Optimizing The Current And Speed Controller - Siemens SINAMICS S120 Function Manual

3.1.12

Optimizing the current and speed controller

General information
Caution
!
Controller optimization may only be performed by skilled personnel with a
knowledge of control engineering.
The following tools are available for optimizing the controllers:
S "Function generator" in STARTER
S "Trace" in STARTER
S "Measuring function" in STARTER
S CU320 measuring sockets
Optimizing the current controller
The current controller is initialized when the system is commissioned for the first
time and is adequately optimized for most applications.
Optimizing the speed controller
The speed controller is set in accordance with the motor moment of inertia when
the motor is configured for the first time. The calculated proportional gain is set to
approximately 30 % of the maximum possible gain in order to minimize vibrations
when the controller is mounted on the mechanics of the machine for the first time.
The integral time of the speed controller is always preset to 10 ms.
S The following optimization measures are necessary in order to achieve the full
dynamic response:
– Increase the proportional gain Kp_n (p1460)
– Change the integral action time Tn_n (p1462)
Example of measuring the speed controller frequency response
By measuring the speed controller frequency response and the control system,
critical resonance frequencies can, if necessary, be determined at the stability limit
of the speed control loop and dampened using one or more current setpoint filters.
This normally enables the proportional gain to be increased (e.g. Kp_n = 3* default
value).
After the Kp_n value has been set, the ideal integral action time Tn_n (e.g. re-
duced from 10 ms to 5 ms) can be determined.
© Siemens AG 2006 All Rights Reserved
SINAMICS S120 Function Manual, 03/2006 Edition
Operating Modes
Servo control
3-107