Protection Devices for Aircraft Electrical Power Distribution Systems: State of the Art D. IZQUIERDO EADS and Universidad Carlos III de Madrid A. BARRADO, Member, IEEE C. RAGA, Student Member, IEEE M. SANZ, Member, IEEE A. L ´ AZARO, Member, IEEE Universidad Carlos III de Madrid The development of all electric aircraft (AEC) has provided new opportunities in the field of electronic devices and power electronics. One of the most interesting areas is focused on the protection devices field and the management of the loads by means of the solid state power controllers (SSPC). This is mainly due to the great increase of these devices in the electrical power distribution system architectures used in the new airplanes such as A380 and B787. This paper presents a survey of conventional and future trends of protection devices in onboard platforms. Moreover a virtual test bench is developed in order to analyze the potential problems that could appear by using SSPC in new onboard platforms. In addition an experimental validation with commercial SSPC and its model are presented. Manuscript received June 6, 2008; revised December 17, 2008; released for publication January 22, 2010. IEEE Log No. T-AES/47/3/941746. Refereeing of this contribution was handled by S. Mazumder. This work was partially supported by the Spanish Ministry of Education and Science through the research project DIMOS (Code: DP12006-14866-C02-02) and by a private contract with EADS-CASA, through the research project “HVDC Load Distribution System, phase II” (Code: 04-AEC0527-000050/2005) financed by the European Regional Development Fund (ERDF) via the Aerospace Sector Plan of the Community of Madrid. Authors’ addresses: D. Izquierdo, EADS, John Lennon Avenue, s/n, 28906 Getafe, Madrid, Spain, E-mail: ([email protected]); A. Barrado, C. Raga, M. Sanz, and A. L ´ azaro, Departamento de Tecnologia Electr ´ onica, Universidad Carlos III de Madrid, Grupo de Sistemas Electr ´ onicos de Potencia, Avda. Universidad, 30: 28911, Legan ´ es, Madrid, Spain. 0018-9251/11/$26.00 c ° 2011 IEEE I. INTRODUCTION Conventional aircrafts are evolving towards airplanes with a greater amount of equipment and electronic/electrical devices such as dc/ac inverters, dc/dc converters, and even electronic protections. In addition new technology developments in the fields of power electronics and microcontrollers provide important advantages. Both features have rekindled the concept of all electric aircraft (AEA) [1, 2]. In the AEA, mechanics, pneumatics, and hydraulics systems have been replaced by electrical ones. These changes provide better performance, lower maintenance, and higher overall efficiency [3—6]. However it is important to highlight that power electronic equipments have a major role in the new power distribution systems (PDS) since the power transferred to the load is processed almost three times [7]. The protection devices of these new PDS are one of the most interesting areas for power electronics systems since they are replacing conventional protection devices. The objective of this paper is described as follows. In Section II, onboard PDS trends are presented. In Section III, the onboard protections devices for all these PDS are reviewed and compared, like circuit breaker (CB), arc fault circuit breaker (AFCB), remote controlled circuit breaker (RCCB), and solid state power controller (SSPC). Particularly SSPC have drastically evolved over the last decade, and their use has been extended to new onboard PDS, since they are an attractive solution due to their advantages compared with conventional devices. Furthermore in Section IV the areas of interest for research groups related to SSPC in the onboard PDS have been presented. One of the main research fields is the modeling of the SSPC because simulation is a necessary tool in the analysis and design of the PDS. Thus in Section V, an SSPC model has been proposed and simulated in a virtual test bench. In addition in Section VI, this SSPC model has been validated with experimental measurement using a commercial SSPC. II. ALL ELECTRIC AIRCRAFT ARCHITECTURES The concept of AEA is being developed by different research groups of the European Union and the United States as well as by private companies. All of them are developing or have developed R&D projects/programmes focused on the definition and implementation of these types of architectures. In the late 1990s, the Division of Militaries Aircrafts of Northrop/Grumman developed the MADMEL project related to the PDS and the power management for building more electric aircraft [8]. A combat aircraft joint strike fighter (JSF), which includes more electric technology and a distribution bus of 270 V dc , is being developed by several American companies [9]. The 1538 IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 47, NO. 3 JULY 2011
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Protection Devices for Aircraft
Electrical Power Distribution
Systems: State of the Art
D. IZQUIERDO
EADS and Universidad Carlos III de Madrid
A. BARRADO, Member, IEEE
C. RAGA, Student Member, IEEE
M. SANZ, Member, IEEE
A. LAZARO, Member, IEEE
Universidad Carlos III de Madrid
The development of all electric aircraft (AEC) has provided
new opportunities in the field of electronic devices and power
electronics. One of the most interesting areas is focused on the
protection devices field and the management of the loads by
means of the solid state power controllers (SSPC). This is mainly
due to the great increase of these devices in the electrical power
distribution system architectures used in the new airplanes such
as A380 and B787. This paper presents a survey of conventional
and future trends of protection devices in onboard platforms.
