ex-602 control system

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ELECTRICAL AND ELECTRONICS ENGINEERING

CONTROL SYSTEM (EX-602)

Experiment: 1

Aim: Temperature controller using P-I-D controller ( Prportional+Integral+ Derivative) controller

Procedure:

1 Make Connection as shown in fig.

2 Switch On the power supply .

3 Ground PV and input of summing Blocks that are not used.

4 Apply square wave to the Set Point SP .

5 Check the output TP 10 of summing block on CRO that will look like as shown in fig.

6 Vary slowly the value of Kp ,Ki and Kd and observe the changes in waveshape.

Circuit Diagram:

LAB MANUAL AND WORKBOOK

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Conclusion :

When we vary the value of Kp the mag of square wave increase and by vary the Kd , the tip

of the first edge equal of the last edge and Kd effect add the Right mark shape between two edges .

Ques1: What is full form of PID Controller?


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Ans: Proportional Integral Derivative Controller.

Ques2: In PID Controller actuating error signal consists of?

Ans: Proportional error signal added with the derivative and integral of errror signal.

Ques3: What are the disadvantages of PID Controller?

Ans: The fundamental difficulty with PID control is that it is a feedbacksystem, with constantparameters,

and no direct knowledge of the process, and thus overall performance is reactive

Ques4: How PID Controller works?

Ans: A PID Controller works by correcting the error between a measured process variable and a desired

setpoint by calculating and then outputting a corrective action that can adjust the process

accordingly - and rapidly - to keep the error minimums.

Ques5: What is the use of PID Controller?

Ans: It is often used as feedback controller.

Experiment: 2

Aim: Formulation of P-D controller ( Prportional+ Derivative controller)

Procedure:


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1 Make Connection as shown in fig.

2 Switch On the power supply .




6 Vary slowly the value of Kp and Kd and observe the changes in waveshape.

Circuit Diagram:


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Conclusion :

When we vary the value of Kp the mag of square wave increase and by vary the Kd , the tip

of the first edge is in slightly greater than the last edge and these decrement is in the shape of

exponentialy decrement shape at both side this effect seen at upper side as well as lower side of wave

shape.

Ques1: What is PD controller?

Ans: Proportional Derivative controller.

Ques2: What is the advantage of a derivative controller?

Ans: Rise time is reduced.

Ques3: What happens to natural frequency of oscillation using derivative control?


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Ans: Natural frequency of oscillation remains unchanged.

Ques4: What is added to a system using derivative control?

Ans: Zero.

Ques5: Which type of system is generally utilized and why for various controllers.

Ans: Underdamped systems are generally utilized for quick response.

Experiment: 3

Aim: Formulation of P-I controller( Prportional + Integral controller)

Apparatus Required:

(1)PID Kit

(2)Multimeter

(3)connecting wire probes

Procedure:


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1 Make connection as shown in fig.

2 On the power supply .




6 Vary slowly the value of Kp and Ki and observe the changes in waveshape.

Circuit Diagram:


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Conclusion :

When we vary the value of Kp the mag of square wave increase and by vary the Ki the slop

will add at the top of the square wave shape .

Ques1: What happens to the order of a system when an integral error control is introduced in a system?

Ans: Order of system increases.

Ques2: What is PI controller?

Ans: Proportional Integral Controller.

Ques3: What happens to the order of a control system by introducing PI controller

Ans: It increases.

Ques4: What happens in a proportional controller?


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Ans: Peak overshoot is reduced by modifying the actuating error signal without sacrificing steady state

error.

Ques5: With integral controller steady state error for unit ramp input is?

Ans: Zero.

Experiment 4

Aim: Determinaton of transfer function of DC Motor (Speed / Vin).

Apparatus required :

1. NV3000-Control System Lab

2. Oscilloscope

3. 2mm patch cords (3)


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Procedure :

1. Make the connections according to the Figure 30

2. Connect the NV3000-Control System Lab to AC mains.

3. Switch ON the trainer by Power switch.

4. Turn voltage POT slowly until the motor begins to rotate. And note down the

corresponding Reference voltage.

5. Increase the input voltage by slowly turning the Reference voltage POT. For

every one volt increment of the reference voltage (1v, 2v, 3v.), record

the corresponding change in voltage on the socket 5 with the help of Digital

Voltmeter.

6. Note down all the readings in table given below

7. Switch Off the power switch.

8. Plot a graph on input voltage vs motor speed.


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Ques1: What is the function of commutator in a DC motor?

Ans: To convert AC to DC and to keep armature mmf wave stationary in space.

Ques2: Which two types of windings are utilized in D.C. Motor?

Ans: Field winding and armature winding.


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Ques3: Which type of supply is given to field winding in a DC motor?

Ans: DC supply.

Ques4: Which type of supply is given to armature winding in a DC motor?

Ans: AC supply.

Ques5: Where DC motors are generally used?

Ans: Whenever wide range of speed control is required DC motors are generally used.


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Experiment: 5

Aim: Study of lead compensating network.

