.Buildings.DHC.ETS.Combined.Controls.SwitchBox

Information

This block implements a control logic preventing flow reversal in the service line, for instance with the hydronic configuration of Buildings.DHC.ETS.Combined.HeatPumpHeatExchanger. The block requires two input signals representing the mass flow rate contributing to a positive flow direction mPos_flow and the mass flow contributing to a reverse flow direction mRev_flow. The output signal y switches to maintain mPos_flow ≥ mRev_flow with a temporization avoiding short cycling. Due to the temporization, the mass flow rate may transiently change direction as illustrated in Buildings.DHC.ETS.Combined.Subsystems.Validation.SwitchBox.

Revisions

• February 28, 2024, by Michael Wetter:
  Added hysteresis to avoid chattering if signals are near zero and have numerical noise.
• February 23, 2021, by Antoine Gautier:
  Refactored with CDL connectors.
• January 23, 2020, by Michael Wetter:
  Added Buildings.Controls.OBC.CDL.Logical.TrueFalseHold to avoid the risk of chattering.
• January 12, 2020, by Michael Wetter:
  Added documentation.