Lag compensators design using frequency response techniques ahmed abu. Design via root locus elec304alper erdogan 1 35 two approaches for feedback compensation 1. Oct 22, 2010 lec41 compensator design using frequency response plots nptelhrd. Compensator design to improve transient performance using. Depending on the effect desired, one or more lead and lag compensators may be used in various combinations. And, i dont have slides, but my handwritten lecture notes are appended instead to this lecture. Control systems course roadmap closedloop design by root locus. Design the lead compensator to meet the transient responsetransient response simulate and redesign to meet the performance. Systems and control theory stadius center for dynamical systems, signal processing and data analytics.
Keywords lead compensator, lag compensator, laglead compensator, root locus approach, frequency response approach. The recent literature shows a renewed interest in the design of leadlagtype controllers 98 for classical. In this post we will deal with lag compensator design with time domain specifications and using the root locus technique. Zhang, liu, dang, zhang and ou 2006 used a lag lead compensator to control asynchronous linear motors for better performance and application to. The lead compensator zero location is placed over the left. State space root locus sketching rules negative feedback rule 1. In this paper we present the step wise procedure for designing a lag compensator to obtain the required stability margins with the help of suitable example. They are known as pd, pi, pid, phaselag,phaselead,and phaselagleadcontrollers. A lead compensator provides phase lead positive phase in the frequency response of system. This document is highly rated by electrical engineering ee students and has been viewed 353 times. Designing a lag compensator with bode plot duration.
Consider the following lag compensation for the previous example. Minimizes the added phase lag at the crossover frequency. It is a combination of both the lag and the lead compensators. A lead compensator in frequency response form is given by the following. Lag compensation suranaree university of technology. So far we have discussed on an introduction to matlab and lag compensator design with bode plot. This handout addresses phase lead compensators and improved damping, specifically. Then design the lag compensator to meet the sse specifications. In this lecture we would see how to design a phase lag compensator 1.
To implement a lead and lag compensator, first design the lead compensator to achieve the desired transient response and stability, and then design a lag compensator to improve the steadystate response of the leadcompensated system. Lec41 compensator design using frequency response plots. Design of nonlinear lead andor lag compensators amir nassirharand and seyed reza mousavi firdeh abstract. Both a lead compensator and a lag compensator have the same.
Figure 1 shows the bode plots of magnitude and phase for a typical lead compensator. The output buffer is normally present only when resistive loads needs to be driver. Tuning of a feedforward laglead secondorder compensator. Lagcompensator the transfer function p z km p z the objective. Lead, lag and leadlag compensators are among the most utilised control architectures in industrial and process engineering, and for this reason they have always received a great deal of attention 3. Lead and lag compensators design with root locus 1. The minor loop is designed to change the open loop poles and open loop transientresponse. Wonhee kim energy system engineering, chungang university. Chapter 6 control systems design by, 1, 1 2 c root.
Design of a leadlag compensator for position loop control of a gimballed payload conference paper pdf available april 2015 with 3,358 reads how we measure reads. Determine the gain to satisfy the requirement on 2. To open the compensator editor dialog box, in control system designer, in an editor plot area, rightclick and select edit compensator. Lag and lead compensators using op amp ece tutorials. Dec 21, 2017 mar 26, 2020 lecture 20 lag compensator design electrical engineering ee notes edurev is made by best teachers of electrical engineering ee. Lead example the process is slightly simpler if we target the lead compensator design at a particular desired. Using control system designer, you can manually edit compensator dynamics to achieve your design goals. Analytical and graphical design of leadlag compensators. For the system with the following block diagram representation find so that the dominant closed loop poles are at. Adding a lead to the ltf changes both the magnitude and phase, so it is di.
Laglead compensator is an electrical network which produces phase lag at one frequency region and phase lead at other frequency region. Root locus lead compensator design example polezero. Oct 23, 2019 most electrical compensator are rc filter. Compensators and pids 34 design via rootlocusintro lead compensator pid controllers design compensated system, example 2.
Design via root locus elec304alper erdogan 1 1 lecture 1. A system which has one pole and one dominating zero the zero which is closer to the origin than all over zeros is known as dominating zero. As with phase lag compensation, the purpose of phase lead compensator design in the frequency domain generally is to. Discrete inversion formulas for the design of lead and lag. Mar 05, 2016 design of lead and lag compensators using frequency domain techniques prof. Introduction to matlab lag compensator with bode plot lag compensator with root locus so far we have seen the design of lag compensators, now we move on to lead compensators which help in improving the transient response. Lead, lag and lead lag compensators are among the most utilised control architectures in industrial and process engineering, and for this reason they have always received a great deal of attention 3. Zhang, liu, dang, zhang and ou 2006 used a laglead compensator to control asynchronous linear motors for better performance and application to. Design of lead compensator for process control using multisim. This is a section in the chapter on classical control analysis techniques. There are three generic compensators as phase lab compensator phase lead compensator notch filter phase lead compensator transfer function phase contribution example open loop transfer function of a system is design a control system for the following specifications 1. 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 compensator editor. Compensators and pids 8 34 design via rootlocusintro lead compensator pid controllers design lead compensator example finding k.
