A comparative study on the energy flow of a conventional gasoline-powered vehicle and a new dual clutch parallel-series plug-in hybrid electric vehicle under NEDC

Abstract

Energy flow analysis is an effective tool for refined development of vehicle to improve its energy efficiency. To reveal the energy-saving principles of hybrid vehicle, a plug-in hybrid electric vehicle (PHEV) which is in charge sustenance phase and a conventional vehicle with the same internal combustion engine (ICE) are selected to conduct energy flow test under New European Driving Cycle (NEDC) of cold start and warm start. Various energy distributions are quantified, the differences are compared, and the influencing factors are analyzed. Research results show that the conventional vehicle with turbocharged engine overcharges in non-supercharging conditions, and this phenomenon could be alleviated in hybrid vehicle. Tested PHEV could reduce the working range of engine to a certain extent through the electrification of powertrain, but the tank-to-wheel efficiency increases little. This indicates that the design purpose of powertrain topology is to ensure that the benefits of improved engine thermal efficiency outweigh the losses caused by longer energy transmission paths. Brake energy regeneration could reduce the demand for effective engine output, which contributes the most to energy saving, so the braking energy should be recovered as much as possible on the premise of safety and driving comfort. The proportion of exhaust gas enthalpy-increase for the tested PHEV is relatively high, and the use of exhaust waste heat recovery technology can further improve its energy efficiency. Compared with tested conventional vehicle, the energy-saving contribution rates of tested PHEV under NEDC are 5% for idling condition, 20% for braking condition, and −5% for driving condition, respectively. These provide guidance for further tapping the potential of hybrid vehicles.