Frequency Control - Daikin 2MXS-W Series Service Manual

Control Specification
4.3

Frequency Control

Outline
Frequency corresponding 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
Parameters Q value
Indoor unit output determined from indoor unit volume, airflow rate and other factors.
S value: Indoor Unit Capacity
S value is the capacity of the indoor unit, and is used for frequency command.
Ex:
98
When the shift of the frequency is less than zero (ΔF<0) by PI control,
the target frequency is used as the command frequency.
Upper limit frequency
Command 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 the 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 function:
Four way valve operation compensation, draft prevention, pressure difference upkeep.
There is a certain prohibited frequency such as a power supply frequency.
Capacity S value
7 kBtu/h
9 kBtu/h
12 kBtu/h
Input current control, etc.
FMAX
Skip control
Limit frequency
Four way valve operation compensation, etc.
FMIN
Capacity
20 15 kBtu/h
25 18 kBtu/h
35 24 kBtu/h
Dropping function
Upper limit function
Compressor protection function
Target frequency
Lower limit function
S value
50
60
71
Part 4 Functions and Control
SiUS122226E
(R18023)