GE AF-300 P11, User Manual

Page: 93 / 154

5-40
H 2 3 I – G A I N
Setting range: 0.0 (Inactive), 0.1 to 3600 seconds
H23 I-gain is used as a parameter to determine the
effect of I operation. A longer integration time delays
response and weakens resistance to external elements.
A shorter integration time speeds up response, but an
integration time that is too short causes vibration.
D-gain operation
An operation where the output frequency is proportional
to the deviation differential is called a D operation. It
outputs an operation amount as the deviation differential
and, therefore, is capable of responding to sudden
changes.
H 2 4 D – G A I N
Setting range: 0.00 (Inactive), 0.01 to 10.0 seconds
H24 D-gain is used as a parameter to determine the
effect of a D operation. A longer differentiation time
causes vibration by P operation quickly attenuating at
the occurrence of deviation. Excessive differentiation
time could cause vibration. Shortening the differentia-
tion time reduces attenuation at the occurrence of
deviation.
PI control
P operation alone does not remove deviation completely.
P + I control (where I operation is added to P operation)
is normally used to remove the remaining deviation. PI
control always operates to eliminate deviation, even
when the target value is changed or there is a constant
disturbance. When I operation is strengthened, however,
the response for rapidly changing deviation deteriorates.
P operation can also be used individually for loads
containing an integral element.
PD control
If deviation occurs under PD control, an output fre-
quency larger than that of D operation alone occurs
rapidly and prevents the deviation from expanding. For
a small deviation, P operation is restricted. When the
load contains an integral element, P operation alone may
allow responses to vibrate due to the effect of the
integral element, in which case PD control is used to
attenuate the vibration of P operation and stabilize
responses. In other words, this control is applied to
loads in processes without a braking function.
PID control
PID control combines the P operation, the I operation
which removes deviation, and the D operation which
suppresses vibration. This control achieves deviation-
free, accurate, and stable responses.
Adjusting PID value
Adjust the PID value while monitoring the response
waveform on an oscilloscope or other instrument, if
possible. Proceed as follows:
Increase the value of H22 P-gain without generating
vibration.
Decrease the value of H23 I-gain without generating
vibration.
Increase the value of H24 D-gain without generating
vibration.
Adjust the response waveform as follows:
To remove the overshoot, increase the value of H23 I-gain,
then decrease the value of H24 D-gain.
To stabilize response quickly, allowing for min. overshoot,
decrease the value of H23
I -gain or increase the value of
H24 D-gain.
To suppress vibration with a period longer than the value
of H23 I-gain, increase the value of H23.
To suppress vibration with a frequency roughly equivalent
to the value H24 D-gain, decrease the value of H24. If
there is residual vibration with 0.0, decrease the value of
H22 P-gain.