Hybrid-Powertrain Development Approach to Reduce Number of Prototype Vehicles by Taking Right Decision in Early Development Phases on Engine Testbeds 2021-26-0449

Today’s automotive industry is changing rapidly towards environmentally friendly vehicle propulsion systems. All over the globe, legislative CO₂ consumption targets are under discussion and partly already in force. Hybrid powertrain configurations are capable to lower fuel consumption and limit pollutant emissions compared to pure IC-Engine driven powertrains. Depending on boundary conditions a numerous of different hybrid topologies- and its control strategies are thinkable. Typical approach is to find the optimum hybrid layout and strategy, by performing certain technical design tasks in office simulation directly followed by vehicle prototype tests on the chassis dyno and road. This leads to a high number of prototype vehicles, overload on chassis dynos, time consuming road test and finally to tremendous costs.

Our developed approach is using the engine testbed with simulation capabilities as bridging element between office and vehicle development environment. This enables to decide for right operating strategy based on real IC-Engine fuel consumption and exhaust emissions measurements which are challenging to predict by office simulation with sufficient quality.

The simulated hybrid control unit and its freely definable operating strategy makes it possible to vary hybrid operating scenarios like electric boosting or electric recuperating within defined areas. Beside of the dimensioning of e-Motor power and Battery size, also threshold levels for load point shifting strategies are freely definable with not so clear foreseeable influence on fuel consumption, gaseous emissions and battery degradation. Using an “active- DoE approach” - ensuring a balanced SOC at the end of each cycle - interdependencies between the amount of IC-Engine load point moving direction sweet spot areas - and emissions as well as fuel consumption is made clear and transparent. This enables to find optimum conditions and derive most effective operating strategies. Key Performance Indicators like Battery current throughput or Battery SOC dependencies can be investigated to achieve a robust and reliable control strategy. This increase the development maturity level in early stages and consequently reduces the development effort on cost intensive prototype vehicles.