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High power IGBT traction drives
Marc DEBRUYNE/Master Expert Traction Systems
Summary
The ALSTOM main high power IGBT traction drives using PALIX water cooled power
modules are described, namely the AEM7 refurbished locomotives for Amtrak US, the Diesel
electric locomotives for Syria, Sri Lanka and Iran Railways and the series of 500 Freight
Europe electric locomotives for SNCF, which are part of our range of PRIMA locomotives.
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1. Introduction
When the first 3,3kV-1200A IGBT transistors appeared on the market in 1997, nobody could
imagine the place this component would take in high power traction drives. Today evidence is
that the GTO thyristor is no more the semiconductor switch that equips the electric traction
drives at the very beginning of the 21st century, the IGBT transistor takes over everywhere.
All the market segments from the electric bus to the most powerful locomotives definitely
chose the IGBT converters.
The research and development program initiated by ALSTOM in early 1997 with the help of
several laboratories and institutes has enabled us to master the use of high voltage IGBTs.
Innovative solutions had to come up to face the specificity of high power traction drives for
the railway applications. Since this time ALSTOM has got many references in high power
IGBT traction drives, namely the AEM7 refurbished locomotives for Amtrak US, the Diesel
electric locomotives for Syria, Sri Lanka and Iran and the series of 500 Freight Europe
electric locomotives for SNCF.
2
 range and the high power traction drives
2. ONIX
Usually we are used to defining the traction drive converters by the nominal power they are
able to control and their input voltage.
Converter Voltage (V)
4000
ONIX 3000
2000
ONIX 1500
ONIX 800
1000
500 Onix 350
100
200
500
1000
1500
Converter Power (kW)
Bus
Trolley
Tram
Metro
EMU
HST
Loco
From 1995 up to now ALSTOM Transport has been developing a comprehensive range of
IGBT converters for the traction applications: the ONIX range. ONIX extends from
350V-100kW up to 3kV- 1500kW.
The buses or trolley buses are fitted with compact water cooled ONIX 350 converters,
metros and trams are equipped with air cooled ONIX 800 rated at 400/600kW, EMUs with
air or water cooled ONIX 1500 or 3000 of 800/1000kW.
At the upper right part of the voltage-power plan the 4 axle locomotives are generally
powered with 4 independent drives of 1000/1500kW each. We consider that this voltagepower zone corresponds to the high power traction which will be described hereafter.
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3. Functionality for high power IGBT traction drives
There are no fundamental differences between a converter intended for metros or trams
compared with that one for a locomotive.
However the higher voltage of the DC bus and the larger electric energy stored within the
capacitors connected to the DC bus have to be considered carefully. As this energy increases
significantly potential dysfunction must be properly managed, mainly in case of
semiconductor short circuits.
As usual a safe IGBT-diode commutation must be ensured to guarantee a good reliability, the
components must stay inside the safe operating current-voltage area defined by the
manufacturer at any time, for any temperature. This can be done by a very low stray
inductance within the switching loop that has not to exceed about 100nH and by an
appropriate IGBT gate control. Due to the higher power and voltage the converter dimensions
are generally enlarged compared with those of low power, low voltage converters which do
not facilitate the IGBT commutation as the stray inductances are directly linked to the
volumes.
Functionality
Solution
Sub-assembly
Input capacitors
Laminated bus bars
Assure a safe switching
Power electronics
Decoupling capacitors
di/
di/dt control
Vce clamping
IGBT monitoring
Gate drives
Protect the traction drive
Short circuit detection
Vge clamping
For this reason the topology of IGBT modules and the input capacitors have to be carefully
designed so as to minimize this stray inductance. Multi terminal capacitors with an internal
inductance as low as 50nH, specially designed for these applications have to be used, the
connection of the capacitors to the IGBT modules is made by copper laminated bus bars
which represent a very small inductance. If necessary small decoupling capacitors
implemented very close to the IGBTs modules also contribute to suppress a part of the
commutation over-voltage. The technology of the bus bar is a sensitive point as voltage and
current go up. The partial discharges and the internal temperature have to be kept low to avoid
an aging of the insulation material. Today their maximum surface temperature is limited to
105°C, which imposes the use of thick copper layers which entail some mechanical
constraints. Studies are in progress to improve the technology so as to increase the operating
temperature.
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The gate drive is always a key element in the commutation process. For high power traction
drives several functions aim at better controlling the on and off switching in any circumstance
have been implemented, as di/dt control and/or collector-emitter voltage clamping.
