Design Of Intelligent Low-voltage Multiphase Motor System For Electric Vehicles

In the context of global warming,achieving low carbon emissions has become a consensus reached by governments of various countries.In order to reduce oil dependence and protect the ecological environment,new energy vehicles represented by electric vehicles have become the pillars of promoting the development of clean energy.The industry and market scale are expanding rapidly.As the core component of electric vehicles,the motor system has made great progress in recent years,but there are still some problems: 1)High-voltage drive brings low safety factor and high maintenance cost;2)High-voltage controller power electronic components expensive production cost;3)Defects such as low redundancy and low fault tolerance caused by three-phase AC motors.Therefore,in order to solve the above problems,it is necessary and urgent to develop a low-voltage multi-phase motor system for driving electric vehicles.This paper aims at an intelligent low-voltage multi-phase motor(Intelligent Stator Cage Drive,ISCAD)system,and has carried out the following work:First,research on the theoretical model of a new type of intelligent low-voltage multiphase motor,and introduce the unique squirrel-cage stator structure of ISCAD motor.The main parameters of the motor are calculated including: magnetomotive force,resistance,inductance,flux linkage and torque calculation methods.The principle of the pole pairs switching of this motor is analyzed.Second,the main points and requirements of automotive motor design are discussed.The electromagnetic design and modeling of ISCAD motors are carried out using finite element simulation software.The running state and performance of the motors under rated conditions are simulated and studied.The reason for the magnetic saturation of the rotor guide bar tooth.By analyzing the influence of pole pair number on motor efficiency under different operating conditions,it is verified that pole pair number switching can improve motor efficiency,and the motor efficiency map is drawn.At the same time,the efficiency comparison with traditional vehicle motors under rated operating conditions highlights the advantages of ISCAD motor.Third,in order to solve the problem of high AC loss caused by squirrel cage stator windings,the composition and causes of the AC loss of the motor windings are explored.The influence of stator slot size,position in the slot,cross-sectional area of the conducting bar,different number of pole pairs and winding material on AC loss is studied,which provides a theoretical basis for further AC loss reduction and motor efficiency improving.Finally,a twelve-phase ISCAD prototype was made,a twelve-phase motor controller was designed,the motor parameters were measured using the d SPACE semi-physical experimental platform,and the no-load speed regulation experiment of the motor was carried out to verify the rationality of ISCAD motor design principles.