General Functions
SiBE04-101
20
Main Function
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 restrictions
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 supplied AC power source is converted into the DC power source for the present.
2
The DC power source is reconverted into the three phase AC power source with 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.
A
B
Cooling
50 class
102
32
60 class
96
28
71 class
84
28
Heating
50 class
108
54
60 class
98
40
71 class
108
34
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.=
A
Hz
DC
po
w
e
r
Amount of heat
exchanged (large)
Amount of heat
exchanged (small)
high f
low f
min. freq.=
B
Hz
freq=variable
capacity=
variable
Refrigerant circulation rate (low)
high speed
low speed
(R1226)
SiBE04-101.book Page 20 Monday, October 15, 2001 3:08 PM
