Research On Control Technology Of Three-phase Permanent Magnet Synchronous Motor Based On Overmodulation

With the continuous development of power electronics and power transmission technology,the control system of permanent magnet synchronous motors has promoted the rapid development of industrial automation.Permanent magnet synchronous motors act as irreplaceable actuators in the entire system due to their advantages such as high power factor,strong formability and stable output torque.In motor control,in order to increase the output torque of the motor and the output voltage of the inverter,overmodulation technology is often used.This dissertation analyzes the modulation principles of Space Vector Pulse Width Modulation in the linear region and the overmodulation region,and elaborates the influence of traditional overmodulation algorithms on the control system,such as inaccurate magnetic field orientation and increased harmonic content.The traditional SVPWM overmodulation method is relatively complicated,which requires the system to provide a large storage space and store a large amount of experimental data in advance,but the control accuracy is not high.Based on the traditional overmodulation algorithm,this dissertation proposes an improved SVPWM overmodulation algorithm.This algorithm does not need to divide the overmodulation part into regions,and can smoothly convert the output voltage vector from a linear modulation region to an overmodulation region.And into a six-step wave working state.The algorithm does not require pre-stored data and is suitable for digital applications.Aiming at the problems of high harmonic current content and poor output torque stability of overmodulation technology,this system uses a vector control strategy of permanent magnet synchronous motor based on current predictive control,and introduces current predictive control instead of vector control.Traditional PI control,this scheme has faster response speed and smaller overshoot.In order to verify the correctness of the SVPWM overmodulation algorithm,a Matlab/Simulink software was used for simulation experiments to build a complete permanent magnet synchronous motor overmodulation control system.Based on the simulation results,the algorithm was analyzed for the output voltage,current and torque of the control system.Influence,and analyze the harmonic distortion(THD)and the change of the current harmonic content according to the spectrogram.Comparative analysis proves that the algorithm has the advantages of low harmonic content,linear fundamental gain,and simple algorithm.It is suitable for digital applications of permanent magnet synchronous motors.Finally,an experimental platform is set up according to the control strategy of this scheme,hardware circuits are designed and software programs are written.The hardware part includes DSP main circuit,position detection circuit,current and voltage detection and protection circuit;the software part gives the main flow block diagram and some algorithms.Finally,experimental research was carried out,and the experimental results verified the feasibility and control accuracy of the scheme.