Frequency Control - Daikin 4MXS-R Series Service Manual

Control Specification
4.3

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.
Details The compressor's frequency is determined by taking the following steps.
1. Determine command frequency
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
93
When the shift of the frequency is less than zero (∆F<0) by PI control,
the target frequency is used as the command frequency.
Upper limit frequency
Command frequency Limit frequency
Initial frequency Lower limit frequency
PI control
Defrost control
Command frequency is determined in the following order of priority.
1. Limiting defrost control time
2. Forced cooling/heating
3. Indoor frequency command
The minimum value is set as upper limit frequency among the frequency upper limits of the
following functions:
Compressor protection, input current, discharge pipe temperature, low Hz high pressure limit,
heating peak-cut, freeze-up protection, defrost.
The maximum value is set as the lower limit frequency among the frequency lower limits of the
following functions:
Four way valve operation compensation, draft prevention, pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
Dropping function
Input current control, etc.
FMAX
Compressor protection function
Skip control
FMIN Four way valve operation compensation, etc.
SiUS121736EA
Upper limit function
Target frequency
Lower limit function
(R18023)
Functions and Control