d.c motor speed contrl

8/14/2019 d.c Motor Speed Contrl

1/14

D.C MOTOR SPEED CONTROL BYA FUZZY APPROACH

Under the Esteemed Guidance of

A Seminar on

Presented By


2/14

a a a aV I R A V I R

N . k .

z P

= =

INTRODUCTION:

DC motor converts electrical energy into

mechanical energy. DC motor is used in applications where widespeed ranges are required. DC shunt motor exhibits a droopingspeed-torque characteristic. The speed of the DC motor is given by

Hence, the speed can be controlled by varying, Flux/pole ( ). Field Control Method Voltage of armature circuit, by varying Ra, Armature Control

Method.


3/14


4/14

THE COMPLETE SPEED CONTROL SYSTEM:

The block diagram of the dc motor speed control system is as shown in

Figure

ErrorComputer

Fuzzy LogicController

DC motor

Ref Speed

Vc

Actual Speed

de/dt

e

WhereSpeed error (e)The derivative of the speed error (de/dt)


5/14

Fig: Derivative of Speed error


6/14

Fig: Speed error


7/14

PL NL NL

PS ZERO NS NL NL

PL PS ZERO NS NL

PL PL PS ZERO NS

PL PL PS

NLNSZEROPSPL

PL

PS

ZERO

NS

NL

Fuzzy control rules


8/14

PROPOSED FUZZY LOGIC CONTROLLER:

KNOWLEDGEBASE

DefuzzifierInterferenceEngineFuzzifier

Dc motor

Error Interpreter

Fig : Block diagram of system with proposed FLC


9/14

The block diagram of the system with the proposed FLC is shownin Figure. A new functional block called the Error Interpreter is added tothe basic system. The function of the block is to sense the error, identifyits ranges. And determine the location of the singletons. In this method,the error and error rate are used to change the supporters in the motor

voltage singletons. The defuzzified output of controller is given by

NLNSPSPL

NLNLVCNSNSVCPSPSVCPLPLVCVc

+++

+++=

....

WherePL, PS, NS. And NL is the inference membership values andPLVC, PSVC, NSVC, andNLVCare the corresponding supports of change inthe motor voltage singletons


10/14

The steps in designing the controller are :

Identify the variables (inputs, states and outputs) of the

plant.Partition the universe of discourse or the internal spanned byeach variable into a number of fuzzy subsets, assigning each alinguistic label.Assign or determine a membership function for each fuzzysubset.

Assign the fuzzy relationship between the inputs or states, fuzzysubsets on the one hand and the outputs fuzzy subsets on theother hand, thus forming the rule base.Choose appropriate sealing factors for the input and outputvariables in order to normalize the variables to the [0,1] or [-

1,1] interval.Fuzzification of the inputs to the controller.Use fuzzy approximate reasoning to inference the outputcontributed from each rule.Aggregate the fuzzy outputs recommended by each rule.Apply defuzzification to form a crisp output.


11/14

SIMULINK ROOT BLOCK DIAGRAM:

PARAMETERS: Source type: DC

Amplitude: 220V.,Rated speed: 1500 rpm

Signal generator Amplitude: 1; Frequency: 1

Gain=9.8


12/14

OUTPUT:


13/14

CONCLUSIONS:

The proposed fuzzy logic controller issuitable for speed control of a DC motor. The personal computer

provides the necessary flexibility in setting any speed profile

with the use of fuzzy packages.The proposed fuzzy controller gives betterresponse compared to the basic fuzzy controller. The stepresponse parameters can be closely controlled with the help ofsimple operations within the controller.


14/14

ThankU

d.c motor speed contrl

Documents