Research On Mode Switching Control Of Single Axis Parallel Hybrid Electric Vehicle

Nowadays,every country is paying more and more attention to the development of hybrid electric vehicles(HEVs).America,Germany,Japan and other developed industrial countries have always been keeping the advantage of technology monopoly over other countries,but Chine is trying to catch up and surpass them.The research target of this study is a kind of single axis parallel HEVs and the research focuses on the coordinated control of mode switch process for HEVs'driving system.Firstly,the evaluation index is determined for the vehicle's coordinated control in mode switch process.The evaluation index includes impact,duration of mode shifting and sliding energy.As this study mainly focuses on ride comfort,the impact degree is regarded as the prioritized index,while shifting time and sliding energy is regarded as the restricted indexes.The working mode the vehicle will be classified into seven types,according to the working conditions of the vehicle(driving,braking and charging).The mode switch of the vehicle is based on the rule-based control strategy and this lay the foundation for the further research of vehicle's control algorithm.Based on motor torque's rapid response property,this study proposed a motor torque compensation algorithm including the engine compensation algorithm and clutch compensation algorithm.In mode switching process when the clutch is changing from disconnection mode to connection mode,based on the clutch compensation algorithm,the fuzzy-PID is added into the clutch control algorithm and this is coordinated by the active speed control of engine.On the premise of strengthening the smooth of the vehicle,and decreasing the impact,the power of the vehicle is maintained and the lifespan of the clutch is increased.What's more,in the dynamic coordinating control algorithm,the combination process of the clutch is regarded as an independent mode and the torque distribution algorithm is reestablished in steady state.In this way,the problem of the dynamic coordinating control is transformed to the distribution problem of torque in steady state,so the dynamic coordinating control is simplify.According to the research object,the hard ware in loop simulation system is established.The hardware includes accelerator pedal,vehicle controller,CAN card and software includes Matlab/Simulink and LabVIEW.Simulink model includes vehicle components'models and bottom controller model.The proposed control algorithm is verified based on the hardware in loop simulation system.Simulation results show that the proposed dynamic coordinating control algorithm has constrained mode shift impact within 1m/s~3.Compared with the control strategy without dynamic coordinating control algorithm,its mode switching impact is reduced.At the same time,the duration of mode shifting is within 2 seconds(including the starting time of the engine,which is one second),and the sliding energy is within 1100J.The performance of the vehicle reaches the standards of the indexes.So the effectiveness of the proposed control algorithm is verified.