Siemens SINAMICS S120 Function Manual page 177

If the moment of inertia has been specified, the speed controller (Kp, Tn) can be calculated
by means of automatic parameterization (p0340 = 4). The controller parameters are defined
in accordance with the symmetrical optimum as follows:
Tn = 4 * Ts
Kp = 0.5 * r0345 / Ts = 2 * r0345 / Tn
Ts = total of the short delay times (contains p1442 and p1452)
If vibrations occur with these settings, the speed controller gain Kp must be reduced
manually. Actual-speed-value smoothing can also be increased (standard procedure for
gearless or high-frequency torsion vibrations) and the controller calculation performed again
because this value is also used to calculate Kp and Tn.
The following relationships apply for optimization:
● If Kp is increased, the controller becomes faster, although overshoot is reduced.
● If Tn is reduced, the controller also becomes faster. However, this increases the
When speed control is set manually, it is easiest to define the possible dynamic response via
Kp (and actual speed value smoothing) first before reducing the integral time as much as
possible. Please note that the closed-loop control must also remain stable in the field-
weakening range.
To suppress any vibrations that occur in the speed controller, it is usually only necessary to
increase the smoothing time in p1452 for operation with an encoder or p1442 for operation
without an encoder or reduce the controller gain.
The integral output of the speed controller can be monitored via r1482 and the limited
controller output via r1508 (torque setpoint).
Note
In comparison with speed control with an encoder, the dynamic response of drives without
an encoder is significantly reduced. The actual speed is derived by means of a model
calculation from the converter output variables for current and voltage that have a
corresponding interference level. To this end, the actual speed must be adjusted by means
of filter algorithms in the software.
Drive functions
Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
However, signal ripples and oscillations in the speed control loop will increase.
overshoot.
Vector control
4.3 Speed controller
175