Toshiba TOSVERT VF-P7 Instruction Manual page 54

(2) Integral gain
Integral (I) gain () is integral gain for PID control.
This gain acts to make the deviation which remains in proportional operation (remained
deviation offset) to zero. Setting this parameter at a large value gives smaller remained deviation
offset, but setting at a too large value may result in an unstable phenomenon like hunting.
Feedback amount
(3) Differential gain
Differential (D) gain () is differential gain for PID control.
This gain acts to improve the response to sudden change of the deviation. Setting this
parameter at a too large value may result in an unstable phenomenon in which output frequency
is greatly unsteady.
The last deviation
ｰ This Time Deviation
Feedback amount
(4) Delay filter
Delay filter () acts to soften a rapid change of the deviation (linear delay function).
Usually, it is not necessary to change the setting. A small setting value makes processing fast, a
large setting value makes it slow.
(5) PID deviation upper limit
PID deviation upper limit () is upper limit over positive deviation.
It limits the instantaneous value of deviation. Usually, it is not necessary to change the setting.
(6) PID deviation lower limit
PID deviation lower limit () is upper limit over negative deviation.
It limits the instantaneous value of deviation. Usually, it is not necessary to change the setting.
 is small.
 is
large.
Remained deviation offset
Time
Time
 is large.
 is small.
Time
C-12
Reference of process
amount