Theory:

Compensaton : A redesign or addition of suitable device is called compensation.

A Lead Compensator:

A lead compensator can be thought of in several different ways.

1.First a lead compensator is a device that provides phase lead in its frequency response.

2. If the compensator has phase lead and never a phase lag then tnere are implications aboutwhere the corner frequencies are in the Bode's plot.

3.Other implications are that the phase lead compensator will have only certain types of pole

zero patterns in the s plane.

Next, we will examine those implications. A lead compensator will have a transfer function of the

form:

since a lead compensator will have only positive phase angle, we must have

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Ques1: The lead compensation network is considered to be which type of filter?

Ans: High pass filter.

Ques2: The maximum phase lead is contributed by a phase lead network at which frequency?

Ans: Mid corner frequency.

Ques3: What is a lead compensator?

Ans: A lead compensator is a device that provides phase lead in its frequency response.

Ques4: Which type of phase angle is possessed by a lead compensator?

Ans: A lead compensator will have only positive phase angle.

Ques5: How is the location of zero with respect to origin in a lead compensator?

Ans: Zero is nearer to the origin.


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Experiment: 6

Aim: Study of lag compensating network

Theory:

Lag compensators are sometimes the best controller to use to get a system to do what you want it to

do. Like other compensators, lag compensators can be used to adjust frequency response by adding

equal numbers of poles and zeroes to a systems.

A Lag Compensator:

A lag compensator can be thought of in several different ways.

First, a lag compensator is a device that provides phase lag in its' frequency response.

If the compensator has phase lag - and never a phase lead - then there are implications about where

the corner frequencies are in the Bode' plot.

Other implications are that the phase lag compensator will have only certain types of pole-zero

patterns in the s plane.

A lag compensator will have a transfer function of the form:

1.Since a lead compensator has only positive phase angle, we must have:

1.wz > wp

For a lead compensator:

wz > wp

Conclusion:

Steady state accuracy is improved by using lag compensating network but as the bandwidth

is reduced the speed of time response is deteriorated to a certain extent.


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Ques1: What is the use of a lag compensator?

Ans: Lag compensators can be used to adjust frequency response by adding equal numbers of

poles and zeroes to a systems.

Ques2: Lag compensator acts as which type of filter?

Ans: Low pass filter.

Ques3: How is the location of pole with respect to origin in a lag compensator.

Ans: Pole is nearer to the origin.

Ques4: What is the effect on bandwidth by introduction of lag- compensator?

Ans: Bandwidth decreases.

Ques5: What happens to the phase shift if a phase lag compensator is introduced in cascade with the forward

path transfer function?

Ans: It is reduced.


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Experiment: 7

Aim: Effect of feedback on DC Servo motor.

Equipments Needed :

1. NV3000-Control System Lab

2. PC Interface Module

3. Oscilloscope

4. 2 mm patch cords (1)

5. One computer along with NV3000-Control System Lab Software.

Circuit diagram :

Procedure :

1. Make connections as shown in Figure 35 between PC interface module and trainer kit.

2. Switch ON the trainer power supply

3. Counter-check the trainer supply. Is it ON? If yes then ok and if not then switch it ON.

4. Now you are ready to Run the software given with the trainer.

5. Single left click on the Connect command button, so that all the application buttons will

get activated.

6. Now, single left click on the Servo Motor command button. A screen will appear asshown in Figure


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7. By changing the cursor position of scroll bar you can change the position of the servo

motor according to your requirement.

8. The change in angle position is shown in the form of an animated picture as shown in

Figure

9. On connecting oscilloscope to digital output (D0) you will observe the change in pulse

width (ON time) with the change in angle.

10. Make an observation table to record the readings between ON time and angle position

Ques1: What is the function of commutator in a DC motor?


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Ans: To convert AC to DC and to keep armature mmf wave stationary in space.

Ques2: Which two types of windings are utilized in D.C. Motor?

Ans: Field winding and armature winding.

Ques3: Which type of supply is given to field winding in a DC motor?

Ans: DC supply.

Ques4: Which type of supply is given to armature winding in a DC motor?

Ans: AC supply.

Ques5: Where DC motors are generally used?

Ans: Whenever wide range of speed control is required DC motors are generally used.


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Experiment 8

Aim: Characteristics of Synchros.

Theory:

SYNCHRO CHARACTERISTICS :

Synchro characteristics play a very important part in synchro troubleshooting and maintenance. By

closely observing these characteristics, you can generally tell if a synchro or synchro system is

working properly. Low torque, overheating, and improper operating voltages are just a few of the

abnormal characteristics found in synchro systems. In general, the load capacity of a synchro system

is limited by the number and types of receiver units loading the transmitter, the loads on these receiver

units, and the operating temperature.

TORQUE

Torque is simply a measure of how much load a machine can turn. In torque synchros, only small

loads are turned; therefore, only a small amount of torque is required. The measure of torque is the

product of the applied force and the distance between the point of application and the center of

rotation. For instance, if a 3-ounce weight is suspended from a synchro pulley having a radius of 2

inches, the torque required to move the weight is 6 ounce-inches. In heavy machinery, torque may be

expressed in pound-feet, but torque synchro measurements are in ounce-inches.


