Control Specification SiUS091133
43 Function and Control
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 temperature
and the target temperature)
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
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 an upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipe temperature, freeze-up protection.
3. Determine lower limit frequency
The maximum value is set as a lower limit frequency among the frequency lower limits of the
following function:
Pressure difference upkeep.
4. Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
For Heat Pump Model
1. Determine command frequency
Command frequency is determined in the following order of priority.
1. Limiting defrost control time
2. Forced cooling
3. Indoor frequency command
Command frequency
Limit frequency
Skip control
Lower limit function
Four way valve operating compensation (∗), etc.
Initial frequency
PI control
Defrost control (∗)
Dropping function
Input current control, etc.
Upper limit function
Compressor protection function
Upper limit frequency
FMAX
Lower limit frequency
FMIN
Target frequency
(R14717)
When the shift of the frequency is less than zero (ΔF<0) by PI control,
the target frequency is used as the command frequency.
(∗): only for heat pump models
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