Overall Frequency Control - Daikin FTKB09AXVJU Service Manual

Algorithm & Control
2.24

Overall Frequency Control

The compressor frequency is determined according to the difference between the room thermistor
temperature and the target temperature.
Command frequency
Initial frequency PI
control Defrost
control (*)
For Cooling Only Model
1. Determine command frequency
Command frequency is determined in the following order of priority.
a. Forced cooling
b. Indoor frequency command
2. Determine upper limit frequency
The minimum value is set as an upper limit frequency among the frequency upper limits of the following
functions Compressor protection, input current, discharge pipe temperature, freeze-up protection.
3. Determine lower limit frequency
The maximum value is set as a lower limit frequency among the frequency lower limits of the following
function:
Pressure difference upkeep.
4. Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
For Heat Pump Model
1. Determine command frequency
Command frequency is determined in the following order of priority.
a. Limited defrost control time
b. Forced cooling
c. Indoor frequency command
2. Determine upper limit frequency
The minimum value is set as an upper limit frequency among the frequency upper limits of the following
functions:
Compressor protection, input current, discharge pipe temperature, heating peak-cut, freeze-up protection,
defrost control.
3. Determine lower limit frequency
The maximum value is set as a lower limit frequency among the frequency lower limits of the following
functions:
Four way valve operation compensation, draft prevention, pressure difference upkeep.
4. Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
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Upper limit function
FMAX
Limit frequency
Lower limit
frequency FMIN
Dropping function
Input current control, etc.
Upper limit function
Compressor protection function
Skip control
Lower limit function
Four way valve operation compensation (*), etc.
(*): only for heat pump models
Target frequency