Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 222)

222 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 4 Motor Control
Configuration
Inertia adaption only works if there is valid inertia value entered in P76 [Total
Inertia]. Total inertia is measured during an assisted startup procedure executed
from the HIM or software wizard. The inertia tune can be executed manually by
setting P70 [Autotune] to option 4 “Inertia Tune” and starting the drive.
Activate inertia adaption by setting P704 [InAdp LdObs Mode] to option 1
“InertiaAdapt.” Once activated, two filters are automatically updated, P705
[Inertia Adapt BW] and P710 [InertAdptFltrBW], when P636 [Speed Reg BW]
is set to a non zero value. Gradually increase P636 [Speed Reg BW] while
operating the motor and load. The final speed reg bandwidth exceeds the value
before inertia adaption was activated providing the system meets the criteria
mentioned below.
When Inertia adaption is activated, disable the two lead-lag filters present in the
speed regulator (setting OFF). These filters are in the speed feedback path P637
[SReg FB Fltr Sel] and at the output of the speed regulator P657 [SReg OutFltr
Sel]. Both filters are disabled by default.
The Inertia Adaption feature can be used in conjunction with inertia
compensation to minimize the acceleration torque required from the Speed
Regulator.
Refer to the PowerFlex 750-Series Programming Manual, publication 750-
PM001 , for detailed parameter explanation.
How does inertia adaption work?
• The inertia adaption algorithm uses a component of acceleration feedback
to create a sort of electronic inertia.
• Electronic inertia supplements the inertia lost when the load is suddenly
disconnected as through a gearbox or lost motion. In this way the velocity
regulator does not see a dramatic change in inertia that is normally
associated with load disconnect and potential instability.
0
1
0
685 +
+
+
+
+
–
662
II
R
657
1
0
0
679
76
705
677
From
Speed Reg
Output
Selected
Trq Ref
Notch
Filtered Trq
Ref
Inertia
Adaption
Total Inertia
Motor Acceleration Feedback
Disabled
Limited Torq Ref
Limit
Inertia Torque Add
Inertia Adapt
Inertia Adapt BW
InertiaAdaptGain
Zero
Trq Ref