Design And Research Of Variable Leakage Flux Reverse Salient-pole Msm Motor For Vehicle

In order to overcome the shortcomings of permanent magnet synchronous motor such as uncontrollable internal magnetic field,narrow constant power speed regulation range and easy demagnetization of permanent magnet,this paper designs a novel Variable Leakage Flux Reverse Salient-pole Motor(VLF-RSPM)on the basis of the traditional motor structure,which mainly realizes the online adjustment of leakage flux by controlling the cross-axis current,thereby adjusting the internal magnetic field.This effectively improves the speed expansion capacity of the motor.At the same time,the reverse salient pole characteristics of the motor can effectively reduce the risk of VLF-RSPM demagnetization.This paper mainly conducts in-depth research from four aspects: VLF-RSPM design,working principle,structural optimization,electromagnetic performance and vibration and noise.Main research contents of this paper:(1)Design and working principle of VLF-RSPM: The design process of VLF-RSPM topology is introduced in detail,and the two characteristic realization conditions of VLFRSPM are analyzed in detail by using the equivalent magnetic circuit method,and the weak magnetic amplification principle of VLF-RSPM and the magnetic leakage under different working conditions are elaborated in detail.Secondly,the changes of flux linkage and torque under the influence of cross-axis current under the magnetic flux leakage characteristics of VLF-RSPM are analyzed.In addition,a simple derivation of the mathematical model of VLFRSPM is carried out.(2)VLF-RSPM structure optimization: Based on the optimization platform of cosimulation,the rotor structure of VLF-RSPM is optimized by multi-objective optimization method.Through the establishment of the model by SOLIDWORKS,to improve the efficiency of optimization,sensitive analysis was selected to screen 10 parameter variables,and the main variables with large influence on output torque,torque ripple,reverse convex pole ratio,iron loss and so on were screened.The response surface and multi-objective genetic algorithm are used to determine the optimal structure parameters of VLF-RSPM and construct the optimal structure of VLF-RSPM.(3)Electromagnetic performance of VLF-RSPM: In-depth analysis of the electromagnetic properties of VLF-RSPM through 2D finite element simulation.First,the basic electromagnetic properties of the motor(such as magnetic field distribution,inductance characteristics,torque characteristics and no-load characteristics)are thoroughly studied.Secondly,the speed regulation range,loss and efficiency of the two motors also need to be studied.Then,to better reflect the advantages of anti-salient pole characteristics on the demagnetization risk,this paper conducts a detailed evaluation of the demagnetization risk of the two motors under different conditions.In addition,considering that the magnetic bridge and magnetic barrier added to the VLF-RSPM design bring the risk of magnetic steel fracture to the motor during high-speed operation,this chapter uses the structural stress method to analyze the mechanical strength.(4)Electromagnetic vibration and noise of VLF-RSPM: The vibration and noise of the two motors are studied in depth by using the harmonic response of Workbench.Firstly,the modal analysis theory is briefly explained,and then three different stator mode finite element models are established,and the finite element model is used to explore the influence of the casing and constraints on its natural frequency.Secondly,the principle of radial electromagnetic force is briefly explained by analytical expression,and on this basis,the radial electromagnetic force and its harmonic distribution of two motors under three different states of no-load,heavy-load and high-speed are studied.Subsequently,the electromagnetic field in the previous step is coupled with the structural field,and the vibration harmonic response analysis of the motor under heavy load and high speed is carried out to obtain its vibration characteristics.Finally,combined with the previous research,the noise characteristics of the two motors under heavy load are mainly studied.