Alstom has unveiled the prototype of the AGV (Automotrice Grande Vitesse), its fourth-generation very high speed electric train. This single-deck train features the Alstom’s articulated architecture used on the TGV combined with a new distributed drive system based on permanent magnet motors (the train’s motors being located on the bogies, under the train), an innovation which considerably increases the potential number of seats onboard the train by eliminating the need for locomotives.
The AGV is designed to reach a commercial speed of 360 kph (224 mph), and already has its first customer: Italy’s new railway operator, Nuovo Trasporto Viaggiatori.
The articulated architecture involves positioning the bogies (axles and wheels) between the carriages of a train, contrary to their traditional positioning under the carriages. This technology eliminates most of the vibrations and noise caused inside the carriages by the train running on the tracks, as well as damping any movement between the carriages.
The architecture also provides a safety advantage—the carriages being tightly meshed together renders the train as a whole more rigid. Thus in case of a derailment, it does not deform (unlike a non-articulated train which will have a tendency to fold up like an accordion); the AGV will remain upright and in one piece.
The main innovation for the AGV involves combining this articulation technology with a distributed drive system. The train’s motors are located under the floor of the carriages rather than concentrating them in dedicated locomotives at the front and back of the train. The removal of the locomotives increases the capacity of the train. For an equal train length, AGV trains have 20% more space than traditional trains.
Another innovation in the AGV is the use of synchronous permanent magnet motors to provide electro-dynamic traction and braking. When fitted with six drive bogies in an 11-car configuration (360 kph), the AGV generates power of 22.6 kW/ton, 23% higher than its main competitor.
The permanent magnet motors provide:
A power/weight ratio greater than 1 kW/kg versus 0.8 kW/kg for previous generations of motors and greater compactness for more convenient installation on the bogies;
Simpler ventilation circuits making maintenance easier and providing greater reliability;
Lower energy consumption, due to an efficiency ratio which is greater than that of an asynchronous electric motor and thanks to a highly simplified drive train.
The new architecture enables operators to vary the length of their trains (from 7 to 14 carriages, and from 250 and 650 seats) depending on demand.
With the AGV, 25% less bogies are needed than on non-articulated trains: in its 11-carriage configuration, the AGV only has 12 bogies versus 16 in competing trains. The cost of maintaining bogies accounts for around 35% of the total cost of maintaining a very high speed train. Another development example which is designed to reduce the cost of ownership: the wheels of the AGV were designed to provide 15% greater resistance to wear than those of the other trains on the market. This all means that overall, the maintenance costs of an AGV train are around 15% lower than those of its main competitors.
The AGV consumes 15% less energy than its main competitors, according to Alstom. The AGV emits 2.2 grams of CO2 per passenger km, 13 times less than a bus (30 grams), 50 times less than a car (115 grams) and 70 times less than a plane (153 grams), based on the rate of CO2 emissions per kWh of electricity produced in France.
The train’s motors are equipped with power electronics that enable the AGV to operate on all four types of railway electricity supplies in use in Europe: 1,500 Volts, 3,000 Volts, 15,000 Volts, and 25,000 Volts, the latter being more extensively used in the rest of the world.
The AGV is also capable of producing and using its own electricity. Its braking system consists of a combined rheostat brake and energy recovery brake. When the energy generated by the motors during the braking phase is not being consumed by the train, it can be fed back into the electric grid. During braking phases, the power which is fed back into the grid can reach 8 MW.
The AGV’s traction system has already been tested under extreme conditions, since it was used in the train which set the world rail speed record on 3 April 2007: 574.8 kph. (Earlier post.)
We have developed this train using our own funds, a very unusual approach in the railway industry, because we understood that the market for very high speed rail travel was about to diversify. In order to maintain our leadership, we needed to broaden and update our range of products. The AGV has arrived on the market just at the time when very high speed rail travel is undergoing a new expansion phase, not only in its traditional markets, but also in many developing countries.—Patrick Kron, Chairman and Chief Executive Officer of Alstom
The company has produced 70% of the very high speed trains which are currently running worldwide at speeds of 300 kph and above. Since the launch of the first TGV in 1981, Alstom has sold 650 very high speed trains.
Italy’s NTV, has placed firm orders worth €650 million (US$953 million) for 25 trains (with options for 10 more), and has signed a maintenance contract with Alstom. Production of the first trains will begin in mid-2008, and they will be delivered from 2010 onwards.