2.3 b: Application
182 YASKAWA TOEPYAIGA5002A GA500 Programming
I control is the integral of the deviation. It uses an integral value of the deviation to output the product (the
controlled output). I control helps align the feedback value and the target value. If you use only a proportional effect
(P control), it will cause and offset. Use a proportional effect with integral control, and the offset will disappear over
time.
• D control
D control is the derivative of the deviation. D control has an effect on drive output when there are sudden, large
changes in the deviation or feedback value. It quickly returns drive output to the value before the sudden change. It
multiplies a time constant by a derivative value of the deviation (slope of the deviation), and adds that result to PID
input to calculate the deviation of the signal, then it corrects the deviation.
Note:
D control has causes less stable operation because the noise changes the deviation signal. Use D control only when necessary.
■ PID Control Operation
Figure 2.27 shows PID control operation. The modified output (output frequency) changes when the drive uses PID
control to keep the deviation (the difference between the target value and the feedback value) constant.
Figure 2.27 PID Control Operation
■ PID Control Applications
Table 2.25 shows applications for PID control.
Table 2.25 PID Control Applications
Application Control Content Sensors Used
Speed Control • The drive uses a feedback signal for the machine speed,
and adjusts that speed to align with the target value.
• The drive uses speed data from other machinery as the
target value to do synchronous control. The drive then
adds that target value to the feedback from the machine
it is operating to align its speed with the other
machinery.
Tacho generator
Pressure control The drive uses feedback from the actual pressure to hold
constant pressure.
Pressure sensor
Flow control The drive uses feedback from the actual flow to hold
constant flow.
Flow rate sensor
Temperature control The drive uses feedback from the actual temperature to
control a fan and hold constant temperature.
Thermocoupler, thermistor
■ Input Methods for the PID Setpoint
Use b5-01 [PID Mode Setting] to select how the PID setpoint is input to the drive.
When b5-01 = 1 or 2 [Standard or Standard (D on feedback)], either the frequency reference set in b1-01 [Frequency
Reference Selection 1] or b1-15 [Frequency Reference Selection 2] will be the PID setpoint, or the one of the inputs in
Table 2.26 will be the PID setpoint.
When b5-01 = 3 or 4 [Fref + PID Trim or Fref + PID Trim (D on feedback)], one of the inputs in Table 2.26 will be
the PID setpoint.
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