Lenze 931W - Manual (Page 40)

Software implementation and parameter setting
Controller menu
Proportional gain
5
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40 HB 13.0001-EN 3.0
5.5.1 Proportional gain
By means of the proportional gain of the PID controller, the damping behaviour of the
speed controller can be influenced. The higher the P component is chosen, the quicker the
controller responds to deviations between the speed setpoint and the actual speed value.
By this, a low overshoot for speed variatons is effected.
If the P component is chosen too high, the drive responds very aggressively to setpoint
changes. Furthermore, the measurement noise which is superimposed on the actual speed
value is too strongly intensified, resulting in a continuously unsteady behaviour of the
drive (”drive hums”). In this case, the gain is to be reduced.
The dimensioning has to be carried out depending on the entire mechanical drive train.
Here, no general values can be specified. The value range of the P component is 0.01 to 100
and can be adjusted in steps of 0.01.
5.5.2 TN - integral-action time
The integral-action time defines the integral part of the PID speed controller. By means of
this time constant, a degree for the dynamics of control processes is defined. The lower the
time constant is selected, the quicker deviations between the speed setpoint and actual
speed value can be compensated. In this regard, it is to be observed that due to the
limitation of the actuating element - i. e. the maximum torque - the integral-action time
cannot be selected in an optionally low manner, but is to be selected depending on the
mass inertias to be accelerated and onthe maximum torque. Integral-actiontimes that are
too low cause excessive dynamics and may result in an instable control system behaviour.
Time constants that are too high cause changes to be compensated only after a longer
time.
The integer value range for entering the integral-action time reaches from 2000 to 65535.
Values are entered in μs. Reasonable values for the integral-action time considerably
depend on the control process, in particular on the mass inertia to be accelerated and on
the torque provided for this. A reasonable dimensioning of the integral-action time for
many applications is between 4000 and 20000 μs.
5.5.3 TV - advance time
The differential component of the PID speed controller is set via the advance time. This
component causes an additional drive torque to be applied in case of changes in the speed
setpoint, in order to realise a quick adjustment of setpoint and actual value. The lower the
time constant is selected, the higher is the additionally applied torque.
For the advance time, integer values from 0 to 30000 can be entered. The values are
entered in μs.