Frequency Control - Daikin K-Series Service Manual

SiBE061121.book Page 31 Monday, April 25, 2011 3:20 PM
SiBE061121
3.2

Frequency Control

Outline Frequency is determined according to the difference between the room thermistor temperature
and the target temperature.
The function is explained as follows.
1. How to determine frequency
2. Frequency command from the indoor unit (Difference between the room thermistor
3. Frequency initial setting
4. PI control
Detail How to Determine Frequency
The compressor's frequency is determined by taking the following steps.
1. Determine command frequency
1. Limiting defrost control time
2. Forced cooling
3. Indoor frequency command
2. Determine upper limit frequency
3. Determine lower limit frequency
4. Determine prohibited frequency
Function and Control
temperature and the target temperature)
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
FMAX
Command frequency Limit frequency
Lower limit frequency
Initial frequency
PI control FMIN
Defrost control
Command frequency is determined in the following order of priority.
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.
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.
There is a certain prohibited frequency such as a power supply frequency.
Control Specification
Dropping function Input
current control, etc.
Upper limit function
Compressor protection function
Target frequency
Skip control
Lower limit function
Four way valve operating compensation, etc.
(R14641)
31