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25
Speed filtering
The measured speed always has a small ripple because of electrical and mechanical interferences,
couplings and encoder resolution (i.e. small pulse number). A small ripple is acceptable as long as
it does not affect the speed control chain. The interferences in the speed measurement can be
filtered with a speed error filter or with an actual speed filter.
Reducing the ripple with filters may cause speed controller tuning problems. A long filter time
constant and fast acceleration time contradict one another. A very long filter time results in unstable
control.
If the used speed reference changes rapidly (servo application), use
the speed error filter to filter the possible interferences in the speed
measurement. In this case the speed error filter is more suitable than
the actual speed filter:
- Set the filter time constant.
If the used speed reference remains constant, use the actual speed
filter to filter the possible interferences in the speed measurement. In
this case the actual speed filter is more suitable than the speed error
filter:
- Set the filter time constant.
If there are substantial interferences in the speed measurement, the
filter time constant should be proportional to the total inertia of the load
and motor, i.e. approximately 10…30% of the mechanical time
constant
t
mech
= (
n
nom
/
T
nom
) ×
J
tot
× 2
π
/ 60, where
J
tot
= total inertia of the load and motor (the gear ratio between the
load and the motor must be taken into account)
n
nom
= motor nominal speed
T
nom
= motor nominal torque
Manual speed controller tuning
Select the following signals to be monitored with the DriveStudio Data
Logger or Monitoring Window:
-
, filtered actual speed
-
, motor torque.
Start the motor with a small speed reference.
Give a speed reference step and monitor the response. Repeat the test for few speed reference
steps across the whole speed range:
Set the speed ramp time to a suitable value (according to the used
application).
Set a suitable speed step (according to the used application): 10% or
20% of the maximum speed of the drive. Accept the new value by
pressing the Set new reference button.
Summary of Contents for ACSM1 Series
Page 1: ...ACSM1 Firmware Manual ACSM1 Speed and Torque Control Program...
Page 2: ......
Page 4: ......
Page 12: ...Table of contents 12...
Page 49: ...Drive control and features 49...
Page 282: ...Standard function blocks 282...
Page 306: ...Application program template 306...
Page 312: ...Control chain block diagrams 312...
Page 331: ...331...
Page 332: ...332...
Page 333: ......