Siemens SINAMICS G120 List Manual page 461

p3844[0...n] Friction characteristic number changeover point upper / FricNo chng_pt up
Access level: 4
Can be changed: U, T
Unit group: -
Min
0
Description: Selects the upper changeover point of the friction characteristic for the frictional torque input controlled by the motor
model of the induction motor.
The speed of this changeover point is pre-assigned when automatically calculating with the changeover speed
p1752. The changeover point located below is pre-assigned with the changeover speed p1752 * (1 - p1753).
Example: p3844 = 3 means that the speed value for the change to the monitor model (p3823 = p1752) is entered into
p3823 (friction characteristic value n3).
Depending on the display of r3840.9, the frictional torque is calculated from the friction characteristic values, which
are associated with these changeover points. For the changeover of the motor model, with hysteresis, the frictional
torque smoothed with p3843 changes between these two states.
Dependency: As part of the automatic calculation (p0340), p3844 is only activated for closed loop control (p1300 = 21, 23) of
induction motors with encoder.
Refer to: p3843
Notice: If the changeover point defined using p3844 does not match the changeover speed p1752, then internally, the model-
controlled friction torque input is automatically deactivated (same as for p3844 = 0).
Note: For p3844 = 0, the model-controlled frictional torque changeover is deactivated. The frictional torque is then
calculated the same as for the encoderless control by interpolating between the points along the friction
characteristic.
p3845 Friction characteristic record activation / Frict rec act
Access level: 2
Can be changed: T
Unit group: -
Min
0
Description: Setting for the friction characteristic record.
After the next switch-on command, the friction characteristic is automatically recorded.
Value: 0:
1:
2:
3:
Dependency: When selecting the friction characteristic measurement, the drive data set changeover is suppressed.
For linear drives (refer to r0108 bit 12) it is not permissible to carry out the friction characteristic measurement for
mechanical systems that limit travel.
Danger: For drives with a mechanical system that limit the distance moved, it must be ensured that during recording, the
friction characteristic is not reached. If this is not the case, then it is not permissible that the measurement is carried
out.
Notice: To permanently accept the determined settings they must be saved in a non-volatile fashion (p0971, p0977).
Note: When the friction characteristic record is active, it is not possible to save the parameters (p0971, p0977).
When the friction characteristic record is active (p3845 > 0), it is not possible to change p3820 ... p3829, p3830 ...
p3839 and p3842.
When recording the friction characteristic, in addition to the friction, the motor losses are also determined (e.g. iron
losses, eddy current losses and re-magnetizing losses). A differentiation is not made between these individual loss
components. We recommend that a motor temperature sensor is used because torque deviations can also be
emulated/mapped on the characteristic due to the thermal influence.
SINAMICS G120 CU250S-2 Control Units
List Manual, 09/2017, A5E33842890
Friction characteristic record deactivated
Friction char record activated for all directions
Friction char record activated for positive direction
Friction char record activated for negative direction
Calculated: -
Scaling: -
Unit selection: -
Max
4
Calculated: -
Scaling: -
Unit selection: -
Max
3
2 Parameters
2.2 List of parameters
Data type: Unsigned8
Dyn. index: DDS, p0180
Func. diagram: -
Factory setting
0
Data type: Integer16
Dyn. index: -
Func. diagram: 7010
Factory setting
0
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