Tuning Parameters - Emerson Control Techniques Epsilon Eb Series Reference Manual

Epsilon Eb and EN Drives Reference Manual
4. Enable the drive and run the system.
5. Adjust Response to obtain the best performance.
General Tuning Hints
The Response is normally the final adjustment when tuning. For best performance the
Response should be lower with a higher inertia mismatch (>10:1) and higher with a lower
inertia mismatch.
If your system has some torsional compliance, such as with a jaw type coupling with a rubber
spider, or if there is a long drive shaft, the Response should be decreased. The highest
recommended Response with High Performance Gains enabled is 100 Hz.
Feedforwards can be enabled if the performance requirements are very demanding. However
when using them, make sure the Inertia Ratio and Friction values are an accurate
representation of the load. Otherwise, the system performance will actually be degraded or
stability will suffer. Enabling the Feedforward makes the system less tolerant of inertia or
friction variations during operation.

Tuning Parameters

Inertia Ratio
Inertia Ratio specifies the load to motor inertia ratio and has a range of 0.0 to 50.0. A value
of 1.0 specifies that load inertia equals the motor inertia (1:1 load to motor inertia). The drives
can control up to a 10:1 inertia mismatch with the default Inertia Ratio value of 0.0. Inertial
mismatches of over 50:1 are possible if response is reduced.
The Inertia Ratio value is used to set the internal gains in the velocity and position loops,
including feedforward compensation if enabled.
To calculate the Inertia Ratio value, divide the load inertia reflected to the motor by the motor
inertia of the motor. Include the motor brake as a load where applicable. The resulting value
should be entered as the Inertia Ratio parameter.
RLI
=
I R
MRI
Where:
IR = Inertia Ratio
RLI = Reflected Load Inertia (lb-in-sec
MI = Motor Inertia (lb-in- sec
If the exact inertia is unknown, a conservative approximate value should be used. If you enter
an inertia value higher than the actual inertia, the resultant motor response will tend to be
more oscillatory.
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