Research On A Less Rare Earth Interior V Permanent Magnet Synchronous Machine Used For Electric Vehicles

In recent years, due to the rapidly rising prices of rare earth permanentmagnet materials, less built-rare earth permanent magnet synchronous motor havecaught more and more attention. Less rare earth interior V permanent magnetsynchronous machine (LRE-IVPMSM) with an advantage of less rare earthconsumption and more power density is used in the field of electric vehicles morewidely. This paper study several aspects of less rare earth built-in V-shapedpermanent magnet synchronous motor, including motor design principle,optimization of structural parameter, analysis and simulation of temperature field,analysis of the mechanical stress.First of all, combined with the finite element simulation and analyticalanalysis, the design rules of machine structure parameters have been determined byanalyzed the effect of the bridge width, the thickness of the permanent magnet, thespan angle of permanent magnet slots and the width of stator slot. For the situationof the high torque ripple of machine when it run at high speed, this paper has takenthe method of fault pole to reduce the electromagnetic torque slightly and the torqueripple greatly.Secondly, the influence of slot-pole combination is analyzed and theelectromagnetic performances of motor electromagnetic torque and torque ripple indifferent layered structure of PM are shown. A48-slot-8-pole LRE-IVPMSM isdeemed to be the optimal design scheme. The influence of cross couplinginductance is considered by the calculation of LRE-IVPMSM’s inductance. Theinfluence rule of cross coupling inductance distribution is proposed and it’s thebasis theory for precise control of LRE-IVPMSM. Besides, the distribution of themachine’s efficiency and the voltage, current and slator loss of LRE-IVPMSM inthe whole work area are shown.Thirdly, the temperature distribution of the machine is analyzed. The eachpart’s loss of machine have been calculated by simulating and the thermalconductivity of the gap and the winding are calculated by using the equivalentmethod. The temperature distribution of the LRE-IVPMSM in different conditionsare analyzed. Then, the maximum temperature point of the machine is found and thereliability and rationality of the machine program are verified.Finally, the mechanical structural strength of the machine is studied since themachine’s speed high, and the bridge width is small. After calculating and analysingthe machine’s various loads, different load’s the stress distribution of the machine indifferent conditions are analyzed by the ANSYS, which is a finite-element-method’ssoftware. The stress distribution of the machine provides an important reference for the structure’s design of LRE-IVPMSM. In addition, to ensure the reasonableness ofthe machine program, the reliability of LRE-IVPMSM’s mechanical strength isverified. Design rules of monolayer, bilayer permanent magnet rotor permanentmagnet rotor and the minimum width of the bridge width which meet themechanical strength are analyzed in the meantime.