Compressor Control - Daikin RTSQ20PY1 Service Manual

Normal Operation
6.2

Compressor Control

6.2.1 Compressor PI Control
Carries out the compressor capacity PI control to maintain Te at constant during cooling
operation and Tc at constant during heating operation to ensure stable unit performance.
[Cooling operation]
Controls compressor capacity to adjust Te to
achieve target value (TeS).
Te set value (Make this setting while in Setting
mode 2.)
Te setting
[Heating operation]
Controls compressor capacity to adjust Tc to
achieve target value (TcS).
Te set value (Make this setting while in Setting
mode 2.)
Tc setting
[Heating operation at low outdoor air temperature]
<Outdoor unit>
This function is used to conduct the same control as that for "Heating operation"
aforementioned.
<Function unit>
This function is used to control the compressor capacity so that the ratio (Ph) of the high-stage-
side compression ratio to the low-stage-side compression ratio will come to the target value.
k Ph =
Pc : Value detected by the high pressure sensor of the function unit (MPa)
Pm: Value detected by the high pressure sensor of the outdoor unit (MPa)
Pe : Value detected by the low pressure sensor of the outdoor unit (MPa)
k Target value of Ph: PhS = 0.5 to 2.0
91
L M (Normal)
(factory
setting)
3 6 7
L M (Normal) H
(factory
setting)
43 46 48
High-stage-side compression ratio
Low-stage-side compression ratio
Te : Low pressure equivalent saturation
temperature (°C)
TeS : Target Te value
(Varies depending on Te setting, operating
frequency, etc.)
H *On multi-outdoor-unit systems, this control is made
according to values of the first-priority unit, which is
detected with the pressure sensor.
8 9 10 11
Tc : High pressure equivalent saturation
temperature (°C)
TcS : Target Tc value
(Varies depending on Tc setting, operating
frequency, etc.)
*On multi-outdoor-unit systems, this control is made
according to values of the first-priority unit, which is
detected with the pressure sensor.
Pc/Pm
=
Pm/Pe
Electronic expansion
valve (1)
Gas & liquid separator
Electronic expansion
valve (2)
Enthalpy
SiBE31-801_C
High
pressure
(Pc)
Function unit
Intermediate
pressure (Pm)
Outdoor unit
Low
pressure
(Pe)
Function