6-12
6-3-2 PID Control Operation
• To simply explain the operation of proportional control, integral control, and derivative control, the fol-
lowing graph is used to show that the output frequency changes while the deviation (i.e., the difference
between the target value and feedback value) is constant.
Deviation
Control
value
Time
PID control
Integral
(I) control
Derivative
(D) control
Proportional (P)
control
Time
• Proportional (P) Control: The output is in proportion to the deviation. The deviation cannot be set to 0
with proportional control only.
• Integral (I) Control: The output is the integral value of the deviation. This control method makes the
feedback value coincide with the target value effectively but cannot catch up with a rapid change in
deviation.
• Derivative (D) Control: The output is the derivative value of the deviation. This control method quickly
responds to a rapid change in deviation.
• PID Control: By combining the merits of the above control functions, ideal control is possible.
6-3-3 Types of PID Control
• Two types of PID control are available to the 3G3MV Inverter. Normally, measured-value derivative
PID control is used.
• Measured-value Derivative PID Control
In this control, the feedback derivative value is used. The Inverter normally uses this control method.
The response will be comparatively slow if the target value changes because the feedback derivative
value is used. The stable control of the target is, however, possible.
Target value
Target of
control
Detected value (Feedback value)
Advanced Operation Chapter 6
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