International Transportation (67) 2 | 2015 49 Academics SCIENCE & RESEARCH Projects in a nutshell An overview of selected mobility research projects Efficient and functional - air-cooled drive unit I n the scope of the Fraunhofer System Research for E-Mobility (FSEM II) project, 16 different Fraunhofer institutes are jointly drafting solutions for the future of e-mobility. The three Fraunhofer institutes IISB, IFAM and LBF are pooling their expertise in the “Drivetrain/ Chassis” cluster for an innovative air-cooled electrified drivetrain with adaptive chassis damper. This drivetrain consists of: • air-cooled wheel hub motor, • air-cooled drive inverter, • multi-level DC-DC converter, • adaptive chassis damper, • rim designed for optimum cooling air flow. The contributions of Fraunhofer LBF: Cooling-air-optimized rim The influence of wheel disk design on air flow was studied to improve the wheel-side forced convection associated with air flow. In addition to the cooling effect and improved air flow, the decision criteria used were the result of the numerical structural durability calculation and the possible weight range. The rim was developed and designed according to the boundary condition for increased tire-sprung masses. The tests carried out in the wind tunnel showed that the wheel design has a significant impact on the cooling behavior and that the design with propeller spokes is beneficial in assisting wheel-side convection, depending on the design goal (figure 1). For example, when using wheel hub motors, an approach aimed at optimum cooling air routing, low weight and a structurally robust design resulted in a 20-inch lightweight rim design with cooling air routing improved by 5% and a weight of only 11.3 kg. Adaptive chassis damper A magneto-rheological damper featuring innovative and energy-efficient magnetic field management was developed to reduce the influence of the increased tire-sprung masses and to ensure maximum driving comfort. Magneto-rheological fluids are suspensions of ferromagnetic particles in a carrier fluid. The application of a magnetic field causes solid-state bridges to form, which lead to an increase in the transferable shear stress. The hybrid magneto-rheological damper utilizes this effect to adjust the damper stiffness in a vehicle: The stronger the magnetic field, the higher the damping force. When used in vehicles, this principle enables any necessary long-term adjustments to the damper stiffness by readjusting the permanent magnet. The coil current can be modified to achieve short-term, rapid adjustments of the damper setting (figure 2). Testing concept for more efficient testing of structural durability In vehicles with subsystems stressed by dynamic forces, the structural durability of these subsystems must first be tested on the test rig. With the multi-channel servohydraulic test rigs typical in this field, often considerable effort is required to define the control signals (drive files) before the test begins. The creation of drive files poses a particular challenge if adaptive components are present in the test specimen. Rather than the usual mapping of system dynamics, a physical non-linear model of the test rig and the test specimen is created, which records the effects of the non-linear system dynamics and is also able to map the dynamic behavior of adaptive components. The following advantages emerged in numerical studies using the model of a three-channel servo-hydraulic test rig and a half-shaft subassembly with a non-linear adaptive damper: • The iterative optimization of the drive file converges significantly faster than when using the previously usual linear transfer matrix. There is considerable potential for saving time and costs when preparing the test - examples illustrate a deviation below 1 % after 3 iterations instead of a deviation of 3.6 % after 10 iterations. • No particular difficulties are encountered when recording the continuously adjusting characteristics of adaptive components with the result that they pose no problem for this form of drive-file generation. red Contact: Dipl.-Ing. Eva-Maria Hirtz, Fraunhofer Institute for Structural Durability and System Reliability LBF, Darmstadt (DE); mail: eva-maria.hirtz@lbf.fraunhofer.de www. lbf.fraunhofer.de Figure 1: Cooling-air-optimized rim Graphics: Fraunhofer LBF Figure 2: Adaptive chassis damper Graphics: Fraunhofer LBF International Transportation (67) 2 | 2015 50 SCIENCE & RESEARCH Academics Portable fuel cell turns diesel into electric power I n the scope of a joint project, a group of research partners have developed an autonomous fuel cell system that is able to convert diesel into electrical energy silently - without the need for a motor or generator. Upon completion of the project, the system’s technical maturity has been demonstrated in isolated operation of fuel cell stacks and electronic modules. As a so-called Auxiliary Power Unit (APU), the fuel cell system for portable applications supplies electrical energy to caravans or boats. The APU delivers a maximum net power of 3 kWel for powering electrical devices such as the air conditioning system or the refrigerator. For efficient use, the diesel fuel already available on board needs to be transformed to hydrogen-rich fuel gas first. In a next step, the fuel cell converts the fuel gas to electric power. Development steps to a marketable power unit The fuel cell system consists of a diesel and a water tank, as well as a hydrogen generator and fuel cell module, consisting of a lowtemperature polymeric membrane fuel cell (NT-PEM) with 