
DC–AC Converters 14-41
Another dierence with traditional carrier-based PWM is that there is no linearity between the
modulation index and the amplitude of the fundamental component i
1
. is is due the fact that the
central segment of π/3 is not modulated, being always in “on” state, thereby forcing a high amplitude
for the fundamental frequency component. In fact, when changing the modulation index through all
its range (from 0 to 1), the peak amplitude for the current fundamental component varies only within
0.9314I
dc
≤ î
1
≤ 1.0465I
dc
. is is no problem, since the current amplitude is controlled by the CSR.
0
0.1
0.2
0.3
0.4
0.5
0 5 10
Harmoinc amplitude ...