Baldor NXE100-1608Dx, Installation Manual

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5-26 Operation MN1941
The remaining gain terms are Velocity Feed forward ( KVELFF ) and Acceleration Feed
forward ( KACCEL ) described below.
In summary, the following rules can be used as a guide:
H
KPROP: Increasing KPROP will speed up the response and reduce the effect of
disturbances and load variations. The side effect of increasing KPROP is that it also
increases the overshoot, and if set too high it will cause the system to become unstable. The
aim is to set the Proportional gain as high as possible without getting overshoot, instability or
hunting on an encoder edge when stationary (the motor will buzz).
H
KVEL: This gain has a damping effect on the whole response, and can be increased to
reduce any overshoot. If KVEL becomes too large it will amplify any noise on the velocity
measurement and introduce oscillations.
H
KINT: This gain has a de-stabilizing effect, but a small amount can be used to reduce any
steady state errors. By default, KINTMODE is always on (mode 1).
H
KINTLIMIT: The integration limit determines the maximum value of the effect of integral
action. This is specified as a percentage of the full scale demand.
H
KDERIV: This gain has a damping effect dependent on the rate of change of error, and so is
particularly useful for removing overshoot.
H
KVELFF: This is a feed forward term and as such has a different effect on the servo system
than the previous gains. KVELFF is outside the closed loop and therefore does not have an
effect on system stability. This gain allows a faster response to demand speed changes with
lower following errors, for example you would increase KVELFF to reduce the following error
during the slew section of a trapezoidal move. The trapezoidal test move can be used to
fine-tune this gain. This term is especially useful with velocity controlled servos
H
KACCEL: This term is designed to reduce velocity overshoots on high acceleration moves.