Control Specification Si04-402A
30 Function and Control
Indoor Frequency Command (∆D signal)
The difference between a room temperature and the temperature set by the remote controller
will be taken as the “∆D signal” and is used for frequency command.
∗Th OFF = Thermostat OFF
Frequency Initial Setting
Outline
When starting the compressor, or when conditions are varied due to the change of the room, the
frequency must be initialized according to the ∆D value of the indoor unit and the Q value of the
indoor unit.
Q value: Indoor unit output determined from indoor unit volume, air flow rate and other factors.
PI Control (Determine Frequency Up / Down by ∆D Signal)
1. P control
Calculate ∆D value in each sampling time (20 seconds), and adjust the frequency according
to its difference from the frequency previously calculated.
2. I control
If the operating frequency is not change more than a certain fixed time, adjust the frequency
up and down according to the ∆D value, obtaining the fixed ∆D value.
When the ∆D value is small...lower the frequency.
When the ∆D value is large...increase the frequency.
3. Frequency management when other controls are functioning
When frequency is drooping;
Frequency management is carried out only when the frequency droops.
For limiting lower limit
Frequency management 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 depending on indoor unit.
When low noise commands come from the indoor unit or when outdoor unit low noise or
quiet commands come from indoor unit, the upper limit frequency must be lowered than the
usual setting.
3.3 Controls at Mode Changing / Start-up
3.3.1 Preheating Operation
Outline Operate the inverter in the open phase operation with the conditions including the preheating
command (only for heat pump model) from the discharge pipe temperature.
Detail Preheating ON Condition
When the discharge pipe temperature is below 10ºC, inverter in open phase operation
starts.
OFF Condition
When the discharge pipe temperature is higher than 12ºC, inverter in open phase operation
stops.
Temperature
difference
∆D
signal
Temperature
difference
∆D
signal
Temperature
difference
∆D
signal
Temperature
difference
∆D
signal
0 ∗Th
OFF
2.0 4 4.0 8 6.0 C
0.5 1 2.5 5 4.5 9 6.5 D
1.0 2 3.0 6 5.0 A 7.0 E
1.5 3 3.5 7 5.5 B 7.5 F
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