The procedure for designing the laglead compensator is presented in section ii. A lead compensator is one which adds a zero the system and is used to improve the transient response of the system. The reader is referred to those notes for details on the individual design procedures. Based on the usual electronic implementation of the compensator 3, the circuit for a lead or lag compensator is the series combination of two inverting operational ampli. Design the lead compensator to meet the transient responsetransient response. This approach is described in more detail in my paper lagleadcompensator design using bode plots, as well as in the references. Lead and lag compensators with complex poles and zeros design formulas for modeling and loop shaping. In this section we introduce their structures and indicate their main properties. Compensator design lead compensators lag compensators lead lag compensators bode design practice lead if the phase margin is insuf. The twostage refers to the number of gain stages in the opamp. In frequency response design, the phaselead compensator adds positive phase. Design via root locus elec304alper erdogan 1 1 lecture. Phase lead compensators are placed in cascade, in the forward path, and are used to manipulate the phase margin. Designing lead and lag compensators control tutorials.
Design example 1 design a lead compensator for the digital control system below so that the pm is 50, the gm is at least 10 db. The lag lead compensator circuit in the s domain is shown in the following figure. Lead compensator design contd evaluate gs at the desired pole. Compensator structure the basic phase lead or phase lag compensator consists of a gain, one real pole, and one real zero. A lead compensator can increase the stability or speed of reponse of. In frequency response design, the phase lead compensator adds positive phase to the system over the frequency range 1 at to 1 t. A known nonlinear compensator design approach is adapted to allow design of nonlinear lead andor lag compensators, and a number of matlab functions are developed that automate the compensator design procedure. Design of lead compensator for process control using. Compensation in control system lag lead compensation. Lag lead compensator is an electrical network which produces phase lag at one frequency region and phase lead at other frequency region. Pdf design of a leadlag compensator for position loop control of. Design a lead compensator to place the dominant poles at the desired places while neglecting the effects of the lag compensator. Design of lead and lag compensators using frequency domain techniques prof.
Discrete inversion formulas for the design of lead and lag discrete compensators r. To provide attenuation reduction in magnitude after z. It brings together the sections on bode and nyquist and use insights from these as a tool for feedback design using lead and lag compensation. Zanasi computer science engineering department dii university of modena and reggio emilia, italy email.
The laglead compensator circuit in the s domain is shown in the following figure. Lead, lag, and lead lag compensators are usually designed for a system in transfer function form. Im going to do this entirely with pen and pencil, on paper here. A comparative analysis of pid, lead, lag, leadlag, and. Lead, lag and leadlag compensators are used to ensure that the stability margins are at the desired levels. Evaluate the steady state performance of the lead compensated system to. Cascade a phaselag compensator with a phaselead compensator to change the overall system characteristics. The simplest network used for compensator are known as lead, lag network.
Closedform solution for design of leadlag compensators article pdf available in international journal of electrical engineering education 412 april 2004 with 368 reads how we measure reads. Apr 22, 2017 a lead compensator design example is worked based on improving transient time domain specifications. Compensator design lead compensators lag compensators leadlag compensators bode design practice lead if the phase margin is insuf. Root locus and step response of lagcompensated system. Design of lead and lag compensators using frequency domain. It is an excellent example to illustrate many important design concepts that area also directly applicable to other designs. A simple lead compensator realized using op amps is shown. Leadlag compensator design example problem design a laglead. The design procedure for the laglead compensator follows. Design a lag compensator for the above system to satisfy the following.
Lecture 20 lag compensator design electrical engineering. Pdf design of a leadlag compensator for position loop. In particular, you can adjust the compensator gain, and you can add the following compensator dynamics. Mar 26, 2020 lecture 20 lag compensator design electrical engineering ee notes edurev is made by best teachers of electrical engineering ee.
Consider compensation as adding poles and zeros to feedback section for the equivalent system. As with phase lag compensation, the purpose of phase lead compensator design in the frequency domain generally is to satisfy speci. 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. Pdf lead and lag compensators with complex poles and. In this page, you will learn how to design digital lead and lag compensators using the rootlocus design method. Another use of compensators is to improve damping and thus reduce overshoot and improve settling time. Use the left hand toolbar to access the other chapters and themes. The conversions page explains how to convert a statespace model into transfer function form. Ee c128 chapter 11 university of california, berkeley. The steps to design the lag compensator are draw the root locus of the given open loop uncompensated. Design of lead compensator using bode plots duration.
Phase lag compensator design using bode plotsandphase lead compensator design using bode plots, theses notes will concentrate on the use of those two designs together. Laglead compensator design using bode plots the gmu ece. A lead compensator design example is worked based on improving transient time domain specifications. Compensator design for a set of plant models matlab. Start with compensator design with is not sufficient. Design of a leaddesign of a lead lag filterlag filter evaluate the performance of uncompensated system and get the desired pole locationsystem and get the desired pole location. Lec41 compensator design using frequency response plots nptelhrd. Systems and control theory stadius center for dynamical systems. Pdf closedform solution for design of leadlag compensators. The transfer function of the lag compensator network is given by equation 1, for.
In this paper, we present the stepwise procedure for designing a lead compensator to obtain the required stability margins with the help of suitable example. Lead compensators design using frequency response techniques. This example shows how to design and analyze a controller for multiple plant models using control system designer. Interactive educational tool for the design of compensators using. Thus the lag compensator and the lead compensator is implemented using the solid thinkingactivate tool. The design does not aim to get the dominant closed loop. Pdf lead and lag compensators with complex poles and zeros.