Block that outputs the set points for the supply air temperature for cooling, heating and economizer control, and the fan speed for a single zone VAV system.
For the temperature set points, the
parameters are the maximum supply air temperature TSupSetMax
,
and the minimum supply air temperature for cooling TSupSetMin
.
The deadband temperature is equal to the
average set point for the zone temperature
for heating and cooling, as obtained from the input TZonSet
,
constraint to be within 21°C (≈70 F) and
24°C (≈75 F).
The setpoints are computed as shown in the figure below.
Note that the setpoint for the supply air temperature for heating
and for economizer control is the same, and this setpoint is
lower than TSupSetMin
when the heating loop signal
is zero and the economizer is in cooling mode, as shown in the figure.
For the fan speed set point, the
parameters are the maximu fan speed at heating yHeaMax
,
the minimum fan speed yMin
and
the maximum fan speed for cooling yCooMax
.
For a cooling control signal of uCoo > 0.25
,
the speed is faster increased the larger the difference is between
the zone temperature minus outdoor temperature TZon-TOut
.
The figure below shows the sequence.
The output TSupCoo
is to be used to control the cooling coil,
and the output
TSupHeaEco
is to be used to control the heating coil and the
economizer dampers.
Note that the inputs uHea
and uCoo
must be computed
based on the same temperature sensors and control loops.
TSupHeaEco
.