• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.26 no.8
• /
• pp.1534-1544
• /
• 2002

The TDCSA(Time Delay Control with Switching Action) method, which consists of Time Delay Control(TDC) and a switching action of sliding mode control(SMC), has been proposed as a promising technique in the robust control area, where the plant has unknown dynamics with parameter variations and substantial disturbances are preset. When TDCSA is applied to the plant with saturation nonlinearity, however, the so-called windup phenomena are observed to arise, causing excessive overshoot and instability. The integral element of TDCSA and the saturation element of a plant cause the windup phenomena. There are two integral effects in TDCSA. One is the integral effect occurred by time delay estimation of TDC. Other is the integral term of an integral sliding surface. In order to solve this problem, we have proposed an anti-windup scheme method for TDCSA. The stability of the overall system has been proved for a class of nonlinear system. Experiment results show that the proposed method overcomes the windup problem of the TDCSA.

• Korean Chemical Engineering Research
• /
• v.58 no.3
• /
• pp.430-437
• /
• 2020

In this research, the anti-windup techniques for the cascade control system are newly developed. Cascade control system has an additional internal feedback control loop to reject disturbances better than the conventional control system. Remarkable difference between the conventional single-loop control system and the cascade control system is the interaction that the controller output saturation of the secondary control loop strongly affects the integral action of the primary control loop. In industry, local back calculation anti-windup method has been mainly used for each controller without considering the interaction between the two controllers. But it cannot eliminate the integral-windup of the primary controller originated from the saturation of the secondary controller output. To solve the problem, the two anti-windup techniques of the cascade conditional integration and the cascade back calculation are proposed in this research by extending the local anti-windup techniques for the single-loop control system to the cascade control system. Simulation confirmed that the proposed methods can effectively remove the integral windup of the primary controller caused by the saturation of the secondary controller output and show good control performances for various types of processes and controllers. If the reliability of the proposed methods is proved through the applications to real processes in the future, they would highly contribute to improving the control performances of the cascade control system in industry.

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

• 제어로봇시스템학회:학술대회논문집
• /
• 1991.10a
• /
• pp.299-304
• /
• 1991

A novel approach based on a nonlinear compensator is proposed to prevent 'windup', which is caused by the saturation of the actuator and the integration action of the controller. The anti-windup compensator is located between the conventional linear controller, designed neglecting the saturation, and the actuator. It was proven based on the describing function method that, if the closed loop control systems are stable assuming no saturation, then there exist a range of compensator gain which prevents any limit-cycle and hence, guarantees the system stability. The computer simulation results show that the compensator proposed in the manuscript can eliminate unstable limit cycle and improve the transient response.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.1060-1066
• /
• 1992

One of the undesirable nonlinear phenomenon called 'wind up' occours when the integrator in the controller and the saturated actuator interact. Large overshoot, slow response, instability, limit cycle and jump resonance are the characteristics of wind up phenomenon. Several 'anti-windup' compensators have been developed to prevent some of the aforementioned nonlinear characteristics such as instabilituy and limit cycle, but none has studied the effect of antiwindup compensator on the jump resonance. In this paper, we developed an analyitcal 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 of effectively.

• 제어로봇시스템학회:학술대회논문집
• /
• 1990.10b
• /
• pp.1289-1294
• /
• 1990

When a saturating control system has integral action, reset windup can cause instability as well as make the system performance unsatisfactory. An antirset-windup (ARW) limiter has been suggested to improve the stability and performance. It has been implemented with analog circuits and tested by simulations. This paper presents the stability condition of a double-integrator plant having the state feedback plus integral-action controller with the ARW limiter by using both Liapunov's second method and graphical method together.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.140-142
• /
• 2005

본 논문은 산업용 전동기 시스템의 속도제어기에서 계단(Step)입력에 대한 속도의 오버슈트를 억제하는 새로운 방식의 반와인드업(Anti-windup)기법을 소개한다. 비례(P)제어기에서 비례적분(PI)제어기로의 전환 시점에 적분기가 적절한 초기값을 가지게 하여 오버슈트를 상쇄 시키고 빠른 응답 시간을 가지게 하였다. 시뮬레이션을 통하여 제안된 방법의 타당성을 확인하고 기존의 반와인드업 기법과 비교하여 그 우수성을 검증하였다.

• Proceedings of the KIPE Conference
• /
• 1997.07a
• /
• pp.357-363
• /
• 1997

The windup phenomenon appears and results in the performance degradation when the PI controller output is saturated. A new anti-windup PI controller is proposed to improve the control performance of the variable-speed motor drives and it is experimentally applied to the speed control of a vector-controlled induction motor driven by a pulse width modulated(PWM) voltage source inverter (VSI). The integral state is separately controlled corresponding to whether the PI controller output is saturated or not. The experimental results show that the speed response has the much improved performances such as small overshoot and fast settling time over the conventional anti-windup technique. Although the operating speed command is changed, the similar control performance can be obtained by using the PI gains selected in the linear region.

• Proceedings of the KIPE Conference
• /
• 2004.07b
• /
• pp.954-958
• /
• 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
• /
• 2004.07a
• /
• pp.312-315
• /
• 2004

This paper presents a tuning-free conditional integration anti-windup strategy for induction machine with Proportional-Integral (PI) type speed controller. The on/off condition of integral action is determined by the frequency domain analysis of machine torque command without a prior knowledge of set-point changes. There are no tuning parameters to be selected by users for anti-windup scheme. In addition, the dynamic performance of the proposed scheme assures a desired tracking response curve with minimal oscillation and settling time even in the change of operating conditions. This algorithm is useful in many high performance induction machine applications not to allow the oscillation and overshoot of speed/torque responses. The main idea can be extended to general applications such as chemical processes and industrial robots.