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360km/h train will be the first powered by PM motors

06 February, 2008

Alstom has unveiled its next generation of high-speed trains which, it says, will be the first to be driven by synchronous permanent magnet (PM) motors. The AGV (Automotrice à Grande Vitesse) is designed to operate at speeds of up to 360 km/h, compared to 320km/h for the current generation of TGV high-speed trains, and will consume 15% less power than its main rivals.

Alstom AGV train

Unlike previous high-speed trains, which use locomotive cars at the front and rear for propulsion, the AGV (shown above) has a distributed drive system with PM motors located under the floor of each carriage. This arrangement increases the capacity of the train, providing 20% more space than traditional trains of a similar length.

The rare-earth PM motors (below), developed at Alstom’s Ornans site, are a third smaller than asynchronous motors, and achieve a power/weight ratio of more than 1kW/kg, compared to 0.8kW/kg for previous-generation motors. They will operate with an efficiency of 97%.

Alstom AGV motors

The motors, controlled by water-cooled IGBT converters, operate in a regenerative mode during braking, returning up to 8MW back into the train’s power supply. Braking is achieved using a combination of rheostat and energy recovery braking. The motors have a simple ventilation design which is said to make them easier to maintain, as well as boosting their reliability.

The trains will be able to operate on four common supply voltages: 25kV, 50Hz; 15kV, 16.7Hz; 3kV DC; or 1.5kV DC. The total power consumption will be from 6–12MW, depending on the length of the train.

Another way that the AGV differs from previous designs is in its use of articulated carriages, with the bogies (axles and wheels) located between the carriages, rather than under them. Alstom claims that this design has several advantages, including lower noise levels, increased rigidity, and reduced maintenance.

The articulated design also allows trains to be formed from 7–14 carriages with a total of 250-650 seats. An 11-car version will have a power/weight ratio of 22.6kW/tonne – 23% better than its closest rival, according to Alstom.

Alstom AGV bogie

The articulated design requires 25% fewer bogies (shown above) than conventional trains, cutting maintenance costs – the cost of maintaining bogies typically represents about 35% of the total cost of maintaining a high-speed train. Overall, says Alsthom, the costs of maintaining the AGV will be about 15% lower than those of its main rivals.

The AGV makes widespread use of composite materials and will weigh around 70 tonnes – some 17% less than rival trains of a similar length. They will also use about 15% less energy. For a fleet of 100 trains, the electricity savings would be worth around €5m a year and carbon emissions would be 22,000 tonnes lower. According to Alstom, the CO2 emissions per passenger-km will be 2.2g, compared to 30g for a bus, 115g for a car and 153g for a plane.

The AGV’s novel traction system has already been tested at speeds of up to 574.8km/h – a record for rail travel, which was set last year. This represents a safety margin of more than 200km/h over the train’s commercial operating speed of 360km/h.

The Italian railway operator NTV has placed the first order for 35 AGV trains, with the option to buy ten more. The trains are due to be delivered from 2010.

Alstom claims to have built 70% of the world’s trains that currently operate at speeds of 300km/h or higher. Since the TGV was launched in 1981, it has sold 650 of the trains which, together, have carried 1.6bn passengers and covered 2bn km.

The company is confident that there will be a continuing demand for the AGVs. They can cover 1,000km in three hours, thus offering an attractive alternative to plane flights over such distances.

A further 6,000km of high-speed lines are due to be built across Europe by 2020, tripling the length of the existing high-speed network. China is expected to build 3,000km of high-speed railways within 15 years, while Argentina has recently announced plans to build a 710km-long line from Buenos Aires to Cordoba – the first high-speed line in Latin America. Other countries looking at building high-speed rail networks include Morocco, Saudi Arabia and the US.








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