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Section
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SM830076
2. Processes and functions
2-16 Electronic Expansion Valve Control
The circulation volume of the refrigerant is controlled by a pulse type electronic control valve.
When the power is switched ON, the opening degree of the electronic control valve is
controlled between 90 and 480 steps after setting the initial step at the time when the
thermostat is ON.
Contents and Order of control
0451_M_S
Outdoor unit coil temperature control
Freeze prevention control
Refrigerant flow distribution control
*
Repeat control in accordance with the priority order.
Discharge gas temperature control
Start
*
Cooling
Discharge gas target temperature
control (Fuzzy control)
High load prevention control
Heating start up control
Refrigerant flow distribution control
Discharge gas temperature control
Start
*
Heating
Discharge gas target temperature
control (Fuzzy control)
Even though the operation is performed every 30 seconds, the control of discharge gas
temperature, high load prevention, outdoor unit coil temperature and freeze prevention
activates when it occurs.
(1) Refrigerant flow distribution control
At the control of flexible combination (a plural number of indoor units are set), the opening
degree of the electronic control valve is controlled by the indoor unit coil temperature.
Cooling: indoor unit coil E2 temperature (located at the middle of coil)
Heating: indoor unit coil E1 temperature (located at the outlet of coil)
(2) Fuzzy control (optimal refrigerant flow rate control)
By outputting the fuzzy estimation result corresponding to the fuzzy input variables (the indoor
unit coil temp., the deviation between the actual discharge gas temp. and the target discharge
gas temperature calculated from the outdoor unit coil temperature and the change thereof),
the electronic refrigerant valve is controlled so that the unit can perform its maximum ability in
accordance with the indoor and outdoor temperature conditions at the operation.
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