| In recent years,new energy vehicles are becoming a hot research field.Permanent magnet motors have been used widely in electric vehicle drives because of their high power density and wide speed range.However,it is difficult to adjust the air gap magnetic field of a permanent magnet motor.In order to increase the field weakening speed regulation range of the motor,it is usually used to adjust the magnetic field method via a direct-axis demagnetization current,which may cause the permanent magnet to face the danger of irreversible demagnetization.In order to improve the speed regulation ability of the motor and reduce the risk of demagnetization of the permanent magnets,a new type of anti-salient permanent magnet motor is proposed.Firstly,based on the analysis of the current research status and development trend of wide-speed adjustable drive motors for electric vehicles,the thesis focused on the problems of traditional interior permanent magnet motors and discussed how to achieve wide-speed operation of the motor and reduce the risk of irreversible demagnetization of permanent magnets.On the basis of the problem that the traditional interior permanent magnet motor required a large direct-axis demagnetization current when the field was weakened,a new type of anti-salient permanent magnet motor with a direct-axis inductance greater than the quadrature-axis inductance was introduced.Secondly,a 25 k W anti-salient permanent magnet motor was designed.From the perspectives of winding factor,cogging torque and unbalanced magnetic tension,the pole-slot ratio of the motor was analyzed and determined,and the winding connection method was analyzed.The interior motor was used as the initial motor,and a new type of rotor structure was proposed.On this basis,the main size and design scheme of the motor were determined.Then,with the aid of the finite element method,the air gap flux density,permanent magnet flux linkage,back electromotive force,magnetic field distribution,no-load cogging torque,and load torque of the anti-salient permanent magnet motor and the traditional permanent magnet motor were compared and analyzed.Characteristics,and analyzed and compared the efficiency characteristics of the two motors.Finally,the influence of the air gap magnetic barrier on the rotor quadrature axis magnetic circuit on the inductance of the motor was analyzed.Three air gap magnetic barriers of different shapes were compared and analyzed.Furthermore,the influence of magnetic circuit cross saturation caused by current on the inductance of the motor was further discussed. |
