23
The available energy capacity depends now on the criteria for the
U
dc,lim
and
the actual DC link voltage supplied into common DC system. Selection of the
value for
U
dc,lim
depends on common DC system configuration and its
general requirements.
Here are the major alternatives for the
U
dc,lim
based on the ACSM1 drive
module DC voltage limits (see also the paragraph
ACSM1 DC voltage
limits
).
•
Absolute maximum limit is defined according to the DC overvoltage trip
limit including some safety margin.
840
≤
,lim
dc
U
V DC
•
DC over voltage control is enabled, but not activated.
810
≤
lim
,
dc
U
V DC
•
DC link voltage level, where the braking choppers are not yet
activated.
780
≤
,lim
dc
U
V DC
To determine whether the energy capacity is adequate (i.e. the selected
U
dc,lim
voltage level is not reached) the following condition must be fulfilled
•
W
dc
>
E
gen
Where
E
gen
is the regenerative energy to the DC link during the generating
period:
•
dt
P
E
gen
gen
=