Moreover a virtual test bench is developed in order to analyze
the potential problems that could appear by using SSPC in new
onboard platforms. In addition an experimental validation with
commercial SSPC and its model are presented.
Manuscript received June 6, 2008; revised December 17, 2008;
released for publication January 22, 2010.
IEEE Log No. T-AES/47/3/941746.
Refereeing of this contribution was handled by S. Mazumder.
This work was partially supported by the Spanish Ministry of
Education and Science through the research project DIMOS
(Code: DP12006-14866-C02-02) and by a private contract
with EADS-CASA, through the research project “HVDC Load
Distribution System, phase II” (Code: 04-AEC0527-000050/2005)
financed by the European Regional Development Fund (ERDF) via
the Aerospace Sector Plan of the Community of Madrid.
Authors’ addresses: D. Izquierdo, EADS, John Lennon Avenue,
the electric installations from overloads and short
circuits. In addition, the SSPC can protect the wire
with an I2t curve equally as it is performed by aCB. Other SSPC characteristics are high reliability
(life cycles), low power dissipation, and remote
control capability by means of software. Moreover
the devices based on power semiconductors like
SSPC provide fast response (instant trip), less
weight and lower susceptibility to vibrations in
comparison to electromagnetic and electromechanic
components such as CB, RCCB, and AFCB; see
Fig. 6. All these characteristics and benefits are a
consequence of the development in power electronics
and microelectronics [32—36]. It is remarkable that the
use of SSPC technology improves the PDS control
and wire-harness protection as compared with the
previous electromechanical devices. Because of
its small size it is possible to group SSPCs inside
equipment. This equipment can be located in a certain
area of the onboard system, close to the loads, and
it can be connected to the main dc bus by means of
a big gauge and a long wire. Finally the power is
Fig. 7. Secondary distribution constituted by SSPC.
TABLE I
Aircraft Electrical Protection Devices
CB AFCB RCCB SSPC
Remote Control X Xp p
Arc Fault Protection Xp
Xp
Mechanical/Electronic
(M/E) Device
M M M E
Wiring Reduction X Xp p
28 Vdc Applicationsp
Xp p
270 Vdc Applications X X Xp
delivered to the loads through a small gauge and short
wires, see Fig. 7.
Therefore this secondary power distribution line
provides electric power to the loads with shorter wires
and a lower gauge by means of the SSPC. This allows
us to minimize the weight and volume of the wires
in comparison with other kinds of protection devices
[34—36].
In summarizing Table I provides the comparison
between different aircraft electrical protection devices,
regarding their applications and capabilities.
IV. ONBOARD SYSTEMS WITH SOLID STATE POWERCONTROLLER TECHNOLOGY
SSPCs provide a similar behaviour to conventional
electro/mechanic contactors using solid state
technology. From the first SSPC design to the current
SSPC architecture, a noticeable evolution has been
introduced by the designers. In this way the solid state
technology was initially installed as a support to the
conventional mechanical systems prolonging the life
of the components and their reliability [37]. Before
the SSPC other similar devices appeared, for example,
the remote power controller (RPC), which combines
mechanical switch and MOSFET [38]; see Fig. 8.
