MATLAB Simulation

The Matlab program is presented below.

% Program to simulate the full-wave fully-controlled 
bridge rectifier
% Simulation at a specified firing angle
% Enter the peak voltage, frequency, 
inductance L in mH and resistor R
disp('Typical value for peak voltage is 340 V')
peakV=input('Enter Peak voltage in Volts>');
disp('Typical value for line frequency is 50 Hz')
freq=input('Enter line frequency in Hz>');
disp('Typical value for Load inductance is 31.8 mH')
L=input('Enter Load inductance in mH>');
disp('Typical value for Load Resistance is 10.0 Ohms')
R=input('Enter Load Resistance in Ohms>');
disp('Typical value for Firing angle is 30.0 degree')
fangDeg=input('Enter Firing angle within range 0 to 180 in deg>');
fangRad=fangDeg/180.0*pi;

w=2.0*pi*freq;
X=w*L/1000.0;
if (X<0.001) X=0.001; end;
Z=sqrt(R*R+X*X);
tauInv=R/X;
loadAng=atan(X/R);
k1=peakV/Z;
k2=2.0*k1*sin(loadAng-fangRad)/(1.0-exp(-pi*tauInv));
k3=k1*sin(loadAng-fangRad);
if (fangRad<loadAng)
  A=k2;
  sw=1;
else
  A=k3;
  sw=2;
end;  

Ampavg=0;
AmpRMS=0;

for n=1:360;
  theta=n/180.0*pi;
  X(n)=n;
  if (sw==1);
    if (n<fangDeg);
          cur=k1*sin(pi+theta-loadAng)
                  +A*exp(-tauInv*(pi+theta-fangRad));
          vbr(n)=peakV*sin(theta+pi);
          vind(n)=vbr(n)-R*cur;
          iLoad(n)=cur;
          vSCR(n)=peakV*sin(theta);
          Ampavg=Ampavg+cur*1/360; 
          AmpRMS=AmpRMS+cur*cur*1/360;
        elseif ((n>=fangDeg) & (n<(180+fangDeg)));   
          cur=k1*sin(theta-loadAng)+A*exp(-tauInv*(theta-fangRad));
          vbr(n)=peakV*sin(theta);
          vind(n)=vbr(n)-R*cur;
          iLoad(n)=cur;
          vSCR(n)=0;
          Ampavg=Ampavg+cur*1/360; 
          AmpRMS=AmpRMS+cur*cur*1/360;
        else (n>=(180+fangDeg)); 
          cur=k1*sin(theta-pi-loadAng)+
              A*exp(-tauInv*(theta-pi-fangRad));
          vbr(n)=peakV*sin(theta-pi);
          vind(n)=vbr(n)-R*cur;
          iLoad(n)=cur;
          vSCR(n)=peakV*sin(theta);
          Ampavg=Ampavg+cur*1/360; 
          AmpRMS=AmpRMS+cur*cur*1/360;  
        end;
  else
    if (n<fangDeg);
          cur=k1*sin(pi+theta-loadAng)+
            A*exp(-tauInv*(pi+theta-fangRad));
          if (cur>0);
            vbr(n)=peakV*sin(theta+pi);
            vind(n)=vbr(n)-R*cur;
            iLoad(n)=cur;
            vSCR(n)=peakV*sin(theta);
            Ampavg=Ampavg+cur*1/360; 
            AmpRMS=AmpRMS+cur*cur*1/360;
          else;
            vbr(n)=0.0;
                vind(n)=0.0;
                iLoad(n)=0.0;
            vSCR(n)=peakV*sin(theta)/2.0;
          end;
          
        elseif ((n>=fangDeg) & (n<(180+fangDeg)));   
          cur=k1*sin(theta-loadAng)+A*exp(-tauInv*(theta-fangRad));
          if (cur>0);
            vbr(n)=peakV*sin(theta);
            vind(n)=vbr(n)-R*cur;
            iLoad(n)=cur;
            vSCR(n)=0;
            Ampavg=Ampavg+cur*1/360; 
            AmpRMS=AmpRMS+cur*cur*1/360;
      else;
            vbr(n)=0.0;
                vind(n)=0.0;
                iLoad(n)=0.0;
            vSCR(n)=peakV*sin(theta)/2.0;
          end;
                        
        else (n>=(180+fangDeg)); 
          cur=k1*sin(theta-pi-loadAng)+
                 A*exp(-tauInv*(theta-pi-fangRad));  
          vbr(n)=peakV*sin(theta-pi);
          vind(n)=vbr(n)-R*cur;
          iLoad(n)=cur;
          vSCR(n)=peakV*sin(theta);
          Ampavg=Ampavg+cur*1/360; 
          AmpRMS=AmpRMS+cur*cur*1/360;  
        end;
  end;
end;  
  
plot(X,iLoad)
title('The Load current')
xlabel('degrees')
ylabel('Amps') 
grid
pause

plot(X,vbr)
title('Bridge Output volt')
xlabel('degrees')
ylabel('Volts') 
grid
pause

plot(X,vind)
title('Inductor Voltage')
xlabel('degrees')
ylabel('Volts') 
grid
pause

plot(X,vSCR)
title('SCR Voltage')
xlabel('degrees')
ylabel('Volts') 
grid

AmpRMS=sqrt(AmpRMS);
[C,message]=fopen('fwrl1ph1.dat','w'); 
fprintf(C,'Avg Load Cur=\t%d\tRMS Load Cur=\t%f\n',Ampavg,AmpRMS);
fclose(C);

The responses obtained for the typical specified values have been displayed below.

The results obtained with a firing angle of 60^o have been displayed below. The other values are the same as for the previous set. When the firing angle is retarded this much, the load current is discontinuous.

 
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