ABB DCS 600 MultiDrive Series Manual page 11

Sequential configura-
tion (continued)
DCS 600 Manual for 12 – Pulse Operation
Sequential control means that the DC voltage of only one converter
varies in order to control the armature current until firing angle has
reached the maximum or minimum limit and then the other converter
starts contolling the DC voltage.
Depending on the armature voltage the first or the second converter
operates with constant voltage or firing angle while the other one
works with varying values.
-1
Slave
150° fixed
T he benefit of this operation mode is that reactive power (Q
be reduced (
Figure 2/5
for long times with full torque at low speeds.
Converters with sequential control are preferred if the saving of reac-
tive power is more important than a lower ripple of the armature cur-
rent and a lower intensity of the line harmonics .
6 - pulse /
12 - pulse
-
U
DC max
-1
theoretical curve
Chapter 2 – Twelve–Pulse Technology
U output
actual
+1
-1
). This is important for drives which have to work
Q
1 α
P
Q
di
max
+1
Sequential
+0,5
-0,5 0
Master
15° fixed
+1
U output
reference
Figure 2/4
/2) can
max
U
DC max
U
0,5 +1
di α
U
di
Figure 2/5
2 - 3
II F2