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 &
class.11
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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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