Investigation On Coordination Control Of Mode Transition For PHEV Considering Characteristics Of Torsional Vibration

The Planetary Coupling Hybrid Transmission(PCHT)is a commonly used core component of new energy vehicle,especially for the Plug-in Hybrid Electric Vehicle(PHEV),as it enables vehicle flexible power coupling,compact structure and high transmission efficiency.However,the complicated architecture also brings about challenges in quality of mode transitions,further investigations on characteristics of torsional vibration of PCHT and development of coordination controller are of great theoretical and engineering significance for the elevation of smoothness during mode transitions.Therefore,this paper takes a PHEV equipped with PCHT as example,and the coordination control for mode transitions considering the characteristics of torsional vibration are developed.(1)Aiming at the issues of large transient torsional vibration caused by multi-sources and wide-band coupled excitations during mode transitions,the general angular displacement of gear is taken as dynamics variable,and then the model of PGHT torsional vibration considering the nonlinear dynamical meshing stiffness of gears is built,as well as the powertrain model for motor,engine and clutch,which are the foundations for dynamics analysis of mode transitions.(2)The typical mode transition with engine-start during vehicle operation is taken as research object,then the piecewise dynamics equation for transition from pure electric mode to hybrid mode is built,and the characteristic analysis for full-band transient torsional vibration are carried out based on continuous wavelet transformation.The result shows that the internal excitation from the nonlinear dynamical meshing stiffness of gears couples with the external excitation from torque variation of motive power sources,and finally stimulates the high-frequency torsional vibration in 100-5000Hz during mode transitions,which has an impact on stability of powertrain system.(3)Full considerations has been taken on discret-continuous characteristics during the transition from electric mode to hybrid mode(EM-to-HM),and the Hybrid model predictive control(HMPC)considering the torsional vibration of meshing gears is developed based on mixed logics dynamics modeling approach and model predictive control;the mixed integer linear programming is employed to solve the optimal control sequence in predictive horizons of HMPC;finally,the vehicle impact and torsional vibration of PCHT are considerably reduced.(4)The NI-based architecture of hardware-in-the-loop testing platform is deployed to verify the effectiveness and applicability of the proposed control algorithm.The result shows that the vehicle impact can be restrained below 6.91m/s~3,and the root mean square value of the transient torsional vibration of mode transition is suppressed by about 23.39%.