Research On Energy Allcation Strategy Of Coaxial Parallel Hybrid Bus

Energy conservation and reducing vehicle fuel consumption have become one of the most important directions for global automotive development in recent years.Under the support of national policies and subsidies,new energy vehicles have been widely used in urban public transportation in China.Among them,the parallel hybrid vehicle has become one of the mainstream configurations of the current hybrid bus.The energy distribution strategy plays an important role in the energy-saving effect of the parallel hybrid system,thus the research on the energy allocation strategy is of great significance.A ton of research work has been carried out around energy allocation strategies and many solutions have been proposed all over the world.However,most strategies focused on theory and simulation analysis,which is difficult to implement on real vehicles.The thesis relied on enterprise mass production projects and focused on the development of energy distribution strategies that can be applied to real vehicles.On the other hand,the smoothness of the multi-mode switching process of parallel hybrid systems has been a hot research topic of mode switching control.The thesis also makes a preliminary exploration in this respect.Based on the "V" model development process,the thesis developed a hardware-in-the-loop simulation platform with high real-time,high reliability and high ease of use based on Matlab/Simulink and xPC Target systems.Besides,the thesis adjusted parameters and response characteristics of the simulation platform components according to the the real vehicle components which improved the simulation accuracy of the simulation platform and provided reliable test support for energy allocation strategy development.The thesis described the control theory of the logic threshold control strategy and instantaneous optimization control strategy which widely used in vehicles on the market.Next the thesis selected the CCBC condition on the xPC simulation platform to simulate the energy consumption and analyze the advantages and disadvantages of these two allocation strategies.Combining with the structural characteristics of the parallel hybrid system of the 6-speed gearbox,the rule-based instantaneous optimization strategy was proposed.The road test was carried out in the standard CCBC test road condition of the traffic test site of the Tongzhou Traffic Department of Beijing,which verified that the rule-based instantaneous optimization strategy has better fuel economy.Based on a large number of road test data analysis,the thesis proposed the starting strategy of the clutch torque phased control and the motor torque gradient gradual control strategy for the chattering problem of the coaxial parallel hybrid vehicle in the process of starting the engine and releasing the torque of the motor.It was verified on the real vehicle that the control strategy had a certain effect on the smoothness of the system.