Main Functions; Temperature Control; Frequency Principle - Daikin SUPER MULTI NX G Series Service Manual

Main Functions

1. Main Functions

1.1

Temperature Control

Definitions of
The definitions of temperatures are classified as following.
Temperatures
 Room temperature: temperature of the lower part of the room
 Set temperature: temperature set by remote controller
 Room thermistor temperature: temperature detected by room temperature thermistor
 Target temperature: temperature determined by microcomputer
Temperature The temperature of the room is detected by the room temperature thermistor. However, there is a
Control difference between the "temperature detected by room temperature thermistor" and the
"temperature of lower part of the room", depending on the type of the indoor unit or installation
condition. Practically, the temperature control is done by the "target temperature appropriately
adjusted for the indoor unit" and the "temperature detected by room temperature thermistor".
1.2

Frequency Principle

Main Control
The compressor is frequency-controlled during normal operation. The target frequency is set by the
Parameters following 2 parameters coming from the operating indoor unit:
 The load condition of the operating indoor unit
 The difference between the room thermistor temperature and the target temperature
Additional The target frequency is adapted by additional parameters in the following cases:
 Frequency restrictions
Control
 Initial settings
Parameters
 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:
Phase
29
Room temperature
 The illustration is for wall mounted type as representative.
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
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.
Room thermistor temperature
Set temperature
Description
SiUS12-928_A
Target temperature
(R12321)
Function and Control