Study On The Optimization Of Control Strategy For A Parallel-Series Hybrid Electric Vehicle

Energy crisis and environmental deterioration are two major problems over the world. The design of low energy consumption and low emissions vehicle can abate the pressure of energy shortage and improve the quality of environment. The hybrid electric vehicle (HEV) is a new type of vehicle combining the traditional fuel vehicle and pure electrical vehicle, with such advantages as low energy consumption, low emissions, long drive distance, etc. It is presently a kind of low consumption vehicle that is most feasible and capable of mass production. HEV has become one of the hot issues and trends in contemporary international development of electric vehicles. For China, a country lacking oil and polluted seriously, it is of great strategic and realistic significance to study HEV.This paper studies the structures and control optimization strategies for Parallel-Series HEV. Based on the analysis of the power flow of the planetary gear structure, a new kind of structure of Parallel-Series HEVs is proposed and its driving modes are analyzed with the level simulation method, and based on the parameters of vehicle and target of dynamic performance, parameters of engine, motorI, motorII, ratio of final drive and battery are determined and mathematic modes of engine, motorI, motorII, battery and dynamic performance of vehicle are also built. And the overall efficiency model for Parallel-Series HEVs is set up, based on the engine efficiency map, motor efficiency map. An optimization control strategy is proposed to decrease the fuel consumption of vehicles. The main optimization target is to maximize the overall efficiency of HEVs at the charging and discharging mode. Through the optimal calculation, the optimal torque and speed of engine and motorI, motorII torque in different driving modes are obtained. And from the optimal results, the optimal control rules for Parallel-Series HEVs are gained too.Connected with Parallel-Series HEV in this paper, ADVISOR is redeveloped under the ADVISOR software, and the simulating model of the Parallel-Series HEV is built based on structure of planetary gear, which is applied to the simulation of dynamic performance and fuel economy of this HEV system. The simulation results of fuel economy indicate that the fuel economy of PSHEV is improved obviously in NEDC cycle mode, compared with the prototype car with traditional internal combustion engine, and show that the optimal control strategy used in this paper can implement the operation modes of PSHEV and get good fuel economy and control effect.