• Journal of Institute of Control, Robotics and Systems
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• v.6 no.4
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• pp.247-253
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• 2000

In this paper, we deal with the full range control problem of nonlinear boiler systems subject to complex actuator constraints. Firstly, $H\infty$ loop shaping design procedure［10］ is used for the controller design. Secondly, modified high-gain feedback［11］ for the loop shaping controller is adopted for the anti-windup function and the bumpless transfer technique between controllers is proposed for the full range control of nonlinear systems. Finally, the performance of the proposed controller is demonstrated through the simulation studies.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.5
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• pp.511-520
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• 1999

An anti-reset windup (ARW) based compensation method for state constrained control systems is studied. First, a linear controller is constructed to give a desirable nominal performance ignoring state-constraints of a plant. Then, an additional compensator is introduced to provide smooth performance degradation under state-constraints of the plant. This paper focuses on the effective design method of the additional compensator. By minimizing a reasonable performance index, the proposed compensator is expressed in terms of theplant and ocntroller parameters. The resulting dynamics of the compensated controller exhibits the dominant part of the linear closed-loop system which can be seen from the singular perturbation model reducton theory. THe proposed method guarantees total stability of overall resulting systems if linear controllers were constructed to meet certain condition.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.6
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• pp.1342-1350
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• 1993

One of the undesirable nonlinear phenomena in feedback control systems is called 'wind up', which is characterized by large overshoot, slow response, and even instability. It is caused by interaction between the integrator in the controller and the saturating actuator. Limit cycle and jump resonance are another nonlinear characteristrics of systems with saturating actuators. Several 'anti-windup' compensators have been developed to prevent some of the aforementioned nonlinear characteristics such as instability and limit cycle, but none has studied the effect of anti-windup compensator on the jump resonance. In this paper, we developed an analytical method to design the compensator to prevent not only limit cycle but also jump resonance. An illustrative example is included to show the compensator eliminates jump resonance effectively.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.2
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• pp.128-136
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• 2003

This paper investigates the application of the anti-windup scheme to control U voltage of the three-phase four-wire active power filter, installed in a three-phase four-wire power system. In order to reduce efficiently the harmonic currents caused by the switching loads and to improve the whole performance of the flower system, the DC voltage of the three-phase four-wire active power filter should be properly controlled. PI controller can be applied to the U voltage controller of the three-phase four-wire active power filter. However, a large error input to PI controller leads to a windup phenomenon which deteriorate the dynamic characteristics of the U voltage controller Therefore, the application of the anti-windup scheme for the DC voltage controller is proposed and the improved performances of the anti-windup U voltage controller are proved through the computer simulation study.

• Journal of Power Electronics
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• v.15 no.1
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• pp.177-189
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• 2015

The output of the controller is said to exceed the input limits of the plant being controlled when a control system operates in a non-linear region. This process is called the windup phenomenon. The windup phenomenon is not preferable in the control system because it leads to performance degradation, such as overshoot and system instability. Many anti-windup strategies involve switching, where the integral component differently operates between the linear and the non-linear states. The range of state for the non-overshoot performance is better illustrated by the boundary integral error plane than the proportional-integral (PI) plane in windup inspection. This study proposes a PI controller with a separate closed-loop integral controller and reference value set with respect to the input command and external torque. The PI controller is compared with existing conventional proportional integral, conditional integration, tracking back calculation, and integral state prediction schemes by using ScicosLab simulations. The controller is also experimentally verified on a direct current motor under no-load and loading conditions. The proposed controller shows a promising potential with its ability to eliminate overshoot with short settling time using the decoupling mode in both conditions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.40-48
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• 2011

An attemperator is a part of the 4-stage superheater in the boiler system of the thermal power plant. The attemperator receives the over-heated steam and makes the steam with proper temperature by adjusting the control valve of the cold steam. In this paper, the attemperator is modeled considering physical point of view and the linearized model is derived for the control purpose. To overcome the integral windup phenomenon due to the opening limitation of the control valve, an anti-windup PI controller is proposed to the attemperator and compared with the PI controller operated in the thermal power plant in view of control performance.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.954-958
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• 2004

본 논문은 부하에 대한 빠른 응답특성을 보이는 새로운 토폴로지를 제안하였다. PI제어기 출력이 포화될 때 windup 현상이 나타나고 그 결과로 성능이 저하된다. 따라서 전동기의 가변속 제어성능을 위해 가속시에는 개선된 Anti-windup PI제어기만을 사용하고, 감속시에는 추가로 부하의 특성을 고려하여 braking 동작을 사용하였다. 시뮬레이션 및 실험결과는 속도성능면에서 제안된 방식이 종래의 다른 제어방식에 비해 우수함을 보여 준다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.71-72
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• 2012

비례-적분(PI) 제어기 출력이 포화되었을 때, windup현상이 나타나며 이것은 큰 오버슈트 및 느린 정착 시간과 같은 성능저하를 야기시킨다. 이 논문에서는 이러한 문제점을 개선하기 위해 적분 상태 예측기를 갖는 Anti-windup PI제어기를 이용한 전류제어 방법을 제안한다. PSIM을 이용한 시뮬레이션을 통해 성능을 증명하였다. 이 방법은 PI제어기 출력이 포화되었을 경우와 그렇지 않을 경우에 따라 적분 상태가 각각 제어된다. 실험결과는 PI제어 방법과 비교하여 오버슈트 및 정착 시간과 같은 제어 성능이 개선되었음을 보여준다.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.5
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• pp.543-550
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• 2014

In many industrial processes and operations, such as power plants, petrochemical industries and ships, shell and tube heat exchangers are widely used and probably applicable for a wide range of operating temperatures. The main purpose of a heat exchanger is to transfer heat between two or more medium with temperature differences. Heat exchangers are highly nonlinear, time-varying and show time lag behavior during operation. The temperature control of such processes has been challenging for control engineers and a variety of forms of PID controllers have been proposed to guarantee better performance. In this paper, a scheme to control the outlet temperature of a shell and tube heat exchanger system that combines the PID controller with feedforward control and anti-windup techniques is presented. A genetic algorithm is used to tune the parameters of the PID controller with anti-windup and the feedforward controller by minimizing the IAE (Integral of Absolute Error). Simulation works are performed to study the performance of the proposed method when applied to the process.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.73-76
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• 1996

This paper presents a dynamical anti-reset windup (ARW) compensation method for saturating control systems with multiple controllers and/or multiloop configuration. By regarding the difference of the controller states in the absence and presence of saturating actuators as an objective function, the dynamical compensator which minimize the objective function are derived in an integrated fashion. The proposed dynamical compensator is a closed form of the plant and controller parameters. The proposed method guarantees total stability of resulting system. An illustrative example is given to show the effectiveness of the proposed method.