5.3.2 Indoor electronic expansion valve control
1 After supplying power, the electronic expansion valve closes
fully before starting to open.
2 When the compressor stops, the electronic expansion valve
closes fully to set its opening.
3 When it starts (the compressor is activated), the electronic
expansion valve opens to a specific degree during cooling
operation, 1 minute.
4 During heating operation, the electronic expansion valve opens
to a specific degree.
5 During defrost, the electronic expansion valve opens to a
specific degree, as indicated in the graph.
6 Normal opening of the electronic expansion valve.
Cooling operation
1 Superheat temperature setting required:
a Heat exchanger SH:
• 3 HP => SH = 0 °C
• 4 HP=> SH = -4 °C
b Heat exchanger SH = Tg - TL
Tg: Indoor gas pipe temperature.
TL: Indoor liquid pipe temperature.
SH: Superheat.
2 Simulated PI control for the electronic expansion valve. the opening of this valve is controlled so that the SH temperature
of the heat exchanger can reach the set temperature.
Heating operation
1 Definition of the set temperature:
a Heat exchanger SH:
Ti < TL < 45 + 0.5 x Ta
TL: Indoor liquid pipe temperature.
Ti: Indoor air inlet temperature.
Ta: Outdoor temperature.
2 Simulated PI control for the electronic expansion valve. the opening of the electronic expansion valve is controlled so
that the temperature of the indoor liquid pipe can reach the set temperature.
5 Control system
177
SMGB0063 rev. 1 - 10/2010
5
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