Reference Story
vacon ac drives save energy
in sugar centrifuge applications
Usina Continental chose Vacon Active Front-End solution for retrofitting
A sugar centrifuge equipped with an AC-drive-controlled
motor is a sweet combination. After hearing the many benefits
that Vacon AC drives can offer, Usina Continental* needed
no further sweet-talk to choose the drives for their retrofit
project. At their plant in Colômbia, São Paulo, in sunny Brazil,
a Vacon Active Front-End unit has excelled in running the
sugar centrifuge since the first harvest in 2007. An essential
element in winning the contract was Vacon’s cooperation with
Vorax Acionamentos Ltda.
Solutions for sugar centrifuge applications
Vacon offers two different solutions for the sugar centrifuge
application, an Active Front-End (AFE) solution and a
Fundamental Front-End (FFE) solution. Both are bidirectional
(regenerative) power converters for the front-end of a
common DC bus drive line-up. These front-end units convert
mains AC power into DC power. The power can be transferred
from the mains to a common DC bus and vice versa.
The Active Front-End uses an external LCL filter at the
input. This unit is suitable for applications where low mains
harmonics are required. The AFE is able to boost the DC link
voltage (default +10%) higher than the nominal DC link voltage
(1.35 x Un). The AFE needs an external pre-charging circuit,
but it does not need any external measurements to operate.
AFE units can be connected in parallel without any special
connections between the parallel units. Furthermore, these
units can be connected to the same fieldbus with inverters,
and be controlled and monitored via fieldbus.
The FFE (Fundamental Front-End) is a device that operates
as a diode bridge for motoring power and like an anti-parallel
thyristor bridge for regenerating power. In the FFE unit, IGBTs
are used instead of thyristors. A dedicated external choke
is used at the input. The FFE unit is suitable as a rectifying
device when a “normal” level of harmonics is accepted but
regeneration to the mains is required. This solution brings
many benefits over anti-parallel thyristor bridges: no
autotransformers are needed (for nominal DC link voltage
1.35 x Un), the maximum motor voltage is the same as the
supply voltage without an autotransformer, operation is
controlled in case of a supply failure, and spare parts are the
same as those used in the standard inverter of the same size.
The FFE needs an external pre-charging circuit, such as an
AFE unit. The FFE unit can be connected to the same fieldbus
with inverters, and be controlled and monitored via fieldbus.
Vacon AFE and FFE units - very energy-efficient
Vacon’s Active Front-End and Fundamental Front-End designs
using the IGBT technology are currently the most energy-
efficient types of AC drives available for the sugar centrifuge.
These solutions ensure optimum motor performance. The
AFE solution also ensures the lowest harmonics impact on
the main supply.
A consistently high power factor results in lower kVA demands
compared with other types of drive systems. This benefit is
especially noticeable with the batteries of centrifuges.
partner in Brazil since 1998, has a policy of keeping one AFE
unit in stock. So a fast delivery time made the difference in
the negotiations.
Vorax was responsible for the cabinet design, assembly,
commissioning and start-up of the centrifugal drives. Vorax
has 24 h service available.
Scope of delivery from Vacon to Usina Continental:
In cycling applications, e.g. in a centrifuge, a full regenerative
drive can restore power back to the mains network during
braking. This feature improves the efficiency of the system and
decreases mechanical wear and the need for maintenance.
The AC drive offers lower thermal losses and the option of
setting the operating speed over a wide range in order to
match the required process conditions.
For large centrifugal installations, multi-drive systems are
available. These provide further advantages such as lower
cost, space-saving benefits and improved energy efficiency.
Fast delivery time as a decisive factor
For Usina Continental, fast delivery was essential in their
retrofit project. This is where Vacon’s extensive partner
and distributor network shows its strength. Vorax, Vacon’s
LCL Filter:
LCL04605A0L010T
Active Front-End: NXA04605A0T02SFA1A2
Inverter:
NXI04605A0T0ISFA1A2
Additional information:
Supply Voltage: 440 Vca
Application:
Centrifuge Mausa MAC 1000 (Retrofit)
Cycles:
27 cycles/hour
Sugar Type:
VHP
* Usina Continental is part of the Group Santa Elisa Vale S/A,
one of the biggest sugar cane producers in Brazil and a global
leader in the production and commercialization of sugar, alcohol,
energy, plastic resins and other sugar cane derivatives. The
Group has plans for further investments to increase production
from 18 million to 35 million tonnes.
Vacon AC drives characteristics
Benefits
Innovative mechanical design, compact and robust
Less free space needed for installation
High level protection classes IP21 or IP54
High switching frequency
Low motor noise
Reduced motor temperature
Sensorless vector or closed loop vector control
High torque availability at low speeds
Active Front-End using IGBT technology - AFE
Not sensitive when connected to weak power supply
Power factor =1
Low harmonic emission, conforms to IEEE-519 Standard
Energy savings
Fundamental Front-End using IGBT technology - FFE
Cost-effective solution when regenerative operation is needed
and the harmonic level can be normal
Energy savings
Fieldbus communication
Many fieldbus adapters:
Profibus, DeviceNet, Modbus, CanOpen, Ethernet, etc.
Acceleration and deceleration control
Start current reduction
Less mechanical stress
Cover photo: Courtesy of Unica - Sugar Cane Industry Union
Tel. +358 (0)201 2121
Fax +358 (0)201 212 205
www.vacon.com
[email protected]
RS00079A
Vacon Plc
Runsorintie 7, 65380 Vaasa, Finland