Siemens Simovert Masterdrives Compendium page 274

09.2008
7.3.7 "Speed controller characteristic" function (function diagram 360)
NOTES
Siemens AG 6SE7087-6QX70 (Version AK)
SIMOVERT MASTERDRIVES
You can select the speed controller characteristic via parameter P238.
P238 = 0: PI controller (default)
The speed controller is optimized in accordance with the known rules,
e.g. Symmetrical Optimum.
While the controller is being optimized, e.g. according to the
Symmetrical Optimum for a good fault response, overshoots occur in
the response to setpoint changes. This should be reduced by
appropriate setpoint smoothing (e.g. P221) or using the reference
model (P238 = 1).
P238 = 1: PIR controller (reference model for the I-action component)
The response to setpoints by the speed controller can be improved
(overshoot reduction) by means of the PIR controller characteristic
(reference model). This is conditional on the controller being set
according to PI controller conditions (see above P238 = 0). For a PIR
controller (P238 = 1), the time constant of the reference model (P239)
for the PIR controller must also be adjusted such that, for example, the
smallest possible overshoot occurs in response to a setpoint step
change.
Plant conditions permitting, you can do this in the following way: Set TN
(P240) to a value of 0 (make note of original value!) and trace K0155 as
the setpoint is changed, the time constant (P239) must be adjusted
such that the areas above and below the zero line of K0155 are
approximately equal in size. Then reset TN (P240) to its original value.
References relevant to reference model:
"Electrical Feed Drives in Automation"
SIEMENS AG; H.Groß, J.Hamann, G.Wiegärtner
(ISBN: 3-89578-058-8)
♦ When you use the reference model (P238 = 1), the source selected
in P228 (Src n (deviation) is inoperative; KK0152 is linked
permanently to the speed controller internally (as per default setting
for P228).
♦ When you use the reference model (P238 = 1), the sampling time /
sampling sequence of the speed controller itself is determined via
U953.45 / U963.45 (not just the speed controller total as per P238 =
0); i.e. the sampling time / sampling sequence set via n959.52 /
n969.52 is inoperative in this case.
♦ When you use the reference model (P238 = 1) we recommend
changing the factory settings of parameters P790 and P802 in
function diagram 480 from KK0150 to KK0161 for V2.5 and above.
Compendium Motion Control
Functions
7-65