The Research Of Anti-windup IMC-PID Controller And Its Design Method

Most control systems in practice are nolinear systems with constraints.Windup is one of the urgent problems of constraints to be solved.The generalized windup consists of the input limitations(physical limitations,actuator saturations)and plant substitutions.The controller windup will do some damages to the systems,significant performance deterioration and even make the systems unstable.So it is very important to design an anti-windup controller.In this paper,we introduced some main current anti-windup controller design methods,in addition,this paper proposed two new anti-windup IMC structures,and transformed them into IMC-PID structures successfully in order to make the method easy to implement.We use intelligent optimization algorithm(IOA)to optimize the parameters of the controller and the compensators.Firstly,we used a classical Internal model control(IMC)structure with windup,took a general plant as example and analyzed the influence of different input saturation values umax on the output of IMC,and the influence of different filter time parameter ? on the output of IMC.The relationship between the input saturation value umax and the filter time constant ? is derived under the condition that the controller can track the output value,which provided the basis for the design of the parameters of the anti-windup IMC structure.Secondly,we modified the classical anti-windup IMC structure base on the anti-windup bumpless transfer(AWBT)schemes,by adding a parameter to the sub-controllers to optimize the compensator through the intelligent optimization algorithm.Then we transformed the new anti-windup IMC structure into a PID structure.Finally we proposed a new anti-windup IMC-PID structure based on the optimal compensator.In the simulation study,the proposed anti-windup design provides better ITAE,ISE performance indicators,which illustrates the systems has a faster dynamic response and a better tracking performance.Finally,we made a qualitative analysis of the general system with windup,and acquired three main effects of windup on the system.According to the three main effects,we designed three static compensators using feed-forward method to compensate the system and to reduce the influence of windup.We transformed the proposed three feed-forward static compensators IMC structure into the IMC-PID structure through the intelligent optimization algorithm(IOA),finally we proposed a new anti-windup IMC-PID structure with feed-forward compensators based on qualitative analysis.In the simulation study,the proposed anti-windup design was proved to improve the adverse effects caused by windup effectively through the analysis of system performance indexes such as overshoot,adjustment time and steady state error.