Experimental and model based evaluation of mile hybrid fuel consumption gains and electric machine utilization for personal vehicle application
Paper in proceedings, 2017
A mild hybrid electric-diesel powertrain for personal vehicles is modeled with respect to longitudinal vehicle dynamics in real-world recorded drive cycles. The potential in terms of fuel consumption reduction in an ideal P0 and P2 mild hybrid electric system is evaluated in order to define the outer boundaries of how much the hybrid topologies can offer. The results are compared with logged data from real-world driving with a prototype vehicle in rural/highway and city drive cycles. The near-ideal powertrain model based simulations offer higher fuel consumption reductions than the prototype vehicle due to the ability of aggressively shutting off the combustion engine during low power requests. The largest reduction of fuel consumption calculated is 41% for a P2 configuration in city driving with a micro hybrid topology as reference. While quantifying the potential gains from an ideal P2 system, the resulting load profile for the traction assist electric machine is also extracted, giving valuable information for the detailed design process of a such machine. Fast cranking of the combustion engine is a key feature for mild hybrids, torque and energy requirements for this procedure is quantified: 1.1 kJ is needed in a 300 ms time window, which is also verified by measurements.