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Evaluation of advantages of high-speed EMUsin the case of series 700 Shinkansen high-speed train

with IGBT applied traction systems

Yoshiyasu HAGIWARA, Mamoru TANAKA, Masayuki UENOCentral Japan Railway Company, Tokyo, Japan

1. IntroductionIn 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-speedrailway. As a pioneer of high-speed railway, the Tokaido Shinkansen had greatly affected thedevelopment of high-speed rail network in Europe. In addition to commercial success, the TokaidoShinkansen is also proud of its highly reliable operation. In fact, the average delay time per trainwas only between 0.4 and 0.6 minutes. This statistic figure includes the delay due to naturaldisasters 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. Interms of vehicle systems, power-distributed system, i.e., Electric Multiple Unit (EMU) system, hascontributed to the improvement of operational reliability with optimized redundancy and goodtraction performance. Historically, the Japanese high-speed train system, Shinkansen, has employedthe EMU system, which has a number of advantages such as maximum axle load reduction, adhesionforce utilization, efficient regenerative brake utility, low energy consumption, environmentalfriendliness, and good traction/braking performance. In contrast, European high-speed trains havemainly employed power-centralized system rather than EMUs. Recently, even in Europe, newpower-distributed high-speed trains have appeared, for the purpose of interoperability and operationon steep gradient routes. In fact, German ICE3 started revenue service in 2000, and French AGV isunder consideration. In addition, in the process of Taiwan high-speed railway project, the Japaneseinnovative high-speed series 700 Shinkansen train (Figure 1) successfully won the competition, evenin the mood that the team of other countries had great advantage. These recent events have indicatedthe 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. Inthe past, in spite of a number of merits of the power-distributed system, European railway engineerspointed out its demerits, such as the large amount of maintenance to use electrical equipment inquantities, l e s s comfortablepassenger cabin with noise fromthe underfloor traction equipment,and difficulties of high-speedcurrent collection with pluralpantographs. These comments areno longer a truth, and amisunderstanding of the innovativehigh-speed EMUs in the 1990s.

In the 1990s, power electronicstechnology such as the ACasynchronous motor drive systemand advanced material technologysuch as the large extrudedaluminum alloy body constructionhave been applied to innovativehigh-speed EMUs in Japan. As aresult, energy saving effect by thelightweight train, maximum axle load reduction, good running performance with high adhesionforce, high-speed running on steep gradient routes, efficient transport capacity and flexibility of trainconfiguration of EMU with optimum traction performance are noticed and utilized.

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In this paper, the advantages of EMUs will be examined quantitatively, in the actual case ofinnovative series 700 Shinkansen high-speed train in Japan. In addition, by focusing on powerelectronics technology for high-speed EMUs, the effect of application of IGBT to series 700 will beintroduced. Moreover, Japanese series 300 and series 700 EMUs and European EMUs, GermanICE3, will be compared from the viewpoint of traction system.

Table__Advantages and disadvantages of power-distributed and power-centralized systemNo. Item Power-

distributedsystem

Power-centralized

system

Merits of power-distributed system

1 Axle load _ _ Reduction construction cost, easier trackmaintenance

2 Unsprung weight _ _ Good riding quality3 Traction system _ _ Simple traction system, Installation only

underfloor and efficient use of cabin space,effective application of innovative electronicstechnology

4 Uti l iza t ion ofadhesion

_ _ High acceleration and deceleration, running onsteep gradients, running on low adhesiveconditions with rain or fallen leaves

5 Electric brake _ _ No brake wearing, efficient regenerative brake6 Changes of MT

ratio_ _ Flexibility for operational conditions with

optimum traction performance7 Changes of train

length_ _ Flexibility for demands with optimum traction

performance8 Initial cost of train _ _ Reduced by optimizing MT ratio,

compensation of initial cost by low runningcost

9 Maintenance costof train

___ _ Easy maintenance asynchronous motor, goodlife-cycle-cost, no dismantling motormaintenance, contacter-less, maintenance-freetraction control system, no brake wearing

10 Comfort of cabin ___ _ Noise reduction measures with IGBT, activesuspension control, body structure with noiseinsulation material

11 Reliability _ _ Optimized redundant system12 Train weight _ _ Lightweight traction system, Lightweight high

power AC motor13 Transport capacity _ _ No locomotive, all cars with a passenger cabin14 Current collection ___ _ Reducing of pantographs with high-voltage

bus lineNote___Excellent, __Good, __Fair, ____Improved for recent EMU with new technologies

2. Comparison of power-distributed and power-centralized systems and examination of advantagesof 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 lowmaximum axle load, good adhesion, running performance and transport capacity, but had problemsin comfort, maintenance and current correction at high speed. However, these problems have beendissolved for the recent innovative high-speed EMUs to provide a number of advantages required forhigh-speed trains. Details of these merits of EMUs will be examined quantitatively in this section.

