| As the global energy shortage and environmental damage are becoming increasingly prominent,traditional internal combustion engine vehicles have been unable to meet the needs of modern society due to problems such as large pollution emissions and low energy utilization.In order to promote the sustainable development of the automobile industry,environmentally friendly,efficient,energy diversified and intelligent electric vehicles have become the mainstream development trend of the automobile industry.The distributed in-wheel direct-drive electric vehicle has many advantages such as short transmission chain,compact structure,high efficiency of the drive system,and independent controllable drive torque.It has become a research hotspot in the electric vehicle industry.The in-wheel motor as the core component of the distributed in-wheel direct drive electric car has attracted the attention of scholars at home and abroad.In this paper,the permanent magnet in-wheel motor is taken as the research object,and the speed loop design and load torque compensation under the vector control strategy of the motor are deeply researched.Firstly,this paper introduces the development status of in-wheel motor drive technology,analyzes the in-wheel motor performance requirements,and selects the permanent magnet in-wheel motor with wide speed range,small output torque fluctuation and high power density as the research object.Then based on the vector control strategy of the permanent magnet in-wheel motor,the structure of the permanent magnet in-wheel motor are given,and the current coordinate transformation relationship and the mathematical of the motor related to the vector control of the permanent magnet in-wheel motor model and space vector pulse width modulation(SVPWM)principle,based on thei_d(28)0vector control method,a motor control model is built in MATLAB/Simulink.Secondly,aiming at the deficiency of traditional PID control in the control of permanent magnet in-wheel motor control accuracy and dynamic performance,the characteristics and control performance of sliding mode control are analyzed.A controller based on non-singular fast terminal sliding mode(NFTSM)is designed for the motor speed control loop and a speed identification method based on model reference adaption control(MRAC)is proposed,which realizes accurate measurement of motor speed and position signal in motor speed loop sliding mode control.The simulation model of the above control method is built in MATLAB/Simulink.The simulation results show that the NFTSM controller designed in this paper has the characteristics of small overshoot,fast response,good dynamic performance,strong robustness,etc.The design speed The identification method can also accurately and quickly track the motor speed and position.Then,for the problem that the torque output of the permanent magnet in-wheel motor changes greatly under severe working conditions,a motor load torque observer is designed,and the motor control current feedforward compensation control strategy is studied.The NFTSM controller is organically combined to form a feedforward-feedback control system,which improves the anti-interference ability of the in-wheel motor.The simulation results show that the designed load torque observer has a faster observation speed and better compensation effect,which can effectively improve the anti-interference ability of the motor during operation.Finally,on the basis of the above theory and simulation analysis,the experimental platform of the permanent magnet in-wheel motor based on Keil uVision5 is built.The feedforward-feedback control system based on NFTSM and load torque compensation designed for this paper is experimentally verified.The experimental results are consistent with the simulation.And the practicality and effectiveness of the proposed control strategy is verified. |
