An engine under the bonnet drives the wheels – this is the configuration that has been powering cars for over a hundred years. However, wheel hub motors – i.e. motors in the hub of the wheel, not under the bonnet – promise many advantages. Electric drive systems make this possible.
It has been said that, at the end of the day, a traditional car is nothing more than a horse-drawn carriage without a horse – just a lot faster, safer and more comfortable. But the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) in Bremen is not content with this, and hopes its research into wheel hub motors will bring about a change in the way the car is perceived.
As Felix Horch, Head of Electric Drive Systems at IFAM, explains: “In a motor car, the ‘horsepower’ is generated by the engine rather than a team of horses, but the principle is still the same: propulsion at the front, load at the back. The same as it has always been. This is where we come in and take the concept a step further. Why not have the drive system directly in the hub of the wheel?” The team on the joint ‘FSEM II – Electromobility Systems Research’ project is dedicated to exactly this question. They are working on air-cooled wheel hub motors with the potential for opening up whole new areas of application for electric motors.
Horch, as project coordinator, and Prof. Matthias Busse, Head of the Fraunhofer IFAM, are promoting this field of study in Bremen with plenty of ambition and motivation. After FSEM I, the preceding project funded by the Federal Ministry of Education and Research (BMBF) to the tune of €34 million, ended in 2011, the team decided to carry on with their research. They all agreed that the expertise gained, and areas of interest identified, over the 22 months of the FSEM I project should not go to waste. “On FSEM I, IFAM was responsible for the development of a wheel hub motor and the construction of FRECCO, the Institute’s concept vehicle. We developed numerous components for the test vehicle here in Bremen. Even then, our vision was conceived for the long term and had sustainability as a goal,” says Horch. “That’s why we and 15 other Fraunhofer Institutes decided in 2012 to continue the project, even without any further funding from the Federal Ministry of Education and Research.”
Since early 2013, 16 Fraunhofer Institutes have conducted research into areas of electromobility with future potential as part of the joint FSEM II project. These include areas such as drive train/chassis, battery/range extenders and configuration/infrastructure. The project is managed and coordinated by Fraunhofer IFAM in Bremen. According to press spokesperson Martina Ohle, the joint project has great potential: “Hybrid and electric vehicles are delivering new solutions based on electric drive systems. Across all areas of application, for example in automotive engineering and agricultural machinery, electric drive systems are addressing the challenges of increasing energy efficiency, torque, performance and reliability, while lowering costs.”
That is why Fraunhofer IFAM’s Electric Drive Systems department has an interdisciplinary team that focuses on the entire development chain, from initial design to producing, testing and deploying drive system prototypes. Air-cooled wheel hub motors promise lower costs and energy consumption as they do not need many of the components of a traditional mechanical drive system. At the same time, they increase the amount of space available in the vehicle, and the individual torque settings of each wheel make active road safety concepts possible.
When the project started in 2009, Fraunhofer IFAM was to some extent entering uncharted territory. “We had experts and plenty of know-how in manufacturing technology, but the research into electric drive systems was entirely new to us. We successfully dealt with this challenge by attracting new employees to Bremen, and by acquiring knowledge over the years that has enabled us to become a technology leader in Germany. IFAM has a unique approach to bringing together manufacturing technology and electric drive systems, as we combine the two areas under one interdisciplinary roof,” says Horch.
One of the most important features of systems research is an open and cross-functional dialogue, and this is also key to the philosophy of the Fraunhofer Society, adds Ohle. “Not only do we think in terms of connecting research and practical application, we also actively encourage a dialogue between our employees at IFAM and those of other institutes.”
“Our ambition is clear: to develop the links between electric drive systems and manufacturing technology,” says Horch. This includes continuing their systems research in the field of electric vehicles at the site in Bremen. And this research is really paying off. It is Horch’s belief that electric and hybrid vehicles will gradually become the norm for all vehicle manufacturers. Wheel hub motors have several advantages over internal combustion engines: their simple construction means they contain only a few parts, and they offer high reliability with virtually no wear and tear. “The development and optimisation of manufacturing technology for electric vehicles and components remains relevant for the future, both from a research and an application point of view. The question we want to answer with our research, therefore, is how we can make this technology more affordable, more reliable and safer,” Horch concludes.
New concepts for electric vehicles could be on the cards. One possibility might be a modular system that could be varied according to use. Horch gives his imagination free rein: “If I was planning a day out with the family, I would use the family module. If I needed to transport furniture, I would select a different body. This would work particularly well in the context of car sharing. Even a radical redesign of the car would be a possibility.” This may still be a long way off, but Horch is sure of one thing: the objective must always be to maximise the utility to the customer. And Fraunhofer IFAM is making a valuable contribution to this through FSEM II.
Whether there will be a third project following FSEM II is currently still under discussion, but either way, electric vehicles and smart cities will remain a focal point of Fraunhofer IFAM’s work. “One of the great strengths of the Fraunhofer Institutes has always been the ability to react to current requirements and questions in society, and to examine relevant topics in order to initiate new research projects – and we will continue this approach once FSEM II has been completed,” Ohle adds.
In 2009 a path was chosen, and it has proven to be the right one. The FSEM projects are great examples of the type of applied research carried out at the Fraunhofer Institutes, where the focus is on the development of new technologies, processes and methods that have real-world applications. The employees have acquired so much advanced expertise that the IFAM is increasingly in demand as a specialist in the field of electric vehicles. “We help companies to use the technology efficiently. Bringing together research and practical application is the key added value that the Fraunhofer Institutes offer. Even after the project has finished,” Ohle adds.
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