Computer Drive Installation Instructions

08.96 12 Functional Descriptions
12.33.4 Speed-dependent current setpoint filter
12.33.4 Speed-dependent current setpoint filter
A speed-dependent current setpoint filter (torque setpoint smoothing) allows the user to reduce
the speed ripple at higher speeds (MSD + FDD).
12.33.4.1 Machine data
MD 1245: Threshold speed-dependent torque setpoint smoothing
MD 1246: Hysteresis speed-dependent torque setpoint smoothing
12.33.4.2 Description
If the threshold value is set to 0, then the filter remains active as a low-pass over the entire
speed range. When other values are set, the settings in
MD 1245: Threshold speed-dependent torque setpoint smoothing and
MD 1246: Hysteresis speed-dependent torque setpoint smoothing
are used to calculate two switchover speeds:
n
upper
=n
threshold
+ n
hysteresis
= MD 1245 + MD 1246
n
lower
=n
threshold
– n
hysteresis
= MD 1245 – MD 1246
The low-pass function is activated then the absolute actual speed value exceeds the value
n
upper
(In
act
I n
upper
). Vice versa, the low-pass function is deactivated when the absolute
actual speed value drops below n
lower
(In
act
I < n
lower
).
If the hysteresis is set to zero, then the two switchover speeds are identical.
Note
The speed threshold is effective only when filter 2 is configured as a low pass. This machine
data has no effect on the closed-loop control.
Filter type
(2nd current setpoint filter)
n
upper
n
threshold
n
lower
Speed n
MD 1246
MD 1245
MD 1246
BypassLow passBypass
Fig. 12-8 Threshold of speed-dependent torque setpoint smoothing
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 12–347
SINUMERIK 840C (IA)