The first patent of SSPC appeared at the end of the
1980s. In this patent a modern SSPC architecture with
several blocks was described. The main advantage
of the aforementioned SSPC was the load remote
control operation and the protection under overload
conditions [32].
IZQUIERDO ET AL.: PROTECTION DEVICES FOR AIRCRAFT ELECTRICAL POWER DISTRIBUTION SYSTEMS 1541
Fig. 8. RPC block diagram.
Fig. 9. Solid state dc power switch.
Furthermore in [39] is shown the new capabilities
of these devices like arc fault detection and the
reduction of bounce effect produced in the contacts
of the conventional contactors; see Fig. 9. This SSPC
was designed with thyristor technology.
In the SSPC field it is important to point out
different areas of interest inside the onboard system
from the research group’s point of view: applications,
operational problems, modeling, implementation, and
new capabilities. All these points are detailed in the
following paragraphs.
A. Applications
In 1992 the first commercial SSPC that appeared
was manufactured by DDC®, Fig. 10. These new
devices were recommended specially for applications
inside the more electric aircraft architectures as
they were able to work with voltage levels of
270 Vdc and 28 Vdc, for maximum current ranges
of 15 A and 25 A, respectively [40]. From the
introduction of these components, the application
of SSPC technology has begun to be considered
a key element to improving the PDS security as
well as the power management and distribution
inside aircrafts. Comparing with CBs the major
benefits of these devices are the switching time
(SSPC requires 3 ¹s, whereas CB needs 10 ms), thesimplicity of the control, and the state monitoring.
In addition the temperature stability, the reliability,
Fig. 10. SSPC block diagram manufactured by DDC®.
and the active control in the limitation of current are
improved [41].
In one of its different applications, the SSPC
has been evaluated with different levels of ionising
radiation or linear transference of energy. These tests
show how the SSPC is able to work with a radiation
level of 80 LET (linear energy transference), whereas
other electronic equipment (dc/dc converters) make
errors or even shut down under these conditions. This
shows the great potential of SSPC in the onboard
PDS [42].
Also modules of various SSPCs have been
included in the International Space Station (ISS).
These modules are constituted by two types of SSPC.
Each module can support loads powered by 120 Vdcand 28 Vdc because it distributes the electric power
and protects the wire [43]. These kind of modules
allow the use of a higher number of SSPCs with lower
size and weight in comparison with the conventional
protection systems and load-switching elements,
constructed by CBs and relays [36, 44]. At the same
time the evolution of the component has allowed
researchers to add new functions and capabilities to
the SSPC, which can be used to control loads with
variable frequency in ac [45, 46].
B. Operational Problems
In the short lifeline of the component some
problems have been identified. NASA has published
studies on cable security and how the activation levels
of I2t protection affect the correct working order.So high levels of the I2t curves are inefficient atdetecting arc fault, increasing the probability of wire
damage. By contrast a minimization of the level of
the I2t curves can also raise the probability of falsealarms [47].
Another problem which has been detected in the
SSPCs is related to the electronic systems/equipments
regards EMI. Function failures have been detected
due to the EMI events. These events produce
instant SSPC shutdowns, which interrupt SSPC
1542 IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 47, NO. 3 JULY 2011
Fig. 11. SSPC model block diagram.
Fig. 12. SSPC with thermal memory effect.
current and affect the load downstream. However
the SSPC does not report any information about
this state to the external bus. These failures are
a consequence of a great internal dependency on
electronics [48].
C. Modeling
To validate the behaviour of the SSPCs in the PDS
and/or with other types of protection, it is necessary
to model the SSPCs together with the rest of the
conventional protection devices. This allows us to
check the whole onboard PDS and the protection
system. Therefore it is possible to see the effects of
this kind of protection upon the rest of the systems
and to predict either failures or malfunctions [38].
Through models in the ISS electrical system the
influence of the MOSFET parasitic capacitances,
which have an important influence on the stability
of the system, have been proven. These capacitors
can provoke a coupling between the current control
loop, which controls the SSPC by means of an error
amplifier, see Fig. 11, and a downstream power
converter. This coupling can cause instability of the
whole system [49].