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Table 2: Comparison of weight and output power of high-speed trainsPower system Power-distributed system Power-centralized systemTrain type Series 0 Series 700 ICE3 TGV-A ICE1 ICE2Max. axle load(as series 700:100%)

16t(140%)

11.4t(100%)

15t(132%)

17t(149%)

19.5t(171%)

19.5t(171%)

Configuration 16M 12M4T 4M4T M+10T+M M+14T+M M+7TTrain length 400m 400m 200_ 240_ 410m 205_Max. speed 220km/h 285km/h 330km/h 300km/h 280km/h 280km/hRated output power 11840kW 13200kW 8000kW 8800kW 9600kW 4800kWTrain weight 967t 708t 409t 490t 905t 410t

Power/Weight[kW/t](Series 700:100%)

12.2(66%)

18.6(100%)

19.6(105%)

18.0(97%)

10.6(57%)

11.7(63%)

Motor output power 185kW 275kW 500kW 1100kW 1200kW 1200kWMotor weight 876kg 390kg --------- 1450kg 1980kg 1980kgMotor power/weight[kW/kg] (Series 700:100%)

0.21(30%)

0.71(100%)

--------- 0.76(107%)

0.61(0.86)

0.61(0.86)

Motor type DC motor ACasynchro-nous motor

ACasynchro-nous motor

ACsynchro-nous motor

ACasynchro-nous motor

ACasynchro-nous motor

Year of commercialService

1964~ 1999~ 2000~ 1989~ 1991~ 1997~

2.2 Weight reduction effectThe 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 axlesthroughout 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 hasrealized a lightweight and compact traction system. In the power-centralized system, however, toobtain 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 2shows a comparison of weight and output power of high-speed trains. The maximum axle load ofpower-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 thanthat of power-centralized ICEs and DC motor driven Series 0 Shinkansen trains. In terms of tractionmotors, the power/weight ratio of AC motor is three times that of DC motor.

2.3 Running resistanceThe 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 runningresistance between series 700 Shinkansen train and TGV. In case of TGV, two train-sets are coupledto equalize length of passenger cars of the series 700. From Figure 2, in spite of the wide and tallbody 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 runningresistance.

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2.4 Energy consumptionThe 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 effectof low running resistance and regenerative brake system. Figure 3 shows a comparison of poweringand braking energy between series 700 Shinkansen and TGV. Figure 3 is the result of computersimulation of running between Tokyo and Shin-Osaka, which is 515km long, on TokaidoShinkansen line, at the maximum speed of 270km/h. As a result, the series 700 consumes runningenergy only 77% of that of TGV.

2.5 Brake energyIn terms of brake system, EMUs have a greatly advantage when compared to the power-

centralized system. In particular, the AC drive system makes a simple regenerative brake systemwithout brake resistors. Figure 3 also shows the result of computer simulation of brake energy inrunning between Tokyo and Shin-Osaka. As a result, it has been found that series 700 absorbsbraking energy only 74% of that of TGV. In addition to the total brake energy, the modes of brakingenergy are rather important. In the case of TGV, mechanical brake absorbs 77% of the total brakeenergy. Therefore, the wear of brake lining requires a large amount of maintenance work. Incontrast, in the case of series 700 Shinkansen, motor cars normally use regenerative brake andtrailers use eddy current disc brake (ECB), while using mechanical brake only when the speed is30km/h or lower to stop at a station. As a result, mechanical brake of series 700 absorbs only 3% ofthe total brake energy. In fact, the average running distance between replacements of brake lining isevery 60,000km to 1,000,000km in the case of Tokaido Shinkansen.

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2.6 Efficient use of adhesion force Because EMUs have a number of tractive axles, they can efficiently utilize adhesion forcethroughout the train-set. This is the most important factor for good traction performance. Todemonstrate the superiority of power-distributed system, the maximum speed, which is limited bythe adhesion coefficient and total axle load, is examined under different operational conditions. Tosimplify the conditions of calculation, assumption is set as shown in Table 3.

