| The interior permanent magnet synchronous motor(IPMSM)is widely used in the electric vehicle industry and has become one of the main driving parts of electric vehicles due to its wide range of speed regulation,good control performance and strong antidemagnetization ability of permanent magnet.However,due to the serious magnetic saturation phenomenon of the interior motor,it is difficult to calculate the nonlinear air gap magnetic field,and the finite element simulation generally takes a long time.At the same time,due to manufacturing and installation errors as well as poor operating conditions,the motor will be eccentric and the magnetic saturation will not be evenly distributed,the complex variation of air gap magnetic field,resulting in unbalanced magnetic pull,and motor vibration and loud noise.Therefore,the analytical calculation of the internal permanent magnet synchronous motor with magnetic saturation,static and dynamic eccentricity and stator slot effect taken into account comprehensively has important theoretical significance and application value.(1)Analytical modeling and analysis of no-load magnetic field and magnetic leakage coefficient of interior permanent magnet synchronous motor.First,the equivalent magnetic circuit model of no-load magnetic field was established,and the double iteration of the end magnetic bridge and the interpolar magnetic saturation was considered by combining the BH curve of the motor material.Combined with the complex relative permeability function,the influence of stator slotting on magnetic saturation is investigated.The saturation coefficient is defined by analytical algorithm,the no-load magnetic flux leakage coefficient is calculated,and the influence of different materials and magnetic bridge structures on the no-load magnetic flux leakage coefficient is analyzed.The research results show that the stator slot has a certain influence on the magnetic saturation and can reduce the magnetic flux entering the air gap.When the width of the magnetic bridge increases,the no-load magnetic flux leakage coefficient will increase.As the length of the magnetic bridge increases,the no-load magnetic flux leakage coefficient will decrease.(2)Analytical modeling and analysis of load magnetic field of interior permanent magnet synchronous motor.The equivalent magnetic circuit model of the loaded magnetic field was established,and the concept of rotor magnetomotive force distribution function was proposed.The loaded magnetic field was divided into two parts from the perspective of magnetomotive force,so as to realize the complete parameter analysis of the armature reaction magnetic field and synthetic magnetic field of the permanent magnet synchronous motor considering magnetic saturation.Based on maxwell’s stress tensor method,an analytical model of electromagnetic force is established to analyze the space-time characteristics of electromagnetic force.(3)Analytical modeling and analysis of static eccentric magnetic field of interior permanent magnet synchronous motor.In view of the different magnetic saturation degrees of the different magnetic poles under static eccentricity,the concept of equivalent average air gap length was proposed,and the different magnetic poles were calculated iteratively.At the same time,the improved complex relative permeability method is used to calculate the complex relative permeability under static eccentricity.The influence of static eccentricity on the spatial order and frequency characteristics of air gap magnetic field and electromagnetic force was analyzed by considering the influence of eccentricity and non-uniform complex relative permeability on magnetic saturation.(4)Analytical modeling and analysis of dynamic eccentric magnetic field of interior permanent magnet synchronous motor.The length of the air gap under dynamic eccentricity is calculated precisely by using geometric relation.The complex relative permeability under dynamic eccentricity is calculated by using the improved complex relative permeability method.The influence of dynamic eccentricity on the spatial order and frequency characteristics of air gap magnetic field and electromagnetic force is analyzed.The research results showed that the air gap magnetic field would generate the spatial order component of ±1 and the frequency component of ±fr on the basis of no eccentricity.(5)Analysis and test verification of electromagnetic characteristics of interior permanent magnet synchronous motor.The electromagnetic torque,cogging torque and unbalanced magnetic pull are calculated by using the analytical model.The effects of different static and dynamic eccentricity on the unbalanced magnetic pull were studied,and the electromagnetic torque was tested. |
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