Configuration Design,Coordination Control And Energy Management Of A Dual Planetary Gears Based Hybrid Electric Bus Powertrain

This dissertation reports on a research project which systematically examined several core mechanical and system control issues in developing and optimizing the performance of one type of hybrid power systems used on city buses.During the past several decades,research and manufacturing of hybrid power systems for buses in China have made significant advancement.Two major models of the hybrid powertrains with demonstrated performance of fuel economy are: Double Motor Coaxial Series-Parallel System and Double Motor Coaxial Transmission Series-Parallel System.However,these hybrid powertrain models are expensive to manufacture.With the increasingly stringent regulations on fuel consumption and emission,developing new hybrid powertrains with optimal performance in fuel economy,drivability,and cost effectiveness has become an important research topic in the New Energy Vehicle(NEV)industry.In this dissertation study,I investigated issues related to the configuration design,dynamic coordination control,and energy management optimization of the CATARC Bus Hybrid System(CBHS)or the Dual Planetary Gears Based Power-Split Hybrid Powertrain System,which was recently developed in a research project titled “Industrialization and Power System Platform Construction of Deep-Hybridization Buses”,a project supported with a grant from China's National High Technology Research and Development Program(or the 863 Program).My first investigation in this dissertation study focused on analyzing the working principles and technical features of the powertrain system of the CBHS buses.Taking into consideration the complexity of the operating conditions of city buses,I analyzed the strengths of the configuration of the CBHS powertrain system through a whole vehicle simulation model.Drawing upon the methods and principles of hybrid electric vehicle modeling,I constructed upfront a simulation system utilizing the Matlab/Simulink environment.This simulation system included models of the drivers,vehicle dynamics,and the CBHS components.Using this simulation system,I tested and verified the feasibility of the CBHS hybrid powertrain system.Second,I proposed a dynamic coordination control solution for the CBHS powertrain system.I first analyzed the mechanism of the occurrence of torque judder of this powertrain by using the mode-switching oriented dynamic model of the CBHS transient process.Taking full advantage of the highly speed-torque coupling characteristics of the CBHS,I constructed a nonlinear observer-based estimation model of engine torque,and proposed a CBHS dynamic coordination control strategy featuring a rule lookup and a model prediction fusion control in conjunction with consideration of reducing the vehicle's jerk.To test the effectiveness of my proposed dynamic coordination control strategy,I constructed a simulation platform to test its effect on driving torque judder and the whole vehicle jerk during engine stop-and-start.Lastly,I proposed a parameter self-adaptive control strategy based on driving condition identification.In this investigation,I first constructed the comprehensive driving cycle and three benchmark driving cycles,using the principal component analysis(PCA)and the fuzzy c-means clustering(FCM)algorithm.I proposed that the improved particle swarm optimization(IPSO)algorithm should be adopted to obtain the optimal control parameters of each benchmark driving cycle.This parameter self-adaptive construct strategy is mainly achieved by the on-line identification and variable parameter control through the Relevance Vector Machine(RVM).Results from the fuel consumption simulation studies showed that,with this proposed strategy,the fuel consumption of the buses is 3.8% lower than that of the buses operating with the rule based fixed parameter strategy.Therefore,my investigation through the simulation models verified the utility of the dynamic coordination control and energy management strategy in real-time application.In addition to simulation based research on the presented control strategies,I tested their effectiveness in application through a study of the CBHS powered buses operating on an existing city bus route in an urban city in China.The results from this study showed that the performance of the CBHS buses meets the driving requirements of the city buses,the dynamic coordination control strategy also improves the drivability,and the energy management optimization control strategy achieves significant fuel economy improvement.