Frequency Control - Daikin Super Multi NX FFQ25B8V1B Service Manual

SiBE121021_C
4.2

Frequency Control

Outline Frequency that corresponds to each room's capacity is determined according to the difference
between the target temperature and the temperature of each room.
The function is explained as follows.
1. How to determine frequency
2. Frequency command from an indoor unit (Difference between a room thermistor
3. Frequency command from an indoor unit (The ranked capacity of the operating room)
4. Frequency initial setting
5. PI control
Detail How to Determine Frequency
The compressor's frequency is determined by taking the following steps.
For Cooling Only Model
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. Forced cooling
2. Indoor frequency command
The minimum value is set as the upper limit frequency among the frequency upper limits of
the following functions:
Compressor protection, input current, discharge pipe temperature, low Hz high pressure
limit, freeze-up protection.
The maximum value is set as the lower limit frequency among the frequency lower limits of
the following functions:
Draft prevention, pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
Drooping function
Input current control, etc.
FMAX
Compressor protection function
Skip control
FMIN Four way valve operating compensation (∗), etc.
(∗): only for heat pump model
Control Specification
Upper limit function
Target frequency
Lower limit function
(R11592)
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