Environmental Engineering Reference
In-Depth Information
defines the amplitude of the synthesized waveform relative to its maximum avail-
able amplitude is given as
U
s
2
=
3
U
dc
m
i
¼
ð
6
:
2
Þ
In (6.1), the maximum available amplitude is 0.577 for current regulated
PWM, or CRPWM, and 0.637 for space vector PWM (SVPWM). More will be said
on these topics in later chapters. It is instructive now to describe modulation in terms
of the six pulse pattern available from the 3-phase inverter shown in Figure 6.1
and repeated here for convenience as Figure 6.7.
Pole-A
Pole-B
Pole-C
D3
D5
S1
D1
S3
S5
U
dc
a
b
c
S4
S6
S2
D4
D6
D2
0
U
ab
U
co
U
bo
U
ao
B
I
a
U
bc
A
I
b
n
C
I
c
U
ac
I
m
-axis
U
3
U
2
U
s
*
U
(
k
+1)
U
1
R
e
-axis
U
0
,
U
7
U
k
U
4
U
5
U
6
Figure 6.7 Full bridge inverter switching states
