5
6
50
0
30
60
90
120
60
70
80
90
Rotational speed (rps)
AC motor
Conventional
DC motor
Reluctance DC motor
Motor efficiency (%)
Small load
Large load
Low capacity
High capacity
More than 20%
Power
source
Raise frequency
Lower frequency
Low-speed rotation
High-speed rotation
Compressor
Compressor
Inverter Power Control
Non-inverter type air conditioner
High
capacity
Low
capacity
Power
source
Constant speed
rotation
Fixed capacity
Inverter Advantages Compared to Non-Inverter
PAM Control
What Is DC Inverter?
Daikin calls an inverter model that is equipped with a DC motor DC Inverter. A DC motor offers higher efficiency
than an AC motor. A DC motor uses the power of magnets to attract and repel to generate rotation. A DC motor
that is equipped with high-power neodymium magnets, which enable even greater efficiency, is called a Reluctance
DC motor.
Energy-Saving Technological Features
Swing Compressor
Reluctance DC Motor for Compressor
Daikin DC Inverter models are equipped with
the Reluctance DC motor for compressor. The
Reluctance DC motor uses 2 different types of
torque, neodymium magnet*
1
and reluctance
torque*
2
. This motor saves energy by generating
more power with a smaller electric current than
AC or conventional DC motors. It is more
efficient at the low frequencies most commonly
used by air conditioners,*
3
improving efficiency
by approximately 20%.
DC Motor for Fan
The DC motor allows fine rotation
control, which reduces energy
consumption. The motor also
provides improvements in
operational efficiency of up to 40%,
compared to an AC motor. These
improvements are particularly
noticeable in the low-speed range.
*1. A neodymium magnet is approximately 10 times stronger than a standard ferrite
magnet.
*2. The torque created by the change in power between the iron and magnet parts.
*3. The frequency range used by air conditioners during periods of stable operation.
This is the range in which air conditioners operate for the longest periods.
The swing compressor can
reduce operational vibration and
sound because its piston moves
smoothly inside the compressor.
Swing bush
Integral piston of
blade and roller
Refrigerant gas
Neodymium magnets are used
in the pink-coloured area.
Reluctance DC motor
Swing compressor
Thanks to its smooth rotation, the
swing compressor decreases
friction and vibration. It also
prevents the leakage of
refrigerant gas during
compression. These advantages
provide quiet and efficient
compression.
PAM (Pulse Amplitude Modulation)
control reduces energy loss by
controlling how often the converter
switches on and off.
Inverters are devices that are able to vary their operating capacity by adjusting frequency. Inverter air
conditioners can vary their cooling capacity by adjusting the power supply frequency of their compressors.
In contrast, non-inverter air conditioners have a fixed cooling capacity and can only control the indoor
temperature by starting or stopping their compressors.
Efficiency of Reluctance DC motor
*
4
Inverter air conditioners are able to vary their operating capacity. Non-inverter air conditioners can
only operate at a fixed capacity.
This diagram is a representation for illustrative purpose only.
Variable Capacity Operation
Comfortable Temperature Control
Too cool
Not cool
During cooling operation
Compressor off
Non-inverter type
Inverter type
Cools a room
in less time
Small temp.
difference
Compressor off
Temp.
Starts
Time
Set
temp.
Energy Saving
After the indoor temperature
approaches the set temperature,
Inverter Control adjusts to low
capacity operation to maintain this
temperature. This makes inverter
models more energy-saving than
non-inverter models, which must
repeatedly start or stop their
compressors to maintain the room
temperature.
Comfortable
Inverter air conditioners finely adjust
capacity according to changes in the
air-conditioning load and the difference
between the indoor temperature and
set temperature is small. These give
higher comfort levels than with non-
inverter air conditioners.
Powerful
Inverter air conditioners operate at
maximum capacity as soon as they
start up. As a result, the set
temperature can be reached more
quickly.
Energy Savings
200
300
400 500
600
700 800
900 1000
0
20
40
80
60
100
Efficiency (%)
Motor speed (rpm)
AC motor
Approx.
40%
increase
Approx.
20%
increase
DC motor
*5. Data are based on studies conducted
under controlled conditions at a Daikin
laboratory using Daikin products.
*4. Data are based on studies conducted
under controlled conditions at a Daikin
laboratory using Daikin products.
Efficiency of DC motor for fan
*
5
(comparison with a conventional AC motor )
