Research On Design And Control System Of Electric Drive Wheel Motor Direct Drive System

At present,in.wheel motor.driven electric vehicles have become one of the mainstream directions for the development of electric vehicle drive systems.Electric vehicles with direct.drive wheel hub motors are more suitable for the inevitable trend of automobile development,which simplifies the mechanical structure,improves mechanical efficiency,facilitates control,and is conducive to the integration of automobiles.However,the hub motor is installed in the rim,the size of the motor is limited by the space,and the output power is limited.Therefore,improving the power density of the motor is a problem that needs to be solved when designing the motor.In addition,the direct drive of the hub motor will directly affect the torque fluctuation of the motor on the drive wheel system,which is likely to cause vibration of the entire hub structure,affect the performance and control accuracy of the motor,and affect the ride comfort and driving comfort of the vehicle.Therefore,when designing a hub motor,fully analyze the causes of the torque fluctuation of the hub motor,and design the motor reasonably to suppress the torque fluctuation In response to the above problems,this paper designs a hub motor with high power density and low torque fluctuation,and studies the control strategy of the drive system for the requirements of the wide speed range and fast response of the hub motor to drive electric vehiclesFirst,establish a hub motor model,and analyze its torque fluctuations to get the factors that affect the motor torque fluctuations,analyze the cogging torque,flux linkage harmonics,and current harmonics of the hub motor with different pole slots,and determine In this paper,the pole slot matching of the hub motorSecondly,in order to obtain higher power density,an analytical model of the block.type Halbach array wheel motor is constructed in this paper.By comparing the effect of different block numbers on the performance of the motor,a Halbach permanent magnet array model with 4 poles per pole interval between poles is proposed.Next,the evolution strategy is applied to the optimization design of the Halbach permanent magnet array,and the center angle α corresponding to each permanent magnet and the angle β between the magnetization directions of two adjacent permanent magnets under the same pole are used as the optimized variables,and the hub motor The fundamental wave amplitude of the air gap flux density and the THD value of the air gap flux density are optimized objective functions.Optimizing the target parameters to achieve the goal of optimizing the design of the wheel motor Halbach permanent magnet array.Finally,Ansoft Maxwell 2D was used for simulation analysis to verify its correctnessThen,in order to meet the requirements of the wide speed range of electric vehicles,this paper uses vector control and field weakening control to control the entire speed range of the motor.By analyzing the limitations of the field weakening control of the traditional SPM in.wheel motor,the field weakening control strategy in the constant torque zone is proposed.Then,based on the Simulink software platform,a permanent magnet synchronous motor control system model is established,and the control effect is simulated and verified.The results prove that the control method studied in this paper can control the permanent magnet synchronous motor stably,and the new field weakening control method has been used.Important roleThe paper has 75 figures,9 tables,and 70 references.