Installation manual

76
Epsilon EP-B Base Drive Reference Manual
Figure 57: PEI = off
Figure 58: PEI = on
Feedforwards gain 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 can actually be degraded or stability will suffer. Enabling Feedforwards 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.
Where:
IR = Inertia Ratio
RLI = Reflected Load Inertia (lb-in-sec
2
)
MI = Motor Inertia (lb-in- sec
2
)
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.
MI
RLI
R I =