7.20.3.2 Optimizing the closed-loop speed controller
Optimum control response - post optimization not required
Preconditions for assessing the controller response:
• The moment of inertia of the load is constant and does not depend on the speed.
• The converter does not reach the set torque limits during acceleration.
• You operate the motor in the range 40%…60% of its rated speed.
If the motor exhibits the following response, the speed control is well set and you do not
have to adapt the speed controller manually:
The speed setpoint (broken line) increases with the set ramp-up
time and rounding.
The speed actual value follows the setpoint without any over‐
shoot.
Control optimization required
In some cases, the self optimization result is not satisfactory, or self optimization is not possible
as the motor cannot freely rotate.
Initially, the speed actual value follows the speed setpoint with
some delay, and then overshoots the speed setpoint.
First, the actual speed value increases faster than the speed
setpoint. Before the setpoint reaches its nal value, it passes the
actual value. Finally, the actual value approaches the setpoint
without any signicant overshoot.
In the two cases describe above, we recommend that you manually optimize the speed
control.
Optimizing the speed controller
Requirements
• Torque precontrol is active: p1496 = 100%.
• The load moment of inertia is constant and independent of the speed.
• The converter requires 10%… 50% of the rated torque to accelerate.
When necessary, adapt the ramp-up and ramp-down times of the ramp-function generator
(p1120and p1121).
Advanced commissioning
7.20Motor control
SINAMICS G115D Wall Mounted distributed drive
Operating Instructions, 07/2023, FW V4.7 SP14, A5E52808211A AA 291
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