590 Series DC Digital Drive Programming
D-33
CURRENT LOOP
Use this to setup the drive's conventional current/torque loop.
It takes the current demand, imposes limits through four clamps, and then uses a PI loop to control
the output.
The four separate clamps - current profile, inverse time overload, bipolar clamps and main current
clamp - the clamps are in series and lowest clamp takes effect. The resultant clamp value can be seen
in the diagnostics ACTUAL POS I LIM and ACTUAL NEG I LIM.
The internal inputs to this block are:
• the current demand from the speed loop or terminal A3 (selected via I DMD. ISOLATE)
• the current limit clamps from CURRENT PROFILE and INVERSE TIME (note that the bipolar
clamps and main current clamp are resident in the CURRENT LOOP block)
• current feedback from CALIBRATION.
The default configuration uses DIGIN 1 and DIGIN 3 for switching modes (BIPOLAR CLAMPS
and I DMD. ISOLATE respectively), ANIN 5 for setting the symmetrical positive and negative
current clamps.
CURRENT LOOP
Parameter Tag Range
CUR. LIMIT/SCALER 15 0.00 to 200.00 %
Current limit scaler. It scales bipolar/unipolar clamps. To achieve 200% current limit, the current limit scaler should be set to 200%.
MAIN CURR. LIMIT 421 0.00 to 200.00 %
Independent symmetric current clamp. Sets symmetric clamps outside scaling from the CUR. LIMIT/SCALER parameter.
PROP GAIN 16 0.00 to 200.00
Proportional gain control for armature current PI loop. This parameter is set during the autotune function.
INT. GAIN 17 0.00 to 200.00
Integral gain control for armature current PI loop, set during the autotune function.
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