SequenceSUPTemp

SequenceSUPTemp (FB)

FUNCTION_BLOCK SequenceSUPTemp

Short description

Supply air temperature control for a ventilation unit with energy recovery (continuous recirculation damper system and energy recovery) including permits for active heating and cooling. Typical application: Supply air temperature control in a ventilation unit

Representation

Function description

General

This function block enables, after enabling ( xOpTCon = TRUE ), the control of the supply air temperature rSAT to the setpoint rReferenceSAT by generating the control signals rYDamp (recirculation damper system 0.0 - 100.0 % outdoor air ratio) and rYER (energy recovery 0.0 - 100.0 %). After the full utilization of the energy recovery systems, if necessary the permit for active heating ( xEnHeat = TRUE ) or active cooling ( xEnCool = TRUE ) is released. The control of the supply air temperature during active heating or active cooling must each be performed via a separate, external PI controller. The control signals of these external PI controllers are fed back to the inputs rHeaterYPISAT and rCoolerYPISAT to ensure energy-efficient control of the energy recovery. By taking into account the current outdoor temperature rOAT or exhaust air temperature rRAT the optimal energy recovery can be performed for each operating case. When using this block, the spatial arrangement of the components (damper system, energy recovery, heater circuit, cooling circuit, etc.) must be considered. Case 1 - Winter case: Supply air temperature < supply air setpoint, outdoor temperature < exhaust air temperature, supply air setpoint > exhaust air temperature

Case 2 - Summer case: Supply air temperature > supply air setpoint, outdoor temperature > exhaust air temperature, supply air setpoint < exhaust air temperature

Enable / disable of the controller xOpTCon

In the disabled state ( xOpTCon = FALSE ) no control or regulation processes take place, the outputs are fixed to the following signals / states: &#xNAN;rYGen = 100.0 % &#xNAN;xEnHeat = FALSE &#xNAN;xEnCool = FALSE &#xNAN;rYDamp = 100.0 % &#xNAN;rYER = 100.0 %

Enable / disable of free night cooling xFNCEn

This input signals ( xFNCEn = TRUE ) the active free night cooling and locks the output for active cooling xEnCool regardless of the other requirements.

Delayed start of the control xPRORamp and xHHWFrost1

The internal sequence controller (PI controller) is locked if either the input xPRORamp and/or the input xHHWFrost1 is active ( = TRUE ). The release of the internal sequence controller occurs with a time delay of 5 minutes after both inputs are inactive again ( = FALSE ).

Feedback of control signals rHeaterYPISAT and rCoolerYPISAT

The feedback of the control signals for active heating rHeaterYPISAT and cooling rCoolerYPISAT is monitored internally and evaluated as follows: Control signal rHeaterYPISAT > 8.0 %: Deactivation of the internal sequence controller Control signal rHeaterYPISAT < 3.0 %: Activation of the internal sequence controller after a time delay of 500 ms Control signal rCoolYPISAT > 8.0 %: Deactivation of the internal sequence controller Control signal rCoolYPISAT < 3.0 %: Activation of the internal sequence controller after a time delay of 500 ms

General control signal from the sequence control rYGen

This control signal in the range 0.0 - 100.0 % (0.0% = maximum energy recovery, 100.0 = no energy recovery) is primarily generated by the internal sequence controller and influenced by the input variables rSAT (supply air temperature), rReferenceSAT (supply air setpoint), rOAT (outdoor air temperature) and rRAT (exhaust air temperature).

Enable / disable of active heating xEnHeat

The permit for active heating is active ( = TRUE ) if the following conditions are simultaneously met: &#xNAN;xOptCon = TRUE (outdoor temperature > exhaust air temperature AND rYGen > 99% ) OR (outdoor temperature < exhaust air temperature AND rYGen < 1% ) In all other situations active heating is disabled ( = FALSE ).

Enable / disable of active cooling xEnCool

The permit for active cooling is active ( = TRUE ) if the following conditions are simultaneously met: &#xNAN;xOptCon = TRUE (outdoor temperature > exhaust air temperature AND rYGen < 1% ) OR (outdoor temperature < exhaust air temperature AND rYGen > 99% ) &#xNAN;xFNCEn = FALSE &#xNAN;rAverage2h > rSetpoint_CoolOAT (disable active cooling at low outdoor temperatures) In all other situations active cooling is disabled ( = FALSE ).

Control signal for the damper system rYDamp

The control signal for the damper system (0.0 - 100.0 %, 0.0 % = no outdoor air fraction, 100.0 % = maximum outdoor air fraction) is generated depending on the general control signal from the sequence control rYGen as follows: The control signal rYGen is in the range r1Damp to r2Damp linearly converted into a signal in the range of 0.0 - 100.0 and limited.

Control signal for the energy recovery system rYER

The control signal for the energy recovery (0.0 - 100.0 %, 0.0 % = no energy recovery, 100.0 % = maximum energy recovery) is generated depending on the general control signal from the sequence control rYGen as follows: The control signal rYGen is in the range r1Er to r2Er linearly converted into a signal in the range of 100.0 - 0.0 and limited.

CODESYS

InOut:

Scope	Name	Type	Initial
Input	rSAT	REAL
Input	rReferenceSAT	REAL
Input	xOpTCon	BOOL
Input	xFNCEn	BOOL	FALSE
Input	rOAT	REAL
Input	rRAT	REAL
Input	rAverage2h	REAL
Input	xPRORamp	BOOL	FALSE
Input	xHHWFrost1	BOOL	FALSE
Input	rHeaterYPISAT	REAL	0.0
Input	rCoolerYPISAT	REAL	0.0
Output	rYGen	REAL
Output	xEnHeat	BOOL
Output	xEnCool	BOOL
Output	rYDamp	REAL
Output	rYER	REAL
Output	xAuto	BOOL
Input Const	rSetpoint_CoolOAT	REAL	14.0
Input Const	r2ER	REAL	100.0
Input Const	r1ER	REAL	30.0
Input Const	r2Damp	REAL	30.0
Input Const	r1Damp	REAL	0.0
Input Const	rTn	REAL	200.0
Input Const	rKp	REAL	3.5
Input Const	rManValueYER	REAL
Input Const	eManModeYER	eMANNUM	eMANNUM.Auto
Input Const	rManValueYDamp	REAL
Input Const	eManModeYDamp	eMANNUM	eMANNUM.Auto
Input Const	eManModeCool	eMANBIN	eMANBIN.Auto
Input Const	eManModeHeat	eMANBIN	eMANBIN.Auto
Input Const	rManValueYGen	REAL
Input Const	eManModeYGen	eMANNUM	eMANNUM.Auto