REGENERATIVE BRAKING POTENTIAL AND ENERGY SIMULATIONS FOR A PLUG-IN HYBRID ELECTRIC VEHICLE UNDER REAL DRIVING CONDITIONS

摘要

There are several possible configurations and technologies for the powertrains of electric and hybrid vehicles, but most of them will include advanced energy storage systems comprising batteries and ultra-capacitors. Thus, it will be of capital importance to evaluate the power and energy involved in braking and the fraction that has the possibility of being regenerated. The Series type Plug-in Hybrid Electric Vehicle (S-PHEV), with electric traction and a small Internal Combustion Engine ICE) powering a generator, is likely to become a configuration winner. The first part of this work describes the model used for the quantification of the energy flows of a vehicle, following a particular route. Normalised driving-cycles used in Europe and USA and real routes and traffic conditions were tested. The results show that, in severe urban driving-cycles, the braking energy can represent more than 70percent of the required useful motor-energy. This figure is reduced to 40percent in suburban routes and to a much lower 18percent on motorway conditions. The second part of the work consists on the integration of the main energy components of an S-PHEV into the mathematical model. Their performance and capacity characteristics are described and some simulation results presented. In the case of suburban driving, 90percent of the electrical motor-energy is supplied by the battery and ultra-capacitors and 10percent by the auxiliary ICE generator, while on motorway these we got 65percent and 35percent, respectively. The simulations also indicate an electric consumption of 120 W.h/km for a small 1 ton car on a suburban route. This value increases by 11percent in the absence of ultra-capacitors and a further 28percent without regenerative braking.