Selection Of Opti-Torque; Field Current Reduction Using Torque Reference - ABB DCS 500B Description

Selection of
OPTI-TORQUE
Field current re-
duction using
torque reference
DCS 500 Software Description
Normal Field Reversal
Field Reversal
with OPTITORQUE-
function
Figure 42 Optitorque function compared with normal field
reversal
If the type of the process is such that before the field reversal only a
small torque is needed, e.g. changing of the speed direction, it is
possible to reduce the field current before the field reversal is acti-
vated.
This technique enables for a faster field reversal. The permissible
reduction in the field current can be defined by the required torque
reference. For example, if the speed direction is changed rather
slowly, the required torque can also be quite small, close to zero
speed, and so the motor field can also be reduced.
The OPTI-TORQUE can be selected by the parameter:
FIELD MODE (1001)
4 [NO EMF, OPTITORQUE] Field rev. + OPTITORQUE
5 [EMF + OPTITORQUE]
The relationship between torque reference and field current refer-
ence is defined by parameter OPTI.REF GAIN (1315) (range
0...10000).
F1 CURR REF (11301) = 
Functional Software description
Field rev. + OPTITORQUE +
EMF-control
OPTI.REF GAIN * Torque reference
98
Speed
Current
Field
Current
Speed
Current
Field
Current
57