• Title/Summary/Keyword: saturation controller

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Improved Conditional Integrator Anti-Windup Method for Seamless Transfer of Bidirectional DC-DC Converter in Grid-Connected Battery Energy Storage System (계통연계형 배터리 에너지저장장치용 양방향 DC-DC 컨버터의 무순단 절체를 위한 조건부 적분 안티-와인드업 연구)

  • Eom, Jun-Yong;Choi, Sung-Jin;Lee, Hong-Hee
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.5
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    • pp.333-342
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    • 2020
  • Power exchanges between the grid and the battery through a bidirectional DC-DC converter are essential for DC microgrid systems. In general, the battery is charged when the grid is connected, and the system is powered by the battery when the grid is disconnected. In this mode transition, the saturation of the voltage controller slows down output response and produces large transient errors in DC link voltage. To solve this problem, a novel anti-windup design is proposed to improve anti-windup performance further. The proposed method stabilizes DC bus voltage through a wider range of battery voltage with faster transition compared with that of conventional methods. The proposed method is verified through an experimental setup composed of a 125 W laboratory-scale DC microgrid system.

Design of a Moving Magnet Type Linear DC Motor (가동 자석형 선형 직류 전동기의 설계)

  • Jung, H.J.;Kim, Y.;Baek, S.H.;Yoon, S.Y.;Kim, P.S.;Kwon, S.D.
    • Proceedings of the KIEE Conference
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    • 1998.07a
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    • pp.224-227
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    • 1998
  • Linear motors are increasingly employed as direct actuators replacing the more conventional systems composed by a rotating motor and a mechanical device. Linear DC motor is useful in a high speed and high accuracy positioning system with a feedback controller. Because of these advantages, linear DC motors have already been used as motors of pen recorders and magnetic disk storage devices, these are moving coil type linear DC motors as these movers are light. Moving magnet type linear DC motor has advantages at long stroke motors because its mover's feeding wires for driving is not necessary. This paper is concerned with the analysis of linear DC motor that is moving magnet type with unipolar. In order to analyze the dynamic behaviour a mathematical model based on a simplified field analysis developed. A two dimensional finite element field solution is employed in order to illustrate the effect of yoke saturation and motor performance. It is deduced the relation between the limit value of the thrust of the linear DC motor and the dimension of the yokes.

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A Dynamic Simulation Model of Electronic-Expansion-Valve-Controlled Evaporators (전자팽창밸브 제어성능 모사용 증발기 동특성 모델링)

  • Shin, Young-Gy;Cho, Soo;Tae, Choon-Seob;Jang, Cheol-Yong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.2
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    • pp.183-190
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    • 2007
  • Controlling superheat of indoor units associated with a multi-type heat pump is one of difficult tasks to be addressed. This study suggests a dynamic model of an evaporator based on heat and mass balance. Thermodynamic properties are calculated by a commercial software, Refprop. The model is programmed in MFC Visual C++ for controller interface in real-time mode. The simulation results shows that PI control works for a narrow range of superheat. Beyond the range, the temperature behavior of the refrigerant is quite nonlinear mainly due to phase change. Thus, it is concluded that PI control of superheat has to be supplemented by nonlinear control ideas to avoid saturation and excessive superheat.

A Control Algorithm for Highly Efficient Operation of Auxiliary Power Unit in a Series Hybrid Electric Bus (직렬형 하이브리드 버스에서 보조동력장치의 고효율 작동을 위한 제어 알고리즘)

  • 함윤영;송승호;민병문;노태수;이재왕;이현동;김철수
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.5
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    • pp.170-175
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    • 2003
  • A control algorithm is developed for highly efficient operation of auxiliary power unit (APU) that consists of a diesel engine and a directly coupled induction generator in series hybrid electric Bus (SHEB). In a series hybrid configuration the APU supplies the electric power needed for maintaining the state of charge (SOC) of the battery unit in various conditions of vehicle operation. As the rotational speed of generator does not depend on the vehicle speed, an optimized operation of engine-generator unit based on the efficiency map of each component can be achieved. The output torque of diesel engine can be controlled by the amount of fuel injection, and the power converted from mechanical to electrical energy can be adjusted by generate control unit (GCU) using the decoupling vector control of torque and flux. As for the given reference of the generating power, the multiply of speed and torque, many combinations of operating speed and torque are possible. The algorithm decides the new operating point based on the engine efficiency map and generator characteristic curve. During the transition of operating points, the speed controller saturation is avoided using variable limit and filtering of generator torque reference. A test rig and SHEB consist of a 1.5L diesel engine and a 30kw induction generator are constructed by Hyundai Motor Company.

