Multi-physics Field Modeling And Vibration Analysis Of Integrated Powertrain

As a core component of new energy vehicles,the NVH performance of electric drive assembly is getting more and more attention.In the design stage of the electric drive assembly,it is essential to carry out vibration research on the electric drive assembly,establish relevant models to analyze the vibration mechanism of the electric drive assembly and study how to improve the NVH performance of the electric drive assembly.In order to improve the NVH performance of the electric drive assembly,this paper establishes the vibration and noise analysis model of the electric drive assembly and analyzes the vibration and noise mechanism of the electric drive assembly,and the main research contents are as follows.The structure principle of permanent magnet synchronous motor is introduced,and the mathematical model of permanent magnet synchronous motor(hereinafter referred to as PMSM),the coordinate transformation principle,is derived.The maximum torque to the current ratio(MTPA)control and weak magnetic control principle of PMSM are studied,and the mathematical model of PMSM in a rotating coordinate system,the expressions of voltage,torque and current are derived,and the essential formulas of MTPA control and weak magnetic control are derived based on the above terms.The two-dimensional electromagnetic field finite element model of PMSM in Maxwell,the vector control model of PMSM in Simulinnk,and the external circuit model of PMSM in Simplorer are built,and the field-circuit coupling model is obtained by implementing the joint simulation through the relevant interface modules.The three-phase current waveforms are obtained by simulating the PMSM field-coupled control model and Simulink permanent magnet synchronous motor control model,and the current comparison analysis shows that the PMSM field-coupled control system can simulate the current harmonics brought by the motor controller power supply well.The expressions for the radial electromagnetic force of the PMSM under a three-phase sinusoidal power supply and controller power supply are derived,and the frequency and spatial order of the radial electromagnetic force of the PMSM under the two power supplies are summarized.Based on the established finite element model of the PMSM in Maxwell,the magnetic line distribution and magnetic density distribution clouds of the motor,the flux density of the air-gap magnetic field and the radial electromagnetic force are obtained by simulation using a three-phase sinusoidal current as the excitation source.The spatial and temporal characteristics of the radial electromagnetic force are analyzed by the Fourier transform,and the results are consistent with the theoretical derivation.Comparing the electromagnetic force generated by the PMSM field-coupling simulation with the electromagnetic force spectrum generated by the finite element method,it can be seen that the harmonic content of the electromagnetic force generated by the field-coupling method is greater,and in the low-frequency band of 0-6000 Hz,the difference between the two electromagnetic force amplitudes is relatively small,and the distribution is consistent;in the frequency band of 6000-9000 Hz,the field-coupling generates a high-frequency electromagnetic force related to the switching frequency,which is consistent with the theoretical analysis This is consistent with the theoretical analysis.The finite element model of the electric drive assembly was established,the constrained modal analysis was performed,the multi-body dynamics model of the electric drive assembly was established in AVL e Axle,and the vibration response of the electric drive assembly under steady-state and transient conditions was analyzed,and the bearing force of the electric drive assembly under steady-state conditions was analyzed,and the vibration acceleration waterfall diagram of the shell surface under transient conditions was analyzed to verify that the electromagnetic and mechanical orders are the main vibration orders of the shell.The main vibration order of the surface was verified.Next,vibration bench experiments were conducted on the electric drive assembly in a semi-anechoic chamber,and the experiments were compared with the simulation to verify the validity of the modelling.