Phase lag compensator design using root locus pdf

Control systemscontrollers and compensators wikibooks. Pdf design of leadlag compensators for robust control. Design via root locus elec304alper erdogan 1 1 lecture 1. Chapter 6 control systems design by, 1, 1 2 c root. A phase lag compensator tends to shift the root locus to the right, which is undesirable. This video walks through a phase lag compensator example using the root locus method. He discussed the tuning of the used compensators 12. In order to have c as the new gain crossover frequency, the lag compensator must give an attenuation. The root locus editor displays the root locus for the nominal model and the closedloop pole locations associated with the set of plants. Designing a lag compensator with root locus youtube. The steps to design the lag compensator are draw the root locus of the given open loop uncompensated. Design via root locus elec304alper erdogan 1 1 lecture. Like pi compensation, lag compensation uses a closely.

Setiawan 2010 presented the evaluation of closedloop controller responses of a tini sma gripper using lag, lead and lag lead compensators. Design and implementation of pid controller with lead. Root locus lead compensator design example polezero. Integrals and derivatives are the commonly using tools for modeling a system. Designing digital lead and lag compensators using the. The app opens with bode and root locus openloop editors open along with a step response plot. In designing laglead compensators, we consider two cases where and. The process is slightly simpler if we target the lead compensator design at a particular desired. In my approach to root locus design, the purpose of compensator design using root locus methods.

In this paper three different methods for the synthesis of lead lag compensators that meet design specifications on the phase margin and the gain crossover frequency are presented. Design via root locus elec304alper erdogan 1 35 two approaches for feedback compensation 1. The compensator adds poles and zeros to the ps in the root locus procedure. A lead compensator design example is worked based on improving transient time domain specifications. May 23, 2012 so far we have discussed on an introduction to matlab and lag compensator design with bode plot. Apr 22, 2017 a lead compensator design example is worked based on improving transient time domain specifications. The stability of a process model is determined by its phase margin and gain margin. Hence adding a compensator can redirect the locus to regions of the splane with greater damping, for example. A firstorder lag compensator cs can be designed using the root locus. Design g cs using root locus or frequency response techniques. Jun 10, 20 designing a lag compensator with root locus brian douglas. Sometimes, proportional control with a carefully chosen value of k is.

There are a number of different standard types of control systems that have been studied extensively. A new phaselead design method using the root locus diagrams article in ieee transactions on automatic control 5011. In this case, the design process is a combination of the design of the lead compensator and that of the lag compensator. The minor loop is designed to change the open loop poles and open loop transientresponse. Root locus and step response of lagcompensated system. Pdf this paper introduce the lead,lag,laglead compensator design of root locus using single composite matlab programme. The laglead compensator circuit in the s domain is shown in the following figure. Lead compensators design using frequency response techniques. Compensator design using the root locus mit opencourseware. Modern control lec 04 analysis and design of control. Compensator design for a set of plant models matlab. A firstorder lag compensator can be designed using the root locus. Introduction design via root locus activecircuit realization in.

If the total network phase angle has a combination of positive and negative phase as a function of frequency then it is a lead lag network. Generic compensators cs are used in such situations in order to change the existing root locus. Design via root locus elec304alper erdogan 1 34 feedback compensation. Design the lag compensator to satisfy the improvement in steady state performance. Craig 4 the root locus plot is a plot of the roots of the characteristic equation of the closedloop system for all values of a system parameter, usually the gain. In industrial process control applications, phase lead lag compensators are widely used next only to pid controllers 1, 2, 3. Designing a lead compensator with root locus youtube. By default, the nominal model used for design is the first element in the lti array. A number of matlab function are developed for the compensator design method. Depending upon the nominal operation design parameters of a system under an active feedback control, a lag or lead network can cause instability and poor speed and response times. Introduction to root locus semester 083 page 4 root locus the root locus of an openloop transfer function hs is a plot of the locations locus of all. Compensator design to improve transient performance using root.

