Research On Torque Ripple Suppression Method Of Synchronous Reluctance Motor Based On FPGA Platform

In recent years,Synchronous Reluctance Motor(SynRM)has attracted more and more attention in the field of AC speed regulation due to its advantages of simple rotor structure,convenient processing,low material cost,high operation efficiency,wide speed range,strong overload capacity and so on are attracting more and more attention in the field of AC speed regulation.It is expected to become a substitute for asynchronous motor in the field of low cost and high performance.But as a result of SynRM internal magnetic field from the stator excitation current,power factor is generally low,although the increase rate of salient pole rotor can effectively solve the problem,but the larger rate of salient pole and inductor saturation effect will make flux density harmonic increases,leading to large torque ripple,so how to reduce the torque ripple of SynRM has become the research emphasis in this paper.In view of the above problems,this paper aims at the motor structure and mathematical model of SynRM,analyzed the inductance fluctuation and torque pulsation generation mechanism of SynRM through the theory of magnetic field modulation.Then the current harmonic injection method considering inductance saturation and cross coupling is proposed to suppress torque pulsation.The Simulink-based simulation and finite element verification are also carried out.In order to enhance the response effect of current harmonics,and improve the bandwisdth of current loop,the control system was designed based on FPGA(Field Programmable Gate Array),and the correctness of theoretical analysis is verified by current loop bandwidth test and torque pulsation test.The main research and innovation points of this paper are as follows:(1)According to the development status of SynRM,the torque pulsation suppression method is summarized from the ontology structure and control method,and the magnetic field modulation theory and FPGA based control system are briefly introduced.(2)Analyze the motor structure and operation principle of SynRM,study mathematical models in different coordinate systems,compare the advantages and disadvantages of vector control and direct torque control,and deeply compare the maximum torque current ratio control,maximum torque change rate control,maximum power factor control and other different current distribution strategies.(3)Based on the theory of magnetic field modulation,the modulation functions of stator and rotor convex poles were established,and then the fluctuation law of winding inductance was analyzed.The inductance of straight axis and cross axis was calculated and fitted by freezing permeability method.On this basis,the mechanism of torque pulsation of SynRM was explained,and the mathematical expression was established.(4)The current harmonic injection method considering inductance saturation and cross coupling is proposed.The electromagnetic torque is divided into fundamental wave torque and harmonic torque,straight axis and cross axis harmonic current with different amplitude and phase is injected for different order harmonic torque.The finite element software is optimized and verified,and the control method is simulated with MATLAB/similink.(5)The software and hardware control system based on FPGA was established,and the experimental platform was built to test the current loop bandwidth.The torque ripple suppression effects of SynRM with different controllers and current harmonic orders were compared,which proved the correctness of the theoretical analysis.Overall,this paper studies the inductance fluctuation and torque ripple generation mechanism of SynRM,proposed a current harmonic injection method considering saturation and cross coupling,and built a high-performance control platform based on FPGA,aiming to reduce the torque ripple of SynRM through the control method,and promote the further development and promotion of SynRM.