Analysis Of Electromagnetic Vibration And Noise Characteristics Of Permanent Magnet Brushless DC Motor

Among the industrial equipment and household products,the permanent magnet motor has a simple structure and a low manufacturing cost,and has been widely used in various occasions.However,the device also provides a large amount of vibration and noise pollution while providing power.Therefore,studying the vibration and noise of permanent magnet motors was of great significance to improve human comforted and reduced environmental pollution.In order to study the vibration and noise of permanent magnet motor,this paper takes a permanent magnet brushless DC motor as the research object.The main research contents were divided into the following aspects:Firstly,starting from the electromagnetic force wave acting on the stator surface of the motor,the order characteristics of the air gap magnetic density were derived by the relationship between the air gap magnetic density and the magnetic conductance and magnetic potential.According to the Maxwell Stress Tensor equation,the analytical analysis method of radial electromagnetic force wave was deduced,and the spatial and temporal order characteristics of radial electromagnetic force were analyzed by means of electromagnetic simulation.Secondly,starting from the structure of permanent magnet brushless DC motor,the modal characteristics of the motor were analyzed.The finite element model of each part of the motor was established.The relationship between the motor modal frequency and the parameters of the anisotropic materials was analyzed for the stator core and winding material property parameters.According to the variation law of modal frequency,a parameter correction method based on modal frequency was proposed.This method can quickly complete the parameter correction of stator finite element model.Secondly,five kinds of equivalent models were proposed for the modeling of windings.The error rate of the equivalent model was analyzed,and it was pointed out that the equivalent model using a hexahedral mesh instead of the winding was the most accurate.Finally,the modal experiment was carried out by hammering method to verify the accuracy of the finite element model and determine the effectiveness of the equivalent material parameter correction method.The modal test of the stator,the error was within 3%,to achieve the purpose of the experimental and simulation benchmarking.The modal test and simulation of the whole machine were all below 7%,which meets the engineering requirements.Finally,the motor was tested and simulated by vibration and noise.The order tracking method was used to identify the source of each order noise of the motor under different working conditions,and the main order of motor vibration was obtained by analyzing the dynamic working conditions.Combining the magnetic field simulation results and the structural modal analysis results,the acoustic model was established and the electromagnetic vibration and noise were calculated by the magnetic field-structure-acoustic multiphysics coupling method.The experiment was compared with the simulation results to verify the rationality of the simulation ideas and the accuracy of the calculation results.