![background image](http://html.mh-extra.com/html/daikin/ftxz25nv1b/ftxz25nv1b_service-manual_2459562059.webp)
SiMT041311E
Control Specification
Function and Control
44
2. Control Specification
2.1
Frequency Control
Outline
The compressor frequency is determined according to the difference between the room
thermistor temperature and the target temperature.
Detail
1. Determine command frequency
Command frequency is determined in the following order of priority.
1. Limiting defrost control time
2. Forced cooling
3. 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 an lower limit frequency among the frequency lower limits of
the following functions:
Four way valve operation compensation, draught prevention, pressure difference upkeep.
4. Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
Command frequency
Limit frequency
Skip control
Upper limit function
Compressor protection function
Lower limit function
Four way valve operation compensation, etc.
Target frequency
(R18023)
When the shift of the frequency is less than zero (
∆
F<0) by PI control,
the target frequency is used as the command frequency.
Dropping function
Input current control, etc.
Upper limit frequency
FMAX
Lower limit frequency
FMIN
Initial frequency
PI control
Defrost control