Research On Coordinated Control For Mode Transition Process Of Power-split Hybrid Electric Bus Equipped With AMT

As an important part of the hybrid electric bus,the planetary hybrid electric bus can achieve good fuel economy and possess high development potential.Limited by many factors such as technical level and control difficulty,simple planetary hybrid electric system using single planetary gear set has exposed many problems in the process of promotion and development,such as parasitic power after mechanical point,high temperature of motor at high speed,insufficient performance in pure electric mode.A novel planetary hybrid electric bus equipped with a two-speed AMT and two wet clutches is studied in this paper,which can overcome the shortcomings of the simple planetary hybrid electric system.However,an increase in the number of components would result in a complicated system structure,increase control difficulty,and lead to obvious jerks in mode transition proces.And thus a bad influence on the riding comfort of the vehicle is arised,which puts higher requirements on the control of the mode transition process of complex hybrid systems.The two-speed-AMT planetary hybrid electric system is an representative of complex planetary hybrid electric system,and the scientific problem of mode transition dynamic quality control two-speed-AMT planetary hybrid electric system is researched is this paper.A corresponding mode transition coordination control strategy based on the hierarchical and segmentation control architecture integrated model predictive control theory is developed,to enhance the vehicle riding comfort of complex planet hybrid electric system.Firstly,based on the inherent dynamic characteristics of the complex planetary hybrid electric system,dynamics analysis of the mode transition process of the two-speed-AMT planetary hybrid electric system is carried out.According to the torque splitting characteristics implied by the dual-degree-of-freedom characteristics of the planetary hybrid electric system,the whole powertrain of the two-speed-AMT planetary hybrid electric system is divided into two part for dynamics analysis: the planetary gear set and the planetary gear to the driving wheel.Combined with the planetary gear lever method,the control target of each component during mode transition is determined,and that provides a basis for mode transition coordination control.Secondly,mixing modeling method combining data-driven modeling method and mechanism modeling method is used to establish a dynamic model for two-speed-AMT planetary hybrid electric system with consideration of both accuracy and simulation speed.Based on the real vehicle data,neural network method is used to establish a full-time artificial neural network engine dynamic model.Based on the parameter identification method,the first-order inertia model of motors is established by identifying and combining the twisting and descending torque conditions.Based on the analysis of working mechanism,the wet clutch mechanism model,the two-speed AMT gearbox mechanism model and the planetary gear mechanism model with integrated clutch torque are established respectively.Above models are integrated to obtain the two-speed-AMT planetary hybrid electric system dynamic model,in order to provide an accurate and fast computing environmentfor control strategy verification.Finally,based on the hierarchical and segmentation control architecture combined with the model predictive control theory,an mode transition coordination control strategy for the two-speed-AMT planetary hybrid electric system is developed.Based on the vehicle jerks,clutch sliding work,AMT gear shift time,the mode transition quality evaluation system is constructed.According to the different characteristics of the typical mode transition process,the mode transition control strategy based on the hierarchical control architecture and the segmentation control architecture is developed respectively.Combined with the model predictive control theory,the optimal control of the typical mode transition process is implemented.Offline simulation and online verification show that the developed mode transition coordinated control strategy has a significant effect,and the mode transition quality of the two-speed-AMT planetary hybrid electric system is effectively guaranteed.