Evaluation of advantages of high-speed EMUs
in the case of series 700 Shinkansen high-speed train
with IGBT applied traction systems
Yoshiyasu HAGIWARA, Mamoru TANAKA, Masayuki UENO
Central Japan Railway Company, Tokyo, Japan
1. Introduction
In 1964, Tokaido Shinkansen started the world first revenue service at high speed of over
200km/h. Since then, the Tokaido Shinkansen has demonstrated a successful business of high-speed
railway. As a pioneer of high-speed railway, the Tokaido Shinkansen had greatly affected the
development of high-speed rail network in Europe. In addition to commercial success, the Tokaido
Shinkansen is also proud of its highly reliable operation. In fact, the average delay time per train
was only between 0.4 and 0.6 minutes. This statistic figure includes the delay due to natural
disasters such as typhoon or earthquake. Therefore, there has been virtually no delay everyday.
This punctual operation has been accomplished by good liaison of highly reliable sub-systems. In
terms of vehicle systems, power-distributed system, i.e., Electric Multiple Unit (EMU) system, has
contributed to the improvement of operational reliability with optimized redundancy and good
traction performance. Historically, the Japanese high-speed train system, Shinkansen, has employed
the EMU system, which has a number of advantages such as maximum axle load reduction, adhesion
force utilization, efficient regenerative brake utility, low energy consumption, environmental
friendliness, and good traction/braking performance. In contrast, European high-speed trains have
mainly employed power-centralized system rather than EMUs. Recently, even in Europe, new
power-distributed high-speed trains have appeared, for the purpose of interoperability and operation
on steep gradient routes. In fact, German ICE3 started revenue service in 2000, and French AGV is
under consideration. In addition, in the process of Taiwan high-speed railway project, the Japanese
innovative high-speed series 700 Shinkansen train (Figure 1) successfully won the competition, even
in the mood that the team of other countries had great advantage. These recent events have indicated
the superiority and good performance of high-speed EMUs.
EMUs are becoming the mainstream of high-speed train, not only in Japan but also in Europe. In
the past, in spite of a number of merits of the power-distributed system, European railway engineers
pointed out its demerits, such as the large amount of maintenance to use electrical equipment in
quantities, l e s s
comfortable
passenger cabin with noise from
the underfloor traction equipment,
and difficulties of high-speed
current collection with plural
pantographs. These comments are
no longer a truth, and a
misunderstanding of the innovative
high-speed EMUs in the 1990s.
In the 1990s, power electronics
technology such as the AC
asynchronous motor drive system
and advanced material technology
such as the large extruded
aluminum alloy body construction
have been applied to innovative
high-speed EMUs in Japan. As a
result, energy saving effect by the
lightweight train, maximum axle load reduction, good running performance with high adhesion
force, high-speed running on steep gradient routes, efficient transport capacity and flexibility of train
configuration of EMU with optimum traction performance are noticed and utilized.
1
In this paper, the advantages of EMUs will be examined quantitatively, in the actual case of
innovative series 700 Shinkansen high-speed train in Japan. In addition, by focusing on power
electronics technology for high-speed EMUs, the effect of application of IGBT to series 700 will be
introduced. Moreover, Japanese series 300 and series 700 EMUs and European EMUs, German
ICE3, will be compared from the viewpoint of traction system.
Table__Advantages and disadvantages of power-distributed and power-centralized system
Merits of power-distributed system
No.
