7.2.2 Torque stop ramp
When using the Torque stop ramp, the output voltage
to the motor is controlled so that the torque will follow
a predefined optimal curve from the Step down level to
end voltage during stop. This has the benefit that the
mechanical stopping behaviour of the equipment driven
by the motor, will be much softer than when using voltage
ramp. See Figure 81.
This can be especially useful in pump applications where
a sudden stop can cause water hammering and pressure
surges.
Torque stop ramp is configured with the following
parameters:
Parameter Description Setting range Default value
02.02 Stop mode Set to Torque ramp. No ramp,
Voltage stop
ramp, Torque
stop ramp
No ramp
02.05 Stop ramp end level Sets the level from where the stop ramp ends and
the power to the motor is cut(voltage level for Voltage
stop and torque level for Torque stop.
10 ... 99% 30%
02.06 Stop ramp time Sets the time it takes for the voltage to reach end
level.
1 ... 120 s 10 s
28.05 Step down level Sets the level from where the stop ramp initiates. 10 ... 100 % 80 %
28.07 Torque finish Sets the operational torque for Torque start ramp
settings in percentage of base torque.
30...500% 100%
28.08 Torque tune Sets the adjustment of resistive losses. 0...1000% 100%
28.09 Torque ctrl gain Sets the speed of the voltage regulator during torque
start and stop. It seldom needs to be changed, but if
a dip occur in the torque curve during stop, increasing
this value might solve it.
0.01 ... 10 0.04
28.10 Torque PI intergration time Sets the integration time of PI controller. 0.001 ... 10 s 0.002 s
28.11 Torque slip Sets the slip difference from nominal to pull-out
torque in percentage.
0.1 ... 100 % 1.0 %
28.12 Torque diff Sets the maximum desired difference between
reference and actual torque in percentage.
0.1 ... 100 % 2.0 %
28.13 Torque filter time Sets the Torque control filter time in seconds. 0.01 ... 10 s 0.02 s
Figure 81: Torque stop ramp
81
1SFC132081M0201
rpm
U
Stop Time
Stop Time
7
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