Analysis And Parameter Optimization Of Electromagnetic Vibration And Noise Of Domestic Refrigeration Compressor

With the continuous improvement of social and economic level,refrigeration technology plays an increasingly prominent role in human production and life,and energy saving,vibration reduction and noise reduction are the main problems affecting the market application of commercial refrigeration compressors.Compressor is the main power source of commercial refrigeration equipment,which will produce large vibration and noise during operation,among which the electromagnetic noise generated by permanent magnet synchronous motor has a great impact on the whole machine.There are two main sources of electromagnetic vibration and noise of permanent magnet synchronous motor.First,the amplitude of radial electromagnetic force generated by air gap magnetic field is large,and vibration and noise are easy to occur when the structural strength of the motor is relatively low.Second,when the frequency of radial electromagnetic force is close to the modal frequency of the motor stator system,structural resonance will be generated.Aiming at the problem of reducing vibration and noise of a commercial refrigeration compressor,this paper studies the electromagnetic vibration characteristics and noise control strategy of permanent magnet synchronous motor by means of experimental simulation and theoretical calculation,so as to provide reference for improving the comprehensive performance of the compressor.This paper firstly analyzes the development status of compressor and electromagnetic noise control technology,and tests the noise of compressor at different rotating speeds with the method of sudden power off.It is found that the influence of electromagnetic noise decreases gradually with the increase of rotating speed.Based on the noise spectrum analysis under normal working conditions,it is found that the noise amplitude of the compressor is mainly between 4kHz and 10kHz frequency,and the peak noise is 67.5dB(A)at 5kHz frequency.At 1k6Hz,2k5Hz,5kHz and 8kHz frequencies,the difference of noise value before and after power failure is 7.5dB(A),indicating that electromagnetic force has a great influence on compressor noise in these frequency segments.In the compressor vibration test,the radial acceleration peaks at lk6Hz and 5kHz frequencies,which are 6.6m/s2 and 6.13m/s2,respectively;the tangency acceleration peaks at 8.05khz frequency,which are 3.36m/s2;and the axial acceleration peaks at 2.837khz,which are 1.51m/s2.Motor was derived by using Maxwell’s law at load and no load when the number of radial electromagnetic force frequency and space,the relationship between the finite element software Ansoft Maxwell established six slot quadrupole permanent magnet synchronous motor physical model,through simulation calculation,get the on time frequency,amplitude and space of the logarithmic three-dimensional distribution of the radial electromagnetic force,and then is obtained by Fourier transform in MATLAB radial electromagnetic force frequency and amplitude on the time of logarithmic relationship.The reliability of theoretical calculation is verified by comparing theoretical calculation with software simulation calculation.Then,the dynamic modal analysis theory of multiple degrees of freedom was used to establish the structure and mechanical models of the compressor stator,equivalent windings,chassis and bracket,etc.The fixed contact mode was set according to the actual contact mode.The modal parameters of the compressor assembly and the whole machine were calculated by using the finite element software ANSYS Workbench.Using LMS Test.Lab vibration Test system for compressor hammering method Test,according to the experimental modal analysis determine first six order natural frequency spectrum,respectively,compared with finite element software to calculate the natural frequency,the minimum error of 1.3%for the second order frequency,the maximum error of 4.5%for the fifth order frequency,shows that the reliability of the finite element numerical calculation and simulation.Through comparative analysis,it is found that the radial electromagnetic force has serious influence on the first mode and the fourth mode of the compressor.Finally,on the premise that the output torque of the motor does not decrease,and with the aim of minimizing the mean value of the radial electromagnetic concentrated force on the stator tooth surface,the physical models of the three-stage stator and locally eccentric stator response surfaces are established,and the structural parameters of the two stator teeth are optimized by using the finite element ANSYS Workbench optimization module.By simulating the radial electromagnetic force of the optimized stator model and comparing the radial electromagnetic concentrated force on the surface of three different stator teeth,it is found that the optimal radial electromagnetic concentrated force on the surface of the optimized stator teeth is the prototype.Then the vibration and noise data of the two new prototypes are tested,and the values are reduced by comparison with the prototype,among which the compressor using three-stage stator teeth has a greater reduction in electromagnetic vibration than the compressor with partial eccentric stator teeth,and the radial vibration is greatly reduced.The compressor with partial eccentric stator teeth has A better performance in noise reduction.Compared with the prototype,the total sound pressure level is reduced by 2.85dB(A),and the noise reduction effect is quite obvious.After testing the main parameters of the motor and the energy efficiency of the compressor unit,the cooling capacity decreased by 0.9%and 0.56%respectively,the energy efficiency ratio decreased by 0.01 and 0.02 respectively,and the performance loss was 0.4%and 0.7%,both less than the design value of 4%.