Frequency Control - Daikin FTX09NMVJU Service Manual

Control Specification
3.2

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
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
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When the shift of the frequency is less than zero (∆F<0) by PI control,
the target frequency is used as the command frequency.
Upper limit frequency
Command frequency
Initial frequency Lower limit frequency
PI control
Defrost control
Command frequency is determined in the following order of priority.
1. Limiting defrost control time
2. Forced cooling
3. Indoor frequency command
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.
The maximum value is set as an lower limit frequency among the frequency lower limits of the
following functions:
Four way valve operation compensation, draft prevention, pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
FMAX
Limit frequency
Skip control
FMIN Four way valve operation compensation, etc.
Dropping function
Input current control, etc.
Upper limit function
Compressor protection function
Target frequency
Lower limit function
Functions and Control
SiUS091601E
(R18023)