Bosch Rexroth IndraDrive MPH-02 Functional Description page 266

6-54
Drive Control
filters
P-0-0048
-
P-0-1125 P-0-1125
v
act
P-0-0004 P-0-0004
The illustration below shows the position of the filters in the overall control
loop:
feedforward
P-0-1120 P-0-1120
P-0-1121 P-0-1121
P-0-1122 P-0-1122
P-0-1123 P-0-1123
P-0-0004: velocity loop smoothing time constant
P-0-0048: effective velocity command value
P-0-1120: velocity control loop filter: filter type
P-0-1121: velocity control loop filter: limit frequency of low pass
P-0-1122: velocity control loop filter: bandwidth of band-stop filter
P-0-1123: vel. cont. loop filter: center frequency of band-stop filter
P-0-1125: velocity control loop: average value filter clock
Fig. 6-37: Possibilities of filtering in the velocity control loop
In practical application there often occur resonant oscillations that mostly
result from deficiencies or restrictions of the mechanical system:
• limited stiffness of connection between mechanical system and motor
shaft
→ possible resonances within the range of 20 Hz ... 1000 Hz
(according to stiffness of connection and mass relations)
• gear play
• bad arrangement of the load-side encoder
→ possible resonances within the range of 1 kHz ... 2 kHz (according
to arrangement of encoder)
This "two-mass oscillation" (or multiple-mass oscillation) mostly has one
(or several) distinctive resonance frequency/frequencies that can be
selectively suppressed by the rejection filters integrated in the drive. With
the implemented filter cascade (N = 8) it is possible to selectively
suppress up to 4 different resonance frequencies.
Note: The implemented
resonance frequencies within the frequency range of 100 Hz
to a max. of 4000 Hz.
The upper limit depends on the velocity loop cycle time TA
(sampling theorem).
When suppressing the mechanical resonance frequencies it is possible to
considerably increase the dynamic response of the speed control loop
and of the position control loop, compared to closed-loop control without
using rejection filters. This results in a higher degree of contour precision
and shorter cycle times for positioning processes with sufficient distance
to the stability limit.
MPH-02, MPB-02, MPD-02
velocity
loop
torque/force
and current
limitation
band-stop filters
DOK-INDRV*-MP*-02VRS**-FK01-EN-P
motor
control
DF000066v01_en.fh7
allow suppressing
n