Page 224 - Power Electronics Handbook

2 14 Phase-controlled rectification and inversion

0 30 60 90 120 150 180
Firing anglo (degrees)
nrprC 9.38 Variations of d.c. voltage ratio with firing angle for various unidirectional
converters

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Harmonic as % of max. d.c. output
Figure 9.39 hedominant harmonia in the output of bidirectional converters

circuit used. Figures 9.40 and 9.41 give the lower harmonic content for
single- and three-phase halfantrolled converters, and, comparing this
with the bi-directional converter, it is seen that harmonics of the same
number are lower in unidirectional circuits.
A useful way of comparing harmonics from several control rectifier
systems is to determine their harmonic factors. The r.m.s. voltage output