Torsional Vibration Analysis And Control Of Transmission System Of CVT Hybrid Electric Vehicle

In recent years,with the increasingly stringent requirements of countries for automobile emissions,major automobile manufacturers have adopted different technical means to achieve more extreme fuel economy.In addition to the promotion of pure electric vehicles,the methods commonly used are engine supercharging,engine Down-sizing,engine Down-speeding,and hybridization.Boosting enhances engine power by increasing the density and pressure of air entering the cylinder,but at the same time it means that the engine is more violent and the engine vibration amplitude is larger;the engine Down-speeding means that the speed range is reduced,but the slower the speed is usually the jitter The greater the amplitude;the trend is to achieve hybridization by means of hybridization,generally by adding multiple motors.The increase of power source makes the hybrid vehicle obtain stronger power while adopting Down-sizing engine,but at the same time The torsional vibration of the transmission system under the excitation of a complex power source will be worse.Hybrid vehicles that are both dynamic and economical are relatively popular with consumers.From the above analysis,it can be seen that with the strict emission regulations,the NVH problem of the automotive transmission system will inevitably become more prominent,especially for hybrid vehicles with multiple power sources.Therefore,it is of great theoretical significance and engineering application value to carry out in-depth research on the torsional vibration of hybrid electric vehicle transmission system.Aiming at the torsional vibration problem of hybrid system,a hybrid SUV with a P2 configuration and a CVT transmission is taken as the research object.Firstly,the dynamic characteristics of the CVT transmission are analyzed to study its torsional vibration characteristics.Then the transmission is established in AMEsim software.The free vibration concentrating mass model of the system;the engine as the main excitation source,the excitation generation principle and the excitation characteristics are analyzed,and the forced vibration model of the drive train under the engine excitation is established.According to the concentrating mass model of the free vibration of the drive train established above,the inherent characteristics of the system are analyzed according to different working modes,the natural frequency of the system is solved and the resonance speed under different gear ratios is analyzed;then in the time domain and frequency domain respectively The excitation characteristics of the engine were simulated and analyzed,and the simulation results were in line with the theoretical analysis.According to the engine excitation model,the sensitivity analysis of the clutch stiffness,clutch damping and half-shaft stiffness of the key structural parameters of the drive train is carried out,and the influence characteristics and effects of structural parameters on the torsional vibration of the system are discussed.As a widely used vibration damping device,the dual mass flywheel(DMF)is of great significance for the study of its torsional vibration characteristics and parameter matching optimization methods.Firstly,the type and characteristics of the double mass flywheel are analyzed.In this paper,the circumferential long curved spring double mass flywheel is selected as the research object.The structural parameters are preliminarily selected according to the matching principle for torsional vibration analysis.Then the model based on Isight and AMEsim co-simulation is used for torsional vibration.The multi-parameter collaborative optimization of the responsive dual mass flywheel achieves a good damping effect after the optimized dual mass flywheel.Because passive vibration damping needs to analyze the structural parameters of complex powertrains,the parameters are numerous and the effects are coupled with each other,which makes the debugging optimization take a long time.By increasing the damping components,the structure of the powertrain is complicated.Hybrid vehicles have a fast response to the power motor,making the motor-based active vibration reduction a solution to the problem of torsional vibration of another transmission system.In this paper,the transmission system is simplified firstly,and the model predictive control(MPC)based vibration damping controller is designed according to the simplified three-degree-of-freedom model.Co-simulation of the MMC controller with the Amesim torsional vibration model was built in Simulink.Finally,the effects of active vibration reduction in the time domain and the frequency domain are compared and analyzed,and a good damping effect is achieved.