Look-forward longitudinal dynamic modelling for a series-parallel hybrid electric vehicle

In this research all components which affect the longitudinal dynamics of a typical series-parallel hybrid electric vehicle have been modelled in MATLAB/SIMULINK1. A look-forward model is developed by coupling an experimentally identified and verified mean value engine model together with longitudinal vehicle dynamic. This model consists of sub-models for power split planetary gear set, permanent magnet synchronous motor/generator with the local controllers, and energy storage system. An energy management strategy has been defined to control the complete model in all vehicle operation modes: pure electric, hybrid, power boost, regenerative braking and engine on/off transient mode. The energy management strategy has been implemented to optimise engine operating conditions. A fuzzy-logic auto-driver model is used to compare the performance of a simulated hybrid vehicle with that of a conventional powertrain in the ECE driving cycle. The simulation results indicate a 40% improvement in fuel economy by converting the conventional vehicle into a series-parallel hybrid vehicle.