.Annex60.Controls.Continuous.LimPID

Information

This model is similar to Modelica.Blocks.Continuous.LimPID, except for the following changes:

1. It can be configured to have a reverse action.

   If the parameter reverseAction=false (the default), then u_m < u_s increases the controller output, otherwise the controller output is decreased. Thus,

   • for a heating coil with a two-way valve, set reverseAction = false,
   • for a cooling coils with a two-way valve, set reverseAction = true.

2. It can be configured to enable an input port that allows resetting the controller output. The controller output can be reset as follows:

   • If reset = Annex60.Types.Reset.Disabled, which is the default, then the controller output is never reset.
   • If reset = Annex60.Types.Reset.Parameter, then a boolean input signal trigger is enabled. Whenever the value of this input changes from false to true, the controller output is reset by setting y to the value of the parameter y_reset.
   • If reset = Annex60.Types.Reset.Input, then a boolean input signal trigger is enabled. Whenever the value of this input changes from false to true, the controller output is reset by setting y to the value of the input signal y_reset_in.

   Note that this controller implements an integrator anti-windup. Therefore, for most applications, keeping the default setting of reset = Annex60.Types.Reset.Disabled is sufficient. Examples where it may be beneficial to reset the controller output are situations where the equipment control input should continuously increase as the equipment is switched on, such as as a light dimmer that may slowly increase the luminance, or a variable speed drive of a motor that should continuously increase the speed.

3. The parameter limitsAtInit has been removed.
4. Some parameters assignments in the instances have been made final.

Revisions

• September 29, 2016, by Michael Wetter:
  Refactored model.
• August 25, 2016, by Michael Wetter:
  Removed parameter limitsAtInit because it was only propagated to the instance limiter, but this block no longer makes use of this parameter. This is a non-backward compatible change.
  Revised implemenentation, added comments, made some parameter in the instances final.
• July 18, 2016, by Philipp Mehrfeld:
  Added integrator reset. This is for issue 494.
• March 15, 2016, by Michael Wetter:
  Changed the default value to strict=true in order to avoid events when the controller saturates. This is for issue 433.
• February 24, 2010, by Michael Wetter:
  First implementation.