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Conclusion:

The unit of torque is the pound-foot or ounce-inch. Do not confuse this with foot-pounds,

which is the measurement of work. Many times in referring to torque, tools are marked in

foot-pounds. While this use of foot-pounds is technically incorrect, common usage has made

it acceptablThe torque developed in a synchro receiver results from the tendency of two

electromagnets to align themselves. Since the rotor can be turned and the stator usually

cannot, the stator must exert a force (torque) tending to pull the rotor into a position where the

primary and secondary magnetic fields are in line. The strength of the magnetic field

produced by the stator determines the torque. The field strength depends on the current

through the stator coils. As the current through the stator is increased, the field strength

increases and more torque is developed.

Ques1: Why synchro is used?


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Ans: For converting angular position difference into proportional a.c. Voltage.

Ques2: List some abnormal characteristics found in synchro system?

Ans: Low torque, overheating, and improper operating voltages

Ques3: Which type of rotor is of synchro transmitter?

Ans: Salient Pole type.

Ques4: Which type of rotor is of synchro control transfortmer?

Ans: Cylindrical type.

Ques5: At what angle the stator winding of synchro transmitter and that of synchro control transformer are

wound at?

Ans: 120 degree.


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Experiment 9

Aim: Transfer function of AC Servo motor.

Theory:

AC servo motors :

These servo motors are basically two-phase, reversible, induction motors modified for servo

operation. Ac servo motors are used in applications requiring rapid and accurate response

characteristics. To achieve these characteristics, these ac servo motors have small diameter, high

resistance rotors. The ac servo motor's small diameter provides low inertia for fast starts, stops, and

reversals. High resistance provides nearly linear speed-torque characteristics for accurate servo motor

control.

An induction motor designed for servo use is wound with two phases physically at right angles or in

space quadrature. A fixed or reference winding is excited by a fixed voltage source, while the control

winding is excited by an adjustable or variable control voltage, usually from a servoamplifier. The

servo motor windings are often designed with the same voltage/turns ratio, so that power inputs at

maximum fixed phase excitation, and at maximum control phase signal, are in balance.

Conclusion:

The inherent damping of servo motors decreases as ratings increase, and the servo motors

are designed to have a reasonable efficiency at the sacrifice of speed-torque linearity. Induction type

servo motors are available in fractional and integral horsepower sizes.


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Ques1: Where Ac servo motors are used?

Ans: Ac servo motors are used in applications requiring rapid and accurate response

characteristics

Ques2: What are the necessary characteristics of AC Servo motors?

Ans: These AC servo motors have small diameter, high resistance rotors.

Ques3: What is the phase difference between the two windings in an AC servo motor?

Ans: An induction motor designed for servo use is wound with two phases physically at right

angles or in space quadrature.

Ques4: How fixed or reference winding is excited in AC servo motor?

Ans: A fixed or reference winding is excited by a fixed voltage source.

Ques5: How the control winding is excited in a n AC servo motor?

Ans: The control winding is excited by an adjustable or variable control voltage, usually from a

servoamplifier.

Which type of system is generally utilized and why for various controllers.

Underdamped systems are generally utilized for quick response.


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Experiment 10

Aim: Transfer function of Second Order System.

Theory: A second order step response. It has characteristics - like decaying oscillations - that you can

have in second order systems. Those characteristic decaying oscillations are not to be seen in first

order systems. If you see decaying oscillations, you know you don't have a first order system. On the

other hand, not every second order system will exhibit those decaying oscillations. Second order

systems are more complex than that.

With that in mind, let's look at some basic ideas about second order systems. The simplest second

order system satisfies a differential equation of this form.

where:

x(t) = Response of the System,

u(t) = Input to the System,

z = Damping Ratio,

wn=Undamped Natural Frequency,

Gdc= The DC Gain of the System.

The parameters you find in a second order system determine aspects of various kinds of responses.

Whether we are talking about impulse response, step response or response to other inputs, we will still

find the following relations.

z, the damping ratio, will determine how much the system oscillates as theresponse decays toward steady state.

wn,the undamped natural frequency, will determine how fast the system oscillates

during any transient response.

Gdc, the DC gain of the system, will determine the size of steady state response

when the input settles out to a constant value.

Conclusion:


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http://www.facstaff.bucknell.edu/mastascu/econtrolhtml/SysDyn/SysDyn2.html#Undamped%20Natural%20Frequencyhttp://www.facstaff.bucknell.edu/mastascu/econtrolhtml/SysDyn/SysDyn2.html#Undamped%20Natural%20Frequency


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Neither the response or the first derivative changes suddenly when the step is applied.

1.Since the step is the integral of the impulse, the step response is the integral of the impulse

response.That means that the response does not change at t = 0, and neither does the derivative of the

response.

2.This observation may not be true if the transfer function of the system has an s-term in thenumerator.

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ex-602 control system

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