Item
PowerPowerdistributed centralized
system
system
1
Axle load
_
_
Reduction construction cost, easier track
maintenance
2
Unsprung weight
_
_
Good riding quality
3
Traction system
_
_
Simple traction system, Installation only
underfloor and efficient use of cabin space,
effective application of innovative electronics
technology
_
_
High acceleration and deceleration, running on
4
U t i l i z a t i o n of
steep gradients, running on low adhesive
adhesion
conditions with rain or fallen leaves
5
Electric brake
_
_
No brake wearing, efficient regenerative brake
6
Changes of MT
_
_
Flexibility for operational conditions with
ratio
optimum traction performance
7
Changes of train
_
_
Flexibility for demands with optimum traction
length
performance
8
Initial cost of train
_
_
Reduced b y
optimizing M T
ratio,
compensation of initial cost by low running
cost
___
_
Easy maintenance asynchronous motor, good
9
Maintenance cost
life-cycle-cost, n o
dismantling motor
of train
maintenance, contacter-less, maintenance-free
traction control system, no brake wearing
10
Comfort of cabin
___
_
Noise reduction measures with IGBT, active
suspension control, body structure with noise
insulation material
11
Reliability
_
_
Optimized redundant system
12
Train weight
_
_
Lightweight traction system, Lightweight high
power AC motor
13
Transport capacity
_
_
No locomotive, all cars with a passenger cabin
14
Current collection
___
_
Reducing of pantographs with high-voltage
bus line
Note___Excellent, __Good, __Fair, ____Improved for recent EMU with new technologies
2. Comparison of power-distributed and power-centralized systems and examination of advantages
of power-distributed system
2.1 Features of power-distributed and power-centralized systems
The features of power-distributed and power-centralized systems are listed in Table 1.
In the past, as indicated in Table 1, the power-distributed system, EMUs, took advantages of low
maximum axle load, good adhesion, running performance and transport capacity, but had problems
in comfort, maintenance and current correction at high speed. However, these problems have been
dissolved for the recent innovative high-speed EMUs to provide a number of advantages required for
high-speed trains. Details of these merits of EMUs will be examined quantitatively in this section.
2
Table 2: Comparison of weight and output power of high-speed trains
Power system
Power-distributed system
Power-centralized system
Train type
Series 0
Series 700
ICE3
TGV-A
ICE1
ICE2
Max. axle load
16t
11.4t
15t
17t
19.5t
19.5t
(as series 700:100%) (140%)
(100%)
(132%)
(149%)
(171%)
(171%)
Configuration
16M
12M4T
4M4T
M+10T+M M+14T+M
M+7T
Train length
400m
400m
410m
200_
240_
205_
Max. speed
220km/h
285km/h
330km/h
300km/h
280km/h
280km/h
Rated output power
11840kW 13200kW
8000kW
8800kW
9600kW
4800kW
Train weight
967t
708t
409t
490t
905t
410t
Power/Weight
[kW/t]
(Series 700:100%)
Motor output power
Motor weight
Motor power/weight
[kW/kg]
(Series 700:100%)
Motor type
12.2
(66%)
18.6
(100%)
19.6
(105%)
18.0
(97%)
10.6
(57%)
11.7
(63%)
185kW
876kg
0.21
(30%)
275kW
390kg
0.71
(100%)
500kW
-----------------
1100kW
1450kg
0.76
(107%)
1200kW
1980kg
0.61
(0.86)
1200kW
1980kg
0.61
(0.86)
DC motor
Year of commercial
Service
1964~
AC
asynchronous motor
1999~
AC
asynchronous motor
2000~
AC
synchronous motor
1989~
AC
asynchronous motor
1991~
AC
asynchronous motor
1997~
2.2 Weight reduction effect
The most important advantage of recent high-speed EMUs is the weight reduction effect. In
EMUs, the traction system equipment can be distributed over a train-set, and tractive axles
throughout the train-set can obtain the required tractive effort without executing a heavy axle load.
As a result, the maximum axle load is reduced. Particularly, recent power electronics technology has
realized a lightweight and compact traction system. In the power-centralized system, however, to
obtain the tractive effort, the axle load of locomotive must be heavier to avoid slip or skid.
Therefore, the innovative lightweight technology is of no use and has to be abandoned. Table 2
shows a comparison of weight and output power of high-speed trains. The maximum axle load of
power-centralized system becomes 50% to 70% heavier than that of series 700 Shinkansen EMUs.
The Power/weight ratio of a train-set of recent EMUs is around 20kw/t, which is 40% larger than
that of power-centralized ICEs and DC motor driven Series 0 Shinkansen trains. In terms of traction
motors, the power/weight ratio of AC motor is three times that of DC motor.
