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EC Fans
1
Overview
Leonardo Evolution units offer the possibility to choose between two
different types of Backward Curved Fans:
 Standard Asynchronous Fans on T**R units;
 Brushless Electronically Commutated Fans on T**V units.
Brushless electronically commutated fans lead to the greatest benefits.
2
Overview
EC (Electronically Commutated) fans, basing on “Brushless” technology, create
substantial advantages in terms of:
 Lower Running costs compared to the traditional backward curved fans;
 More flexibility on the adjusting of fan speed basing on the real needs of the
aeraulic circuit;
 High performance with low noise, thanks to a particular shape of this last
generation impeller;
 Starting current lower than nominal current;
 Continuous fan speed regulation from the microprocessor;
 Integration, thanks to the possibility of interfacing with the AFPS and Active
Floor System.
3
General Information
In any motor, either the rotor or the
stator, must have a rotating magnetic
field in order to cause the motor to turn.
This rotation can be accomplished by:
 Three-phase AC power;
 Single-phase power with some sort
of circuit element like a capacitor,
inductor, or resistance to synthesize a
second phase (that is timed differently
from the first);
 An electro-mechanical commutator
to switch power to different coil groups
as the motor turns.
4
General Information
There are limitations with each of the previous methods:
 Three-phase AC power is not available everywhere and the frequency and
voltage are constant, making the speed control difficult.
 Single phase power has all the characteristics of three-phase power. In addition,
phase-shifting methods produce a very imperfect rotating field, tend to
introduce considerable losses in the motor and produce a very weak starting
torque.
 An electro-mechanical commutator
solves several of the above problems.
It can accomplish wide-range speed
control, and it can provide high
starting torque. The limitation is that
the electro-mechanical commutator
has friction and wear problems that
reduce efficiency and require frequent
maintenance.
Also, a voltage controller has to be
used to accomplish speed control.
5
General Information
Power Supply
6
General Information
Electronic commutation potentially eliminates all the previous problems.
Power is pulsed on and off electronically with semi-conductor devices; the pulsed
signals power three or more circuits or coil groups within the motor.
By varying the timing and duration of pulses, the electronic controller can
accomplish speed control and maintain high torque at start and over a
broad speed range.
Permanent Magnets
Coils
7
General Information
The EC motor is equipped with periferal
permanent
magnets
and
internal
electromagnets which are electronically
commutated.
The commutation is made by a power
transistor, therefore there are non mechanical
elements such as a collector of brushes which
would noticeably reduce the life.
In EC motors the magnetic field is generated
by the same rotor thanks to the presence of
permanent magnets. The commutation of the
magnetic field is electronic and consequently
free of wear and tear resulting from contact
between static and rotating parts.
The operating mode and the materials used
lead to an increased efficiency which is shown
in less absorption with the same performance.
8
Advantages of the EC motor
BRUSH DC motor
• it requires carbon brushes to commutate (drive) the motor
• limited operating hours, few 1000h
Startup Current = 3.5 x Nominal Current
BRUSHLESS DC motor (EC motor)
• no carbon brushes required
• extremely long service life, commonly over 80.000h
Startup Current < Nominal Current
9
Basic Principles of the EC motor
With the EC motor, the magnetic field is generated in the rotor itself by permanent
magnets.
Commutation is electronically and therefore without wear-and-tear.
Depending on their layout and the application, EC motors can be operated from:
• the DC power supply
• via an external / integrated commutation unit
• directly from an AC mains supply.
10
Characteristics
EC motors are controlled via PWM or linear (0-10 Vdc) input signal. There is an
open loop speed control so that the speed changes depending on the load.
Closed loop speed control is possible with integrated electronics.
There are inputs for potentiometers, 0-10 Vdc or PWM signals.
PWM (pulse width modulation)
A PWM signal is a square wave signal with a
variable pulse-pause ratio.
Linear closed loop /open loop speed control
At 0 Vdc, the motor is de-energised and does not
rotate. From 1 Vdc onwards, the motor starts to
run. Maximum speed is reached at 10 Vdc.
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Electrical Specifications
Input voltage range:
Frequency:
Input power:
Protection:
Control input
380-480VAC
50/60 Hz
max. 3kW
IP54
0-10 Vdc@100 kΩ
Ambient temperature: -20 bis +55°C
-20 bis +60°C
with cooling
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Electrical Connections
This is how the EC fan can be connected to the driving circuit.
As told before the main ways to control it is through the PWM or the 0-10V signal
Other ways (not used) are controlling the load (temperature) or at full speed or
through a potentiometer.
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Electrical Connections
QH1
QH2
QH3
commutation logic
T1
T1
T2
T3
T3
T4
T5
T5
T6
U
W
N
UDC
S
=
T2
T4
T6
V

0
14
Electrical Connections
0 -10 V
Input
3~ phase
main-supply
PE(2x)
0 - 10 V
Input
3~ Phase
main-supply
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Why using an EC fan?
