SiBE121021_C Control Specification
Function and Control 113
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
temperature and the target temperature)
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

Command frequency is determined in the following order of priority.
1. Forced cooling
2. Indoor frequency command
2. Determine upper limit frequency

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.
3. Determine lower limit frequency

The maximum value is set as the lower limit frequency among the frequency lower limits of
the following functions:
Draft prevention, pressure difference upkeep.
4. Determine prohibited frequency

There is a certain prohibited frequency such as a power supply frequency.
Command frequency
Limit frequency
Skip control
Lower limit function
Four way valve operating compensation (∗), etc.
Initial frequency
PI control
Defrost control (∗)
Drooping function
Input current control, etc.
Upper limit function
Compressor protection function
Upper limit frequency
FMAX
Lower limit frequency
FMIN
Target frequency
(R11592)
When the shift of the frequency is less than zero (∆F<0) by PI control,
the target frequency is used as the command frequency.
(∗): only for heat pump model
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