Research On Torsional Vibration Active Control For Commercial Vehicles With Planetary And Multi-speed Hybrid System

The development of new transmission mechanisms with good energy-saving effects and strong adaptability to operating conditions has become one of the research hotspots in the field of commercial vehicles.The planetary and multi-speed hybrid system,with its multi-degree of freedom coupling characteristics,meets the requirements of commercial vehicles with complex and variable operating conditions.In this system,however,the engine,dual-motor and wet clutch are dynamically coupled to the AMT gearbox and the planetary system.In addition,the clutch and transmission elements are in different states.When the vehicle is in transient conditions,such as sharp acceleration and deceleration(Tip-in/Tip-out),gear shift,regenerative braking,engine start and stop,and mode change,the transient changes of multiple power sources will cause stronger torsional vibration in the transmission system and worsen the vehicle ride comfort.If the torsional vibration is severe,the excitation from multiple power sources will resonate with the transmission system,causing shaft breakage and damage to the torsional damper.For planetary and multi-speed hybrid power systems with fixed structural design,the study of active torsional vibration control,which combines the torsional vibration characteristics of the system and the operating conditions of multiple excitation sources,is an effective way to solve the torsional vibration problem of the system.Based on the general program of the National Natural Science Foundation of China Project“Balanced Control of Energy Saving and Dynamic Quality of Multi-system Coupled Hybrid Commercial Vehicles” and the general program of the Chongqing Natural Science Foundation“Research on Nonlinear Multi-scale Dynamic Quality Control for Commercial Vehicles with Planetary and Multi-speed Hybrid System”,this paper carries out the research on the adaptive control of torsional vibration in the motor drive,the torsional vibration control in engine start and stop,and coupled mode switching control with multiple source excitation.The main work of the full text is summarised as follows:(1)Modelling and verification of planetary multi-speed hybrid power system.The structure and basic operating modes of a planetary and multi-speed hybrid transmission system are analysed,and the torsional vibration dynamic model including the excitation source model and transmission system model is constructed.The simulation results of the model are compared with the test results of real vehicle,verifying the rationality of the model and laying the foundation for the development of torsional vibration control algorithms.(2)Research on adaptive control of torsional vibration during motor driving process.In order to suppress the torsional vibration of the transmission system during the motor driving process,a torque reconstruction and feedback control algorithm based on the theory of nonidentical phase superposition has been developed;Considering the application requirements of torque reconstruction and feedback control algorithms in multiple operating conditions,a method of adaptive adjustment of control parameters for multiple operating conditions is proposed,which automatically adjusts control parameters according to changes in operating conditions;an interference observer and a Butterworth low-pass filter are designed for adaptive compensation of interference,which improves the anti-interference ability of torque reconstruction and feedback control algorithms.The simulation results show that the combined adaptive control algorithm has good control performance.(3)Research on torsional vibration control during engine start and stop process.Through frequency domain analysis,the resonance mechanism of the engine start and stop process is clarified.In order to improve the torsional vibration improvement effect during engine start and stop,a Least Mean Square(LMS)adaptive filter control algorithm based on torque observer is designed.Aiming at the problem that unknown inputs in the actual system may cause divergence or failure,an unknown input observer(UIO)is constructed by reconstructing the measured output to achieve accurate estimation of the torque transmitted by the torsional damper and transmission shaft.On this basis,LMS adaptive filter control is applied to the torsional vibration control field,and the parameters of the LMS filter control algorithm are adaptively adjusted according to the estimated torque changes of the torsional damper and transmission shaft.The simulation results verify the good effect of the LMS adaptive filter control algorithm.(4)Research on the hierarchical torsional vibration control with multi-source excitation coupling mode switching.Through the analysis of the switching process between the hybrid drive mode and the engine drive mode,the problem of multi-source excitation coupling control in the transient mode switching process is clarified,and a torsional vibration control algorithm in the mode switching process based on the hierarchical control architecture is proposed.To realize the cooperation between the excitation sources and the coupling actuator,the upper controller combines the fuzzy adaptive sliding mode control algorithm,the hybrid adaptive control algorithm and the torque distribution algorithm at the end of the sun wheel to calculate the target commands of the excitation sources and the actuator.The lower controller uses the three-step method to control the output oil pressure.The simulation results show that the hierarchical torsional vibration control algorithm can significantly reduce the torsional vibration during the mode switching process and improve the stability of the planetary gear mechanism and output torque.(5)In order to verify the real-time performance of the proposed torsional vibration control algorithm in the process of motor drive,engine start and stop,and mode switch,the hardwarein-the-loop(HIL)test platform for planetary and multi-speed hybrid power system was built for verification based on d SPACE/Simulator and Rapid ECU-U2 prototype controller.The test results under various transient conditions show that the designed transient torsional vibration control algorithm has good real-time performance.