Another advantage of the performing model
of components is the possibility of including and
combining different effects like temperature evolution
in the protected wire (thermal memory), the effect of
Fig. 13. SSPC implemented with IGBT.
environmental temperature, or thermal heat dissipation
produced in the wire. All these factors depend on the
surroundings where the wire-harness and the SSPCs
are located; see Fig. 12 [50].
D. Implementation
SSPCs are commonly implemented with FET
technology, which presents yet another unsolved
problem related to current limitations. For this reason
the use of SSPC is now limited in architectures of
270 Vdc until 25 A. Beyond these levels the use of
electromechanical contactors is necessary [7]. Other
technologies that allow higher current levels are being
investigated, for example IGBT; see Fig. 13 [33]. This
technology also provides a reduction of the voltage
drop between the device terminals, and consequently
reduces power losses. In addition it has lower cost,
compared with the CoolMOS technology, and it is
also applicable in higher voltages scenerios.
It is remarkable that the increase of the current
levels can be confronted with other types of
semiconductors, like silicon carbide (SiC), that allow
us to increase the device operating temperature range
and its efficiency [51—54].
E. New Capabilities
Among the new capabilities the development
of the components which permit them to connect
big capacitive loads is especially notable. It is
possible to connect this type of load using a digital
SSPC by limiting the current level using foldback.
With this type of load connection, the maximum
current supplied to the load is limited and controlled.
Therefore during the switching of a load, the current
can be limited by 20% above the nominal current.
In this way the SSPC control circuit makes the
current level inversely proportional to the voltage in
the downstream load during the connection of the
load [55].
The limited current avoids the generation of
high peaks of voltage/current during the connection
of the loads; it also avoids possible short circuits
IZQUIERDO ET AL.: PROTECTION DEVICES FOR AIRCRAFT ELECTRICAL POWER DISTRIBUTION SYSTEMS 1543
Fig. 14. Current limiting SSPC.
Fig. 15. SSPC with “sleep mode.”
downstream in the SSPC. In addition this avoids
the transitions to the PDS of voltage and current
perturbations; see Fig. 14 [56]. Another new SSPC
capability is to avoid the load disconnections during
the switching of the power bus bars, a common
event in the onboard systems during the intervals of
distribution changes from one bus bar to another. This
phenomenon does not appear in the CB device as they
are connected mechanically to the bus bar, and they
do not depend upon an electronic control. However in
the SSPC, a lack of power supply in the SSPC control
area could lead to the disconnection of the load. In
Fig. 17. Voltage and current of connected capacitive load (10 −=25 ¹F) using two different SSPCs.
Fig. 16. Virtual test bench.
this way the load will not be powered even with
electric power above the SSPC after the distribution
bus bar is switched. So the new SSPC designs are able
to support lack of power periods within normative
limits by means of a “sleep mode,” see Fig. 15 [57].
Finally it is important to note that some features
of the SSPC like arc fault detection cause a great
amount of improvement. This capability is one of
the most important since arc fault is considered the
Modeling and stability analysis of a dc power system
with solid state power controllers.
In Proceedings of the Applied Power Electronics
Conference and Exposition (APEC’96), vol. 2, Mar. 3—7,
1996, 685—691.
[50] Barrado, A., et al.
SSPC model with variable reset time, environmental
temperature compensation and thermal memory effect.
In Proceedings of the Applied Power Electronics
Conference and Exposition (APEC ’08), Feb. 24—28, 2008,
1716—1721.
[51] Feng, X. and Radun, A.
SiC based solid state power controller.
In Proceedings of the Applied Power Electronics
Conference and Exposition (APEC ’08), Feb. 24—28, 2008,
1855—1860.
[52] Garuda, V. R., et al.
High temperature performance characterization of buck
converter using SiC and Si devices.
In Proceedings of IEEE Power Electronics Specialists
Conference (PESC’98), vol. 2, May 17—22, 1998,
1561—1567.
[53] Shenai, K.
Silicon carbide power converters for next generation
aerospace electronics applications.
In NAECON 2000, Oct. 10—12, 2000, 516—523.
