Research Of Modeling And Power Management Strategies Simulation For Parallel Hybrid Electric Vehicles Propulsion System

The general definition of hybrid electric vehicles (HEV) is a vehicle in which propulsion energy is available from two or more kinds or types of energy stores, sources, or converters and at least one of them can deliver electrical energy. HEV techniques have been widely studied recently because of their potential to significantly improve the fuel economy and emissions.Power management strategy is the pith of HEV techniques. The fuel economy, emission and drivability are strongly determined by power management strategy, which determines the torque distribution between engine and electric motor.First, the quasi-statics simulation models of the propulsion system are built, according to the kinetics equation and control-oriented mathematical model in this paper, which include vehicle body model, engine model, motor/generator model, battery model and gear box model. And these models are used to constitute a parallel hybrid vehicle (PHEV) propulsion system.Then, three strategies are presented for PHEV, they are simple rules control strategy, fuzzy logic strategy and a suboptimal control strategy based on the equivalent consumption minimization strategies (ECMS).The last strategy is a model-based strategy for the real-time load control. The aim of the strategy is to develop a fuel-optimal control which is not rely on the a priori knowledge of the future driving conditions (global optimal control), but only upon the current system operation. In order to weight the fuel energy and the electrical energy, a new definition of the equivalence factor is derived. Then a suboptimal control is found with a proper definition of a cost function to be minimized at each time instant. The "instantaneous" cost function concludes the two forms of energy.Finally, by comparing with the simulation results of the other two strategies, the potential of ECMS in term of fuel economy is illustrate.