blockSwitchBox
Controller for flow switch box
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.
Parameters
| Type | Name | Default | Description |
|---|
| Real | trueHoldDuration | | true hold duration |
| Real | falseHoldDuration | trueHoldDuration | false hold duration |
| Nominal condition |
| Real | m_flow_nominal | | Nominal mass flow rate, used for scaling to avoid chattering |
Revisions
-
June 21, 2024, by Antoine Gautier:
Added moving average to break the algebraic loop when using components configured in steady state.
This is for #3906.
-
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.
