12-1
CONTROL SYSTEM
SM YBD018 1-A.1 GB
12. CONTROL
SYSTEM
12.1
Electronic Control
12.1.1
General Functions and Operating Rules (for single split models)
The DCI software is fully parametric.
All the model dependent parameters are shown in Blue color and with Italic style [
parameter
].
The parameters values are given in the last section of this control logic chapter of the service
manual.
12.1.2
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.
The capacity request is transferred via indoor to outdoor communication, and is represented by a
parameter called ‘NLOAD’. NLOAD is an integer number with values between 0 and 127, and it
represents the heat or cool load felt by the indoor unit.
12.1.3 Compressor
Frequency
Control
12.1.1.1 NLOAD setting
The NLOAD setting is done by the indoor unit controller, based on a PI control scheme.
The actual NLOAD to be sent to the outdoor unit controller is based on the preliminary LOAD
calculation, the indoor fan speed, and the power shedding function.
NLOAD limits as a function of indoor fan speed:
Indoor Fan Speed
Maximum NLOAD Cooling
Maximum NLOAD Heating
Low
Max NLOADIF1C
127
Medium
Max NLOADIF2C
127
High
Max NLOADIF3C
127
Turbo
Max NLOADIF4C
127
Auto
Max NLOADIF5C
127
12.1.1.1 Target Frequency Setting
The compressor target frequency is set by the following table, according to the NLOAD number
received from the indoor unit.
NLOAD
Target Frequency [Hz]
0 0
0 < NLOAD
MinFreq
MinFreq
>MinFreq
MinFreq
MinFreq}
ne)
LoadDeadZo
(NLOAD,
{min
MinFreq
ne
LoadDeadZo
MinFreq
MaxFreq
