Start-up
26
Optimise the P-part of the speed controller: Set the integration time to
0 to change the PI (proportional integral) controller into a P controller:
28.03 INTEGRATION
TIME
Give a step change up, for example 10% (of the maximum speed of
the drive). When the speed is stabilised, give a step change down, for
example -10% (of the maximum speed of the drive).
Increase the proportional gain until the response is sufficient:
28.02 PROPORT GAIN
Reduce the integration time (TI) until an overshoot is observed in the
response.
Adjust the integration time so that there is no overshoot or only a slight
overshoot (depending on the drive application). The integral part is
used to correct the error between the reference and actual value
(which is caused by the proportional control) as quickly as possible.
If the drive is stable and allows a high proportional gain,
an overcompensated step response is obtained if the integration time
is set short.
28.03 INTEGRATION
TIME
Acceleration (deceleration) compensation can be used to improve the
speed control dynamic reference change (when the speed ramp times
> 0). In order to compensate inertia during acceleration, a derivative of
the speed reference is added to the output of the speed controller.
Set the derivation time for acceleration (deceleration) compensation.
The value should be proportional to the total inertia of the load and
motor, i.e. approximately 10…30% of the mechanical time constant
(t
mech
). See the mechanical time constant equation in section Speed
filtering on page 25.
26.08 ACC COMP
DERTIME
Gain too low Gain too high Gain optimal
1.01 SPEED
ACT
1.01 SPEED
ACT
TI too long TI too short TI optimal
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