
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    • 1996
  • This paper discusses the maintenance of the water level of steam generators at its programmed value. The process, the water level of a steam generator, has the nonminimum phase property. So, it causes a reverse dynamics called a swell and shrink phenomenon. This phenomenon is severe in a low power condition below 15 %, in turn makes the start-up of the power plant too difficult. The control algorithm used here incorporates a pole-assignment scheme into the minimum variance strategy and we use a parallel adaptation algorithm for the parameter estimation, which is robust to noises. As a result, the total control system can keep the water level constant during full power by locating closed-loop poles appropriately, although the process has the characteristics of high complexity and nonlinearity. Also, the extra perturbation signals are added to the input signal such that the control system guarantee persistently exciting. In order to confirm the control performance of a proposed pole-assignment self-tuning controller we perform a computer simulation in full power range.

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Performance Enhancement of RMRAC Controller for Permanent Magnent Synchronous Motor using Disturbance compensator (외란보상기를 이용한 영구자석 동기전동기에 대한 참조모델 견실적응제어기의 성능개선)

  • Jin, Hong-Zhe;Lim, Hoon;Lee, Jang-Myung
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.57 no.5
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    • pp.845-851
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    • 2008
  • A simple RMRAC (Robust Model Reference Adaptive Control) scheme for the PMSM (Permanent Magnent Synchronous Motor) is proposed in the synchronous frame. A current control of PMSM is the most inner loop of electro-mechanical driving systems and it requires a fast and simple control law to play a foundation role in the control hierarchy. In the proposed synchronous current model, the input signal is composed of a calculated voltage by proposed adaptive laws and real system disturbance. The gains of feed-forward and feedback controllers are estimated by the proposed modified Gradient method respectively, where the system disturbances are assumed as filtered current tracking errors. After the estimation of the system disturbances from the tracking errors, the corresponding voltage is fed forward to control input voltage to compensate for the disturbances. The proposed method is robust against high frequency disturbance and has a fast dynamic response. It also shows a good real-time performance due to it's simplicity of control structure. Through the simulations and real experiments, efficiency of the proposed method is verified.

Design of Corrective Controllers for Model Matching of Switched Asynchronous Sequential Machines (스위칭 비동기 순차 머신을 위한 모델 정합 교정 제어기 설계)

  • Yang, Jung-Min
    • Journal of the Korean Institute of Intelligent Systems
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    • v.25 no.2
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    • pp.139-146
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    • 2015
  • This paper presents the solution to model matching of switched asynchronous sequential machines by corrective control. We propose a model of switched asynchronous sequential machines, in which the system can have different dynamics of asynchronous machines governed by a pre-determined sequence of switching. The control objective is to derive a corrective control law so that the stable state behavior of the closed-loop system can match that of a prescribed model. A new skeleton matrix is defined to represent the reachability of the switched asynchronous machine, and a novel control scheme is presented that interweaves the switching signal and the corrective control procedure. A design algorithm for the proposed controller is illustrated in a case study.

Joint Optimization for Congestion Avoidance in Cognitive Radio WMNs under SINR Model

  • Jia, Jie;Lin, Qiusi;Chen, Jian;Wang, Xingwei
    • ETRI Journal
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    • v.35 no.3
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    • pp.550-553
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    • 2013
  • Due to limited spectrum resources and differences in link loads, network congestion is one of the key issues in cognitive radio wireless mesh networks. In this letter, a congestion avoidance model with power control, channel allocation, and routing under the signal-to-interference-and-noise ratio is presented. As a contribution, a nested optimization scheme combined with a genetic algorithm and linear programming solver is proposed. Extensive simulation results are presented to demonstrate the effectiveness of our algorithm.

Estimation of Rotational Center and Angle for Image Stabilization (영상 안정화를 위한 회전중심 및 각도 추정기법)

  • Seok, Ho-Dong;Yoo, Jun;Kim, Do-Jong
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.7
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    • pp.611-617
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    • 2004
  • This paper presents a simple method of rotational motion estimation and correction for roll axis stabilization of an image. The scheme first computes the rotation center by taking least squares of selected local velocity vectors, and the rotational angle is found from special subset of motion vectors. Roll motion correction is then performed by the nearest neighbor interpolation technique. To show the effectiveness of our approach, the synthetic and real images are evaluated, resulting in better performance than the previous ones.

A Target State Estimator Design to Improve the Gun Driving Command (포 구동명령 개선을 위한 표적상태 추정기 설계)

  • Lee, Seok-Jae;Kwak, Hwy-Kuen;Lyou, Joon
    • Journal of Institute of Control, Robotics and Systems
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    • v.13 no.11
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    • pp.1053-1059
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    • 2007
  • This paper presents a target sate estimator(TSE) with low pass filter for improving the gun driving command. The ballistic computer uses target information such as predicted range, velocity, acceleration of a target to generate the gun command. We adopt the finite impulse response(FIR) filter as our TSE to shorten calculation time for the driving command and due to its inherent stability property. We also introduce a post-processing filter to reduce the high frequency components in the output signal of a TSE which may cause instability of gun driving. The first order low pass filter has been designed based on $H{\infty}$ criteria considering the noise characteristics. To show the validity of the present scheme, simulation results are given for the overall gun driving system including aircraft target information.

Power Factor Correction Method without Input Current Sensor (입력전류센서 없는 단상전력변환기의 역률개선 기법)

  • Jung, Young-Seok;Moon, Gun-Woo;Rho, Chung-Wook;Lee, Jun-Young;Youn, Myung-Joong
    • Proceedings of the KIEE Conference
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    • 1996.07a
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    • pp.564-566
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    • 1996
  • New simple control method of power factor correcting(PFC) boost convertor without instantaneous measurement of input current is proposed. Using the averaged model, the power factor correction scheme is presented. With the measurements of input voltage and output voltage, the control signal is generated to make the shape of the line current same as the input voltage. The validity of the controller is verified through the computer simulations.

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Sensorless Vector Control of SPMSM using Adaptive Observer (적응관측기를 이용한 SPMSM의 센서리스 벡터제어)

  • Jung, Tack-Gi;Lee, Jung-Chul;Lee, Hong-Gyun;Lee, Young-Sil;Chung, Dong-Hwa
    • Proceedings of the KIEE Conference
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    • 2003.10b
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    • pp.200-202
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    • 2003
  • This paper is proposed to position and speed control of surface permanent magnet synchronous motor(SPMSM) drive without mechanical sensor. A adaptive state observer is used for the mechanical state estimation of the motor. The observer was developed based on nonlinear model of SPMSM, that employs a d-q rotating reference frame attached to the rotor. A adaptive observer is implemented to compute the speed and position feedback signal. The validity of the proposed sensorless scheme is confirmed by various response characteristics.

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