90 cells, a battery and the required power electronics. The developers’ objective was to improve process control, reduce system complexity and evolve individual components as well as complete modules up to marketability. They optimized the system´s configuration to reduce complexity: Residual gas, i.e. gas that cannot be converted by the fuel cell, is not burned in a separate component anymore, but directly oxidized on the reformer part’s side of combustion (figure 1). An important step was to speed up the system start: For this purpose, the developers optimized the hydrogen generator module. The starting time of the fuel processor could be reduced to about half an hour through the use of a burner-side mixture controller, which can function either as an ignition burner or as a mixture controller with cold-flame technique. A new starting strategy was developed to reduce the whole system’s starting time to less than 30 minutes. As soon as the reformer reaches the operating temperature required for oxidative steam reforming (OSR), fuel, water vapor and air are dosed into the reformer. The resulting temporary partial oxidation of the fuel gas initiates the generation of heat directly in the reformer component. The aim is to provide an earlier supply of reformate that will heat the water gas shift- reactors reactively. At the same time, the fuel cell can reach the required operating temperature faster. With this procedure, the overall starting time (i.e. the time until the system is ready to start steam reforming) has been reduced to 20-25 minutes. In March 2015, the design, construction and commissioning of the demonstrator were completed (figure 2). With the help of a representative test cycle, the system’s functionality was successfully demonstrated in isolated operation of fuel cell stacks and electronic module. In this setup, the process worked without any connection to the laboratory infrastructure. All required fluid media were provided from tanks. The air dosage was ensured by blowers. The generated electrical energy was used for the internal system component’s supply, for battery charging and for the connected load. For the demonstrator operation, building site spotlights rated at about 300 W each and an air conditioner drawing about 1 kW of electrical power were used as load. Several self-sufficient system starts could be realized with the battery. Currently, the “Möwe” system is the only project that combines diesel steam reforming and a PEMFC polymer electrolyte fuel cell. Its advantages as compared to other technology combinations are: • No additional fuel type and storage is needed because the system operates on diesel. Besides, diesel is commonly available and has a high energy density. • Because of the steam reforming, hydrogen yield and hydrogen partial pressure are very high (up to 70 % dry concentration, to that no dilution with N2 is required). • The NT-PEM fuel cell is ready for series production, has a long service life and only short starting times. Figure 1: Basic design of the autonomously operating PEM fuel cell system for use as mobile APU Illustration: OWI Figure 2: Hydrogen generator of the dieseloperated fuel cell system Photo: OWI International Transportation (67) 2 | 2015 51 Academics SCIENCE & RESEARCH During the whole joint project, the developers had to face the challenge that the continuous operative stability of a low-temperature PEM depends on the reformer´s operating point. In a test run for the continuous operation of the reformer with low-sulfur domestic fuel oil, it was shown that a new regeneration strategy can largely prevent the typical degradation of the catalyst’s reforming capacity caused by sulfur and soot. Replacement for conventional power generators In the performance class of about 3 kWel, the only portable power generators currently available are powered by petrol or diesel motors. Their use at campsites for caravans or in port areas is strictly limited in order to prevent excessive noise and pollutant emissions. In contrast, the new fuel cell system works silently and generates hardly any emissions or vibrations. This is why the developers see the diesel fuel cell APU technology as a promising approach to power generation in several market sectors, for example caravans and yachts. red Contact: OWI Oel-Waerme-Institut GmbH, Herzogenrath (DE); mail: m.ehring@owi-aachen.de www.owi-aachen.de BACKGROUND INfORMATION “Möwe” project partners • Mahle Behr GmbH & Co. KG, Stuttgart • Enasys GmbH, Berlin • Inhouse Engineering GmbH, Berlin • OWI Oel-Waerme-Institut GmbH, Herzogenrath “Möwe” is the working title for the project funded by the Federal Ministry of Economic Affairs and Energy, following a decision of the German Bundestag. Kinetic Energy Recovery System for road haulage S keleton Technologies and Adgero SARL have developed the world’s first Kinetic Energy Recovery System (KERS) for road freight vehicles. The unique hybrid system is designed to reduce fuel consumption and associated emissions by up to 25 %, and is optimised for intermodal road transport solutions. The Adgero Hybrid System consists of a bank of high-power ultracapacitors working alongside an electrically-driven axle, which is mounted under the trailer. The technology is controlled by an intelligent management system that tracks driver input in order to automatically control the regenerative braking and acceleration boost. Road haulage accounts for over a fifth of the EU’s total CO 2 emissions, so fuel-efficient solutions are crucial. The technology is projected to reduce fuel consumption