Within the project OpEneR (Optimal Energy consumption and Recovery based on a system network), the engineers and researchers worked on topics as different as improvements of the electric power train and the regenerative braking system, the navigation system and the surround sensors as well as of functions that interconnect all these building blocks. They built functioning electric vehicles prototypes that already were able to prove their potential for more energy efficient driving under real-world traffic conditions.
One of the tasks was developing a so-called eco routing – a feature in the route guidance that takes into account the specific characteristics of an electric vehicle. The navigation system continuously calculates the real energy consumption into routing. In tests it turned out that energy-optimised routes reduced the energy consumption by up to 30%. However, these optimised routes affected the driving time – it took the cars up to 14% longer to get from A to B. Shortcuts in city traffic had a particularly energy-saving effect.
It is generally accepted that anticipatory driving is the best method to reduce fuel consumption. Based on this insight, the Adaptive Cruise Control (ACC) algorithm was optimised for an energy-saving driving style. In addition, improved navigation data provided information as to ascents, descents, and speed limits, and the vehicles communicated with the traffic lights to know id advance at which speed they would encounter a green traffic light. All these data were aggregated and formed an “electronic horizon”, enabling the engineers to further optimise ACC and the soaring function. The latter informs the driver as to when to take the foot off the gas pedal ahead of speed limits or built-up areas. To make the best use of the vehicles momentum, the transmission was switched to idle during soaring phases.
Even the HMI concept was affected; the researchers felt that an intuitive human-machine interface and a programmable instrument cluster facilitated the readability of relevant information. Thanks to the improved navigation data, the remaining driving range could be determined more precisely and was easier to understand for the driver.
Another challenge was optimising the interplay of the electric powertrain and the regenerative brake system. To optimise energy recuperation, the researchers equipped two vehicles (Peugeot 3008e with four-wheel drive) with Bosch’s iBooster, an electromechanical brake booster and an ESP brake control system that was optimised for electric vehicles. The drive concept provided for an electric motor each for front and rear axle which was capable of recuperating energy when decelerating. On this technical basis, the researchers developed recuperation strategies such as regenerative power distribution between front and rear axle. This distribution scheme did not only regain kinetic energy and transformed it into electrical one but at the same time improved the vehicle’s stability.
To improve quality and speed of these development processes, the team utilised sophisticated distributed simulation techniques which included realistic interaction between vehicle and environment. A seamless simulation concept enabled the fast transfer from the functions developed and the related simulated test cases to the approval on the AVL InMotion powertrain test stand.
After these functions have been integrated into the test carriers, numerous test drives were conducted. To measure the efficiency gain, the researchers used test stands developed by project participants AVL, Bosch and FZI; the real-world driving tests were conducted at test circuits of Bosch and CTAG as well as on CTAG’s ‘Intelligent Public Road Corridor’. In comparison to a typical “sporty” driver, the technologies and strategies devised during the project achieved a reduction of energy consumption by 27% to 36% according to the willingness of the driver to comply with the system’s recommendations. In exchange, the driving time rose by 8% to 21%. Five percentage points of the energy savings were attributed to the intelligent torque distribution of front and rear axle.
Participants of the OpEneR project were the Austrian powertrain developer AVL List GmbH, Spanish research centre Centro Tecnolgico de Automocin de Galicia (CTAG), Forschungszentrum Informatik (FZI) of Karlsruhe, Germany, carmaker Peugeot Citroen PSA as well as automotive suppliers Robert Bosch GmbH and Robert Bosch Car Multimedia. Being a part of the European Union’s seventh Frame Program for Research and Development, the project has been funded by the European Directorate General of Communications Networks, Content and Technologies with 4.4 million.
Source: http://www.electronics-eetimes.com/en/reducing-energy-consumption-for-e-cars-in-small-increments.html?cmp_id=7&news_id=222921790&vID=209&page=2
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