Siemens SINAMICS S120 Function Manual page 142

Servo control
5.14 Encoderless operation
4. If the total moment of inertia has not already been determined using the rotating
measurement, you have the possibility of determining the total moment of inertia as follows:
– If an encoder is being used, and the motor has a restricted traversing path (e.g.
– If the motor can endlessly rotate (with and without encoder)
– You can also determine the moment of inertia using the "Moment of inertia estimator"
5. Set the speed controller:
– When the "Moment of inertia estimator" function module is active, accept the moment of
– Deactivate the "Moment of inertia estimator" function module (p1400.18 = 0).
– Start a trace recording of parameter r0063 (speed actual value) and r0079 (torque).
– Adjust the moment of inertia (p1498; if possible, increase), and in the controlled range,
– Optimize the settling behavior using the P gain (p1470) and the integral time (p1472).
– Exit the trace recording.
– Finally, again set the appropriate total moment of inertia - or activate the "Moment of
140
encoderless operation is only used when an encoder develops a fault or only for the
upper speed range):
Determine the moment of inertia using the rotating measurement of the motor data
identification (p1959 = 420 hex (i.e. only commutation angle and Lq characteristic),
p1960 = 1).
Determine the moment of inertia using the rotating measurement of the motor data
identification (p1959 = 404 hex (i.e. only commutation angle and moment of inertia),
p1960 = 1).
function module (see Chapter "Moment of inertia estimator (Page 540)"). As the moment
of inertia is also determined in operation using this function module, we recommend that
the "Moment of inertia estimator" function module is used if the total moment of inertia
changes during operation.
inertia that has been determined.
enter a speed setpoint (speed higher than p1755).
inertia estimator" function module
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
Drive functions