and associated CO 2 emissions by 15-25 %, depending on terrain and traffic profile. It will also pay for itself in as little as three years through reduced consumption alone, and where subsidies are available the payback can be even quicker. The product has also been designed to exceed the typical 10-year lifetime of the trailer itself. Skeleton Technologies is the only ultracapacitor manufacturer to use a patented graphene material that allows better conductivity and a higher surface area, delivering twice the energy density and five times the power density of competitors’ products. Over the last year, Skeleton Technologies has worked with Adgero to adapt an 800 V ultracapacitor power module that is proving successful in the motorsport industry to meet the needs of road freight vehicles. The module consists of five 160 V units. With monitoring for each individual cell, the module is able to actively selfbalance. Adgero’s system will be fully compatible with existing infrastructure and staff training programmes, and has been optimised for intermodal solutions. Any truck equipped with an Adgero monitor becomes a parallel electric hybrid when paired with an equipped trailer. If a truck without a monitor picks up a retrofitted trailer, the hybrid system will simply stay in standby mode. Successful tests In recent months the system ran through rigorous testing procedures including vibration, shock and immersion testing. Road testing will begin in 2016 with Altrans, a French logistics company that is part of a trade organisation representing 11,000 vehicles across Europe. Adgero and Skeleton Technologies then plan to ramp up production, with the objective of producing 8000-10,000 units annually by 2020. red More information: Adgero, Strasbourg (FR), www.adgero.eu Skeleton Technologies, Bautzen (DE), www.skeletontech.com Graphics: Adgero International Transportation (67) 2 | 2015 52 SCIENCE & RESEARCH Academics H ybrid aircraft combining the best of an airship, plane, helicopter and hovercraft could provide major benefits in numerous applications. Scientists improved current concepts in a rigorous experimental and modelling campaign. Designed to enable extremely short takeoff and landing on all surfaces, such hybrid aircraft are well-suited to accessing remote areas without airports. Applications could include search-and-rescue missions, island hopping and tourism, and expanded business connections (figure 1). Building on a partner’s previous experience and a working full-size prototype, scientists set out to test the theoretical solution to the low stability problem observed in certain situations. With EU support of the project Estolas, the team proposed an architecture akin to a mixed-type flying wing. The main part was a disk-shaped centreplane housing the helium and with a channel in its centre for a cargo cabin. On the edges were the pilot and passenger cabin, cantilevered wings and the tail. The combined take-off and landing gear were placed underneath. Estolas set out to optimise the aerodynamic flanges to resolve stability issues for four different models accommodating small, medium, large and super-large payloads. Within the scope of the project, scientists also evaluated the performance of demonstrators in wind tunnel and remote-controlled flight tests and studied aspects related to runways, safety and certification. Aerodynamic experiments on the Estolas hybrid aircraft provided important data on lift. In addition, the team evaluated performance with both currently available advanced engines as well as planned future engine concepts. The proposed propulsion system paves the way to pioneering flight control that enables vertical take-off and landing operations even for aircraft with heavy payloads. The team proposed an optimal architecture for a future all-electric Estolas in line with EU goals for the transport industry. The Estolas concepts were superior to other aircraft in their capabilities for short take-off and landing as well as all-surface operation. However, to achieve additional clear advantages over traditional aircraft in other respects as well, the team identified specific technological areas for development. Scientists have contributed comprehensive computer-aided design methodology and protocols for research and evaluation of hybrids. Together with models to predict performance criteria with minimal uncertainty, the tools will support knowledgebased advances in the hybrid aircraft model that has captured global attention. red Download the final report here: http: / / cordis.europa.eu/ docs/ results/ 308/ 308968/ final1-estolas-publishable-summary-finalreport.pdf Project coordination: Riga Technical University, Riga (LV), www.estolas.eu Galileo Online: GO! Highly accurate navigation receiver for rail applications T he objective of the project ‘Galileo Online: GO! ’, which is scheduled to last until 2018, is the development of a highly accurate navigation receiver designed specifically for applications in rail transport. This receiver is to be connected seamlessly to a service platform for the provision of special services that will enable the receiver to be used directly in rail operation. The work focuses on ensuring powerful connectivity across the system as a whole, as well as on optimum accuracy, availability and robustness of the receiver’s positioning solution. Fraunhofer IIS, IMST GmbH, SCISYS GmbH, Vodafone and RWTH Aachen University are involved in the project. InnoZ GmbH supports the innovation process by contributing its socio-technical transfer method. ‘Galileo Online: