Frequency Control - Daikin FTXS20K2V1B Service Manual

SiBE041134
3.2

Frequency Control

Outline Frequency is determined according to the difference between the room thermistor temperature
and the target temperature.
The function is explained as follows.
1. How to determine frequency
2. Frequency command from the indoor unit (Difference between the room thermistor
3. Frequency initial setting
4. PI control
Detail
How to Determine Frequency
The compressor's frequency is determined by taking the following steps.
1. Determine command frequency
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
Function and Control
temperature and the target temperature)
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
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.
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.
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 operating compensation, etc.
FMIN
Control Specification
Upper limit function
Target frequency
Lower limit function
(R14951)
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