Research On Coordinated Control During Mode-Switching In PHEV

As one of the key issues of HEV，state-switch control has gained more and moreattention. In order to carry out power-transferring smoothness and riding comfort duringstate-switch processes, the coordinative control issue is discussed in this thesis.Taking a single axis parallel hybrid electric vehicle as the research object, theoperating modes of hybrid system and switching condition are analyzed，based onwhich, the dynamic equations are built for different operating modes and switchingprocesses between different modes.According to different state switching processes and torque characteristics of bothpower sources, a coordinative control algorithm so-called engine speed regulation+engine/motor torque optimal distribution, in which, the rates of engine and motortorques are taken as control object, is proposed. On the basis of evaluation criterion inswitching process, the optimal controller for status switching is designed with quadraticoptimal control algorithm.There exist some influence factor such as model parameter uncertainty andexternal disturbances during mode-switch processes. In order to improve the robustnessof the switching processes, a coordinated control strategy is set out and an H∞robustcontroller is designed according to H∞robust control theory based on LMI method.The two control methods described above are compared with non-coordinatedcontrol are simulated in several typical state-switch processes. The simulation resultsshow that both control method can effectively reduce the torque fluctuation, improvethe performance on riding comfort, and ensure power transfer smoothly. Also, the robustcontrol can restrain external disturbances and improve the system robust performance.