Frequency Control - Daikin BA-Series Service Manual

SiBE05-722ED
3.2

Frequency Control

Outline The compressor frequency is determined according to the difference between the room
thermistor temperature and the target temperature.
Detail For Cooling Only Model
1. Determine command frequency
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
For Heat Pump Model
1. Determine command frequency
2. Determine upper limit 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. Forced cooling
2. 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, freeze-up protection.
The maximum value is set as a 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.
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.
Dropping function
Input current control, etc.
FMAX
Compressor protection function
Skip control
FMIN Four way valve operation compensation (∗), etc.
(∗): only for heat pump models
Control Specification
Upper limit function
Target frequency
Lower limit function
(R17857)
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