Si12-714
Control Specification
Function and Control
77
3.2
Frequency Control
Outline
Frequency that corresponds to each room’s capacity will be determined according to the
difference in the temperature of each room and the temperature that is set by the remote
controller.
The function is explained as follows.
1. How to determine frequency.
2. Frequency command from an indoor unit. (The difference between a room temperature and
the temperature set by the remote controller.)
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 will finally be determined by taking the following steps.
For Heat Pump Model
1. Determine command frequency
Command frequency will be determined in the following order of priority.
1.1 Limiting frequency by drooping function
Input current, discharge pipes, low Hz high pressure limit, peak cutting, freeze-up protection,
dew prevention, fin thermistor temperature.
1.2 Limiting defrost control time
1.3 Forced cooling / heating
1.4 Indoor frequency command
2. Determine upper limit frequency
Set a minimum value as an upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipes, Low Hz high pressure, peak cutting,
freeze-up protection, defrost.
3. Determine lower limit frequency
Set a maximum value as an lower limit frequency among the frequency lower limits of the
following functions:
Four way valve operating compensation, draft prevention, pressure difference upkeep.
4. Determine prohibited frequency
There is a certain prohibited frequency such as a power supply frequency.
For Cooling Only Model
1. Determine command frequency
Command frequency will be determined in the following order of priority.
1.1 Limiting frequency by drooping function
Input current, discharge pipes, freeze-up protection, dew prevention, fin thermistor
temperature.
1.2 Indoor frequency command
Command frequency
Limit frequency
Skip control
Each upper limit function
Compressor protection function
Each lower limit function
Four-way valve operating compensation, etc. (*)
Initial frequency
PI control
Defrost control (*)
Each drooping function
Input current control, etc.
Upper limit frequency
FMAX
Lower limit frequency
FMIN
Target frequency
Command frequency X repeats when frequency becomes lower
Frequency changes by PI control < repeats when frequency becomes lower
*; only for heat pump model
(R1375)
