Matlab Environment AC Locomotive Variable Frequency Speed Control Process Simulation

As an independent branch of electric transmission control,traction ac transmission control system plays an important role in the field of transportation traction transmission.It is a nonlinear,variable and strong coupling system,energy transfer through the converter to complete the AC-DC-AC conversion,the converted alternating current transfer to the asynchronous motor to complete the transmission.In the whole process,the traction motor is taken as the control object,and the speed parameters of the traction motor are controlled in real time by the open-loop or closed-loop control system,so as to achieve the purpose of controlling and adjusting the drive object.The construction of the actual transmission system is quite detailed and complex,and there are many factors that affect the operation stability.Among them,the harmonics generated during the operation of the system have a serious impact on the stability of the system.The main source of these harmonics is the peak voltage caused by IGBT switching elements.To improve the stability of the system is running,this paper aimed at the problem of harmonic,mainly in the Matlab environment ac frequency control of motor speed locomotive process simulation analysis and do the work of system improvement,mainly includes: the train traction communication system,the basic principle of operation,to understand its operation process will produce the main reason for the harmonic,and then on the Matlab/simulink platform structures,transmission system simulation model,the complete simulation and analysis results;The relevant principles of the filter circuit are studied,and the simulation circuit is improved for the harmonic problem.The improvement scheme is to add the designed three-phase filter circuit into the circuit of the inverter output terminal,and to simulate the improved model,and then compare and analyze the simulation results with the simulation results before the improvement.The research results show that in the traction drive system,when the converter completes the AC-DC-AC energy conversion,the harmonic generated by the IGBT component shutdown has a significant impact on the stability of the system operation,which is manifested in the instability of the output phase current and torque waveform of the asynchronous motor,indicating that the stability of the system is significantly affected by the harmonic;the closed-loop feedback control system built in the system The simulation results show that the speed of the asynchronous motor can be used as the feedback signal,and a series of transformations can be input to the inverter to complete the feedback control.The feedback effect is significant,which achieves the experimental expectations.In order to verify the harmonic problem,the improved scheme proposed in this paper is added to the simulation system,and the designed three-phase filter circuit is added to the output of the converter.After debugging and running the improved system simulation,comparing the simulation results before and after the improvement,it is found that the output torque and current waveform of asynchronous motor become relatively stable,which shows that it is consistent with the preset situation.The instability of system operation is caused by harmonic problems.This scheme is reasonable and in line with the preset situation.Therefore,the proposed design has a theoretical support,and has a certain theoretical guidance significance for the actual,and then shows that this scheme can be very good to improve the harmonic problem.