Numerical study of the effects of driving patterns on energy flow and fuel consumption in parallel hybrid electric vehicles

Electrification and hybridization constitute an expanding paradigm shift in transportation industry towards creation of more efficient alternative propulsion systems. The change is driven by environmental and market objectives to minimize pollutant emissions and reduce fossil fuel dependence. Nonetheless, the additional complexity of electrified powertrains brings a challenge to derive city and highway fuel consumption estimates. The present work analyzes the role of different driving patterns on energy flow and fuel consumption in a parallel hybrid electric vehicle (HEV) by employing vehicle powertrain simulations. The computational study considers five standard drive cycles representing various traffic conditions and driving styles. The investigation is performed to understand and quantify the effect of drive cycle dynamics on vehicle energy use, fuel consumption, and kinetic energy recuperation through regenerative braking. The results show that a parallel HEV is more efficient in city driving conditions compared to the highway driving. Decreased fuel consumption is due to the usage of the electric motor, which is more efficient in frequent start-and-stop traffic conditions as the braking energy is recaptured and stored in the battery. The amount of energy recovered by regenerative braking correlates with vehicle inertia wheel work across drive cycles. The internal combustion engine (ICE) is clearly the main parameter affecting vehicle fuel consumption. The impact of the engine operation is characterized by analyzing engine usage duration and engine energy losses. The observations and assessments presented herein are useful inputs for further optimization studies on improving the robustness of optimized vehicle design that is greatly influenced by drive cycle characteristics