Research On Design And Control System Of Alternating Pole Permanent Magnet Motor For Electric Vehicle

With the progress of human science and technology,people pay more attention to the conservation of resources and the protection of the environment,guarding the green water and green mountains.Traditional power vehicles use oil as energy,and oil is known as the blood of industry,so should cherish the use.In addition,the processing and utilization of oil resources will produce a large amount of sulfur-containing substances to pollute the air.Therefore,it is imperative to study motor drive instead of internal combustion engine.As the key component of electric vehicle,this paper studies the motor drive system.The aim is to design a reliable and sensitive control method with constant power speed regulation interval.The main contents are as follows:First of all,in view of the deficiency of the external rotor table attached hub motor in the constant power speed regulation section,this paper intends to increase the convex polarity of the motor by changing the magnetic circuit structure of the motor,and enhance the weak magnetic expansion ability of the motor.In this paper,according to the index parameters of the traditional external rotor table-mounted permanent magnet motor,by comparing the performance of 5/6 and 8/9 unit motors,a suitable sinusoidal matching scheme is chosen as the pole-slot ratio scheme of the motor,and the comprehensive advantages of 5/6 unit motors in the complementarity of waveform linearity and electromagnetic performance are analyzed in essence.Through finite element analysis and theoretical calculation,and then strengthen to prove the performance advantage of 5/6 motor in theoretical analysis.Secondly,because of the particularity of the structure,the alternating pole structure in this paper can not adopt the MATLAB self-contained model,so it is necessary to make the new model more suitable for the characteristics of the new motor by nonlinear modeling.As the key parameter of the motor,the inductance of the motor is specially calculated in this paper.Too many geometric approximations are introduced in the traditional flux method to calculate the inductance of motor,which results in the problem of large error in calculation accuracy.In this paper,the air gap of the motor is equivalent to a regular geome try by conformal transformation of the new structure alternating pole hub motor.According to the formula in the transformation,the concept of complex relative permeability is introduced,and then the magnetic field distribution of the motor is accurately analyzed,and the accuracy is verified by comparing with the finite element results.After that,the self-inductance and mutual-inductance values of the motor rotor at different positions are obtained by flux method and the d-q axis inductance is obtained by Parker transformation.Finally,the analytical calculation results are compared with the experimental results,and the data agree well,which proves the accuracy of the calculation.Finally,this paper adopts the MTPA control method to the new structure motor,and combines the weak magnetic control method to make its speed regulation performance dynamic response and according to the reliability,so that the motor has a good expansion range.Finally,the correctness and reliability of the control strategy are verified by MATLAB simulation.It is proved that the expansion range of motor can reach 2 times or more,and it has sufficient output torque to ensure the demand of electric vehicle operation.