| Vigorously development of new energy vehicles is one of the effective ways to solve the energy crisis and environmental pollution.Electric drive system consisting of driving motor and transmission device is the core device of new energy vehicles.In order to improve the power density of the system and reduce the cost of production,high speed electric drive system with integrated design and control is the future development trend.At the same time,problems are brought by the high-speed motor,such as system reliability and NVH,especially in pure electric vehicles.In order to improve the NVH quality of electric drive system system,aiming at the high power density,high efficiency and high reliability electric drive system,aiming at the basic scientific problems such as the mechanism and characteristics of vibration and noise under high speed and high integration,as well as the key technical problems such as vibration and noise suppression methods and test methods,the mechanism analysis of vibration and noise of electric drive system,the construction of simulation platform of electric drive system and the prediction analysis of vibration and noise under multi-source excitation,the method of vibration and noise suppression of transmission device,the vibration and noise bench and the whole road test are studied.The key technologies such as the construction of simulation platform of electric drive system based on finite element method,the vibration and noise suppression of gear transmission system based on micro-modification of gears,the torque ripple suppression of motor based on rotor skew pole,and the vibration and noise bench and road test of electric drive system are mainly studied.In conjunction with the National Key Research and Development Program of Ministry of Science and Technology " Development of High Performance and Precision Integrated Driving Motor System",the main research contents are as follows:(1)Analysis of vibration and noise mechanism of electric drive system.From the vibration and noise sources and transmission paths,the causes of vibration and noise of electric drive system are analyzed.In view of helical gear noise,the generation mechanism of internal excitation of gear system such as meshing stiffness,transmission error,meshing impact and tooth surface friction,and the generation mechanism of external excitation of gear system such as stiffness excitation of bearing,torque ripple and radial electromagnetic force of motor,and random excitation of road surface are analyzed.The generation mechanism of vibration and noise caused by magneto-solid coupling are analyzed.(2)Construction of simulation platform for multi-source excitation electric drive system.According to substructure composition method and finite element method,the finite element model of the electromagnetic field of the motor is established and the torque ripple and radial electromagnetic force excitation of the motor are obtained.The finite element model of shell structure is established and the simulation modal of shell is obtained and the modal test of shell is carried out.The experimental results are in good agreement with the simulation results.The coupling dynamic model of gear transmission system is established and the transmission error excitation is obtained.Based on the motor model,shell model and gear transmission system model are synthesized,and a joint simulation platform for vibration and noise of the electric drive system supported by three bearings is constructed.(3)Prediction of vibration and noise under multi-source excitation based on simulation platform of electric drive system.Based on the simulation platform,in order to predict the vibration of electric drive system under multi-source excitation,the vibration acceleration response of bearings and it’s shell joints on motor shaft and response joints on shell under the transmission error of gear,the torque ripple and the radial electromagnetic force of motor,and different order excitation of torque ripple and radial electromagnetic force are analyzed.The concept of root mean square of velocity is introduced to reflect the radiated noise of the system.The root mean square of the average normal velocity of the surface nodes of the electric drive system under multi-source excitation such as transmission error,motor torque ripple and radial electromagnetic force are analyzed to predict the radiated noise of the electric drive system.The effectiveness of the simulation platform is verified by comparing the simulation results with the bench test results.(4)Vibration and noise suppression method of transmission device.A method of vibration and noise suppression of transmission system based on micro-modification of gears is proposed.Smith slice method is used to obtain the transmission error and load distribution on the tooth surface of meshing gear pairs.Taking the minimum transmission error fluctuation,the minimum max load on the tooth surface and the different weight ratios of the two as optimization objectives,the multi-objective optimization of gear modification parameters based on particle swarm optimization is carried out to obtain the Pareto optimal solution.The method of suppressing motor torque ripple by rotor oblique pole is studied,and the working principle and form of rotor oblique pole,the influence of segmented oblique pole on electromagnetic torque and the determination method of oblique pole angle are analyzed.The influence of the number of oblique poles on the torque ripple under different conditions is analyzed by using the linear oblique pole method based on the simulation platform,and the optimal scheme of two oblique poles is finally determined.Torque ripple bench test was carried out to verify the feasibility of rotor oblique pole method to suppress torque ripple.(5)Vibration and noise bench of electric drive system and full-lane road test verification.A common control platform for automotive transmission system is proposed for vibration and noise bench test of electric drive system.Under the conditions of constant speed,constant torque acceleration,coasting,feeding coasting and off-line detection,the vibration acceleration value and near-field noise order distribution of the shell of the electric drive system before and after gear micro-modification and rotor bevel optimization are compared and analyzed,and the effectiveness of the vibration and noise suppression method is verified.A domestic pure electric vehicle with the optimized electric drive system is selected as test platform,the order contribution distribution and order distribution of vehicle interior noise under slow acceleration and coasting conditions are measured.The effect of optimization method on NVH quality of vehicle is verified.The research results lay a theoretical foundation for the integrated design of the electric drive system,and provide an effective method and technical means to improve the NVH quality of the electric drive system.It has important social and economic value and broad engineering application prospects. |
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