In the high power traction drive applications particular care must be brought to fight against
DC bus capacitor short circuits in case of an IGBT failure as the current may reach very high
values. For this reason the collector emitter voltage is permanently monitored and compared
to the input signal coming from the controller, in case of IGBT desaturation or an abnormal
state, a special firing-blocking sequence strategy is initiated to minimize the consequences of
the failure, the idea being to switch off quickly the converter semiconductors to avoid a shootthrough. All types of converter short-circuits have to be mastered to end the sequences safely.
If it is rather easy to cut off a IGBT when is fired on a already established short-circuit (no
saturation), it is more difficult to control it when the short-circuit occurs during the on state of
the IGBT (desaturation), for that the gate-emitter voltage must be carefully controlled in
transient mode and kept below a certain value by a clamping device.
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4. Semiconductor evolution and IGBT transistors
6,5kV-600A
4,5kV-1200A
IGBT
3,3kV- 1200A
1,7kV-2x800A
1,6kV-1200A
GTO
1985
4,5kV-4000A
1990
1995
2000
2005
The first samples of IGBT for traction applications appeared in the early 1990’s. At that time
they allowed us to build converters for 600 and 750V DC lines with 1600V then 1700V
devices respectively. The high power converters started with the introduction in 1997 of the
3300V packs allows the direct operation with 1500V DC lines or regulated DC buses of
1800V up to 2000V. The 4,5kV IGBT which followed is mainly used in press-pack version to
replace the 4,5kV GTO thyristors in refurbishment applications where the DC bus is rated up
to 2,8kV as it was usual in most of the high power drives equipped with GTOs. The 4,5kV
module version with only a 6kv insulation between its baseplate and ground requires an
isolated heatsink that can be a drawback for traction use where the cooling system is generally
at earth. The 6,5kV IGBT insulated at 10kV promises an easy direct access to 3kV DC lines
thanks to a simplification of the power schemes, 3,3kV devices in series are no longer
necessary. This device is due to be delivered in series next year.
For the high power applications two IGBT packages have to be considered:
•
the well known modules which provide the insulation to the ground as those
commonly used for the urban and suburban vehicles,
•
the press-packs similar of those used for GTOs.
Some high power IGBTs
EUPEC
EUPEC
Module
Module
600A-6,5kV
600A-6,5kV
EUPEC
EUPEC
Module
Module
1200A-3,3kV
1200A-3,3kV
FUJI
PPI
PPI
1200A-4,5kV
1200A-4,5kV
TOSHIBA
TOSHIBA
PPI
PPI
1200A-4,5kV
1200A-4,5kV
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The IGBT press-pack can be a suitable solution for very high voltage applications whenever
several devices have to be connected in series. As with this kind of package technology a
failure always finishes by a short circuit not an opened circuit, in some cases presenting very
high thermal cycling constraints the press-packs may present an advantage as they use pressed
chips less sensitive to temperature variations
In the on going traction applications the power schemes do not use any more devices in series
due to the high voltage withstand capability, furthermore thanks to extensive study programs
(European RAPSDRA project) carried out by institutes and IGBT manufacturers the IGBT
module was made much more robust against thermo-mechanical constraints, the replacement
of copper by AlSiC in the IGBT baseplate goes in this direction.
At the end we are considering that the module package profiting of a large return of
experience in the urban domain remains with the current technology the best compromise in
terms of cost, simplicity of use, reliability requirements. The products presented hereafter are
exclusively built with IGBT modules.
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5. PALIX™ Range: power modules for high power applications
The development of high power, high voltage IGBT traction drives widely took advantage of
the large return of experience acquired in the urban and suburban applications and entailed
noticeable advancements in numerous fields of power electronics.
A new and comprehensive power module range, PALIX™, was created to answer any
traction power from 3 to 6MW, a new cooling system based on glycoled water plates enabled
to benefit the optimal performances from IGBTs while keeping a good thermal margin
assuring the high reliability level. Low stray inductance copper laminated bus bars allowing
high current flows had to be used to ensure a safe IGBT commutation, the passive
components, mainly the capacitors, progressed drastically making possible a compact lay-out
greatly appreciated in the railway high power traction drives as the space is always tight.
Water cooled power modules
for the PRIMA locomotive range
The PALIX™ water cooled IGBT modules have been developed with a high level of
standardization to ensure an important carry over between all the multi-voltage electric
locomotives of the PRIMA™ class and with the Diesel electric locomotives applications too.
The PALIX™ modules can cover all the needs of the power schemes of the PRIMA™ range.
