Research On The Control Of Torque Synchronization Of Pure Electric Bus

Pure electric bus is gradually developing in urban public transport construction because its route is fixed and the charging fac ilities are more easily arranged.And promotion and use of pure electric bus also have an important practical significance for energy saving and environmental protection.At the same time,with the development of pure electric vehicles,the drive form of "motor + multi-gear mechanical automatic transmission(AMT)" has become a popular research field.With that drive form,we can not only improve the power and economy of the pure electric bus,but also reduce the requirements for the motor and the battery,which further develops its advantages as a pure electric vehicle.However,it is found that the spline rigid connection between the motor and the AMT increases the moment of inertia of the synchronizer active end during the shifting process.The increase of the moment of inertia will increase the impact during the shifting,increase the wear of synchronizer and result in shifting fa ilure.Therefore,for this drive form,in addition to the traditional speed synchronization,we should also focus on the torque synchronization at both ends of synchronizer during the shifting process so that we can effectively reduce the impact of shifting,the wear of the synchronizer and improve the success rate of shifting.Therefore,this article focuses on the torque changes of both ends of the synchronizer in the shifting process,and achieving of torque synchronization to improve the shifting quality by the motor active control.The subject of the study is the pure electric bus with a motor and a four-speed electronic control mechanical automatic transmission(AMT).First of all,the drive motor works in the speed mode to achieve speed synchronizatio n.On this basis,the output torque of the drive motor is controlled before gearing and torque compensation is realized by using the motor resistance torque as the target torque value of the synchronous.The main contents of this study can be divided into the following aspects:(1)Modeling of synchronization process.According to the structural characteristics of the synchronizer and the movement mode of the synchronization process,AMEsim were used to model the main components of the synchronizer: including the sleeve,the hub,the ring and the idle gear;and reflecting the working characteristics of a single taper ring loop synchronizer.(2)The mechanism of gear-shifting and synchronizing was analyzed,and it was explained that the increase of moment of inertia is the main reason of shifting impact and failure.Simulation analysis shows that the increase of shift force can not overcome the difficulties caused by the increase of inertia.(3)Based on the existing shifting process,the shifting process was optimized.The mathematical model of the synchronizer was established.It is concluded that the torque compensation of the motor is an effective method to rea lize the torque synchronization.After that,the running resistance of the up / down shifts of the motor during the shifting process was measured by bench test.(4)Research on torque synchronization control.Simulink components were used to establish the torque fuzzy control mode,and the co-simulation was realized with AMEsim.The fuzzy control method was used to adjust the output torque of the drive motor in the synchronization process.The drive motor speed and it's error were used as fuzzy control input and the target torque was used as the fuzzy control output.The out target torque was used for the motor torque control.With motor's fast and accurate torque response characteristics,we can achieve torque synchronization.Then the effectiveness of the proposed torque synchronization was verified by co-simulation and test.And the torque synchronization control method was evaluated from the aspects of impact degree and success rate of gear-shifting.It was proved that the torque synchronization control method can effectively improve the smoothness and reliability of AMT shifting of pure electric bus,and achieve the expected effect.