Control Specification SiUS041829E
46 Part 4 Functions and Control
3.2 Frequency Control
Outline The compressor frequency is determined according to the difference between the room thermistor
temperature and the target temperature.
Details 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
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, heating peak-cut, freeze-up
protection, defrost control.
3. Determine lower limit frequency
The maximum value is set as an lower limit frequency among the frequency lower limits of the
following functions:
Four way valve operation compensation, draft prevention, pressure difference upkeep.
4. Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
Initial Frequency When starting the compressor, the frequency is initialized according to the D value of the indoor
unit.
D signal: Indoor frequency command
The difference between the room thermistor temperature and the target temperature is taken as the
D value and is used for D signal of frequency command.
Command frequency
Limit frequency
Skip control
Upper limit function
Compressor protection function
Lower limit function
Four way valve operation compensation, etc.
Target frequency
(R18023)
When the shift of the frequency is less than zero (ΔF<0) by PI control,
the target frequency is used as the command frequency.
Dropping function
Input current control, etc.
Upper limit frequency
FMAX
Lower limit frequency
FMIN
Initial frequency
PI control
Defrost control
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