Research On Matching Of Power System And Optimization Of Control Strategy For Parallel Hybrid Electric City Bus

Facing with the growing problem of energy shortage and environmental pollution,the parallel hybrid electric vehicle(PHEV)that can effectively achieve energy conservation and emission reduction has been the important direction of Chinese energy-saving and environment-friendly bus.As a key technology of PHEV,the matching of power system has a great effect on the performance of PHEV.Meanwhile the economic performance of PHEV can be effectively improved by optimizing the relative parameters of control strategy.Therefore,the research on matching of the power system and optimization of control strategy for Parallel Hybrid Electric City Bus has important theoretical significance and practical value in engineering.By analyzing the merit and demerit of different configurations,the uniaxial configuration is used for the power system of parallel hybrid electric city bus.With the guidance of the shape parameters and the performance requirements,the method of theoretical calculation combined with simulation analysis is used to achieve the parameter matching and selecting for the power system' components on the basic of dynamic and economic performance.The electric auxiliary control strategy(EACS)with the logic threshold is used for the charged parallel hybrid electric city bus.Then,the design of the shifting condition between different operation modes,the demand torque distribution and the shifting strategy of the parallel hybrid electric city bus is achieved.The dynamic and economic performance of the parallel hybrid electric city bus is simulated and analyzed by setting up the facing-forward simulation model with the simulation software for vehicle performance.The results show the power system of the parallel hybrid electric city bus can meet the requirement of dynamic performance and the rate of gas saving compared with the same traditional city bus can reach 40%.Then by comparing the results of energy consumption test with the simulation results,the simulation model of the parallel hybrid electric city bus is further proved to be correct and reliable,which lays the foundation for the following research on optimization of control strategy.Aiming at the optimization problem of control strategy of the parallel hybrid electric city bus,the multi-objective optimization of gas consumption and electricity consumption using non-dominated sorting genetic algorithm ?(NSGA-?)is proposed.The optimization method can effectively avoid the defect that it is difficult to reflect the nature of every objective after the multi-objective is translated to the single-objective.The comparison of simulation results before and after optimization demonstrates that the optimization method can effectively improve the operation area of engine and electric motor in the charge depletion period and the economic performance of the parallel hybrid electric city bus.The research method of theoretical calculation,simulation analysis and experiment verification is used to scientifically research the matching of power system and the optimization of control strategy for the parallel hybrid electric city bus.This thesis identifies a set of effective design process and provides a reasonable reference for the design of power system of the parallel hybrid electric city bus.Therefore,this thesis has great actual application value.