Daikin FTXS09HVJU, Service Manual

Page: 33 / 274

SiUS04-904 Main Functions
Function and Control 23
1. Main Functions
1.1 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 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 a DC power source.
2 The DC power source is reconverted into a three-phase AC power source with variable
frequency.

When the frequency increases, the rotation speed of the compressor increases resulting
in increased refrigerant circulation. This leads to a higher amount of heat exchange per
unit.

When the frequency decreases, the rotation speed of the compressor decreases
resulting in decreased refrigerant circulation. This leads to a lower amount of heat
exchange per unit.
50 Hz
60 Hz
Refrigerant circulation rate (high)
Amount of heat
exchanged air (large)
Amount of heat
exchanged air (small)
AC
po
w
e
r
freq=
constant
DC
po
w
e
r
Amount of heat
exchanged air (large)
Amount of heat
exchanged air (small)
high f
low f
freq=variable
capacity=
variable
Refrigerant circulation rate (low)
high speed
low speed
(R2812)