Frequency Control - Daikin CTXS09GVJU Service Manual

SiUS12-814
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
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
1.1 Limiting frequency by dropping function
1.2 Limiting defrost control time
1.3 Forced cooling / heating
1.4 Indoor frequency command
Function and Control
temperature set by the remote controller.)
Frequency changes by PI control < repeats when frequency becomes lower
Command frequency X repeats when frequency becomes lower
Command frequency
Initial frequency
PI control
Defrost control (*)
Command frequency will be determined in the following order of priority.
Input current, discharge pipes, low Hz high pressure limit, peak cutting, freeze-up protection,
dew prevention, fin thermistor temperature.
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.
Each dropping function
Input current control, etc.
Upper limit frequency
Each upper limit function
Compressor protection function
Limit frequency Skip control
Each lower limit function
Lower limit frequency
FMIN Four-way valve operating compensation, etc. (*)
*; only for heat pump model
Control Specification
Target frequency
(R1375)
41