Tomaz Katrasnik

Analysis of Energy Conversion Efficiency in Parallel and Series Hybrid Powertrains

The aim of this paper is to present a simulation and analytical analysis of the energy conversion efficiency in parallel and series hybrid powertrains. The analytical approach is based on the energy balance equations, whereas the simulation approach is based on an accurate and fast forward-facing simulation model for simulating parallel and series hybrid powertrains. A very good agreement between simulation and analytical results gives confidence pertaining to the accuracy of the performed analysis and confirms the validity of the analytical framework. Thus, combined simulation and analytical analysis enables deep insight into the energy conversion phenomena in hybrid powertrains and reveals the advantages and disadvantages of both hybrid concepts running under different operating conditions. It is obvious from the presented results that the parallel hybrid powertrain features better fuel economy than the series one for the applied test cycles, whereas both hybrid powertrain concepts feature the best fuel economy at light-duty application.

Mechanistic Modeling in System Engineering: Real-Time Capable Simulation of a TGDI Engine Powered Vehicle

A mechanistic overall vehicle model is presented. Besides the mechanical driveline domain it comprises a mean value based air path, a crank-angle resolved cylinder description, exhaust gas aftertreatment, cooling and lubrication models and a software ECU to run transient operating conditions. An innovative coupling of different domains and sub-domains that allows for a very good ratio between modeling depth and computational expenses is presented. The capability of the overall model to adequately capture the interaction of different domains is demonstrated by a certification cycle simulation for cold start engine conditions. Enhancements on the engine performance are investigated by electrifying the propulsion of the water pump. The study highlights that even small changes in the powertrain topology and their assessment already call for a comprehensive multi domain system engineering model capable to mechanistically describe all essential effects.