Siemens Simovert Masterdrives Compendium page 429

09.2008
n
cmd
Path
Interpolation
x
–
cmd
x
act,NC
1
Master Controller (NC)
n : speed command
cmd
x : position command
cmd
x : position error command
err
x : actual position
act
Operation
Siemens AG 6SE7087-6QX70 (Version AK)
SIMOVERT MASTERDRIVES
With DSC the actual position calculated inside the drive is also fed back
directly:
Transmission
delay
T
pc
Zero Offset
and
Compensation
Fig. 8.2-33 Structure of the LR circuit based on the speed setpoint interface with DSC
For this to be possible, the control error calculated in the master is
transmitted as well as the speed setpoint. The additional feedback
network can use the internal formats in the drive for position presentation
and is thus independent of the position presentation in the master. The
above presentation assumes that the network is calculated in the speed
controller sampling time T
way the maximum possible dynamic improvement is achieved. However,
greater clock times T are also possible, if the calculation time is short
≤ T ≤ T
(T ).
SC PC
The structure contains a total of three feedback branches for the actual
position value (No. 1, 2 and 3). Feedback branch no. 2 compensates fully
for the action of no. 1 in respect of the actual value transmitted by the
drive x , so that the dead time in branch no. 1 no longer has to be
act
considered for the stability of the position control circuit. As a result, the
position control circuit is initially open. Feedback branch no. 3 closes the
circuit again, but with a shorter delay, so that greater gains can be set.
Compendium Motion Control
Interpolation Position
(T ) control
pc
B
K
pc
–
2
x
act,NC
T
pc
A
T : speed controller sampling time
sc
T : position controller sampling time (= T
pc
K : position controller gain
pc
which will be possible in many cases. In this
SC
Communication / PROFIBUS
n
cmd
Speed filter
n
Drive
3
x
act, Drive
T
sc
x
act
Drive Controller
)
MAPC
Speed control
–
Speed
calculation
4
8.2-99