Common Dc Capacitance; Dc Link Capacitance; Energy Capacity In Common Dc - ABB ACS850 Application Manual

28

Common DC capacitance

Many acceleration and deceleration processes are typical for applications with high
performance machinery drives. It is useful for such applications to connect those drives
into the common DC link to utilize also the DC link energy storage behavior. In the
common DC system, all the capacitor banks of the individual drive modules are
connected in parallel and they act as a common energy storage. This provides the
following advantages:
The need for the braking resistor in the drive system may be eliminated. The heat
•
dissipation in the control cabinet is considerably reduced.
The energy stored in the DC bus capacitors during the regenerating can be used
•
afterwards for the motoring power. The energy demand from the supply is then
reduced.

DC link capacitance

Each drive module has its own capacitor bank. The capacitance value of each drive
size is given in the table below.
ACS850 Type
03A0-5, 03A6-5
04A8-5, 06A0-5,
010A-5
014A-5, 018A-5
025A-5, 030A-5,
044A-5, 050A-5
061A-5
078A-5, 094A-5

Energy capacity in common DC

The energy capacity W
way:
W
DC
Where:
• C
dc1
common DC link.
• U
dc,lim
• U
dc
The actual DC link voltage to be used in energy calculations should be calculated as:
U
•
dc
Common DC configurations
C
dc
µ
F
120
240
370
740
670
1000
1340
2000
in the common DC system can be determined in following
dc
(
+ + +
C C C
=
1 2 3
dc dc dc
2
...C are the actual capacitance values of the drive modules connected to the
dcn
is the DC link voltage level that is allowed for the system.
is the actual DC link voltage level in a normal situation.
= 2 ×
U
ac
ACS850 Type
103A-5
144A-5
166A-5, 202A-5
225A-5, 260A-5, 290A-5
430A-5
521A-5
602A-5
693A-5, 720A-5
)
(
+
... C
2
× −
dcn
U U
dc , lim
C
dc
µ
F
2400
3600
4700
7050
8600
10800
12900
15100
)
2
dc