Page 315 - Solutions Manual to accompany Electric Machinery Fundamentals

3V 2 1 5   1  5      
V  M   sin  sin
rms      
2  2  6 6  4  3 3  
3V 2   1  5    3V 2    1  3 3  
V  M  sin  sin  M     
rms      
2  3 4  3 3   2   3 4  2 2   

3V 2   1  3 3   3V 2   3 
V  M       M   0.8407 V
rms     M
2  3 4  2 2   2   3 4 
The resulting ripple factor is

 V  2  0.8407 V  2
r    V rms    1 100%     0.8270 V  M   1 100% 18.3%


M
DC
The ripple can be calculated with MATLAB using the ripple function developed in the text. We must
right a new function halfwave3 to simulate the output of a three-phase half-wave rectifier. This output
v
is just the largest voltage of  tv A ,   tv B , and   t at any particular time. The function is shown
C
below:

function volts = halfwave3(wt)
% Function to simulate the output of a three-phase
% half-wave rectifier.
% wt = Phase in radians (=omega x time)

% Convert input to the range 0 <= wt < 2*pi
while wt >= 2*pi
wt = wt - 2*pi;
end
while wt < 0
wt = wt + 2*pi;
end

% Simulate the output of the rectifier.
a = sin(wt);
b = sin(wt - 2*pi/3);
c = sin(wt + 2*pi/3);

volts = max( [ a b c ] );

The function ripple is reproduced below. It is identical to the one in the textbook.

function r = ripple(waveform)
% Function to calculate the ripple on an input waveform.

% Calculate the average value of the waveform
nvals = size(waveform,2);
temp = 0;
for ii = 1:nvals
temp = temp + waveform(ii);
end
average = temp/nvals;

% Calculate rms value of waveform
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