2.3 Running resistance
The total weight reduction, together with smooth surface of the train and aerodynamic nose shape,
contributes to the reduction of running resistance. Figure 2 shows a comparison of running
resistance between series 700 Shinkansen train and TGV. In case of TGV, two train-sets are coupled
to equalize length of passenger cars of the series 700. From Figure 2, in spite of the wide and tall
body cross-section to ensure a large seating capacity, the series 700 realizes low running resistance,
compared to that of TGV. That is, Shinkansen provides a high transport volume with low running
resistance.
3
2.4 Energy consumption
The total weight reduction also contributes to low energy consumption. Lightweight trains can
obtain high acceleration from low tractive effort. As a result, energy saving is achieved as the effect
of low running resistance and regenerative brake system. Figure 3 shows a comparison of powering
and braking energy between series 700 Shinkansen and TGV. Figure 3 is the result of computer
simulation of running between Tokyo and Shin-Osaka, which is 515km long, on Tokaido
Shinkansen line, at the maximum speed of 270km/h. As a result, the series 700 consumes running
energy only 77% of that of TGV.
2.5 Brake energy
In terms of brake system, EMUs have a greatly advantage when compared to the powercentralized system. In particular, the AC drive system makes a simple regenerative brake system
without brake resistors. Figure 3 also shows the result of computer simulation of brake energy in
running between Tokyo and Shin-Osaka. As a result, it has been found that series 700 absorbs
braking energy only 74% of that of TGV. In addition to the total brake energy, the modes of braking
energy are rather important. In the case of TGV, mechanical brake absorbs 77% of the total brake
energy. Therefore, the wear of brake lining requires a large amount of maintenance work. In
contrast, in the case of series 700 Shinkansen, motor cars normally use regenerative brake and
trailers use eddy current disc brake (ECB), while using mechanical brake only when the speed is
30km/h or lower to stop at a station. As a result, mechanical brake of series 700 absorbs only 3% of
the total brake energy. In fact, the average running distance between replacements of brake lining is
every 60,000km to 1,000,000km in the case of Tokaido Shinkansen.
4
2.6 Efficient use of adhesion force
Because EMUs have a number of tractive axles, they can efficiently utilize adhesion force
throughout the train-set. This is the most important factor for good traction performance. To
demonstrate the superiority of power-distributed system, the maximum speed, which is limited by
the adhesion coefficient and total axle load, is examined under different operational conditions. To
simplify the conditions of calculation, assumption is set as shown in Table 3.
Table 3: Assumption for the case study of adhesion force and maximum speed
Power-distributed system
Power-centralized system
Motored car/Trailer
12M4T
(M+10T+M)_2
(Model of series 700)
(Model of 2 train-sets of
TGV)
Motored car in a train-set (%) 75%
17%
5
Axle load of tractive axle
Number of tractive axles
Total weight of tractive axles
Train length
Train weight
Running resistance
11t
48 axles
528t
400m
700t
Experimental result of series
700 Shinkansen
Adhesion coefficient in dry Used for Shinkansen in dry
condition (Figure 4)
condition
Adhesion coefficient in wet Used for Shinkansen in wet
condition (Figure 5)
condition
Steep gradient (Figure 6)
3% gradient
Failure of a traction unit 25% (3/12) traction down
(Figure 7)
17t
16 axles
272t
400m
700t
Experimental result of series
700 Shinkansen
Used for Shinkansen in dry
condition
Used for Shinkansen in wet
condition
3% gradient
25% (1/4) traction down
2.6.1 Efficient adhesion used for highly reliable operation of power-distributed system
The power-distributed system contributes to highly reliable operation. To demonstrate this merit,
in addition to the considerations of dry condition in Figure 4, gradient resistance is considered in
Figure 5; a low adhesion coefficient in wet condition in Figure 6; and failure of traction unit in
Figure 7. These results are shown in Table 4. In the dry condition, both systems reach over
300km/h, but in the conditions of wet, steep gradient or failure of traction unit, power-centralized
system cannot exceed 300km/h. In fact, the Tokaido Shinkansen takes into account the failure of
one traction unit under the wet condition in planning the traction performance. These results
demonstrate the high reliability of power-distributed system even in difficult operational conditions.
