Research Of The Economics Of The Series Hybrid Electric Vehicle

Electric Vehicle (EV) is now undergoing a development apex under the pressure of energy resource and environment preservation issues. Because battery and other energy device can not all take place internal-combustion engine, hybrid power system becomes the optimal choice. It can not only improve the economics and emission of vehicle, but also make the control of engine more simple and effective, and promote the development of energy technology,control strategy and means of control.The series hybrid power system is the best kind of hybrid power system, which adapts to run in the city bus cycle. But it has the disadvantage of low efficiency of energy transforming. So many people pay most attention to its economics. There are many factors that influence its economics, such as the hybrid density , the performance of battery, matching of power system, energy management, regenerated brake unit, mass of vehicle, driving cycle and etc. Based on the real bus route of Wuhan city, the paper has made some research about matching of power system, energy management and regenerated brake unit of the series hybrid electric bus.Matching of Power System By studying the rules of vehicle driving cycle, including speed,demand of power,demand of energy and etc., and analyzing the running state of each power components, the paper has concluded some disciplines about power matching of the series hybrid electric bus, which can make each components run in the optimal state, and improve work efficiency of the system.Energy Management On the base of creating energy flow model of vehicle and the work efficiency analysis of each power components, the paper analyzed the advantages and disadvantages of two kinds of typical control strategy ("Thermostat Control Strategy" and "power follower control strategy "), and brought forward the control strategy of "one route one bus" , engine separately working in different economy area and adaptive regulation of engine. Experimentation claimed that the kind of control strategy could work well, advanced the efficiency of energy transforming and improve the economics of vehicle.Regenerated Brake Unit The paper analyzed the configuration, work theory, control strategy of regenerated brake unit, regenerate brake system of double energy resources and the effect of regenerated brake. Results claimed that regenerated brake unit has great effect on the economics of electric vehicle, especially the vehicledriving on city bus route, for its high brake frequency and low brake intensity. So regenerated brake unit is an important breakthrough direction to improve the economics of the series hybrid electric bus.In brief, if only the series hybrid electric bus make some improvement in three above-mentioned aspects, its disadvantage of low efficiency of energy transforming should be overcome, and the economics of vehicle should be improved to a great extent.