Optimizing The Speed Controller - Siemens SINAMICS G120 Operating Instructions Manual

Advanced commissioning
6.24 Motor control
6.24.3.2

Optimizing the 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 inverter 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 inverter 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).
● STARTER and Startdrive have trace functions that allow the speed setpoint and actual
value to be recorded.
308
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.
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34257946B AE
Converter with the CU230P-2 Control Units