Daikin FVXG25K2V1B Service Manual page 43

SiBE061121
Indoor Frequency Command (∆D signal)
The difference between the room thermistor temperature and the target temperature is taken as
the "∆D signal" and is used for frequency command.
∗Th OFF = Thermostat OFF
Frequency Initial Setting
<Outline>
When starting the compressor, the frequency is initialized according to the ∆D value and the Q
value of the indoor unit.
Q value: Indoor unit output determined from indoor unit volume, airflow rate and other factors.
PI Control (Determine Frequency Up / Down by ∆D Signal)
1. P control
2. I control
3. Frequency management when other controls are functioning
4. Upper and lower limit of frequency by PI control
Function and Control
∆D
Temperature Temperature
difference signal
∗Th
–2.0
OFF
–1.5 1
–1.0 2
–0.5 3
The ∆D value is calculated in each sampling time (15 ~ 20 seconds), and the frequency is
adjusted according to its difference from the frequency previously calculated.
If the operating frequency does not change for more than a certain fixed time, the frequency
is adjusted according to the ∆D value.
When the ∆D value is low, the frequency is lowered.
When the ∆D value is high, the frequency is increased.
When frequency is dropping;
Frequency management is carried out only when the frequency drops.
For limiting lower limit
Frequency management is carried out only when the frequency rises.
The frequency upper and lower limits are set according to the command on 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.
∆D
Temperature
difference signal difference
0 4
0.5 5
1.0 6
1.5 7
Control Specification
∆D
Temperature
signal difference
2.0 8 4.0
2.5 9 4.5
3.0 A 5.0
3.5 B 5.5
∆D
signal
C
D
E
F
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