Lenze 931E/K Small Drives Control - Manual (Page 34)

Commissioning
Speed control
Optimising the speed controller
5
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34 SW−HB 13.0002−EN 4.1
5.2.7 Optimising the speed controller
To optimise the speed controller for your application, select Parameters
W Controller
parameters
W Speed controller to open the menu for selecting the controller parameters:
931e_222
In this menu, you can set the Gain and the Time constant for the PI controller.
The actual speed will be smoothed by means of an Actual speed filter to improve the
control behaviour. The effective filter time constant can be parameterised:
)
Note!
If the time constant of the actual speed filter is too high, the dynamic
performance of the controller will be reduced because interferences can only
be detected with a delay. In certain cases, the stability of the speed control
circuit may be reduced, if the selected time constant is too high. The additional
propagation time may lead to vibrations.
If the time constant is too low, high gain factors will lead to current noises in
the speed controller and slight disturbances at the shaft. This will lead to an
increased temperature rise in the motor.
For stability reasons, select the time constant as low as possible. The minimum
value will be determined by the measuring noise. Typical values for the actual
speed filter are 0.6 msec to 2.0 msec.
The speed controller setting must ensure that the actual speed will only overshoot once.
The overshoot should be approx 15% above the setpoint speed. The falling edge of the
overshoot should, however, not or only slightly fall below the speed setpoint to reach the
speed setpoint. This setting applies to most motors that can be operated with the servo
positioning controller. If a stricter control behaviour is necessary, the speed controller gain
can be increased further. The gain limit will be determined by the vibrations occurring with
high speeds or disturbances at the shaft.
The maximum possible gain of the speed control circuit depends on the load conditions at
the motor shaft. This is why the speed controller setting must be checked once again when
the drive has been installed.
)
Note!
If the speed controller is parameterised with a free−running motor shaft, the
speed controller must be adapted to your application when the drive has been
installed.