## Transit operator launching test of wireless charging of electric buses in Mannheim, Germany

##### 02 March 2013
 Powertrain components of the PRIMOVE bus. Click to enlarge.

German regional transit operator Rhein-Neckar-Verkehr GmbH (RNV) is introducing a pair of electric buses with Bombardier PRIMOVE wireless charging technology (earlier post) in a research project serving the city of Mannheim, Germany.

During the “PRIMOVE Mannheim” research project, the electric buses will recharge wirelessly while passengers get on and off the vehicles at bus stops along the inner city route 63. Both e-buses, built by the Swiss manufacturer Carrosserie HESS AG, are also equipped with the new Bombardier MITRAC e-bus powertrain for city buses. In addition, an electric van equipped with wireless PRIMOVE technology will be tested as a RNV service vehicle.

The MITRAC eBus portfolio includes two different propulsion and control configurations for three vehicle types ranging from 12 m to 18 m in length. These buses can be equipped with platform wheel drive, where each wheel is powered separately, or with a platform central motor, where both wheels on the rear axle are powered by a single unit. MITRAC equipment is also used in rail vehicles from Bombardier as well as in vehicles of other manufacturers, offering high reliability, modular design, energy efficiency and ease of maintenance.

Bombardier’s PRIMOVE charging technology is based on inductive energy transfer and comprises two sets of components: wayside components that are buried underground and onboard components that are fitted onto the vehicle frame. Both sets are designed to enable maximum structural integration, as well as for energy transfer at high power and efficiency. The charging process begins as soon as the vehicle completely covers the charging segment.

PRIMOVE technology
Wayside Onboard
• Fully buried underground and can be covered with different materials.
• Primary cable segments provide the actual power transfer to the vehicle and are installed just under the road surface.
• Magnetic shielding under the primary winding (magnetic layer) prevents electromagnetic interference.
• The Vehicle Detection and PRIMOVE Segment Control (VDSC) cable senses when a PRIMOVE-equipped vehicle is above the segment and switches the segment on. Segments otherwise remain inactive to comply with electromagnetic interference protection requirements
• The Supervisory Control and Data Acquisition (SCADA) interface provides information for system control and diagnostics.
• Inverters convert the DC supply voltage to the AC voltage used in the system. DC feed cables supply power to the inverters.
• The PRIMOVE Power Receiver System consists of the pick-up together with a compensation condenser, which are both installed underneath the vehicle. They convert the magnetic field from the primary winding into alternating current.
• Inverters convert the alternating current from the pick-up into direct current that powers and charges the vehicle.
• Energy storage device (e.g. battery).
• The Vehicle Detection and PRIMOVE Segment Control (VDSC) antenna detects cable segments and coordinates the on/off switching.

The project partners will initially test the PRIMOVE technology during a testing and approval phase to collect information for the subsequent scheduled passenger operations, as well as for RNV’s internal operations and its training of personnel. Innovative features of the project include the planned optimization of the charging process by evaluating real-time data on the vehicle’s position on the route and its battery’s level of charging.

The Karlsruhe Institute of Technology’s department for vehicle systems technology will provide the project with scientific support under the direction of Prof. Dr.-Ing. Peter Gratzfeld. The research will focus on an energy simulation that demonstrates the entire power flow in the electric buses and at the inductive charging stations.

This will allow the battery size and the charging infrastructure to be adapted to each other and determine the demands on the power supply network. The institute’s work will also confirm the greater energy efficiency of the system compared to conventional propulsion methods. A measurement programme will verify the results of the simulations when the electric vehicles enter passenger service.

