A Whole Universe Full of Possibilities

IAV powertrain synthesis: development methodology for systematic variation and evaluation of all solution variants for complex powertrain systems

IAV‘s unique powertrain synthesis gives OEMs an objective basis for taking fundamental strategic decisions about their future vehicle fleet. The method analyzes all powertrain components in an integrated way to obtain the global optimum in terms of efficiency, costs and performance, right through to producing complete modular solutions from millions of possible technology variants. The huge potential of this new method has been verified by initial projects and the positive echo from experts.

Today already, manufacturers and suppliers are thinking about the powertrains they want to bring on the market in 2025 and 2030. They are confronted by the trade-off between CO2 emissions, modular solutions and production costs, with the powertrain playing a central role. There is an almost unmanageable range of possibilities: diesel and gasoline engines, electric motors, transmissions, power electronics and battery systems are just some of the components that have to be taken into account in terms of their degrees of freedom in the design and dimensioning process.

End-to-end, systematic, semi-automated

”The target requirements are so high and the technical effects so complex that conventional development methods can simply no longer cope“, says Christoph Danzer, IAV development engineer in the Powertrain Concepts department. ”Today it‘s not enough to optimize individual powertrain components. Instead, we need an integrated development approach.“ This is where IAV‘s powertrain synthesis comes in. As a systematic, semi-automated and agile process, it considers all relevant facets and variants in terms of requirements and technology and quickly supplies reliable results.

In contrast to conventional optimization methods, powertrain synthesis takes a systematic approach that actually includes all conceivable scenarios and powertrain configurations of combustion engines, transmissions, electric motors, power electronics, batteries, operating strategies, vehicles and topologies. For example, it is thus possible to ascertain which hybrid topology with which combination of technologies offers the greatest benefit in terms of energy efficiency, performance and system costs under specific boundary conditions. The analysis process goes right down to the last detail. Among others, it illustrates the sensitivity actually existing between design parameters and result quantities in the global context, permitting precise quantitative comparisons between different topology variants for hybrid and electric powertrains.

Basis for strategic development decisions

At the end of the iterative process, powertrain synthesis results in the global system optimum under the specific boundary conditions. “Depending on the project, it lets us analyze the properties of several million variants in terms of power flows, efficiency levels, energy losses, battery charge states and operating points of combustion engine and electric drives. By filtering the limit values across all variants and automatic evaluation by means of a costutility analysis, we obtain a ranking of the solutions found. The evaluation parameter ascertained in this way can then be used as the basis for analyzing the sensitivity and frequency of important properties (e.g. cycle consumption in the WLTC). ”In the end, we have an objective evaluation of the powertrain concepts as well as a clear recommendation for our customers“, says Danzer.

When searching for an optimum electrification scenario for example, the powertrain synthesis tool can objectively compare various technology packages, from simple 48-volt auxiliary drives through to different variants with highvoltage hybrid concepts. IAV customers can then use objective criteria, including cycle consumption and production costs for each individual solution, when deciding in favor of one of the alternatives.

IAV has developed a powertrain configurator specifically for hybrid powertrains. It runs on a tablet PC and is intended to give users a feeling for the implications of deciding for or against various technologies. ”With the intuitive user interface, our customers can enter parameters such as number of cylinders, charging technology, torque, power output and efficiency of the electric motor or the number and spacing of gears“, explains Danzer. ”The impact of their choice is immediately visible in terms of consumption, performance and production costs, for example.“ Users can see the position of their specific solution in a data cloud with millions of possible variants, gaining an indication as to how far it is from alternative configurations.

Optimum modular systems

IAV powertrain synthesis also helps OEMs to develop modular systems for their future powertrains. A limited number of scalable technology and design variants for combustion engine, transmission and electric components is expected to reduce the costs of future models. ”Although economically appropriate, this often leads to less-than-ideal powertrains“, Danzer warns. ”The aim therefore is to find a compromise between technical diversity for implementing favorable system properties and increasing the number for carry-over parts.“The modular variation of the powertrain synthesis is the perfect tool: it finds those points in the huge data cloud that offer the best possible combination of lowest fleet consumption and production costs with limited component variety.

Powertrain synthesis is meeting with a very positive response from IAV customers, demonstrated among others by the successful appearance at the Vienna Engine Symposium on April 28 and 29, 2016. ”Since introducing the new method, we have talked with many developers and senior executives from motorbike manufacturers and carmakers through to manufacturers of commercial vehicles“, says Danzer. ”Powertrain synthesis is already being used in several customer projects to answer a huge range of complex questions about conventional, hybrid and pure-electric powertrains.“

One result of powertrain synthesis consists in a description of the detailed requirements on powertrain components, based on the layout parameters and nominal maps. This gives IAV developers a direct interface for using their tools for engine, electric motor and transmission synthesis to obtain the detailed technology package as well as the structure and layout for these components. IAV engine synthesis defines all key parameters such as number of cylinders, displacement, supercharging concept, valve train variability and combustion process. Electric motor synthesis by IAV looks at the target power loss map to derive among others the function type, lamination and necessary cooling concept for the motor. IAV transmission synthesis generates completely new transmission structures based on the optimum ratio series which can also be optimized in terms of efficiency, shifting options, package and variability. Upcoming editions of automotion will be taking a closer look at these three development tools.