Electromagnetic Performance Analysis Of Permanent Magnet Assisted Synchronous Reluctance Motor

In recent years,with the increasing air pollution and the depletion of fossil fuels,our country has accelerated the pace of research in the field of electric vehicle technology.At the same time,new preferential policies for this industry have been continuously introduced in China,which makes the domestic electric vehicle industry achieve leapfrog development.The gradual replacement of traditional fuel vehicles by electric vehicles has become a trend.The drive motor is the core component of an electric vehicle,and it must meet the requirements of high torque density and wide speed range.The permanent magnet assisted synchronous reluctance motor(PMASynRM)has good application prospects in the field of electric vehicle drive motor field owing to its advantageous such as high efficiency,high power factor,high torque density,high power density,wide speed range,small size and light weight.However,the related research on the motor at home and abroad is not mature,and the motor is rarely successfully applied to engineering practice.Because the magnetic circuit structure of the motor is complicated,and the commercial finite element software takes a long time to calculate the magnetic field,this paper mainly studies the magnetic circuit structure,structural parameters and magnetic field analytical modeling of the permanent magnet assisted synchronous reluctance motor,the main contents are as follows:First of all,through reviewing a large number of domestic and foreign literatures,this paper expounds the research background significance of the subject and the development status of permanent magnet synchronous motor,synchronous reluctance motor and permanent magnet assisted synchronous reluctance motor,and deeply studies the magnetic field analytical modeling method of the motor.Secondly,the basic structure of permanent magnet assisted synchronous reluctance motor is introduced in detail,the advantages and disadvantages of two different rotor structures are analyzed,the mathematical model of the motor is established,and the operation characteristics of the motor under two different conditions are analyzed.The equivalent magnetic circuit models of the q-axes and d-axes of the motor are established,and the mathematical equations of the q-axes and d-axes of the motor are derived respectively according to the magnetic circuit model.In addition,the finite element method is used to analyze the influence of the main structural parameters of the motor on the electromagnetic performance of the motor,such as the inductance difference between the q-axis and the d-axis,salient pole ratio and electromagnetic torque.These structural parameters include the shape of flux barrier,the number of flux barrier layers,the proportion of magnetic isolation layer,the length of the air-gap,the width of the rib,the position of the permanent magnet,the duty ratio of the permanent magnet,and the thickness of the permanent magnet.The optimal structural parameters are selected to optimize the performance of the motor.Finally,the equivalent magnetic network method is used to establish the equivalent magnetic network model of the motor under two working conditions of armature current acting alone and permanent magnet acting alone.Then,based on the equivalent magnetic network mode,the analytical model of armature air-gap flux density,no-load air-gap flux density,load air-gap flux density,reluctance torque,no-load flux linkage,no-load back EMF,electromagnetic torque are deduced theoretically.Then the results are compared with those calculated by the finite element method to verify the validity of the analytical model established in this paper.