Germany’s Federal Ministry of Transport, Building and Urban Development (BMVBS) will fund the project with €3.3 million (US$4.3 million). The Government considers the promotion of alternative propulsion technologies a high priority. We want to turn Germany into a leading e-mobility supplier and market. The Ministry of Transport’s wide-ranging approach to R&D supports the introduction into the market of innovative drive systems and new concepts for all modes of transport. It is particularly important to harness the benefits of e-mobility in public transport, where new technologies are tested in an integrated system of vehicles, transport infrastructure and maintenance sites. Our research and pilot projects are setting in motion today the solutions of tomorrow. —State Secretary at BMVBS ### Comments 190kw is some serious juice. If this works at the right cost, then I can't see why this should not be the way to go. Health concerns are overdone, emissions from these products are well tested. I could see a natural gas diesel plug hybrid with recharge. Clean, quiet, good range and good mileage without a ton of batteries. This automatic (on/off) wireless charging system is the way to go for city e-buses and e-taxis. The Bombadier charging system was designed for subways and is very rugged. City buses can carry 1++ tonne of batteries instead of heavy diesel motor + heavy transmission + essential accessories + etc without increasing the total weight. Secondly, e-city buses can easily be made with aluminum to reduce total weight by about 4 tonnes. Aluminum city buses is nothing new. Their weight was about 34 tons instead of 38 tons. Our city was using 600+ of them between 1936 and 1956++ i.e. up to the time GM flooded the market with cheaper steel buses. Both Germany and the US promote sustainability, yet Germany has many times the solar/wind power per ca-pita while having 1/2 the solar radiation intensity of the typical US state. The US EPA regulations constantly change. The Ford C-Max hybrid may actually have attained EPA rules 47/47/47 MPG and had to report this - only then to be sued and mocked(esp. by imports) for the under 40 mpg reality. The 2013 Nissan Leaf improved its range by 15% AND lowered it's price by 18% - WITHOUT ANY 3 YEAR-OLD BATTERY IMPROVEMENTS YET. Without tax credit, the 2013 Leaf has a low(Corolla-like) 5 year projected cost of ownership. With all tax credits, it has the projected lowest ownership costs. Yet EPA Leaf range will only go from 73 to ~75 miles(not 84) because of calculation changes. The huge EV strenght is that range/economy IMPROVES by 5-10% per year - something that ICE hasn't and can't do. But a 'range improvement' from 73 to 75 miles in 2 years hides the truth. Nissan should visit Tesla to learn how to increase e-range to 300 miles? No secret, put in a half ton of batteries. And pay the outrageous cost. I think I read somewhere simply that; "190kw is some serious juice. If this works at the right cost, then I can't see why this should not be the way to go. Health concerns are overdone, emissions from these products are well tested." And I believe it. The natural gas plug in diesel hybrid bus with 1/10th the batteries can be used on other routes where there are no chargers and work fine. Color me skeptical. Inductive charging while a bus is stopped at an appropriate station can certainly be made to work. However I see no significant advantages -- and several significant disadvantages -- over the alternative of direct charging from overhead power rails. The fraction of time that the bus spends stopped at a station is small. That means that operation of the charger is in short bursts, with very low overall duty cycle. That taxes the power delivery lines to the charger and requires both the stationary charger and the mobile receiver to be heavy duty and expensive. With overhead power rails, the bus can draw power over 90% of its route distance. The power lines need not be continuous. That avoids the complications of dealing with route crossings and splits, at the cost of requiring robotic contactors that home in on the rails in sections where they are present. That's no problem, however. @Silverthorne: The cost of overhead chargers is significant, and they are visually intrusive, especially unsuitable in places like historic European town centres. Inductive charging is a well-proven technology, and has been running buses in Italy for a decade: http://wheels.blogs.nytimes.com/2012/05/30/in-italy-electric-buses-wirelessly-pick-up-their-power/ What has changes is that the air-gap they can manage is now getting bigger, the charges faster, and the batteries which the bus still does use are cheaper and more energy dense. As for the economics: 'While the cost of electric buses exceeds that of conventionally powered vehicles, Conductix-Wampfler estimates a payback period of less than four years, based on an electric power cost of$9,000 a year versus a diesel fuel cost of $50,000.' (ibid) Great link. Ten years in operation covers a lot 'but, what if,..Fox news, "..would never work"..can't' Silver....overhead cables (of all kind) is a real visual disaster in towns and cities. I fully agree with Davemart that we should do without them. All cables are buried in our area and we all agree that it should stay like that. There's a limit to cheapness. DaveM has it right....this is the right path. The batteries will get cheaper and cheaper and the inductive charging better. These buses will pay for themselves and the ROI time will continue to drop. Assuming no maintenance savings, the$41,000 annual energy savings and a “payback period of less than 4 years” implies an initial battery cost in the \$150,000 range. Using German energy costs, which are about 10% lower than the Italian costs, presumably used in the reference cited, the payback period would increase by about 11%; for US energy costs, which are 40 to 45% less than Italy’s, the payback period would increase by 70 to 80%.

With the inevitable increase in energy prices, particularly fuel prices, and the expected decrease in battery costs, this payback period will decrease substantially.

@Northern Piker:
Much of the cost will not be in batteries, but in the installation of the charging equipment.
The roads have to be dug up and the coils installed.
In fact for public transport as well as fuel both drivers wages and maintenance costs are important.

Clearly this will not affect the drivers wages, but once installed the underground coils are going to be pretty maintenance free, and electric vehicles are much cheaper to maintain than diesel, around half the cost.

So the economics are not limited to questions of battery and fuel costs, although both are important.

Installing chargers will be a big cost. Most city bus buying decisions are based on total cost of ownership and versatility. These buses can only run on a charger route.

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