Question

5x3 +7x-4 2. (a) A diode allows the flow of current only in one direction which is used as a half wave rectifier. For a real diode, the voltage v, across the load Ri is given by: [10) v.- vs-0.6 if vs > 0.6 if vs >0.6 the supply voltage is: vs (t-3 e-t/3 sin(nt) where t is in seconds. Using if, if'else write a MATLAB program for plotting the voltage vi, versus t for osts8

Answer 1

The given condition is a combination of the load and diode. Whenever, the source voltage is more than 0.6 volts, the diode starts conducting in one direction and the voltage across the load will be V_s - 0.6.

The voltage across the load is expressed as

Vs-0.6 V, > 0.6 ï, < 0.6 0 V

Given that, $V_s(t) = 3 e^{-\frac{t}{3}} \sin (\pi t)$ , where '' is in seconds.

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MATLAB code to plot the load voltage from 0 to 8 seconds.

======= START OF MATLAB CODE ======

%------------------------------
% Diode Conduction
%------------------------------
% Time required for plotting
Ts = 8;
% Time interval of 1 milliseconds from 0 to 8 seconds
t = 0:0.001:Ts;
% Generation of supply voltage
% Dot multiplication for element-wise multiplication
Vs = 3.*exp(-t/3).*sin(pi*t);
% Checking all the voltages in the interval 0 to 8 seconds
% to generate load voltage using if/else condition
for i=1:length(Vs)
   if Vs(i) > 0.6
       Vl(i) = Vs(i) - 0.6;
   else
       Vl(i) = 0;
   end
end
% Plotting load voltage
figure,plot(t,Vl)
xlabel('Time in seconds')
ylabel('Vl')
title('Load voltage')
grid on
% Plotting supply voltage
figure,plot(t,Vs)
xlabel('Time in seconds')
ylabel('Vs')
title('Supply voltage')
grid on
============== END OF MATLAB CODE =============

Save the MATLAB code in a file named as 'diode.m' and run the command 'diode' in command window of MATLAB to generate load voltage and supply voltage plots. There are comments in each line and comments start with the symbol '%' in MATLAB.

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The plot of load voltage from 0 to 8 seconds is shown below

Load voltage 2 1.5 2 4 Time in seconds

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The plot of supply voltage from 0 to 8 seconds is shown below

The plot of supply voltage is provided as a reference.

Supply voltage 2 -2 2 4 Time in seconds

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