Frequency Control - Daikin C-Series Service Manual

Control Specification
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.
For Cooling Only Model
1. Determine command frequency
1. Forced cooling
2. Indoor frequency command
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
For Heat Pump Model
1. Determine command frequency
1. Limiting defrost control time
2. Forced cooling
3. Indoor frequency command
30
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.
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, freeze-up protection.
The maximum value is set as an lower limit frequency among the frequency lower limits of
the following function:
Pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
Command frequency is determined in the following order of priority.
Drooping function
Input current control, etc.
FMAX
Compressor protection function
Skip control
FMIN Four way valve operating compensation (∗), etc.
(∗): only for heat pump model
SiBE07-618_C
Upper limit function
Target frequency
Lower limit function
(R11592)
Function and Control