5 of them are 6kV insulated; the last one benefits a 10kv insulation level for the 3kV line
applications.
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6. High power IGBT traction drive applications
It is difficult to be exhaustive, the following part quickly presents some key applications of
high power modules for traction systems, namely the AEM7 locomotives, first series of 6MW
electric locomotives equipped with IGBTs, the Diesel electric locomotives for Syria and the
large series of Freight locomotives for SNCF
6.1 AEM7 locomotives for AMTRAK
Amtrak, the American railway company, which run in the North East Corridor (NEC)
between Boston New York and Washington decided some years ago to refurbish a part of its
AEM7 passenger locomotive fleet. These locomotives originally had been fitted with DC
motor traction drives based on oil cooled thyristor controlled rectifiers.
AEM7 locomotive refurbishment
First IGBT series locomotive in the world
•ASEA traction drives
•Service in 1981
•DC motors
•Thyristor rectifiers
•Oil cooling
•Fleet: 53 locomotives
•ALSTOM traction drives
•Service in Feb 2000
•AC motors
•ONIX IGBT inverters
•Water cooling
•Fleet: 30 locomotives
They have been in commercial service since 1981.
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Customer:
Order:
Service:
Type:
Contract:
Supply:
Power:
Effort:
Max speed:
Bogie:
AMTRAK (US)
30 locomotives
Feb 2000
Boston-Washington
AEM7
Refurbishment with
IGBT AC drives
25 kV-60Hz
12,5kV-60Hz
12 kV-25Hz
~ 6000kW input
5000kW traction
4326kW regeneration
2290kW rheostatic
1375kVA auxiliaries
230kN @ 70kmh
125mph (~ 200kmh)
BoBo
Power scheme: 4 AC traction drives
4 PMCFs intercaled
4 motor inverters
1 auxiliary inverter
4 rheo choppers
Semiconductors: IGBT 3,3kV-1200A
Converter cooling: Glycoled water
Power modules: c NIX 1500-PALIX
Control:
AGATE Control
Motor:
1250 kW
15780 Nm at starting
1985rpm @125mph
Transformer: 7326 KVA
4 x 1050V
Tap changer
13,2 T
Mass:
91T
Attempts to equip these powerful locomotives, about 6000kW, with GTO based AC drives
failed due to a lack of volume left in the body. At the end an IGBT traction drive based on
PALIX modules was envisaged and its compactness ensured the project feasibility but it
was a real challenge to enter the electric equipment within such a narrow place due to the
short length of the body.
The AEM7 locomotives operate with three different supplies: 12,5kV and 25kV at 60Hz and
12kV at 25Hz. Each asynchronous traction motor delivers a traction power of 1250kW at 125
mph (200km/h). The electric braking is generally regenerative with a maximum power of
4300kW, limited to 2200kW in rheostatic mode.
The auxiliary power for the whole trainset is rated at 1375 KVA to ensure at any time a high
level of comfort to the passengers.
The auxiliary function always has priority over the traction, in case of failure of the auxiliary
converter the traction inverter N°2 is diverted to ensure the feeding of the three phase 480V60Hz network.
The input rectifiers are interlaced to reduce the line current distortion at a minimum
12,5 & 25kV-60Hz
12kV - 25Hz
ASM1
ASM2
480V-60Hz
1375KVA
ASM3
ASM4
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while the power factor is maintained to unity. The four intermediate 2kV buses are linked
together via the 2f (here 2*25Hz) filter inductances to equally share the power between the 4
input rectifiers.
The first locomotive was delivered in late 1999 and commercial service started in February
2000.
At this time fifteen passenger trainsets are daily running between the cities of Boston, New
York and Washington.
AEM7 Amtrak Locomotive
Traction Central Block
6.2 Diesel Electric Locomotives for Syria
This Diesel electric locomotive for Syria Railways is the first one of a large series of heavy
freight locomotives fitted with IGBT AC/AC traction drives.
The same mechanical lay-out with identical products have been used for the 10 units for SriLanka and for the 100 units for Iran Railways ensuring a optimum reference proven carry
over.
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INVERTER 1
ASM
ASM
ASM
Rectifier
Rheo Chopper
Diesel Engine
Main
Alternator
INVERTER 2
ASM
ASM
ASM
Rheo Chopper
The traction system is based on two independent traction drives. Each one via 3
PALIX modules controls 3 asynchronous motors in parallel. Another PALIX phase leg is
dedicated to the rheostatic chopper function in braking mode. The DC bus voltage varies from
900 to 1800V depending on the required traction power.
