matlab programming & its applications for electrical engineers

8/12/2019 MATLAB Programming & Its Applications for Electrical Engineers

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A

WORKSHOP ON

MATLAB PROGRAMMINGITS APPLICATIONS FOR ELECTRICAL

ENGINEERSOrganized by

Department of Electrical EngineeringMARUDHAR ENGINEERING COLLEGE,

Raisar, NH-11, Bikaner

Created by

- Rohan Sharma-


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WORKSHOP SCHEDULE

Day 1 Basics of MATLAB & Familiarization

Mathematical Operations using MATLAB

Working with Script files & user defined functions

Applications of MATLAB in Electrical Circuits

Day2

Numerical Methods using MATLAB

MATLAB Applications in Electrical Power System

Applications of MATLAB in Power Electronics

Simulink Toolbox for Electrical Engineers

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Basics of MATLABMATLAB is a software package for high

performance computations & visualizations.

It has very wide application in the field of

engineering & technology.

The word MATLAB stands for MATrices

LABoratory.

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MATLABWINDOWS[A] Matlab desktop -

Workspace: All the information and details of everyvariable entered into the command window isdisplayed here.

Command History stores history of every command.

Every operation which we want to perform is to beentered in command window.

[B] Edi tor Window

This window is used to write any program, which

includes many command statements. By using thiswindow one can edit any previously written command.

[C] Figure Window

All the figures are shown in a separate figure window. 4


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MATLAB FILE TYPES

.m Files: Every script and function file iswritten in this format, with .mextension.

.p Files:This format is fixed for coded files,source codes are neither visible nor be edited

in these files..mex Files: Any program written in someother language like C, JAVA or FORTRANcan be imported into matlab using .mexextension files.

.mat Files: These are the machine code ofm-files.

.fig Files: any figure can be shown by

machine code using .figextension. 5


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SOME USEFUL COMMANDS>>ver >> help >> clf

>>computer >> exit >> clock

>>dir >> quit >> date>>clc >> help >> home

>>pwd

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ARITHMETIC OPERATIONSArithmetic operation Symbol

Addition +

Subtraction -

Multiplication *

Right Division /

Left Division \

Exponentiation ^

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EXPONENTIAL OPERATIONSFunction Description

exp(x) Exponential (ex)

log(x) Natural logarithm

log10(x) Base 10 logarithm

sqrt(x) Square root

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TRIGONOMETRIC OPERATIONSFunction Description

sin(x)Computes the sine of x, where x is in

radians.

csc(x)Computes the cosec of x, where x is in

radians.sind(x)

Computes the sin of x, where x is in

degrees.

asin(x)Computes the arcsine or inverse sine of x,

where x is in radians.

sinh(x)Computes the hyperbolic sine of x, where x

is in radians.

atanh(x)

Computes the inverse hyperbolic tangent of

x. 9


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COMPLEX NUMBER FUNCTIONSFunction Description

conj(x)

Computes the complex conjugate of the

complex number x. Thus, if x is equal to

a+ib, then conj(x) will be equal to a-ib.

real(x) Computes the real potion of the complexnumber x.

imag(x)Computes the imaginary potion of the

complex number x.

abs(x) Computes the absolute value of magnitudeof the complex number x.

angle(x)Computes the angle of the complex number

x.

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COMMANDS FOR MANAGING VARIABLES

Command Description

clear Removes all variables from the memory.

clear a, b Clears only variables a and b from

memory.

who Lists the variables currently in

workspace.

whos Displays a lists of the variables currentlyin the memory and their size together

with information about their bytes &

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WORKING WITH ARRAYS

Row Vector :

X=[7 5 3 1]

Column Vector :

Y=[7; 5; 3; 1]

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EXERCISE:

Solve the given equations inMATLAB.

Hint: A=[3X3] B=[3X1] Ans=inv(A)*B

9942

20483

10235

zyx

zyx

zyx

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EXERCISE :

Write a program to draw thefollowing curves in a spitted single

window by using the subp lo t

command. Also use legendcommand to distinguish between

different plots.

p = 3x + 5 q = ex

r = 1/x s = sin(x)

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SOLUTION:

x = 0:.1:2*pi;

subplot(2,2,1); plot(3*x+5)

legend('p')

title('Plot of 3x+5')

subplot(2,2,2);

plot(exp(x)); legend('q')

title('Plot of exponent of x')

subplot(2,2,3);

plot(1./x);

legend('r')

title('Plot of 1/x')

subplot(2,2,4);

plot(sin(x));

legend('s')

title('Plot of Sin(x))

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INPUT - OUTPUT STATEMENTS:

Input function:

Syntax: variable = input(string)

Example: x = input(Enter the value of x)

Display function:

Syntax: disp(string)

Example: disp(I am learning MATLAB)

fpr int f function:Syntax: fprintf(string, variable, escape character,

data)

Example: fprintf(The sum of a & b is =%d \n, sum)

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USE MATLAB IN ELECTRICAL CIRCUITS :

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SOLUTION USNG MATLAB :

Z = [40 -10 -30;

-10 30 -5;-30 -5 65];

V = [10 0 0]';

% solve for the loop currents

I = inv(Z)*V;

% current through RB is calculated

IRB = I(3) - I(2);

fprintf('the current through R is %f Amps \n',IRB)

% the power supplied by source is calculated

PS = I(1)*10;

fprintf('the power supplied by 10V source is %f watts\n',PS)

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MATLAB answers are :

the current through R is 0.037037 Amps

the power supplied by 10V source is 4.753086watts

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Example:>> x=2.3;

>> y=3.3;

>> addtwo(x,y)

ans =

5.6000

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Defining of a function

function [r,theta] = cart2plr(x,y)

% cart2plr Convert Cartesian coordinates to polar

coordinates

% [r,theta] = cart2plr(x,y) computes r and theta with% r = sqrt(x^2 + y^2);

% theta = atan2(y,x);

r = sqrt(x^2 + y^2);

theta = atan2(y,x);

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Example:

>> [r,th]=cart2plr(2,-.7)

r =

2.1190

th =

-0.3367

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End of day one.!

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matlab programming & its applications for electrical engineers

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