Vacon 50X User Manual

Contents

Vacon 50X User Manual Manual pdf 108 page image

107 z vacon fundamentals of pi controlTel. +358 (0)201 2121 • Fax +358 (0)201 2122051010. Fundamentals of PI Control10.1 IntroductionThe Vacon 50X AC drive has a built-in PI (Proportional-Integral) Controller that makes it possible to con-trol a process by adjusting motor speed using a reference input and a feedback input. When the drive isconfigured to operate with feedback from a transducer, the Vacon 50X AC drive essentially ceases to bea frequency controller and instead becomes a process controller.Several Vacon 50X parameters are specifically designed for PI control. These include:• 490 (Appl Macro)• 850 (PI Configure)• 851 (PI Feedback)• 852 (PI Prop Gain)• 853 (PI Int Gain)• 854 (PI Feed Gain)• 855 (PI Error 1)• 856 (PI Error 2)• 857 (PI High Corr)• 858 (PI Low Corr)The function performed by each of these parameters is described in the following section. Figure 22 onpage 108 provides a flowchart of PI control and shows the interaction of these parameters.10.2 Configuration of PI Control ParametersThis section discusses the parameters used for PI control and provides advice on how best to configurethese parameters for your particular application.10.2.1 Parameter 490 (Appl Macro)Parameter 490 (Appl Macro) is used to active the PI mode for either a Fan with PI or Pump with PI appli-cation.10.2.2 Parameter 857 (PI High Corr) and 858 (PI Low Corr)These two parameters define the correction limits for the drive’s response to a change in, or loss of, thefeedback signal.