Environmental friendliness, economy, and individuality are the fundamental ideas associated with the topic of eMobility (electromobility). The increasing scarcity of resources and constantly rising prices are being felt by everyone, as will be the follow-up costs if we don’t succeed in reducing environmental pollution such as greenhouse gas emissions. At the same time, the demand for individual mobility is growing, e.g. in big cities and the urban centers that surround them, in which around 40% of the world's population will live by 2015.

“Real” Electric Vehicles

The StreetScooter from RWTH Aachen University.
You occasionally see them out on the road — electric cars that conserve resources, ease the burden on the environment, and facilitate individual mobility. But these vehicles certainly won’t succeed in turning eMobility into a popular movement, because at present, they are simply too expensive for most people to buy. “Today’s electric vehicles are essentially nothing more than standard cars with the combustion engine taken out and an electric motor dropped in instead,” said Dr. Bernd Schimpf, Head of Generating Process Management at Wittenstein (Bartlett, IL). “With respect to space and range, these vehicles are often unsuitable for daily use, and what’s more, far too expensive, because they are one-off or mini-series conversions for which both the components and the conversion work are relatively dear.”

Wittenstein’s electric motor.
What, then, is so special about a “real” electric vehicle? This is a question scientists at RWTH Aachen University (Germany) have been asking themselves, setting up the StreetScooter project that brings together automotive suppliers and technologies that are key to electromobility. This collaboration is targeted at developing all technologies required for an all-electric city vehicle through to series production. At the same time, the StreetScooter is also to serve as a model for the production of electromobiles, because one of the chief aims of the project is to realize a selling price of approximately $6,500 plus battery (or battery leasing). “We’re talking not only about product development, but about the development of inexpensive production technologies,” explain ed Dr. Schimpf.

With respect to vehicle assembly, the experts at RWTH Aachen have developed a totally new production concept for the StreetScooter. The vehicle is divided into a number of vertical modules — the front end and front section of the passenger compartment, the rear section of the passenger compartment, and the rear-end module. The classic mode of final assembly in the automobile industry is being replaced by a concept in which pre-tested modules, which can come from different suppliers, are joined together. It’s the modules that then determine the diversity of vehicle models available, from two-seaters, to convertibles, to pickups. Differentiation and personalisation of vehicles in line with customer tastes will then no longer take place at the factory; instead, external StreetScooter-certified customizers will kit out each StreetScooter with precisely what the buyer wants, such as a leather interior, satellite navigation system, or sound system.

The Drive Technology of eMobility

What sounds so simple — namely, designing an electric vehicle segment by segment and compiling the different model variants by piecing together the modules — requires a large amount of development and coordination work and the right technology partners. To this end, a total of nine LEGs (Lead Engineering Groups), each responsible for a different technology (bodywork, safety, or memory systems), were set up for the StreetScooter project. One of these LEGs goes by the name of “Electric Drive,” and is led by Wittenstein. “How important the results produced by this LEG in particular really are becomes very apparent as soon as one realizes that 30% of the production costs for a StreetScooter are accounted for by the drive system,” explained Dr. Schimpf. “As a drive specialist, we therefore bear a huge share of the responsibility when it comes to the success or failure of the StreetScooter project, which is why we are investing our entire experience with compact and even miniaturized drive system solutions — with maximized efficiency and power/weight ratio — from other industries, such as aerospace and medical engineering."

The eMobility drive technology is a highly compact electric drive system from Wittenstein.

Of great importance to the StreetScooter project is that the motor, gearhead, and electronics in the drive modules are optimally harmonized to achieve maximum efficiency, and therefore the maximum possible range. Moreover, the drives conform to the strictest operating, safety, and reliability requirements. “All components are made by Wittenstein and optimally matched,” said Dr. Schimpf. “What’s more, we will be rolling out various systems one after the other — in line with the modular concept. This means we can configure drives for different performance classes and in different quantities while still exploiting the cost benefits of high-volume production for the individual components. And by realizing economically viable manufacturability of the drives, we are making a massive contribution toward achieving the $6,500 target price for the StreetScooter.”

This article was written by Dr. Bernd Schimpf, Head of Generating Process Management at Wittenstein AG. For more information, Click Here .