Optimizing The Closed-Loop Speed Controller - Siemens SINAMICS G115D Operating Instructions Manual

6.17.2.2

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:
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.
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 (p1120 and p1121).
SINAMICS G115D distributed drive
Operating Instructions, 09/2020, FW V4.7 SP13, A5E48681219B
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.
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 final value, it passes
the actual value. Finally, the actual value approaches the set-
point without any significant overshoot.
Advanced commissioning
6.17 Motor control
235