Since March 2000 an increasing fleet of more than 20 AD32C Diesel electric CoCo
locomotives haul daily 1800T heavy loads in Syria and ten similar ones have been in service
since September 2000 in Sri-Lanka. The first locomotive for Iran is due to be delivered in
early 2002.
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 Range
6.3 Prima
The dual voltage locomotive BB427000 is part of a large SNCF order of 500 Europe freight
locomotives to be delivered from 2001 until 2008.
All these locomotives are part on the new PRIMA range of ALSTOM locomotives which
can address the European market with its multi-voltage locomotives based on PALIX IGBT
traction drives.
For this family a high level of standardization is reached in any field to ensure a carry over as
high as possible between all traction drives whatever the line voltage involved.
Effort (kN)
500
450
Starting effort: 320kN
Max speed: 140km/h
Tractive power: 4200kW
Braking power: 2600kW
Weight :90t
400
350
300
250
200
150
100
Rheostatic or regenerative braking
50
0
0
10
20
30
40
50
60
S
70
80
d (k /h)
90
100
110
120
130
140
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The different power schemes of the PRIMA locomotive range were studied as early as
1997/1998 as a whole with the goal to reuse a maximum of parts and sub-assemblies.
All the PRIMA schemes can be covered with only 4 PALIX modules fitted with proven
3,3kV-1200A IGBTs whatever the voltage line. For example, with 3kV line an innovative
scheme named “PMCFs series” was developed. The aim was to keep the DC intermediate bus
at 1800V with its negative pole always linked to ground, this procedure avoids an overinsulation and allows the reuse of a large part of components sized for 1500V line, namely
DC bus capacitors, PALIX inverters,
DJ(C)
25 kV-50Hz
15 kV- 16Hz 2/3
3000 V DC
1500 V DC
DJ(M)
PMCF 3kV
M1
PMCF & RH
}
Inverter
=
X3
~
380 V~
CVS-AUX
traction motors and auxiliary converters. Only the upper PALIX module used, as an input
rectifier, has to be 10kV insulated for 3kV lines.
Each motor block houses two independent axles drives plus a cooling tower located at the
right side. There are two motor blocks located against the lateral walls in the locomotive
body.
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BB427000: motor block for 2 axles
The two axle compartments and theirs components are strictly identical except the length of
the water pipes which have to be connected to their respective air-water radiators both located
within the cooling tower.
Recently, in May 2001, the first BB427000 dual voltage locomotives successfully passed the
SNCF validation and homologation tests allowing them to run on the RFF infrastructure
tracks. By the end of this year seventeen locomotives will be delivered, ten of them will start a
freight commercial service in December 2001.
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7 Conclusion
DEL/EL
Type
Customer
Power
Supply
Speed
Quantity
Delivery
Loc
AD32C
Syria Railways
2370kW
Diesel
120km/h
30
1999
Loc
AEM7
Amtrak
6000kW
12,5 & 25kV-60Hz
12kV-25Hz
200km/h
30
1999
Loc
AD27C
Sri Lanka
1900kW
Diesel
110km/h
10
2000
Loc
AD43C
Iran Railways
2877kW
Diesel
140km/h
100
2001
Motor
car
Fossil fuel
Bombardier
3700kW
Turbine
240km/h
1
2000
Loc
427000
SNCF
4200kW
25kV-50Hz
1500V
140km/h
415
2001/2008
Loc
437000
SNCF
4200kW
25kV-50Hz
15kV-16,7Hz
1500V
140km/h
54
2002/2008
Loc
437500
SNCF
4200kW
25kV-50Hz
1500 & 3000V
140kmh
31
2003/2008
Loc
NJT
New Jersey
Transit
2600kW
Diesel
160km/h
33
2003
Egypt Railways
700kW
Diesel
80km/h
30
2003
Loc
The number of high power IGBT traction drives is increasing daily. At this time about 70
locomotives with 700 PALIX™ modules operate but the total number of orders already
exceeds 760 units as shown in the reference chart. This represents a fleet of 7000 PALIX™
power modules up to 2008.
The 3,3kV-1200A IGBT is now a standard produced by several manufacturers. Its extensive
use in industrial and traction applications for high power converters makes it cost effective. In
the very near future the 6,5kV IGBTs will be available for mass production for 3kV
applications, compared with the 3,3kV devices. Its use will probably be smaller due to the
limited market addressed but it will allow us to jump a new step by a drastic simplification of
the power schemes.
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