Alstom in cooperation with French National Railways (SNCF) is developing a new design of TGV called AGV. It will be the first articulated high-speed train with distributed traction rather than power cars at each end. Prototype AGV cars are under construction and should be ready to start testing in March 2001.
THERE are a number of reasons why Alstom is keen to develop the AGV, which stands for Automotrice à Grande Vitesse. It perceives a commercial need to increase the maximum speed of TGV from 300 to 350km/h but with the same operating performance and cost as a 300km/h train. Advances in technology now make this possible. AGV will have 9% more capacity within the same length of train (200m) than a conventional TGV.
AGV will combine the best elements of TGV and things such as eddy current brakes developed for the former TGV New Generation project, and introduce distributed traction. This would enable Alstom to meet the recently-announced aspirations of the president of French National Railways (SNCF) and the chairman of German Rail (DB) to draw up jointly specifications for the next generation of high-speed trains to reduce development and procurement costs (IRJ February p3). Alstom is keen for AGV to be a contender for the new TGV Est Européen project.
Alstom will bid for the contract to supply between 26 and 40 trains to Spanish National Railways (Renfe) for the new Madrid--Barcelona high-speed line. "Renfe would like to achieve a 2h 15min journey time for the 651km Madrid--Barcelona trip to compete effectively with air," Mr Georges Palais, Alstom';s high speed product manager, told IRJ in Paris. "We could achieve this with 350km/h operation, with an allowance for recovery time."
The key element from TGV which will be retained in AGV is the articulation and the articulated bogies, as Palais explained. "The goal is to conserve the articulation because of its excellent ride characteristics and good safety record." The articulation performed well in two derailments involving TGVs. The trains remained upright and in alignment with track.
Distributed power high-speed trains are not new. The Japanese Shinkansen family of trains has always had distributed power, as has the Italian Pendolino, and now ICE 3, the latest generation of German high-speed train. However, as Palais pointed out, "it has only recently become possible to marry distributed power with articulation while keeping within the 17 tonne axleload restriction, which is the European standard." This is thanks to the advent of new power semi-conductors of the IGBT type. "The potential gains in mass resulting from this type of component now mean that it is possible to design an articulated train capable of operating at speeds in excess of 320km/h," Palais said. AGV will therefore have Alstom';s Onix IGBT traction system. However, technology has not advanced enough yet to allow a double-deck AGV.
AGV train configurations will be based on a module of three coaches with two powered bogies (each axle driven by a 600kW asynchronous motor) and a trailer bogie. This makes it possible to produce various formations which each have virtually the same traction and braking performance. Thanks to the variable sizes of traction equipment, it is possible to add non-powered trailer coaches to permit seven, 10, and 14-car trains. There will be only two types of coach: one with a driver';s cab and an intermediate coach.
The result is that a 200m-long 10-car AGV will have only 11 bogies compared with 13 on a 10-car TGV Réseau set (two power cars and eight trailers), which should reduce rolling noise. AGV will seat 411 passengers compared with only 377 in a TGV Réseau, so the cost per seat should be less with AGV.
AGV represents a number of technical challenges. As Palais was quick to point out: "It would be unthinkable to increase the operating speed while at the same time reducing the level of dynamic comfort in the trains or imposing additional stresses requiring increased track maintenance. Any increases in speed must be achieved while offering the same level of comfort as that obtained with TGVs running at 300km/h on the same quality of track."
Alstom has therefore developed an active lateral suspension system, which will be fitted to each trailer bogie, to stabilise the coach laterally in relation to the movement of the bogie on the track. An electric actuator will maintain the coach body virtually within the axis of the bogie thereby avoiding contact with the stops. This re-centring will make it possible to soften the secondary suspension which should increase comfort during alignment. The electric actuators will be controlled to stabilise low and medium frequency lateral movements of the car body in relation to the bogies. In addition, the level of comfort does not vary according to the position of the coach in the train.
Alstom has fitted active lateral suspension and electric actuators to a TGV Réseau and tested it at 350km/h on the Lille--Calais section of TGV Nord Europe. The dynamic comfort at 350km/h matched that of a non-equipped train at 300km/h. Another set of tests will be conducted next month with a modified design of actuator.
Another key challenge is to brake a train from 350km/h effectively and economically without increasing the braking distance, which would reduce line capacity. Two motor bogies equipped with eddy current brakes were fitted to a TGV and tested by Alstom and SNCF at up to 350km/h. Eddy current brakes are able to produce an emergency braking effort of 20kN per bogie between 350 and 200km/h. Braking power is reduced to 10kN under normal braking conditions. On a line with 3-minute headways, these power levels are acceptable both in terms of heating the rails, and the vertical effort generated by the magnetic pull. Endurance tests were conducted in 1998, which proved the system. "We consider that this brake development is now finished," Palais told IRJ. The first and last bogies on a 350km/h AGV will have eddy current brakes.
As the traction motors on AGV will be suspended from the bodyshell directly beneath the passenger accommodation, this could lead to increased vibrations. "We have defined a silent block between the traction motor and the bodyshell which will eliminate the vibrations inside the vehicle," Palais explained.
Having a powered articulated bogie makes it difficult to use forced air cooling, so the motors will have a self-cooling system with a fan inside the motor. To solve the problem of dust ingress, a vortex will separate out the large particles.
The end cars on AGV will have the heaviest components, such as the 6.5-tonne transformer, to improve their stability at high speed. "AGV will have a lower centre of gravity on the leading coach than a TGV power car," Palais remarked. The end coaches will have three axles so the 17-tonne axleload will not be compromised.
AGV will utilise the same aluminium bodyshell technique developed for TGV Duplex. This will save 2 tonnes compared with a steel TGV bodyshell. The only major steel elements will be the inter-car gangways and the cabs. AGV will have the same crashworthiness as TGV Duplex and will be able to absorb up to 6MJ of energy.
Alstom recognises that operators now expect to refurbish the interiors of their trains more frequently than in the past, for example at five to seven year intervals. Alstom has developed a modular concept for the interior fittings that can be applied to all high-speed trains depending on the length of journey. Passenger areas are divided into zones with common mechanical and electrical interfaces. Zones include:
•toilet and baby changing areas
•information centre and conductor';s compartment
•office and conference room
•bar and at-seat meal service, and
•flexible areas so that the seating layout can be changed.
AGV will have a level floor throughout, unlike TGV where the floor rises over the articulated area. AGV will have wide doors to ease passenger flows.
Alstom is currently building two AGV prototype coaches fitted with AGV trailer and motor bogies. One coach will have a driver';s cab and the other will be an intermediate car. The two prototypes will be attached to four TGV Réseau coaches and a power car (taken from a set damaged in an accident) to form a test train. "This will enable us to test the dynamic performance of the train, the performance of the pantograph in relation to the articulated bogie, the behaviour of the motor bogie, and test the air cooling of the traction system," Palais explained.
While SNCF and Alstom have now moved on to the development of AGV, testing with the tilting TGV prototype is continuing, and a tilting version of AGV with a maximum speed of 320km/h is envisaged. "French regions such as Brittany and Limousin are interested in the tilting TGV," Palais explained. "This was why a demonstration was organised in these regions last month of the tilting TGV prototype equipped with electrical actuators and our command control system."
|
[复制链接]
发表于 2004-9-6 19:38:47
楼主
