Research On Torque Ripple Suppression Strategy Of Multi-unit Hub Motor

As the development of new energy vehicles is committed to the pursuit of higher power density and energy conversion efficiency,hub motors have gradually entered the public view.In order to better apply the hub motor to the field of new energy vehicles,this paper studies the two difficulties of overcoming the in-wheel motor: high reliability requirements and high torque ripple requirements.In order to solve these two difficulties,this paper uses multi-unit permanent magnet synchronous motor as the research object,and applies harmonic method to suppress torque ripple strategy.The multi-unit permanent magnet synchronous hub motor(MU-PMSHM)model,control strategy establishment,platform hardware and software design are discussed in this paper.Then the simulation analysis is completed by PLECS and MATLAB,and the experimental verification is completed on the hardware platform.Firstly,the basic structure and working principle of traditional permanent magnet synchronous motor(PMSM)are introduced in detail.The mathematical model of PMSM is established in both rest and rotating frame,and its electromagnetic torque expression is solved by various methods.On this basis,the special structure and working principle of MU-PMSHM are studied,and its unique mathematical model is established.The difference between the basic control strategies of traditional PMSM and MU-PMSHM is further analyzed.Secondly,considering the harmonic mathematical model of PMSM under non-ideal factors,the torque ripple caused by harmonic back EMF and slot effect of PMSM is studied,and the expressions of torque ripple are obtained respectively.Considering the harmonic current generated by the high-speed operation of the motor,the application of the rotating PI controller to the harmonic suppression method is explored to achieve the torque ripple suppression effect,and the current distortion caused by the nonlinear characteristics of the inverter is also studied.The distortion compensation strategy is used to compensate the distortion caused by the nonlinear characteristics of the inverter.In addition,in order to explore the combination of MU-PMSHM and harmonic method to suppress torque ripple,the advantages of carrier phase-shifting control used for both are expounded: reducing bus capacitance ripple and harmonic interleaving control.Finally,the hardware experimental platform of MU-PMSHM is designed,and the hardware selection method of electric vehicle electric drive system is summarized,which is of great significance for engineering application.On the hardware platform,the harmonic injection / suppression method suppresses the torque ripple,carrier phase shift control improves harmonic control,and distortion compensation improves the distortion caused by the nonlinear characteristics of the inverter.It verifies the superiority of the combination of multi-unit permanent magnet synchronous motor and harmonic method to suppress torque ripple strategy for hub motor...