(McGraw-Hill) (Instructors Manual) Electric Machinery Fundamentals 4th Edition Episode 1 Part 6 pps

95

% 10 V.

for ii = 1:length(t)

vin(ii) = 10 * sin(2*pi*50*t(ii));

end

% Now calculate vout

for ii = 1:length(t)

[vout(ii) vu(ii) vv(ii)] = vout(vin(ii), vx(ii), vy(ii));

end

% Plot the reference voltages vs time

figure(1)

plot(t,vx,'b','Linewidth',1.0);

hold on;

plot(t,vy,'k--','Linewidth',1.0);

title('\bfReference Voltages for fr = 500 Hz');

xlabel('\bfTime (s)');

ylabel('\bfVoltage (V)');

legend('vx','vy');

axis( [0 1/30 -10 10]);

hold off;

% Plot the input voltage vs time

figure(2)

plot(t,vin,'b','Linewidth',1.0);

title('\bfInput Voltage');

xlabel('\bfTime (s)');

ylabel('\bfVoltage (V)');

axis( [0 1/30 -10 10]);

% Plot the output voltages versus time

figure(3)

plot(t,vout,'b','Linewidth',1.0);

title('\bfOutput Voltage for fr = 500 Hz');

xlabel('\bfTime (s)');

ylabel('\bfVoltage (V)');

axis( [0 1/30 -120 120]);

% Now calculate the spectrum of the output voltage

spec = fft(vout);

% Calculate sampling frequency labels

len = length(t);

df = fs / len;

fstep = zeros(size(t));

for ii = 2:len/2

fstep(ii) = df * (ii-1);

fstep(len-ii+2) = -fstep(ii);

end

% Plot the spectrum

figure(4);

plot(fftshift(fstep),fftshift(abs(spec)));

title('\bfSpectrum of Output Voltage for fr = 500 Hz');

xlabel('\bfFrequency (Hz)');

ylabel('\bfAmplitude');

96

% Plot a closeup of the near spectrum

% (positive side only)

figure(5);

plot(fftshift(fstep),fftshift(abs(spec)));

title('\bfSpectrum of Output Voltage for fr = 500 Hz');

xlabel('\bfFrequency (Hz)');

ylabel('\bfAmplitude');

set(gca,'Xlim',[0 1000]);

When this program is executed, the input, reference, and output voltages are: