A graphical representation of the integration in the Fourier series coefficient
of Eq. (8-20) gives some insight into harmonic elimination. Recall from Chap. 2
that the Fourier coefficients are determined from the integral of the product of the
waveform and a sinusoid. Figure 8-6a shows the output waveform for 30
and the sinusoid of
3
o. The product of these two waveforms has an area of
zero, showing that the third harmonic is zero. Figure 8-6b shows the waveform
for 18 and the sinusoid of
5
o, showing that the fifth harmonic is eliminated for this value of .