The design procedure for the laglead compensator follows. The examples and plots presented here are all done in matlab. In my approach to root locus design, the purpose of compensator design using root locus methods generally is to establish a speci. Laglead compensator is an electrical network which produces phase lag at one frequency region and phase lead at other frequency region. In a phase lead compensator if you recall the transfer function ds is of the. The comparative analysis is conducted with respect to different time domain specifications like gain, percentage overshoot, settling time, and rise time. Pdf computer aided design of lead compensator using root. Design three lead compensators for the system to reduce.

Rlocus analysis design nyu tandon school of engineering. Apr 29, 2017 modern control lec 04 analysis and design of control systems using root locus slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. It is a combination of both the lag and the lead compensators. First design the minor loop then design the major loop. We include a variable gain k in a unityfeedback con. Leadlag compensator using root locus 504 chapter 9 1. Consider compensation as adding poles and zeros to feedback section for the equivalent system. Computer aided design of lead compensator using root locus method. To provide attenuation reduction in magnitude after z.

The lead compensator zero location is placed over the left. Compensation in control system lag lead compensation. Compensator design to improve transient performance using. Lagcompensator the transfer function p z km p z the objective. The design process of phase lead, lag, lead lag, and cascaded lead controllers is performed by applying the principles of the root locus technique 2628, using matlab sisotool 2931. Compensator design to improve steadystate error using root locus. So far we have discussed on an introduction to matlab and lag compensator design with bode plot. Controller design based on root locus general effects of addition of pole and zero lead lag compensator realization with op amp lead compensator design lead compensator improves stability and transient response. Lead, lag and leadlag compensators are used to ensure that the stability margins are at the desired levels. Then design the lag compensator to meet the sse specifications. Lag compensators design using frequency response techniques ahmed abu. This video walks through a phase lead compensator example using the root locus method. A new phaselead design method using the root locus diagrams. In this post we will deal with lag compensator design with time domain specifications and using the root locus technique.

However, it is harder to design phase lag leadcontrollers than either phase lag or phase lead controllers. Compensator editor to open the compensator editor dialog box, in control system designer, in an editor plot area, rightclick and select edit compensator. Prior to carrying out these steps, it is assumed that all transient response speci. Problem of root locus design root locus design can locate poles only on the root locus. The basic requirement of the phase lag network is that all poles and zeros of the transfer function of the network must lie in ve real axis interlacing each other with a pole located or on the nearest to the origin. A lag compensator in root locus form is given by the following. In this section we introduce their structures and indicate their main properties. They are known as pd, pi, pid, phaselag,phaselead,and phaselagleadcontrollers. Such controllers are tuned usually with specifications on gain and phase margins which can lead to good performance and robustness. The method cannot change the root locus and locate poles desired locations if they are outside the existing root locus. Tuning of a feedforward laglead secondorder compensator.

For the robust design of a closed loop system, it is required to keep these margins to be greater than zero. Design a lead compensator to place the dominant poles at the desired places while neglecting the effects of the lag compensator. This paper introduce the lead, lag, lag lead compensator design of root locus using single composite matlab programme. You can add dynamics and modify compensator parameters using the compensator editor or using the graphical bode editor, root locus editor, or nichols editor plots. Li, sheng and chen 2010 derived the impulse response of the distributed order lead lag compensator using matlab and compared with the numerical inverse laplace transformation method 10. These controllers, specifically the p, pd, pi, and pid controllers are very common in the production of physical systems, but as we will see they each carry several drawbacks. The following steps outline the procedure that will be used to design the special lag compensator using root locus methods in order to satisfy steadystate speci. If you continue browsing the site, you agree to the use of cookies on this website. May 23, 2012 lag compensator design with bode plot. A comparative analysis of pid, lead, lag, leadlag, and. Using rootlocus ideas to design controller we have seen how to draw a root locus for given plant dynamics. Design of lead compensator for process control using multisim. When poles or zeros are added to the forward path these shift the root locus curves by changing the number of asymptotes or asymptote center.