Page 260 - Rashid, Power Electronics Handbook

14 Inverters 249

FIGURE 14.33 The three-phase CSI. Ideal waveforms for space-vector Modulation ð ^ i c ¼ 0:8, f sn ¼ 18Þ: (a) modulating signals; (b) switch S 1 state; (c)
switch S 3 state; (d) ac output current; (e) ac output current spectrum; (f) ac output voltage; (g) dc voltage; (h) dc voltage spectrum; (i) switch S 1
current; (j) Switch S 1 voltage.

high switching frequency is used, the phase voltages become the ac output currents are considered sinusoidal and the dc
nearly sinusoidal balanced waveforms. On the other hand, if link current is assumed constant i ðtÞ¼ I , Eq. (14.59) can be
i i
simpli®ed to

v ðtÞ¼
i
p p
8   9
2V sinðotÞ 2I sinðot ÿ fÞ
> on o1 >
> >
1 < p  p  =

þ 2V sinðot ÿ 120 Þ 2I sinðot ÿ 120 ÿ fÞ
on
o1
I > >
i > p  p  >
: ;
þ 2V sinðot ÿ 240 Þ 2I sinðot ÿ 240 ÿ fÞ
o1
on
ð14:60Þ
FIGURE 14.34 Phase voltage de®nition in a wye-connected ®lter.