6 -108 Using PID ControlPID control is a method of making the feedback value (detection value) match the set target value. By combin-ing proportional control (P), integral control (I), and derivative control (D), you can even control targets(machinery) with play time.The characteristics of the PID control operations are given below.PID Control OperationTo understand the differences between each PID control operation (P, I, and D, the variation in the amount ofoperation (output frequency) is as shown in the following diagram when the deviation (i.e., the differencebetween the target value and feedback value) is fixed.Fig 6.62 PID Control OperationPID Control ApplicationsThe following table shows examples of PID control applications using the Inverter.P control Outputs the amount of operation proportional to the deviation. You cannot, however, set thedeviation to zero using P control alone.I control Outputs the amount of operation that integrates the deviation. Used for matching feedbackvalue to the target value. I control is not suited, however, to rapid variations.D control Outputs the amount of operation derived from the deviation. Can respond promptly to rapidvariations.Applica-tion Control Details Example of Sen-sor UsedSpeed Con-trol• Feeds back machinery speed information, and matches speed to the target value.• Inputs speed information from other machinery as the target value, and performssynchronous control using the actual speed feedback.Tachometer genera-torPressureControl Feeds back pressure information, and performs constant pressure control. Pressure sensorFlow RateControl Feeds back flow rate information, and controls the flow rate highly accurately. Flow rate sensorTempera-ture Con-trolFeeds back temperature information, and performs temperature adjustment controlby rotating the fan.• Thermocouple• ThermistorDeviationI controlAmount of operationD controlTimePID controlTimeP control