Table 4: Possible maximum speed in different operational conditions
Possible maximum speed
Power system
Power-distributed system
Power-centralized system
Dry condition (Figure 4)
480km/h
370km/h
Wet condition (Figure 5)
360km/h
280km/h
Steep gradient condition of 330km/h
190km/h
3% in dry condition (Figure
6)
1 traction unit failed condition 320km/h
240km/h
in wet condition (Figure 7)
2.6.2 Efficient adhesion used for a train-set
Figure 8 shows accumulated actual data of occurrences of skid at different axle positions in a trainset. Figure 8 indicates that skid often occurs on front cars rather than on middle or end cars. That is,
the expected adhesion coefficient becomes low on the front car. Generally, the power-centralized
system has tractive axles in the slippery front car. Therefore, the average adhesion coefficient
reduces. Wet condition test of ICE1 (Figure 9) shows that slip often occurs and tractive effort
suddenly drops. Therefore, it is supposed that the power-distributed system cannot obtain the
expected tractive effort on rainy days.
6
7
3. Elimination of disadvantages of
power-distributed system
In regard to power-distributed and
power-centralized
systems,
European railway engineers pointed
out the demerits of power-
8
distributed system, such as the large amount of maintenance work of traction equipment, less
comfortable passenger cabins, and difficulties of high-speed current collection. Recent innovative
power electronics technologies have addressed and completely solved these problems.
3.1 Maintenance work reduction of electrical equipment
The power-distributed system has distributed power converters and traction motors. In the past,
DC motors were used for traction system, which required maintenance of brushes and contactors to
require large amount of maintenance work. Recently, however, the innovative power electronics
technology has developed the AC asynchronous motor drive system, which has no contactors in
convertors or no brushes in traction motors. As a result, problems in maintenance were dissolved.
In addition, a non-dismantling inspection line for AC traction motors is used in Japan, and the AC
drive system accomplished reduction of maintenance.
Moreover, each piece of the equipment of traction system has its own CPU. The monitoring
function of operational conditions of the equipment and remote control function are also improved to
make maintenance work easier.
3.2 Improvement of comfort of passenger cabin
To improve comfort, power electronics and microelectronics technologies apply to the traction
system to reduce noise. The lightweight traction system has also contributed to compensating the
additional weights of noise insulation and active suspension system, and reduced the weight and
improved the comfort of train-set.
3.3 Improvement of current collection in high-speed running
In the old power-distributed system, each traction unit has its own pantograph. As a matter of fact,
the Series 0 Shinkansen train-set has eight pantographs. Recent Shinkansen trains, however, have a
high-voltage bus line through the train-set, which connects the traction system and two pantographs.
In addition, the bus system takes advantage of the flexibility of pantograph position in a train-set. In
the power-centralized system, the front or end locomotive must be equipped with pantographs, and
the noise from the nose section and from the pantograph in use are mixed and increased. Therefore,
the flexibility of pantograph position of power-distributed system contributes to reduction the noise
outside the train.
4. Technological development of power-distributed system
The power-distributed system readily takes advantage of innovation such as electronics
technology, and develops according to the advancement of power devices. For example, the series
700 Shinkansen train uses innovative IGBT technology as the world first application to high-speed
trains, which improves higher harmonics and noise emission from the traction system by means of
higher switching frequency of IGBT and three-level control method.
4.1 Trend of weight reduction and performance improvement by traction system changes
Owing to utilizing innovative technologies, weight reduction and performance improvement have
been realized for power-distributed systems.
