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.