High Precision Control of Servo Control System Using The Adaptive Fuzzy Controller (적응 퍼지제어기를 이용한 서보 제어 시스템의 정밀제어)

  • 조정환
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.16 no.3
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    • pp.110-115
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    • 2002
  • This paper proposes the adaptive fuzzy control system using the microprocessesor for high precision control of automation systems which exist non-linearities such as saturation, relays, hysteresis, and dead zones. The proposed system which provides the improvement in terms of the control region in transient and adaptive control, first used the frequence-locked mothed driving a system to generate a output voltage proportional to the frequency diffierence of relnence input signal and feedback signal for fast transient response,, and when the error reaches the preset value, used the adaptive fuzzy logic for precision control. The theoretical and experimental studies have been carried out. The presented results from the above investigation show considerable improved performance in the precision control of servo control systems.

Link Layer Traffic Control Algorithm to Improve the Performance of WLANs (무선 랜 성능 향상을 위한 링크 계층 트래픽 제어 알고리즘)

  • Choi, Sun-Woong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.4
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    • pp.758-765
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    • 2008
  • Wide-spread deployment of infrastructure WLANs has made Wi-Fi an integral part of today's Internet access technology. WLANs suffer from degraded system throughput and each node's throughput fluctuates significantly in the saturation regime. In this paper, we propose a link layer traffic control mechanism which controls the offered load of DCF system. It is shown that the link layer traffic controller can improve DCF system throughput and reduce nodes' throughput fluctuation with properly controlled offered load. We propose a dynamic traffic control algorithm which can find an optimal offered load and show its performance improvement with ns-2 simulation.

Design and implementation of power-controlled front-end module for direct conversion receiver (전력제어 직접변환수신 6단자 소자 설계 및 제작)

  • Kim, Young-Wan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.11
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    • pp.2391-2396
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    • 2010
  • The power-controlled six-port element that can control the local oscillator signal power and receiving RF signal power was designed and implemented in this paper. The direct conversion six-port element configuration was proposed, which provides the constant six-port output power by controlling the six-port input power with various signal strength. The direct conversion six-port element protects the power detector element of six-port receiver from the saturation status and compensates the transmission performance degradation. For implementation of power-controlled six-port element, the power-controlled six-port element including the power controller was analyzed. The implemented power-controlled six-port element shows the power control capability of 36 dB and gain imbalance of about 1.6 dB, phase imbalance of about $4^{\circ}$ in the frequency range of 1.69 GHz. The measured results show the good performance as direct conversion front-end element.

Handling Deflection Limit in Open-Loop-Onset-Point PIO Analysis (Open-Loop-Onset-Point PIO 해석의 변위한계)

  • Park, Sang-Hyuk
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.2
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    • pp.135-140
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    • 2010
  • A new treatment is proposed to handle a deflection limit in the open-loop-onset-point (OLOP), which is commonly used in the prediction of pilot in-the-loop oscillation (PIO) due to a rate saturation. The new approach is motivated by the frequency response of a stand-alone actuator in that, unlike the suggestion by the original OLOP procedure, the rate limit onset is not delayed to a higher frequency by a deflection limit. Indeed, if a feedback control loop is closed, the rate limit onset can be shifted to a lower frequency since the controller tends to react with larger commands when deflection limited. The amplitude of the command at this onset frequency is combined with the deflection limit to estimate the associated gain reduction in the open-loop-onset-point in the final step of the OLOP process. The comparison of the new approach with the previous method reveals that an inaccurate optimism which can occur in the previous method is corrected by the proposed treatment.

A New Robust Continuos VSCS by Saturation Function for Uncertain Nonlinear Plants (불확실 비선형 플랜트를 위한 포화 함수에 의한 새로운 강인한 연속 가변구조제어시스템)

  • Lee, Jung-Hoon
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.48 no.3
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    • pp.30-39
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    • 2011
  • In this note, a systematic design of a new robust nonlinear continuous variable structure control system(VSCS) based on the modified state dependent nonlinear form is presented for the control of uncertain affine nonlinear systems with mismatched uncertainties and matched disturbance. After an affine uncertain nonlinear system is represented in the form of state dependent nonlinear system, a systematic design of a new robust nonlinear VSCS is presented. The uncertainty of the nonlinear system function is separated into the tow parts, i.e., state dependent term and state independent term for extension of target plants. To be linear in the closed loop resultant dynamics and in order to easily satisfy the existence condition of the sliding mode, the transformed linear sliding surface is applied. A corresponding control input is proposed to satisfy the closed loop exponential stability and the existence condition of the sliding mode on the linear transformed sliding surface, which will be investigated in Theorem 1. For practical application, the discontinuity of the control input as the inherent property of the VSS is improved dramatically. Through a design example and simulation studies, the usefulness of the proposed controller is verified.

Modified Direct Torque Control using Algorithm Control of Stator Flux Estimation and Space Vector Modulation Based on Fuzzy Logic Control for Achieving High Performance from Induction Motors

  • Rashag, Hassan Farhan;Koh, S.P.;Abdalla, Ahmed N.;Tan, Nadia M.L.;Chong, K.H.
    • Journal of Power Electronics
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    • v.13 no.3
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    • pp.369-380
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    • 2013
  • Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.