Dsc (Dynamic Servo Control) - Siemens SINUMERIK 840DiE sl Manual

01/2007
11.5.8

DSC (Dynamic Servo Control)

Requirements
Switch ON/OFF
© Siemens AG 2007 All Rights Reserved
SINUMERIK 840Di sl Manual (HBIsl) – 01/2007 Edition
The DSC function eliminates the deadtime that necessarily exists at the speed–
setpoint interface normally used between the NCK and drive due to relocation of
the position controller into the drive.
That results in the following advantages for an axis operated with DSC:
S
Considerably improved fault response/stability of the position control loop
S
Improved control behavior (contour precision) if the higher servo gain (KV
factor) that can be set in conjunction with DSC is used.
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A reduction of the cyclic communication load on the PROFIBUS, if the posi-
tion control cycle/PROFIBUS cycle is reduced by adjusting the above pa-
rameters, even if the control loop performance is the same.
Note
The speed feedforward control can be used in conjunction with DSC.
Before you can activate DSC mode, the following preconditions must be fulfilled:
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DSC–capable drive, e.g.:
– SINAMICS S120
– SIMODRIVE 611 universal
– SIMODRIVE POSMO CD/CA
– SIMODRIVE POSMO SI distributed servo drive
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A DSC–capable message frame type has been parameterized in the S7
project for the drive (see Section 8.9, Page 8-223).
The DSC function is switched ON via the following axis–specific NCK machine
data:
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MD32640: STIFFNESS_CONTROL_ENABLE (dyn. stiffness control)
If DSC operation is switched ON or OFF, it might be necessary to adjust the
following machine data:
S
MD32200: POSCTRL_GAIN (KV factor)
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MD32610: VELO_FFW_WEIGHT (feedforward control factor)
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MD32810: EQUIV_SPEEDCTRL_TIME (substitute time const. of the closed
speed control loop).
Notice
Before you can switch off DSC operation you might have to adapt (reduce) the
KV factor of the axis. Otherwise, instability of the position control loop might
result.
11 NCK Commissioning with HMI Advanced
11.5 Axes and spindles
11-329