Control Specification; Frequency Control - Daikin FTXZ25NV1B Service Manual

SiMT041311E

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
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
Function and Control
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 Limit frequency
Lower limit frequency
Initial 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, draught prevention, pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
Dropping function
Input current control, etc.
FMAX
Compressor protection function
Skip control
Four way valve operation compensation, etc.
FMIN

Control Specification

Upper limit function
Target frequency
Lower limit function
(R18023)
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