Collaboration across the whole value chain is the key to success
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Range and weight – the two main problems for electric cars. It is impossible to consider either of these aspects individually. During the development of their “Light Car” project, EDAG relied on TechniaTranscat (formerly Transcat PLM) and their CATIA V6 expertise. A central view of the whole car allows for the interaction between the required parameters to be simulated in a multi-disciplinary and comprehensible fashion, thus making the development process for the battery module considerably more efficient.
The developers have christened their concept EDAG Light Car Sharing – an electrically powered car that anyone can rent, but no one has to buy. The car has been designed by development service providers from Fulda, especially for the car sharing market. The “Light” in the title has a double meaning; on the one hand it refers to the car’s special exterior lighting design, which is used to communicate the car’s current status. If the car is currently charging, it lights up red and the word “Charging” is projected on the ground. With green light and the words “Rent Me”, the car indicates that it is free for hire whilst white light and “Reserved” signals that it is currently being used.
But “Light” also refers to the car’s construction. By using fibre composite elements in the car body, its weight has been significantly reduced. The design has been well-thought-out to cater to temporary usage. The unfavourable drag coefficient is hardly significant for a city vehicle. The cockpit has been reduced to a bare minimum in this car. Accelerator, brakes, steering wheel, indicators and a display that only shows the speed, battery condition, range and navigational help. Sensors are used to automatically operate the heating, windscreen wipers and lights.
Finally, the only challenge left for achieving the longest possible reach was to develop a fully-optimised battery module in terms of performance and weight – a very crucial component in an electric car. EDAG brought Karlsruhe-based company Transcat PLM GmbH and their partners Modelon on board to tackle the systems engineering. In this process, EDAG sought to exchange expertise as this was the developer’s first project by which the interdisciplinary CATIA V6 platform was used to carry out a transparent simulation of the overall system. “Electromobility also presents new challenges for developers. We wanted to test the potential of V6 in practice, across all fields of development, and then draw conclusions from this for optimised development processes in the future,” explains Michael Hog, Director of Vehicle Integration at EDAG. Reducing the number of interfaces involved seemed to be a very promising approach in this case – after all, EDAG currently uses around 40 different software solutions. “The staff at Transcat PLM are absolute professionals when it comes to system engineering. They were able to apply this expertise to the development of the battery module in a highly efficient way,” recalls Michael Hog.
First of all, TechniaTranscat (formerly Transcat) drafted the product specifications, for example with regard to driving performance, potential mileage, energy consumption, charging times and battery life. This method of requirements management was then incorporated into ENOVIA V6, CATIA’s management module and made available for all parties involved in development. This degree of transparency saved a considerable amount of time and clearly helped to reduce errors. In the next stage, known as “packaging”, all possible spatial configurations of the components within the vehicle were analysed in CAD. For this purpose, the technical data sheets for the battery cells in question, together with their cooling units were stored in the database. The attribution of requirements for the whole vehicle was thus visible for all project participants. The use of V6 3DLive and the ever-comprehensible version management system meant that it was very easy to visualise the project’s progress and the product details, even for users without any knowledge of CAD.
With the application of battery preselection and simulation, work moved more and more towards the practical implementation stage. The dynamic behaviour of the battery module in use could be tested using the CATIA Systems simulation model. To do this, the battery types and all relevant data were modelled by Modelon, using Modelica as a basis. This means that the different battery types could be used as variants of the model to create realistic simulations. It could thus be determined, which version was the best, in terms of performance, space dimensions and the requirements. Finally, the FEM was used to analyse the module’s thermo-management, after all, a considerable amount of energy is required to keep the battery cells at the optimum operating temperature.
EDAG’s use of V6 to achieve the coordinated rendering of the overall vehicle concept on e-components and the continuous depiction of the development process for the battery module can be seen as very forward-looking. “The V6 solution with the integrated, multidisciplinary collaboration clearly has several advantages compared to the method of working with several different tools, particularly in terms of time, transparency, traceability and also offers us excellent data consistency,” says Michael Hog in summary.
Photo: EDAG Group