ABB ACSM1 - Page 23

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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≤
,limdc
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≤
,limdc
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:
• dtPE
gengen

=