| Permanent magnet synchronous motor has the advantages of simple structure,high power density and excellent speed regulation performance and is widely used in the new energy vehicle industry.Modern permanent magnet synchronous motor with frequency converter power supply,provide strong support for motor stability at the same time also introduces abundant harmonic current in the armature winding,and the harmonic current and motor loss,closely linked to the electromagnetic wave,on the one hand is the motor loss caused by temperature rise caused the motor structure deformation,influencing the dynamic characteristics of the motor structure.On the other hand,the influence of harmonic current on electromagnetic wave and torque ripple makes it difficult to predict the vibration and noise of motor.Therefore,in order to simulate actual permanent magnet synchronous motor power supply condition,low harmonic current caused by the electromagnetic vibration,this study taking a car for permanent magnet synchronous motor as the research object,starting from the excitation current,the perspective of many physical field coupling in the forecast the vibration response of a permanent magnet synchronous motor,the main work includes the following aspects:The three phase current source of permanent magnet synchronous motor was collected,and the Fourier transform of the collected time domain current signal was carried out.The current spectrum results showed that the controller introduced low order harmonic current of 5 and 7 times fundamental current frequency,and the high order harmonic current was mainly concentrated in the carrier and its integer frequency multiple.Based on Maxwell tensor method,the expression of air gap electromagnetic force wave including harmonic current was derived,the electromagnetic finite element model of motor was built,and the electromagnetic force wave order analysis and spectrum analysis under different harmonic current excitation were completed.The simulation results were consistent with the theoretical analysis.The finite element method was used to solve the loss of each part of the motor,and the influence of different harmonic current excitation on the loss of each part of the heat source was analyzed,and the motor thermal coefficient and related boundary conditions were determined.According to the direct magneto-thermal coupling method,the temperature field of the motor under specific working conditions was calculated.Considering the anisotropy of the material after the stacking of the stator silicon steel sheet and using the equivalent model to replace the armature winding,the finite element model of the motor structure was established to complete the free modal calculation.Then the elastic rope was used to simulate the unconstrained state of the motor,and the modal test was carried out to verify the validity of the structural characteristics of the motor.Based on the verified structure model,the constraint modes of each order were calculated,and the resonance risk of the motor was judged by comparing with the electromagnetic wave frequency.The structural deformation of the motor structure under the action of thermal stress in the temperature field was calculated.The electromagnetic and structural finite element models of the motor were reconstructed based on the deformed structural model.The electromagnetic wave of the reconstructed electromagnetic model was used as the excitation,and the reconstructed structural model was used as the "path" to calculate the vibration response of the motor shell.The NVH performance test of the motor bench was completed.The vibration and noise characteristics of the motor were clarified through order analysis and spectrum analysis,and the vibration and noise of the motor was mainly caused by electromagnetic force wave.The test data are compared with the simulation results,the trend is consistent,and the validity of the motor multi-field coupling vibration response model is verified. |
PDF Full Text Request