To study the effect of lightweight and high efficiency of power-distributed system, traction systems
of high-speed Shinkansen trains are compared in terms of systematic weight, power and energy
consumption. In this study, the series 100 Shinkansen train represents the DC motor traction system;
the series 300 represents the GTO applied AC drive system; and the series 700 represents the IGBTapplied AC drive system.
Table 5: Comparison of weight, rated output and power/weight ratio of traction system
of the series 100, 300 and 700
Items
Series 100
Series 300
Series 700
Composition of a train-set
12 motored cars and 4 10 motored cars and 12 motored cars and
(No. of traction units)
trailers
6 trailers
4 trailers
(6 units)
(5 units)
(4 units)
9
a) Traction transformer_kg_
b) Power convertor (kg)
2600_6=13800
Re:2300_6=13800
CS:900_6=5400
SL:710_6=4260
Rf: 750_6=4500
820_48=39360
280_32=8960
91880
3080_5=15400
2825_10=28250
c) Traction motor (kg)
405_40=16200
d) ECB disc brake (kg)
245_48=11760
e) Total weight of
71610
traction system (kg)
(e=a+b+c+d)
f) Weight comparison
100%
78%
among train types
(Series 100 = 100%)
g) Rated power of
11040
12000
a train-set (kW)
h) Power/Weight ratio
0.12
0.17
(kW/kg) (h=g/e)
i) Power/Weight ratio
100%
142%
comparison among train
type (Series 100 = 100%)
Note) Re: Resistor, CS: Controller, SL: Smoothing Reactor, Rf: Rectifier
3100_4=12400
1660_12=19920
390_48=18720
245_16=3920
54960
60%
13200
0.24
200%
4.1.1 Effect of weight reduction
Table 5 shows a comparison of weight, rated output and power/weight ratio of traction systems of
the series 100, 300 and 700. As the series 100 uses a DC motor driven system, a number of
components are equipped for the power conversion system and total weight of the system is 92ton.
The series 300 employs AC drive systems to realize lightweight and a high power traction system.
The total weight is 72ton, which reduces the weight more than 20% when compared to the series
100. The series 300 also employs total weight reduction technologies, such as the extruded
aluminum alloy body and bolster-less bogie. Consequently, 25% of total weight of a train-set was
reduced to realize service operation at 270km/h. Furthermore, the series 700 succeeded in reducing
the weight of traction systems. As a result, 40% of weight reduction and 200% of power/weight
ratio are accomplished, when compared to the traction system of the series 700.
The weight of traction system of series 700 itself is largely reduced, but the total weight of a trainset is similar to that of the series 300. The reason for this is that the lightweight traction system
compensates for the additional weight of countermeasures to improve riding comfort and quietness
for passengers, such as noise insulation materials, semi-active anti-vibration controllers and
dampers. Figure 10 shows a comparison of weight of Shinkansen trains. For the riding comfort and
quietness for passengers, the
traction system contributes
directly to reducing the higherharmonics and magnetstrictive
noise, and also indirectly to
reducing the weight and
compensating for the weight
increase in the car body.
Table 6: Comparison of
energy consumption in
running between Tokyo and
Shin-Osaka
of the series 100, 300
and 700
(including
10
regenerative brake)
Items
Series 100
220km/h operation
18.9MWh
Comparison of energy consumption in 220km/h 100%
operation among train types (Series 100 =100%)
270km/h operation
---------Comparison of energy consumption in 270km/h ---------operation among train types (Series 300 =100%)
Series 300
16.9MWh
89%
Series 700
15.2MWh
80%
21.2MWh
100%
19.4MWh
92%
4.1.2 Effect of higher efficiency
Table 6 shows a comparison of simulation results of energy consumption in running between
Tokyo and Shin-Osaka of the series 100, 300 and 700. Because of the improved efficiency of
traction system, reduction of running resistance and effectiveness of utility of regenerative brake by
12 motored cars, energy consumption is improved by 20% when compared to the series 100, and by
10% when compared to the series 300. This contributes to the reduction of running cost in the long
run.
