| The electromagnetic noise in the motor is the main noise source of the motor.Therefore,the calculation of the electromagnetic force wave in the motor,Analysis and accurate expression are the key to electromagnetic vibration analysis and calculation.Therefore,this paper starts with the root causes of motor vibration and noise,analyzes and calculates the electromagnetic excitation force waves and electromagnetic vibration of the built-in permanent magnet synchronous motor in detail,and studies its weakening measures.The main work and results achieved as follows:1.Analysis of Fast and Accurate Calculation Method for Air-Gap Flux of Interior Permanent Magnet Synchronous MachineThe key to solving electromagnetic excitation force waves is to solve the air-gap magnetic field of the motor.At present,there are mainly three methods for the calculation and analysis of the air-gap magnetic field:analytical method,magnetomotive force-permeability method,and finite element method.The MMF method cannot obtain the accurate value of the air gap magnetic density,and it can only be used for stereotype analysis but not quantitative analysis.The application range is limited.When considering the saturation of the core and the complex shape of the cogging,the calculation period will be longer and the calculation accuracy will be reduced.The finite element method can more accurately calculate the air gap magnetic field and electromagnetic force density,but it cannot effectively analyze the excitation force wave.The source term cannot be derived for specific waves.The combined method of the derivative method and the finite element method is used to calculate the air gap magnetic flux density of the built-in permanent magnet synchronous motor.When calculating the no-load magnetic field of the motor,the permanent magnet magnetomotive force and air gap magnetism were introduced into the hand.Based on the two-dimensional static field.two finite element simulations of the motor model with and without cogging were performed to obtain the permanent magnet magnetomotive force and air gap magnetism.Derivative distribution and Fourier decomposition of it can accurately obtain the no-load magnetomotive force and air-gap permeability expressions including amplitude,frequency,and phase.When calculating the load magnetic field,a new d-axis reluctance model was proposed using the principle of frozen magnetic permeability to consider the effect of rotor saturation on the air gap magnetic density generated by the armature magnetic field to resolve the gas generated by the armature magnetic field.Gap magnetic density.Based on the superposition of the no-load magnetic field and the armature magnetic field,a unified air-gap magnetic density expression is derived.At the same time,when there is a harmonic current in the motor,the magnetomotive force generated by the harmonic current is projected on the d and q axes of the rotor by using the principle of frozen permeability.Harmonic content.This method can quickly and accurately obtain the air gap magnetic density of the motor under no-load,load,and harmonic current conditions,and prepare for electromagnetic force wave calculation.2.Analysis of Fast and Accurate Calculation Methods for IPMSMThe generation of electromagnetic force waves is due to the interaction between air-gap magnetic-dense harmonics.Different harmonic air-gap magnetic densities generate electromagnetic force waves of different orders and frequencies.At the same time,electromagnetic force waves of different orders and frequencies affect electromagnetic waves.The effects of vibration are different,so solving the source of electromagnetic force waves of various orders and frequencies is also an important aspect of the research content.According to the obtained air-gap magnetic density expression of the motor under no load,load and harmonic current,and according to the interaction relationship between the harmonics,the electromagnetic force wave expression is obtained from the solved air-gap magnetic density according to the Maxwell tensor method.The amplitude and phase of the electromagnetic force waves of each frequency and order are obtained,and the source of the low-order electromagnetic force waves in the motor is obtained,and preparations are made for the reduction of the electromagnetic force waves in the future.At the same time,the electromagnetic force wave is a two-dimensional function in time and space.This chapter uses Matlab to perform two-dimensional Fourier decomposition of the electromagnetic force wave to accurately obtain parameters including amplitude,frequency,and phase.3.Effect of Stator and Rotor Structure Parameters on the Force WavesFirstly,the influence of slotting in the motor on the electromagnetic excitation force wave in the motor was studied through different pole-slot coordination.Derived.Based on the no-load electromagnetic force wave,the influence of the stator and rotor structure parameters on the electromagnetic excitation force wave is studied for the structural parameters of the motor.The stator side content includes the stator slot opening width,the stator slot auxiliary slot,the number and width of the auxiliary slot slots,the shape and depth of the auxiliary slot,and the influence of the stator inclined slot on the electromagnetic excitation force wave.At the same time,the rotor side includes the rotor pole arc coefficient and The effect of rotor slotting is deduced by theory and a finite element verification is performed to achieve the purpose of weakening the electromagnetic excitation force wave.4.Motor modal analysis and vibration analysis It is very important to study the influence of electromagnetic excitation force waves of different frequencies and orders on electromagnetic vibration,so this paper analyzes the natural frequency of the motor and its vibration characteristics.Firstly,the finite element method is used to analyze the modes of the stator core,including the stator core,the stator core plus windings,the stator casing and the end cover,and the mode modes and natural frequencies of the stator are obtained.Then,the electro magnetic excitation force wave under no-load,load and harmonic current is added to the stator to obtain the stator vibration response,which provides a theoretical basis for the motor to avoid strong electromagnetic vibration. |
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