SIEMENS

A location in Germany in 2013. An electric BMW leaves the A9 autobahn, which links Munich with Leipzig, and glides into a gas station. The driver gets out and opens the fuel tank flap. But instead of reaching for a gas pump, she pulls out a charging cable. Because the cable transmits electricity at up to 50 kilowatts, the lithium-ion battery can be quickly recharged. After a 20-minute coffee break, the motorist has enough fuel for another 100 to 150 kilometers.

Although no decision has been made as to the specific locations of such charging stations, they will definitely be set up as part of a recently launched showcase project called “Electric mobility links Bavaria and Saxony.” Germany will launch four such showcase demonstration projects to evaluate how well users accept electric cars in everyday life.

"It will be particularly exciting to see how effective our fast charging technology is and how much it will be used," says Matthias Felten, who coordinates Siemens’ contribution to the project. Siemens plans to set up nine charging stations along a 400-kilometer stretch of the A9 on what will be Europe’s first full-length electric vehicle highway.

Siemens has been researching fast charging systems for years and has found solutions for some of the associated problems. For example, a powerful rectifier is needed to turn the alternating current from the grid into direct current for a car’s lithium-ion battery. Although this can be done onboard the vehicle, Siemens has also developed direct current charging stations that supply the right kind of electricity. Progress has also been made regarding plug development. Almost all automakers in Germany now support the "Combo" plug (IEC 62196-3), which is apparently also becoming the standard throughout Europe. This plug, which is also known as the combined charging system, works with the direct current of fast charging stations as well as with the 230-volt alternating current used in private garages. The system is so simple that even people lacking any kind of technical know-how can’t use it incorrectly.

All you have to do is insert the plug, and the current begins to flow. For a long time, experts were uncertain about how electricity would be transmitted. Although charging should be fast, batteries age quickly when they become hot. However, for safety reasons alone, it is already necessary to equip lithium-ion batteries with temperature sensors. As a result, the charging current can be regulated in line with the battery’s temperature: The hotter the battery, the lower the current. This approach strikes a good balance between aging and charging speed.

Batteries and charging stations need to speak the same “language” if they are to understand one another. To ensure this is the case in the showcase project, the systems use powerline communication technology, in which data piggy backs along charging cables. Using an additional, high-frequency signal, a battery can always tell the charging station how strong a current it can tolerate. However, it’s not always necessary to transmit as much energy as possible to a battery at the fastest possible rate. That’s because electric cars, like their conventionally-powered counterparts, are stationary for 22 hours per day on average. In private garages, the 3.6-kilowatt connection to the household network will therefore continue to dominate. Completely recharging a car at home will thus take six to eight hours, depending on battery size. According to Dr. Dieter Barnard, who is responsible for the lifecycle management of charging infrastructures at Siemens’ Infrastructure and Cities Sector, charging stations at public parking places will have a “medium-fast” 20-kilowatt speed and a charging time of about one hour.

Roaming Vehicle Charging. Due to their limited range, electric cars face a major challenge when it comes to long-distance trips — particularly if the destination is abroad. Questions that remain to be answered include whether a car’s navigation system can reliably depict the location of available charging stations, and whether charging stations will be able to reliably communicate with a vehicle’s battery. A joint research project called Green eMotion was launched in Europe to find answers to these and other questions. With a budget of €42 million, the initiative is one of the largest electric mobility projects ever conducted. Like the projects previously mentioned, Green eMotion studies real-life mobility conditions on the road. The project partners include ten cities and regions in eight countries, ranging from the Danish island of Bornholm to cities such as Berlin, Dublin, Rome, and Malaga. A total of 2,000 electric vehicles are currently on the road in the participating regions, and this figure is scheduled to reach 70,000 by 2015, when the project comes to a close. The number of charging stations is to increase from 2,500 to 80,000 during this period.

The project is being coordinated by Dr. Heike Barlag, a researcher from Siemens’ Infrastructure and Cities Sector. Her goal is to combine various isolated solutions by harmonizing the associated information. For example, the standardization of data formats will enable organizers to provide services throughout Europe in a manner similar to the roaming process used in mobile communications. “Here, we’re talking about much more than just charging and payment processes. These are also possible using credit cards or cell phones,” says Barlag. It’s more important to ensure that a range-oriented route planning service will work abroad and reliably guide drivers to available charging stations at all times. Where possible, electric cars should be recharged whenever renewable sources of energy, such as solar and wind power are abundantly available. This last requirement can only be met with the help of a smart, interregional system for managing battery charging.

Unlike charging infrastructures that are being extensively tested on the road, vehicle-to-grid (V2G) technology is still limited to lab environments. Such systems enable power suppliers to use the batteries inside electric vehicles as buffers that store excess wind and solar energy. This allows electricity that was previously used to charge vehicle batteries to be fed back into the grid when required — a process that enables car owners to earn money. The vehicle-based and charging systems parts of this technology have been developed. What’s more, a solution has been found to the frequently voiced concern that using batteries in this way could cause them to age prematurely. The trick is to feed the energy back into grid in such a way that the battery’s charge level doesn’t become too low and the battery always operates within a specific temperature range (generally between 30 and 40 degrees Celsius). When treated in this manner, batteries lose only 20 percent of their capacity after 3,000 to 4,000 complete charging cycles.

Researchers are also striving to standardize the communication protocols that inform network operators of each car’s charge status. The results are promising. However, many more electric vehicles will have to hit the road before “V2G” evolves into more than just an abbreviation on PowerPoint slides. And that’s where the current projects come in.