Speed Controller - Siemens SINAMICS S120 Function Manual

Operating Modes
Vector control
3.2.3

Speed controller

Both closed-loop control procedures with and without an encoder (VC, SLVC) have
the same speed controller structure, which contains the following components:
S PI controller
S Speed controller pre-control
S Droop function
The total of the output variables result in the torque setpoint, which is reduced to
the permissible magnitude by means of the torque setpoint limitation.
Speed controller
The speed controller receives its setpoint (r0062) from the setpoint channel and its
actual value (r0063) either directly from the speed sensor (control with sensor
(VC)) or indirectly via the motor model (control without sensor (SLVC)). The sys-
tem deviation is increased by the PI controller and, in conjunction with the pre-con-
trol, results in the torque setpoint.
When the load torque increases, the speed setpoint is reduced proportionately
when the droop function is active, which means that the single drive within a group
(two or more mechanically connected motors) is relieved when the torque be-
comes too great.
- -loop
Closed
speed control
r0062
r1084
--
Speed setpoint
r0063
Actual speed value
*) Only active if pre --control is active
Fig. 3-25 Speed controller
The optimum speed controller setting can be determined via the automatic speed
controller optimization function (p1900 = 1, rotating measurement) (see also Sub-
section 3.2.11).
3-112
Droop
injection
--
Pre
control
K
T
p
n
*)
PI speed
controller
--
T
i
SLVC
(p1496 > 0)
VC
r1508
r1482
r1538
r1547 [0]
r1547 [1]
r1539
T K
i p
: p1452 p1470
: p1442 p1460
© Siemens AG, 2005. All rights reserved
SINAMICS S120 Function Manual, 06/05 Edition
r0079
Torque
setpoint
T
n
p1472
p1462