Table 3: Assumption for the case study of adhesion force and maximum speedPower-distributed system Power-centralized system

Motored car/Trailer 12M4T(Model of series 700)

(M+10T+M)_2(Model of 2 train-sets ofTGV)

Motored car in a train-set (%) 75% 17%

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Axle load of tractive axle 11t 17tNumber of tractive axles 48 axles 16 axlesTotal weight of tractive axles 528t 272tTrain length 400m 400mTrain weight 700t 700tRunning resistance Experimental result of series

700 ShinkansenExperimental result of series700 Shinkansen

Adhesion coefficient in drycondition (Figure 4)

Used for Shinkansen in drycondition

Used for Shinkansen in drycondition

Adhesion coefficient in wetcondition (Figure 5)

Used for Shinkansen in wetcondition

Used for Shinkansen in wetcondition

Steep gradient (Figure 6) 3% gradient 3% gradientFailure of a traction unit(Figure 7)

25% (3/12) traction down 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 inFigure 5; a low adhesion coefficient in wet condition in Figure 6; and failure of traction unit inFigure 7. These results are shown in Table 4. In the dry condition, both systems reach over300km/h, but in the conditions of wet, steep gradient or failure of traction unit, power-centralizedsystem cannot exceed 300km/h. In fact, the Tokaido Shinkansen takes into account the failure ofone traction unit under the wet condition in planning the traction performance. These resultsdemonstrate the high reliability of power-distributed system even in difficult operational conditions.

Table 4: Possible maximum speed in different operational conditionsPossible maximum speed

Power system Power-distributed system Power-centralized systemDry condition (Figure 4) 480km/h 370km/hWet condition (Figure 5) 360km/h 280km/hSteep gradient condition of3% in dry condition (Figure6)

330km/h 190km/h

1 traction unit failed conditionin wet condition (Figure 7)

320km/h 240km/h

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 train-set. 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-centralizedsystem has tractive axles in the slippery front car. Therefore, the average adhesion coefficientreduces. Wet condition test of ICE1 (Figure 9) shows that slip often occurs and tractive effortsuddenly drops. Therefore, it is supposed that the power-distributed system cannot obtain theexpected tractive effort on rainy days.

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3. Elimination of disadvantages ofpower-distributed system

In regard to power-distributed andp o w e r - c e n t r a l i z e d systems,European railway engineers pointedout the demerits of power-

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distributed system, such as the large amount of maintenance work of traction equipment, lesscomfortable passenger cabins, and difficulties of high-speed current collection. Recent innovativepower 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 torequire large amount of maintenance work. Recently, however, the innovative power electronicstechnology has developed the AC asynchronous motor drive system, which has no contactors inconvertors 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 ACdrive system accomplished reduction of maintenance. Moreover, each piece of the equipment of traction system has its own CPU. The monitoringfunction of operational conditions of the equipment and remote control function are also improved tomake maintenance work easier.

3.2 Improvement of comfort of passenger cabin To improve comfort, power electronics and microelectronics technologies apply to the tractionsystem to reduce noise. The lightweight traction system has also contributed to compensating theadditional weights of noise insulation and active suspension system, and reduced the weight andimproved 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 ahigh-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. Inthe power-centralized system, the front or end locomotive must be equipped with pantographs, andthe 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 noiseoutside the train.

4. Technological development of power-distributed systemThe power-distributed system readily takes advantage of innovation such as electronics

technology, and develops according to the advancement of power devices. For example, the series700 Shinkansen train uses innovative IGBT technology as the world first application to high-speedtrains, which improves higher harmonics and noise emission from the traction system by means ofhigher 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 havebeen realized for power-distributed systems. To study the effect of lightweight and high efficiency of power-distributed system, traction systemsof high-speed Shinkansen trains are compared in terms of systematic weight, power and energyconsumption. 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 IGBT-applied 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 700Composition of a train-set (No. of traction units)

12 motored cars and 4trailers(6 units)

10 motored cars and6 trailers(5 units)

12 motored cars and4 trailers(4 units)

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a) Traction transformer_kg_ 2600_6=13800 3080_5=15400 3100_4=12400b) Power convertor (kg) Re:2300_6=13800

CS:900_6=5400SL:710_6=4260Rf: 750_6=4500

2825_10=28250 1660_12=19920

c) Traction motor (kg) 820_48=39360 405_40=16200 390_48=18720d) ECB disc brake (kg) 280_32=8960 245_48=11760 245_16=3920e) Total weight of traction system (kg) (e=a+b+c+d)

91880 71610 54960

f) Weight comparison among train types (Series 100 = 100%)

100% 78% 60%

g) Rated power of a train-set (kW)

11040 12000 13200

h) Power/Weight ratio (kW/kg) (h=g/e)

0.12 0.17 0.24

i) Power/Weight ratio comparison among train type (Series 100 = 100%)

