.Annex60.Controls.Continuous.PIDHysteresis

Information

Block of a controller for set point tracking with a hysteresis element that switches the controller on and off.

If the controller is off, and the control error becomes larger than eOn, then the controller switches to on and remains on until the control error is smaller than eOff. When the controller is on, the set point tracking can be done using a P-, PI-, or PID-controller. In its off-mode, the control output is zero. Thus, the parameters yMin and yMax are used to constrain the output of the controller during its on mode only. This can be used, for example, to modulate a device between 0.3 and 1.0, and switch it to off when the control error is small enough.

Revisions

• September 29, 2016, by Michael Wetter:
  Removed parameter limitsAtInit because it is no longer used in the PID controller.
• April 13, 2016, by Michael Wetter:
  Set zer(final k=0) and made swi, zer and zer1 protected which they are also for Annex60.Controls.Continuous.PIDHysteresis. These changes are not backwards compatible.
• March 15, 2016, by Michael Wetter:
  Changed the default value to strict=true in order to avoid events when the controller saturates. Also assigned propogated values to be final. This is for issue 433.
• February 24, 2010, by Michael Wetter:
  Changed PID controller from Modelica Standard Library to PID controller from Buildings library to allow reverse control action.
• October 2, 2009, by Michael Wetter:
  Fixed error in default parameter eOn. Fixed error by introducing parameter Td, which used to be hard-wired in the PID controller.
• February 14, 2009, by Michael Wetter:
  First implementation.