Design And Electromagnetic Analysis Of In-wheel Direct Drive Motor Based On Magnetic Field Modulation Technology

In-wheel drive is considered to be the basic configuration of next-generation electric vehicles.Permanent magnet synchronous motors have gained a lot of research and development due to their outstanding advantages such as compact structure and high efficiency.However,due to the limitation of the space in the wheel,the torque output density that the permanent magnet synchronous motor can provide is still far from the driving power demand of the vehicle.The thesis proposes a new configuration of magnetic field modulation type in-wheel drive compound motor,which uses the principle of magnetic field modulation to achieve deceleration output,which will greatly increase the output torque of the motor and increase the speed range of the motor.In this thesis,combined with the development needs of integrated electric wheels based on the in-wheel suspension structure,the system has deeply developed the design of the magnetic field modulation type composite direct drive motor and the finite element simulation study of its electromagnetic performance.The thesis first designed the basic structure of the magnetic modulation compound direct drive motor.Based on the internal suspension type of the electric wheel and the multifunctional layout space conditions,the structural scheme and overall size of the direct drive motor were determined;By analyzing the power requirements of electric vehicles under different working conditions,the performance design indicators of the drive motor were matched and calculated.Combined with the analysis of the magnetic field modulation principle,the main configuration parameters such as the number of pole pairs of the internal and external stator magnetic fields and the reduction ratio were determined.The thesis carried out the basic performance analysis of new motors and the optimization design of electromagnetic structure parameters.Using Maxwell electromagnetic simulation software,the finite element model of the electromagnetic field of the motor is established;Simulation analysis of air gap magnetic field reveals the magnetic field modulation mechanism;Taking the study of magnetic field modulationperformance as the goal,using power factor and air gap magnetic density amplitude as performance evaluation indicators,the system simulation analysis of the motor modulation ratio and the electromagnetic parameters of the magnetic ring on the motor performance,and finally completed the design of the main electromagnetic parameters of the motor.The thesis makes an in-depth study on the main performance of the designed motor.First,the finite element simulation calculation of the no-load characteristics and static torque characteristics of the motor is carried out to verify that the motor can achieve large torque output characteristics;Analysis of motor torque ripple and its influencing factors,through analysis and optimization of the proportion of the magnetic adjustment ring and the width of the inner and outer stator slots,the torque ripple of the direct drive motor is effectively reduced;Finally,the calculation and analysis of the iron loss and copper loss of the motor under various operating conditions.Based on the analysis results of 2 times overload condition,the influence law of different internal and external stator winding current combinations on drive motor torque and loss is revealed.The thesis research provides a new technical solution for the in-wheel direct drive motor,provides a prototype of the motor body design,and at the same time lays a solid theoretical foundation for the in-depth research and effective application of magnetic modulation technology in the electric wheel in-direct drive.