Electronic Expansion Valve Pi Control; Step Control Of Outdoor Unit Fans - Daikin CMSQ200A7W1B Service Manual

SiBE28-805
2.3

Electronic Expansion Valve PI Control

Main Motorized Valve EV1 Control
Carries out the motorized valve (Y1E) PI control to maintain the evaporator outlet superheated
degree (SH) at constant during heating operation to make maximum use of the outdoor unit
heat exchanger (evaporator).
SH = Ts1 - Te
The optimum initial value of the evaporator outlet superheated degree is 5°C, but varies
depending on the discharge pipe superheated degree of inverter compressor.
Subcooling Motorized Valve EV2 Control
Makes PI control of the motorized valve (Y2E) to keep the superheated degree of the outlet gas
pipe on the evaporator side for the full use of the subcooling heat exchanger.
SH = Tsh -Te
2.4

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.
0
1
2
3
4
5
6
7
8
*
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.
Function
Fan revolutions (rpm)
CMSQ200A7
0
285
315
360
450
570
710
Cooling: 951
Heating: 941
Cooling: 951
Heating: 941
SH : Evaporator outlet superheated degree (°C)
Ts1: Suction pipe temperature detected by
thermistor R6T (R7T) (°C)
Te : Low pressure equivalent saturation
temperature (°C)
SH : Outlet superheated degree of evaporator (°C)
Tsh : Suction pipe temperature detected with the
thermistor R5T (°C)
Te : Low pressure equivalent saturation
temperature (°C)
CMSQ250A7
0
350
370
400
450
540
670
760
Cooling: 796
Heating: 780
Basic Control
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