Si04-115
General Functionality
Main Function
21
1.3
Frequency Principle
Main control
parameters
The compressor is frequency-controlled during normal operation. The target frequency is set by
the following 2 parameters coming from the operating indoor unit:
"
the load condition of the operating indoor unit
"
the difference between the room temperature and the set temperature.
Additional
control
parameters
The target frequency is adapted by additional parameters in the following cases:
"
frequency limits
"
initial settings
"
forced cooling/heating operation.
Inverter principle
To regulate the capacity, a frequency control is needed. The inverter makes it possible to vary
the rotation speed of the compressor. The following table explains the conversion principle:
Drawing of
inverter
The following drawing shows a schematic view of the inverter principle:
Phase
Description
1
The single phase power supply in AC is converted into DC.
2
The single phase power supply DC is converted into a three phase chopped DC voltage
with a variable frequency.
"
When the frequency increases, the rotation speed of the compressor increases resulting
in an increased refrigerant circulation. This leads to a higher amount of the heat
exchange per unit.
"
When the frequency decreases, the rotation speed of the compressor decreases
resulting in a decreased refrigerant circulation. This leads to a lower amount of the heat
exchange per unit.
Min. frequency
A
J type
Max. frequency
B
J type
Cooling
34
Cooling
98
Heating
34
Heating
98
50 Hz
60 Hz
Refrigerant circulation rate (high)
Amount of heat
exchanged (large)
Amount of heat
exchanged (small)
AC
po
w
e
r
freq=
constant
max. freq.=
B
Hz
DC
po
w
e
r
Amount of heat
exchanged (large)
Amount of heat
exchanged (small)
high f
low f
min. freq.=
A
Hz
freq=variable
capacity=
variable
Refrigerant circulation rate (low)
high speed
low speed
(R1900)
