A blog to help electrical engineers and students to learn electrical engineering topics. Basic Electrical Engineering, Power Systems, Electrical Machines, tec.. Now special course on MATLAB for Beginners.



Wednesday, September 21, 2016

MATLAB Scripts - Examples with Electrical Engineering Applications

This lecture we will practice some Basic MATLAB Scripts.
›We will start with simple scripts and will discuss some electrical engineering applications.

Program to calculate Electricity bill.

w = input('Enter power of your device (in watts): ');
h = input('Enter time (in hours): ');
r = input('Enter electricity rate (in dollars per KWH): ');
ec = w * h/1000 * r;
disp(’Your Electricity bill is’)

Power transfer vs Load resistance curve

RL = 1:0.01:10;
Vs = 12;
Rs = 2.5;
P = (Vs^2*RL)./(RL+Rs).^2;
xlabel('Load resistance')
ylabel('Power dissipated')

Torque-Speed Curve for a squirrel cage Induction Motor 

›Ns=1500; % Synchronous speed;
›R1=15.6 ;R2=14;X1=18; X2=23;Xm=260;Vt=400/sqrt(3);
›s = 0.002:0.002:1; % vector of slip
›N = Ns.*(1-s); % Speed, in RPM
›Ws = 2*pi*Ns/60; % Synchronous speed in rad/sec
›Rr = R2./ s; % Rotor resistance
›Zr = j*X2 + Rr; % Total rotor impedance
›Za = j*Xm*Zr./(j*Xm+Zr); % Air-gap impedance
›Zt = R1 + j*X1 +Za; % Terminal impedance
›Ia = Vt ./ Zt; % Terminal Current
›I2 = j*Xm*Ia./(j*Xm+Zr); % Rotor Current
›Pag = 3* (abs(I2)).^2.*Rr; % Air-Gap Power
›Pm = Pag.* (1-s); % Converted Power
›Trq = Pag/ Ws; % Developed Torque
›plot(N, Trq)
›xlabel('Speed in RPM')
›ylabel('Torque (Nm)')
›plot(Ia, Trq)
›xlabel('Load Current')
›ylabel('Torque (Nm)')

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