The power input of an axial fan in EC technology is
compared to that of an axial 3-phase fan in figure 3,
With three different control modes used.
In the maximum air flow range, the EC motor
requires 15% less power input than the 3-phase
motor, which is due to its better efficiency.
When it comes to lower air flow values, especially in
the partial load range, then the advantage of the EC
technology get even more pronounced. This is
simply due to the fact that the EC motor has a high
efficiency across a wide speed range, whereas the
efficiency of the 3-phase motor quickly drops with
decreasing speed.
Power input in the partial load range is more than
50% lower than what the 3-phase motor requires.
Based on an average annual operation time of 4,000
h/a and the power saving , the annual saving in
costs by simply using an EC fan can be calculated
easily.
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Why using an EC fan?
Whenever a 3-phase fan is operated with
triac control or frequency converter, the
noise behaviour in the partial load range
gets negatively influenced.
This is illustrated, and comes as a result of
the oscillations in the electromagnetic fields
and deviations in electric
conductance
which form electro-magnetic harmonics
with their resulting power and torque
excitations.
The fan emits them in the form of air-borne
or structure-borne noise.
So far, and from an acoustic point of view,
the most harmless case has been operating
a 3-phase fan with a transformer.
The same positive noise behaviour can now
be achieved with EC fans, with phases and
their time sequence being impressed in a
suitable way.
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Why using an EC fan?
Electronically commutated motors also allow the advantages of “soft start” which
means lower inrush currents compared to nominal values.
The voltage range is much wider than that which is available for traditional motors
and due to a 0-10V input these fans can be regulated continuously.
This means that the speed can be selected from the user terminal or may be
integrated with the AFPS which can vary the speed based on the static pressure
present underneath the floor.
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Functioning
The Hall effect IC is a solid state electronic device with no mechanical
parts and therefore it is more reliable than a reed switch.
To no surprise it is now the most widely used sensor in industrial
brushless motors.
Normally, however, they include a lot of other components
When magnet #1 gets close to the Hall IC, the sensor sends a signal to the base of the
power transistor.
The transistor opens, and allows a bigger collector current to flow through the
electromagnet.
The electromagnet pushes magnet #3 away.
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Functioning
When the rotor spins away, magnet #1 stops affecting the Hall IC.
Since the signal to the base of the power transistor has been removed, it is turned off.
This disables the electromagnet.
The rotor continues to spin due to inertia until magnet #2 moves into the working
range of the Hall IC. The Hall IC sends a signal to the base of the transistor. The
transistor opens, and allows a bigger
collector current to flow through the
electromagnet. The electromagnet pushes magnet #4 away. This process continues
until the power is disconnected.
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Efficiency of Electric Motors
1
Shaded pole motor
2
Shaded pole external rotor motor
3
Q-motor (small refrigeration motor - shaded pole)
4
ASY motor (asymmetric shaded pole motor)
5
Single phase AC PSC motor *
6
Three phase AC motor *
7
JB motor (fully enclosed toroidal core motor)
8
EC motor with ferrite segments M3G150
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Losses
Induction motor
EC motor
rotor loss
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Power consumptions in CW units
Power consumption [kW]
Lower absorbed power respect to asynchronous motor, by
15% at full load and 45% as average, in a Uniflair CW units.
-100%
5
-57%
4
3
-45%
-90%
-47%
-80%
-45%
-48%
-70%
-60%
-50%
-40%
2
-30%
-20%
1
-10%
0
0%
1000
1200
BCF EC-fans
1700
BCF fans
2000
2500
delta %
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Power consumptions in CW units
E n erg y S av in g p er Y ear
En e rgy Sa v in g pe r Ye a r [€ ]
3000
2500
T *C V 1 0 0 0
T *C V 1 2 0 0
T *C V 1 7 0 0
T *C V 2 0 0 0
T *C V 2 5 0 0
2000
1500
1000
500
0
0 ,0 2
0 ,0 3
0 ,0 4
0 ,0 5
0 ,0 6
0 ,0 7
0 ,0 8
0 ,0 9
0 ,1
0 ,1 1
0 ,1 2
En e rg y C o s t [€ /k W h ]
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Power consumptions in DX units
Power consumption [kW]
Lower absorbed power respect to asynchronous motor, by 15%
at full load and 60% as average, in a Uniflair DX units.
5,5
-100%
-73%
4,5
3,5
- 36%
- 44%
-90%
-80%
-64%
-70%
-60%
2,5
-50%
-40%
1,5
-30%
-20%
0,5
-10%
-0,5
0%
721
1121
BCF EC-fans
1422
BCF fans
1822
delta %
25
Power consumptions in DX units
Energy Saving per Year
3000
Energy Saving per Year [€]
2500
T*AV0721
T*AV1121
T*AV1422
2000
T*AV1822
1500
1000
500
0
0,02
0,03
0,04
0,05
0,06
0,07
0,08
0,09
0,1
0,11
0,12
Energy Cost [€/kWh]
26
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