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Electric city buses (IAA 2018): market overview, range

Jochen Knecht
Electric city buses (IAA 2018)
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D he commercial vehicle branch likes to claim for himself that he does not always immediately focus on the latest technological trends. This corresponds to the expectations of the extremely cost-sensitive target group, but ensures comparatively long development and innovation cycles. And yet there are countless series-ready electric vehicles in the halls of the Commercial Vehicle IAA in Hanover. Regardless of whether it is a van, truck or bus: (Almost) nothing works without an electric drive. Especially in the case of city and regular buses, it is really hard to see what speaks against a comparatively quiet, efficient and at least regionally emission-free drive. Not to mention the fact that electric buses were never really gone. Catenary buses were not only part of the street scene behind the iron curtain, these things are still quite successful today.

Battery or intermediate charging ?

HVV
Instead of lugging around huge batteries, intermediate charging by pantograph should increase the efficiency of the electric buses.

Nevertheless, today practically all manufacturers rely on high-performance batteries, which are ideally charged in the bus depots and then last all day. It therefore has to be 150 kilometers of electric range, a classic solo bus with a length of around 18 meters can do this with just one battery capacityof at least 225 kWh. That matters and drives the costs up. Batteries are expensive. In other words: Such an electric bus has to compensate for the disadvantage of its high acquisition costs with massively better operating costs. Opinions differ as to whether this is even possible, especially with buses with extremely large batteries. So, it's better to recharge smaller batteries and on the go. The experts call this opportunity charging. Inductive charging is a nice idea in this context, but it is still a long way from being usable in everyday use. Too complex, too expensive, too prone to malfunctions. And that's why at least the European bus manufacturers have developed the right current collectors (pantographs) for the roof for their electric vehicles. They latch onto the designated breakpoints in charging stations hanging above the roadway and charge the batteries. Charging capacities of up to 600 kW are possible. There are similar solutions for an existing overhead line infrastructure.

Infrastructure as a regulating factor

Jochen Knecht
Electric buses come in all sizes. This one comes from Karsan in Turkey, is eight meters long and uses the electric drive of the BMW i3.

The magic word in this context clearly infrastructure. Even if the additional acquisition costs for the vehicles can be roughly offset by better operating costs, the issue of infrastructure remains. None of the providers ministered to that. “The technology in the form of the vehicles is now there!” Says Daimler. 'But municipalities, network operators and fleets must now want that too!' The Swabians celebrated the world premiere of the eCitan in Hanover and are sure that it can 'replace a comparable diesel bus!' But only if the infrastructure is right. The best example: the bus depots. Mostly located in a relatively central location and above all designed to ensure the operation of classic bus fleets. One or two electric buses are still no problem. But what if 50 buses withRoll empty 300 kWh batteries into the depot in one fell swoop? Just load? Every power grid reaches its limits. So intelligent fleet management is needed, with the help of which charging times and depot capacities can be matched to the conditions of the power grid. 'And we are still at the very beginning in Germany and Europe!', Reports an annoyed developer at MAN and please do not want his name to be mentioned in this context.

The electrical issue will fail Buses no longer exist. The social pressure is too great, the technical development is too far. In the picture gallery we have put together all the electric buses of the Commercial Vehicle IAA.

Electric drive for retrofitting

Man knows them from practically every major city around the globe: the sightseeing buses with which tourists are driven from viewpoint to viewpoint. A niche market, one might think, but actually the topic is not entirely trivial, as the Ziehl-Abegg company from the Swabian Künzelsau explains using Berlin as an example. There are mostly converted double-decker buses that are used by tourists, which in their first life served in the classic regular service of the Berlin transport company. The drive technology of these models is correspondingly old and polluting. With the new 'ZAwheel' baptized drive technology, Ziehl-Abegg has a solution ready to convert conventional buses to electric drive.

Ziehl-Abegg
Wheel hub motor with integrated power electronics from Ziel-Abegg

ZAwheel is a Wheel hub motor with integrated power electronics. The permanent magnet synchronous motor (PMSM) with an integrated inverter was specially developed for commercial vehicles and, according to Ziel-Abegg, will now be used for several hundred old diesel buses. The majority of the traction batteries are housed in the rear of the buses instead of the engine. The first converted models are to be delivered as early as 2019. At the same time, new vehicles are also equipped with the electrical engineering from Swabia directly from the factory, so they cooperate with the Spanish companySpecialist UNVI, who manufactures sightseeing buses and has already marketed electrically powered variants in Paris, Amsterdam and London.

Electric drives for commercial vehicles

But Ziel-Abegg does not want the ZAwheel system to be in this niche see limited and has developed a complete axle system with independent suspension that is suitable for all commercial vehicle applications. The independent suspension and the wheel hub motors enable a low, space-saving underfloor construction to be implemented, which creates more space in the vehicle compared to the rigid axles that are common today. While the axle drive module is already on the market, Ziehl-Abegg sees the independent suspension as a future concept. 'We are in talks with several manufacturers of commercial vehicles who are very interested in independent suspension,' explains Ralf Arnold, Managing Director of Ziehl-Abegg Automotive.

Visitors to the IAA Commercial Vehicles in Hanover can try out the new technology also: Ziehl-Abegg has a drivable prototype on the open-air site. The supplier IAV, Ziehl-Abegg and the vehicle manufacturer Tassima are working together to convert the Berlin buses. A production hall is planned south of Berlin-Schönefeld, in which around 25 buses a year, and later up to 100, are to be converted to electric drives. The range of the electric buses is given as around 120 kilometers.

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