Electronic Expansion Valve Pi Control - Daikin VRV II-Q RQYQ8-48PY1B Service Manual

Detailed Control Functions

2.4.5 Electronic Expansion Valve PI Control

Main electronic expansion valve control
When the outdoor unit heat exchanger is performed via the evaporator, this function is used to exert PI control
on the electronic expansion valve (Y1E) so that the evaporator outlet superheated degree (SH) will become
constant.
SH = Tg - Te
Subcooling electronic expansion valve control
In order to make the maximum use of the subcooling heat exchanger, this function is used to exert PI control
on the electronic expansion valve (Y2E or Y3E) so that the evaporator-side gas pipe superheated degree
(SH) will become constant.
SH = Tsh - Te
2.4.6 Step Control of Outdoor Unit Fans
Used to control the revolutions of outdoor unit fans in the steps listed in table below, according to condition
changes.
STEP
No.
RQYQ8PY1B RQYQ10PY1B RQYQ12PY1B
0 0
1 350
2 370
3 400
4 450
5 540
6 610
7 760
Cooling: 796
8
Heating: 780
* Figures listed above are all those controlled while in standard mode, which vary when the system is set to high static
pressure or capacity precedence mode.
[Control at a low outdoor temperature during cooling]
Secure the liquid pressure and circulating rate in the indoor unit through high pressure control with the outdoor fan when
the outdoor temperature is low during cooling. Control the fan with the target Tc (high pressure equivalent saturation
temperature) = 34°C
50
0 0
350 350
370 370
400 400
460 460
560 560
710 710
Cooling: 821
870
Heating: 800
Cooling: 821
870
Heating: 800
SH: Evaporator outlet superheated degree (°C)
Tg : Suction pipe temperature (°C) detected by the
thermistor R8T.
Te : Low pressure equivalent saturation temperature (°C)
SH: Evaporator outlet superheated degree (°C)
Tsh: Suction pipe temperature (°C) detected by the
subcooling heat exchanger outlet thermistor R5T.
Te: Low pressure equivalent saturation temperature (°C)
Fan revolutions (rpm)
RQYQ14PY1B
MF1 MF2
0
230
380
290 260
375 345
570 540
720 690
1091 1061
1136 1106
RQYQ16PY1B
MF1
0 0
0 230
0 380
290
375
570
720
1091
1136
SiBE341027
MF2
0
230
380
290
375
570
720
980
980
Function