GO! ’ is a project carried out with the financial support of the German Ministry for Economic Affairs and Energy (BMWi). red Contact: Valentin Jahn, Innoz GmbH, Berlin (DE); mail: valentin.jahn@innoz.de www.innoz.de/ e-gap0.html DEUTSCHER GALILE O-EMPFÄNGER FÜR BAHN-ANWENDUNG EN GALILEO ONLINE A novel aircraft with many capabilities Figure 1: Isometric view of Large-Estolas International Transportation (67) 2 | 2015 53 Academics SCIENCE & RESEARCH New high energy density automotive battery system F raunhofer IISB participated in the European AVTR project that has addressed the powertrain systems for light EVs. The IISB was responsible for a novel fully redundant battery system of an electric vehicle. An advanced battery management system was integrated, comprising control algorithms. The international AVTR project focused on a special EV that may fulfill the Japanese Kei Car specification. With the vehicle developed within the AVTR project, highest modularity, low costs and reduced complexity were implemented, as well as high-end Italian product design. During the European AVTR project “Optimal Electrical Powertrain via Adaptable Voltage and Transmission Ratio” Fraunhofer IISB was responsible for the entire battery system of an electric vehicle (EV). In general, the Fraunhofer IISB Battery System Group focuses on innovative mechanical and thermal design of battery modules and systems including the related battery management system (BMS) with battery monitoring and the corresponding battery models. The project has addressed the development and the industrialization of complete powertrain systems for light electric vehicles. In contrast to already available EVs, the international project consortium focused on a special electric vehicle that may fulfill the Japanese Kei Car specification. The vehicle, developed by the Italian companies IFEVS and Polimodel, strictly follows four main objectives: low cost, modularity, producibility, and high-end Italian product design. The vehicle’s total length is about 3 m, making it ideal for crowded inner-cities (figure 1). Being part of the international consortium, Fraunhofer IISB was responsible for the novel fully redundant battery system. The main focus was on the battery system, its battery management system, and battery monitoring (figure 2). The battery modules were designed in cooperation with the Dräxlmaier Group and manufactured by them. Highest modularity and independence of the battery cell manufacturer was achieved by using automotive grade 3 Ah cylindrical lithium-ion battery cells of type 18650 from an Asian battery manufacturer. Type 18650 battery cells are in highest mass production for years now, thus providing lowest costs, low manufacturing tolerances and are available from most premium cell manufacturers. The eight battery modules provide 12 kWh of energy to the 15 kW powertrain (30 kW peak power). The modules use a 20p7s cell configuration and have a weight of only 9.4- kg, thus providing a gravimetric energy density on battery module level (i.e., with electronics included) as high as 160 Wh/ kg. Furthermore, battery monitoring placed on battery modules followed the same objectives. Battery monitoring was optimized for lowest size and bill of materials. The PCB size could be reduced to only 47-cm 2 , still providing best voltage measurement accuracy, temperature sensing and passive balancing. The small size could be realized by using a highly integrated stateof-the-art battery monitoring IC with highest voltage measurement accuracy. Panasonic developed and provided novel prototypes of MOSFETs including protective elements for passive battery cell balancing. By using these novel MOSFETs, the bill of materials can be drastically reduced, with positive effects on costs and reliability. Finally, an advanced battery management system developed by Fraunhofer IISB and based on an Infineon 32 bit microcontroller running an automotive OSEK / Autosar operating system was adapted to the needs of the AVTR project and integrated into the battery system. The BMS comprises control algorithms (e.g. power contactor control), data communication via CAN bus, and advanced safety mechanisms for protecting the battery system. This BMS was integrated into both battery systems and configured to work as independent systems. Thanks to full redundancy the driver of the EV is able to check the state of each battery system on the dashboard and even driving with only one axle is possible at any time. The shown concepts and prototypes prove the feasibility of a light electric vehicle with reduced complexity, reduced costs and improved modularity. This development may lead to affordable EVs, thus increasing the attractiveness of EVs for the mass market. The final presentation of the vehicle prototype took place during the unique Parco Valentino car show in June 2015 in Turin, Italy. The AVTR project received funding from the European Union’s Seventh Framework Program for research, technological development, and demonstration under grant agreement no 314128. red Contact: Vincent Lorentz, Fraunhofer Institute for Integrated Systems and Device Technology IISB, Erlangen (DE); mail: vincent.lorentz@iisb. fraunhofer.de www.iisb.fraunhofer.de Figure 1: Kei Car electric vehicle prototype designed and assembled by IFEVS-Polimodel (Italy) Photo: Pietro Perlo, IFEVS Figure 2: High energy density automotive battery module with cost-optimized battery monitoring electronics developed by Fraunhofer IISB with Dräxlmaier (Germany), Panasonic (Japan), and IFEVS (Italy) Source: Fraunhofer IISB