Research On Dynamic Coordinated Control Of Mode Switching For Hybrid Electric Vehicles

The paper takes a double planetary Hybrid Electric Vehicle(HEV)as the research object,and researches on the problem of ride comfort and vibration and noise characteristics during mode switching.The model predictive control algorithm is introduced to formulate dynamic coordinated control strategy of mode switching and the joint simulation platform is used to verify its effectiveness.In addition,a rigid-flexible coupling dynamic model of power coupling mechanism is established,and the improvement of vehicle vibration and noise during mode switching is analyzed based on this model.The main works of this paper are as follows:Firstly,the structural characteristics of HEV power system are studied,the freebody diagram of each part is established by the isolation method,and the dynamic analysis of power system is carried out in combination with the torque and speed relationship of planetary gear mechanism.Next,taking a HEV as the test vehicle,acceleration signals and noise signals are collected during mode switching to analyze the changes in vehicle ride comfort and vehicle vibration and noise.What's more,an evaluation index of mode switching is proposed based on the evaluation method of vehicle comfort.Then,the problem of dynamic coordination control of mode switching is analyzed.Aiming at switching process from pure electric mode to hybrid mode,dynamic coordinated control strategies for engine participation phase are formulated based on the model predictive control algorithm.Next,the vehicle dynamics model and dynamic coordinated control strategy model are built based on AVL/CRUISE and MATLAB/Simulink environment.In the simulation test of mode switching,the dynamic coordinated control method is compared with uncoordinated control method and traditional PID control method.The results show that the method of MPC can effectively reduce the vehicle longitudinal impact and the superiority of MPC control method is verified.Finally,a three-dimensional model of power coupling system is established by UG,and its rigid-flexible multi-body dynamic model is established using ADMAS and ANSYS.Taking mode switching process as the simulation condition,the multi-body dynamics simulation of power coupling system is performed.Compared the dynamic characteristics of power coupling system under dynamic control strategy with the dynamic characteristics without dynamic control strategy.The results show that the torsional vibration characteristics of input shafts are improved and the average value of bearing restraint forces are reduced when the coordinated control was applied to mode swithcing process.These indicate that this control strategy is beneficial to improve the level of vehicle vibration and noise.