100% 142% 200%

Note) Re: Resistor, CS: Controller, SL: Smoothing Reactor, Rf: Rectifier

4.1.1 Effect of weight reduction Table 5 shows a comparison of weight, rated output and power/weight ratio of traction systems ofthe series 100, 300 and 700. As the series 100 uses a DC motor driven system, a number ofcomponents 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 series100. The series 300 also employs total weight reduction technologies, such as the extrudedaluminum alloy body and bolster-less bogie. Consequently, 25% of total weight of a train-set wasreduced to realize service operation at 270km/h. Furthermore, the series 700 succeeded in reducingthe weight of traction systems. As a result, 40% of weight reduction and 200% of power/weightratio 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 train-set is similar to that of the series 300. The reason for this is that the lightweight traction systemcompensates for the additional weight of countermeasures to improve riding comfort and quietnessfor passengers, such as noise insulation materials, semi-active anti-vibration controllers anddampers. Figure 10 shows a comparison of weight of Shinkansen trains. For the riding comfort andquietness for passengers, thetraction system contributesdirectly to reducing the higher-harmonics and magnetstrictivenoise, and also indirectly toreducing the weight andcompensating for the weightincrease in the car body.

Table 6: Comparison ofenergy consumption inrunning between Tokyo andShin-Osaka of the series 100, 300and 700 (including

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regenerative brake)Items Series 100 Series 300 Series 700

220km/h operation 18.9MWh 16.9MWh 15.2MWhComparison of energy consumption in 220km/hoperation among train types (Series 100 =100%)

100% 89% 80%

270km/h operation ---------- 21.2MWh 19.4MWhComparison of energy consumption in 270km/hoperation among train types (Series 300 =100%)

---------- 100% 92%

4.1.2 Effect of higher efficiency Table 6 shows a comparison of simulation results of energy consumption in running betweenTokyo and Shin-Osaka of the series 100, 300 and 700. Because of the improved efficiency oftraction system, reduction of running resistance and effectiveness of utility of regenerative brake by12 motored cars, energy consumption is improved by 20% when compared to the series 100, and by10% when compared to the series 300. This contributes to the reduction of running cost in the longrun.

4.2 Japanese and German power-distributed systems, series300, series700 Shinkansen train andICE3 Recently, to adapt to interoperability and steep gradient running, the innovative power-distributedtrain, German ICE3, appeared in Europe. In terms of composition of traction systems, the system ofICE3 is similar to that of series 300 Shinkansen train. Figure 11 summarizes trajectory of thechanges 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.

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4.2.1 Comparison of traction systems

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Figure 12 also compares traction systems of ICE3 and series 700, based on that of series 300Shinkansen train. The traction unit composition of ICE3 resembles that of series 300, with threecars, two motored cars and one trailer (M1, Tp, M2). To make the best weight balance in a train-setand to reduce the maximum axle load, heavy electrical equipment, one traction transformer and twotraction converters are mounted on three different cars. As for 700 series, to reduce the cost andtotal weight, the number of traction unit is reduced to four from five of the series 300. The tractionunit 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 weightbalance 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

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of a traction motor is 275kW (Figure 13). Both the PWM convertor and PWM inverter apply three-level control method. Both the pressedpackage type IGBT and module type IGBT are used for the power converter. Specifications of thepower 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 ofICE3, the power/weight ratio increased to almost 20kw/t, which is close to the levels of series 300and 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.

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5. Conclusion To demonstrate the superiority of power-distributed system, EMUs, this paper examined weightreduction effect, environmentally friendliness, energy saving effect and good traction performancewith efficient use of adhesive force. As mentioned above, to realize highly reliable high-speed andhigh 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, goodadhesion utilization, efficient regenerative brake, low energy consumption, environmentalfriendliness, and good traction/braking performance. These features are suitable and required forhigh-speed trains.(2) Because of the application of AC drive system, recent high-speed EMUs have solved long-lasted 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 tractionsystem. The power-distributed system readily realizes the merit of new technologies. As for thepower-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 practicaldifferences in the traction performance between power-distributed and power-centralizedsystems. Operation at the speed over 300km/h is possible.(5) In contrast, in wet condition or steep gradient condition, it is difficult for the power-centralized 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 Japaneseseries 300 and 700 and German ICE3 have reached this level.(7) The power electronics technology will continuously advance in the future. The power-distributed system will enjoy the merits of innovation and will improve according to theinnovative electronics technologies.(8) For highly-reliable, high-frequency, high-speed operation at the speed over 300km/h, thepower-distributed system is the best solution

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<References>1) Ito J., �Conceptual design of rolling stock for Taiwan high-speed railways�, 19992) Ito J. and UENO M., �Optimized use of adhesion with power-distributed system�, JREA Vol.42

No.5, 19993) Hagiwara Y., �Technological development of an IGBT applied traction system for the series 700

Shinkansen train�, ERRI conference of light weight low-cost passenger rolling stock, 19994) Hagiwara Y.,“Technological trend of innovative AC drive system”, JORSA Japanese railway

information No.86, 19995) Wolfram M. and Theo R., �ICE High-tech on rails, third edition�, 1996