Control System - Airwell CADE024 Service Manual

CONTROL SYSTEM

11. CONTROL SYSTEM
11.1 Electronic Control
11.1.1 Abbreviations
Abbreviation
Air Condition
A/C
BMS Building Management System
PWR System Power
CTT Compressor Top Temperature sensor
DCI DC Inverter
EEV Electronic Expansion Valve
HE Heating Element
HMI Human Machine Interface
HST Heat Sink Temperature sensor
Hertz (1/sec) – electrical frequency
Hz
ICT Indoor Coil Temperature (RT2) sensor
IDU Indoor Unit
MCU Micro Controller Unit
OAT Outdoor Air Temperature sensor
OCT ODU Coil Temperature sensor
ODU Outdoor Unit
OFAN Outdoor Fan
PFC Power Factor Corrector
RAC Residential A/C
RC Reverse Cycle (Heat Pump)
RGT Return Gas Temperature sensor
Rounds per second (mechanical speed)
RPS
RV Reverse Valve
SB,STBY Stand By
SUCT Compressor Suction Temperature sensor
Software
S/W
TBD To Be Defined
TMR Timer
11.1.2 System Operation Concept
The control function is divided between indoor and outdoor unit controllers. Indoor unit is the
system 'Master', requesting the outdoor unit for cooling/heating capacity supply. The outdoor unit is
the system 'Slave' and it must supply the required capacity unless it enters into a protection mode
avoiding it from supplying the requested capacity.
Target frequency is transferred via indoor to outdoor communication, and the calculation is based
on room temperature and set point temperature.
11.1.3 Compressor Frequency Control
The Compressor Frequency Control is based on the PI scheme.
When starting the compressor, or when conditions are varied due to the change of the room
condition, the frequency must be initialized according to the ΔD value of the indoor unit and the Q
value of the indoor unit.
Q value: Indoor unit output determined from indoor unit capacity, air flow rate and other factors.
1. P control
Calculate ΔD value in each sampling time (20 seconds), and adjust the frequency according to its
difference from the frequency previously calculated.
SM YUDE 2-A.1 GB
Definition
11-1