[54] Chante, J. P., et al.
Silicon carbide power devices.
In Proceedings of International Semiconductor Conference
(CAS’98), vol. 1, Oct. 6—10, 1998, 125—134.
[55] Mussmacher, K. A. and Froeb, W. L.
SSPCs handle heavy loads with fold-back current
limiting.
National Hybrid Inc., Ronkonkoma, NY, Jan. 2003.
[56] Komatsu, M., Ide, N., and Yanabu, S.
A solid-state current limiting switch for application of
large-scale space power systems.
In Proceedings of IEEE Power Electronics Specialists
Conference (PESC’07), June 17—21, 2007, 1471—1476.
[57] Beneditz, B. D. and Donald, G. K.
Power interruption system for electronic circuit breaker.
US2006/0044723 A1, U.S. patent application publication,
Mar. 2, 2006.
[58] Lazarovich, D.
Arc fault detection for SSPC based on electrical power
distribution systems.
Honeywell International Inc., WO2004/073131 A1,
international application published under the patent
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[59] MIL-STD-704
Aircraft Electric Power Characteristics.
[60] DDC Data Device Corporation
Multi-channel power controller capabilities 28VDC
270VDC 115 VAC. 1 to 25 amps/channel.
1548 IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 47, NO. 3 JULY 2011
Daniel Izquierdo was born in Madrid, Spain in 1975. He received the M.Sc. andPh.D. degrees in electrical engineering from the Carlos III University of Madrid,
Spain in 2001 and 2011, respectively.
Since 2001 he has worked at EADS Company in the Electrical, Control, and
Monitoring System Department where he is actively involved in R&D projects.
Since 2005, he has been a part-time professor at the Carlos III University
of Madrid, Spain. His research interests include electrical power distribution
systems, electrical onboard protection devices, and more electric aircraft.
Andres Barrado was born in Badajoz, Spain in 1968. He received the M.Sc.degree in electrical engineering from the Polytechnic University of Madrid, Spain
in 1994 and the Ph.D. degree from the Carlos III University of Madrid, Spain in
2000.
Since 1994 he has been an associate professor at the Carlos III University
of Madrid, and since 2004 has been Head of the Power Electronics Systems
Group (GSEP). His research interests are switching-mode power supply, inverters,
behavioural modelling of converters and systems, solar and fuel cell conditioning,
and power distribution systems for aircraft.
Carmen Raga was born in Madrid, Spain in 1976. She received the M.Sc. degree
in 2005 in electrical engineering from the Carlos III University of Madrid, Spain,
where she is a Ph.D. student.
Her research interests are switching-mode power supplies, modelling and
control of switching converters, fuel cell conditioning, and power distribution
systems for hybrid electrical vehicles and aircrafts.
IZQUIERDO ET AL.: PROTECTION DEVICES FOR AIRCRAFT ELECTRICAL POWER DISTRIBUTION SYSTEMS 1549
Marina Sanz was born in Burgos, Spain in 1973. She received the M.Sc. andPh.D. degrees in electrical engineering from the Universidad Politecnica de
Madrid, Spain in 1997 and 2004, respectively.
Since 2001 she has been an assistant professor at the Electronic Department,
Universidad Carlos III de Madrid, Spain. Her main research interests include
switching-mode power supplies, modeling, and design of piezoelectric
transformers and engineering education.
Antonio Lazaro was born in Madrid, Spain in 1968. He received the M.Sc. inelectrical engineering from the Universidad Politecnica de Madrid, Spain in 1995.
He received the Ph.D. in electronic engineering from the Universidad Carlos III
de Madrid in 2003.
He has been an assistant professor of the Universidad Carlos III de
Madrid since 1995. He has been involved in power electronics since 1994,
participating in more than 30 R&D projects for industry. His research interests
are switched-mode power supplies, power factor correction circuits, inverters (ups
and grid connected applications), modelling and control of switching converters,
and digital control techniques.
Dr. Lazaro holds three patents and he has published nearly 100 papers in
IEEE journals and conferences.
1550 IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS VOL. 47, NO. 3 JULY 2011