4.2 Japanese and German power-distributed systems, series300, series700 Shinkansen train and
ICE3
Recently, to adapt to interoperability and steep gradient running, the innovative power-distributed
train, German ICE3, appeared in Europe. In terms of composition of traction systems, the system of
ICE3 is similar to that of series 300 Shinkansen train. Figure 11 summarizes trajectory of the
changes in the train concept and systems from series 0 Shinkansen to German ICE3, including ICE1,
ICE2, and series 300 and series 700 Shinkansen trains in the chronological order.
11
4.2.1
Comparison of traction systems
12
Figure 12 also compares traction systems of ICE3 and series 700, based on that of series 300
Shinkansen train. The traction unit composition of ICE3 resembles that of series 300, with three
cars, two motored cars and one trailer (M1, Tp, M2). To make the best weight balance in a train-set
and to reduce the maximum axle load, heavy electrical equipment, one traction transformer and two
traction converters are mounted on three different cars. As for 700 series, to reduce the cost and
total weight, the number of traction unit is reduced to four from five of the series 300. The traction
unit of series 700 is composed of four cars, three motored cars and one trailer (T, M2, M’, M1).
Like in the series 300, heavy electrical equipment is mounted on different cars to ensure weight
balance and a low axle load. That is, M1 car has one converter; M’ car has one traction transformer;
M2 car has two converters, and T car has auxiliary circuit equipment.
A traction transformer has three secondary winding traction circuits, and each circuit connects
PWM convertor and PWM inverter, then parallel four traction motors are driven. The rated output
13
of a traction motor is 275kW (Figure 13).
Both the PWM convertor and PWM inverter apply three-level control method. Both the pressed
package type IGBT and module type IGBT are used for the power converter. Specifications of the
power converter are 1,220V of input voltage, 1,030A of input current, 1,500Hz of career frequency
and 2,400V of DC stage voltage.
4.2.2 Comparison of traction performance
As shown in Table 2, the power/weight ratio of train-set is examined in Figure 14. In the case of
ICE3, the power/weight ratio increased to almost 20kw/t, which is close to the levels of series 300
and 700. It seems that power/weight ratio of 20kW/t is a standard level of current high-speed EMU,
but is almost twice that of power-centralized ICE1 and ICE2.
14
5. Conclusion
To demonstrate the superiority of power-distributed system, EMUs, this paper examined weight
reduction effect, environmentally friendliness, energy saving effect and good traction performance
with efficient use of adhesive force. As mentioned above, to realize highly reliable high-speed and
high frequency operation over 300km/h, the power-distributed system will be the best solution.
From this study, following results are induced.
(1) Recent high-speed EMUs take advantages of low maximum axle load, lightweight, good
adhesion utilization, efficient regenerative brake, low energy consumption, environmental
friendliness, and good traction/braking performance. These features are suitable and required for
high-speed trains.
(2) Because of the application of AC drive system, recent high-speed EMUs have solved longlasted problems in maintenance work, passenger comfort, and current collection. Therefore,
EMUs are now evaluated better than in the past.
(3) The power electronics technology realizes high-power, lightweight and compact traction
system. The power-distributed system readily realizes the merit of new technologies. As for the
power-centralized system, locomotives become heavier to avoid slip or skid. Consequently,
lightweight systems are of no use.
(4) From the viewpoint of adhesion performance, in dry condition, there are no practical
differences in the traction performance between power-distributed and power-centralized
systems. Operation at the speed over 300km/h is possible.
(5) In contrast, in wet condition or steep gradient condition, it is difficult for the powercentralized system to operate at the speed over 300km/h.
(6) The power/weight ratio of the latest high-speed train is around 20kW/t, and Japanese
series 300 and 700 and German ICE3 have reached this level.
(7) The power electronics technology will continuously advance in the future. The powerdistributed system will enjoy the merits of innovation and will improve according to the
innovative electronics technologies.
(8) For highly-reliable, high-frequency, high-speed operation at the speed over 300km/h, the
power-distributed system is the best solution
15
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Shinkansen train”, ERRI conference of light weight low-cost passenger rolling stock, 1999
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16