Torque Step; Output Limitation And Its Indication; Current_Control Function Block; Torque / Current Reference Selection - ABB DCS 500B Description

Torque Step

Output Limitation
and its Indication
CURRENT_CONTROL
function block
Torque / Current
Reference Selec-
tion
Current Re-
sponse Test
Regulation
Blocking
Armature Current
Scaling
Current Refer-
ence Rise Time
Current Refer-
ence Limitation
Current Differ-
ence Alarm
DCS 500 Software Description
[TORQ STEP] (2409) input is available for testing the current
regulation or for direct control of the current regulator.
Output signal OUT (12402) can be limited by internal signals
[TORQ MAX2] and [TORQ MIN2] in the function block TORQUE /
CURRENT LIMITATION.
Output IN LIM (12404) is in logical state 0, when the input of the
limitation block is within the TORQMAX2 and TORQMIN2.
The current reference is formed by dividing [TORQ REF] (401) by
the FLUX REF1 signal according to formula
Current = Torque / Flux
The current reference can be connected to input [CURR REF]
(402). Selection between these two references is made with pa-
rameter REF TYPE SEL (405), logical state 1 selects the current
reference.
A current regulation response test can be done by connecting the
step reference to input [CURR STEP] (403).
The current regulation can be blocked by setting input [BLOCK]
(404) to logical state 1.
The torque reference from the torque reference selector is con-
nected to the current reference by means of the flux reference so
that with nominal flux and nominal torque the current reference will
be equal to nominal current of the motor. The scale of the current
reference is 4095 == nominal current of motor I MOTN A (502).
The rise time of the current reference can be adjusted by parame-
ter ARM CURR REF SLOPE (406), scaling 1 = 1ms. This is used,
for example, if a too fast rise time causes problems in the motor
commutator.
After the slope the armature current reference goes through the
current limiter. Positive/negative limits of the current reference are
based on parameter ARM CURR LIM P (2307) and ARM CURR
LIM N (2308) or on a speed-dependent current limitation.
The difference between the ARM CURR REF and the ARM CURR
ACT (10502) goes directly to the current regulator. If the difference
between these values is larger than 20% (from nominal 4095) and
this situation remains at last 5 seconds, then the ARM. CURR.
DEV. ALARM will be given.
Functional Software description
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