Algorithm & Control
30
2.24.1 Initial Frequency
When starting the compressor, the frequency is initialized according to the ∆D value of the indoor unit.
<∆D signal: Indoor frequency commands>
The difference between the room thermistor temperature and the target temperature is recognized as the ∆D
signal and is used for frequency command.
Temperature
difference
∆D
signal
Temperature
difference
∆D
signal
Temperature
difference
∆D
signal
Temperature
difference
∆D
signal
-2.0°C (-3.6°F)
*OFF
0°C (0°F)
4
2.0°C (3.6°F)
8
4.0°C (7.2°F)
C
-1.5°C (-2.7°F)
1
0.5°C (0.9°F)
5
2.5°C (4.5°F)
9
4.5°C (8.1°F)
D
-1.0°C (-1.8°F)
2
1.0°C (1.8°F)
6
3.0°C (5.4°F)
A
5.0°C (9.0°F)
E
-0.5°C (-0.9°F)
3
1.5°C (2.7°F)
7
3.5°C (6.3°F)
B
5.5°C (9.9°F)
F
*OFF = Thermostat OFF
2.24.2 PI Control
1. P control
The ∆D value is calculated in each sampling time (20 seconds), and the frequency is adjusted according to
its difference from the frequency previously calculated.
2. I control
If the operating frequency does not change for more than a certain fixed time, the frequency is adjusted
according to ∆D value.
When the ∆D value is low, the frequency is lowered.
When the ∆D value is high, the frequency is increased.
3. Frequency control when other controls are functioning
• When frequency is dropping;
Frequency control is carried out only when the frequency drops.
• For limiting lower limit;
Frequency control is carried out only when the frequency rises.
4. Upper and lower limit of frequency by PI control
The frequency upper and lower limits are set according to the command of the indoor unit. When the indoor
or outdoor unit quiet operation command comes from the indoor unit, the upper limit frequency is lower than
the usual setting.
ON
<Cooling / Dry>
OFF
A
B
C
-1.5°C (-2.7 °F)
Room thermistor temperature - target temperature
Cooling : -0.5°C (-0.9 °F)
Dry : -0.5°C (-0.9 °F)
Cooling : -2.0°C (-3.6 °F)
Dry : -2.5 - 2.0°C (-4.5 - 3.6 °F)
ON
<Heating>
OFF
A
B
C
1.5°C (2.7 °F)
Room thermistor temperature - target temperature
2.0°C (3.6 °F)
0.5°C (0.9 °F)