Research On Matching And Control Strategy Of Hybrid-specific Engine

With the development of automobile industry and the increasing car ownership, the environmental pollution and energy shortage problems are increasingly prominent. Against this background new energy vehicle has become a hot research area. And at present, the technologies of power battery and motor for electric vehicle are still immature and lack in reliability, on the contrary, hybrid vehicles have the qu alities of long range, good power performance, fine emission performance and economy, which are the advantages which conventional vehicles and electric vehicles are incomparable with, hence hybrid vehicle is considered as a new energy vehicle with reliabil ity, convenience, and practicability.In this study, to meet the research goal, a prototype carrying model of one hybrid vehicle, which was a school-enterprise cooperation project, was used; and a kind of private car was set as the platform. The popurse of this paper was to find out the effects what Otto and Atkinson cycle engine ’s carrying and control strategy had on vehicle performance and fuel economy. What was more, theoretical analysis, numerical simulation and experimental validation were employed as the research methods. Main research work and innovation points of the paper are as follows:(1)The original car Otto cycle four-cylinder engine was altered to Atkinson cycle that specialized for hybrid vehicle, which has a higher thermal efficiency of low speed partial load; a powertrain structure was also designed and key parts were selected and matched, at the meantime a vehicle model was built, calibrated and its confidence coefficient was tested;(2)According to the properties of the Atkinson cycle engi ne, the logic threshold value for control strategy was set, and the vehicle operation pattern was divided into five patterns, they were pure electric motor drive pattern, engine active charging pattern, pure motor drive pattern, hybrid drive and brake reco very pattern. Under these working patterns, the vehicle fuel economy was to be improved by a reasonable matching of the engine and motor torque which kept the engine in high efficient working condition.(3)Matlab/Simulink platform was adopted to set up a control module for the different patterns, then the control module was embeded into Cruise ’s(a business software) vehicle pattern to conduct an offline joint simulation, from which the author got the data of the hybrid vehicle gradability, full load acceleration time(0-100 km/h), top speed, the engine working point distribution under NEDC cycle working condition, and hundreds of kilometers integrated fuel consumption and so on. The results provides evidences that hybrid vehicle carries Atkinson cycle engi ne is much more economic, also proves that its control strategy is of accuracy, reasonability and practicability.(4)Under all working patterns the powertrain efficiency objective function is established. In the premise of keeping control of the vehicle p ower performance, on the basis of global optimization for the control strategy accomplished by the instantaneous request power, under all working patterns, the highest powertrain efficiency was set as the goal to optimize the torque distribution between CV T speed ratio control and power producer, which further improved the fuel economy of the hybrid vehicle that carries Atkinson cycle engine.