Optimization Modulation Strategy And Control For Traction Application

Aiming at the problems of wide range of drive speed,large power,large switching loss,high DC bus voltage and increasing power demand for high power locomotives,it is proposed to realize the modulation method applied to locomotive traction and the driving type,which can improve the power level.In this paper,the modulation method is used as the main line,and a synchronous carrier SPWM overmodulation implementation method based on zero sequence voltage injection is proposed.This method combines the synchronous modulation and overmodulation,The deitail process of the method was deduced,The simulation is carried out in MATLAB /Simulink,and the high-power induction motor platform and the low-power permanent magnet synchronous motor platform is used to the experimental verification.The simulation and experimental results show that the proposed method can reduce the current harmonics,improve the voltage utilization,reduce the switching frequency and can transit smoothly from the circular flux to the hexagonal flux.Aiming at the existing problems,a synchronous multi-mode carrier modulation method based on SPWM and SHEPWM is proposed.The theory of realization SHEPWM in multi-mode is analyzed,and the point of switching is deduced in detail.A synchronous multi-mode switching strategy is designed,and the modulation is realized by DSP 28335.The simulation is carried out with MATLAB / Simulink,and the harmonic analysis is carried out under the resistive load.Finally,the experiment is carried out under the asynchronous motor.The simulation and experimental results show that the proposed multi-SHEPWM carrier modulation method can reduce the current harmonics to eliminate low frequency torque ripple and reduce the switching frequency,achieve smooth transition between different mode.The method can be used as locomotive traction modulation method.With the increasing of electric locomotive power,the application of multi-phase high-speed motor in locomotive traction becomes more and more important.Based on the three-phase motor control,the high-performance speed sensorless vector control and modulation method Research,the traditional multi-phase motor modulation method using carrier modulation SPWM,the method of low voltage utilization,low carrier frequency ratio in the high speed range and switching losses.In order to solve the above problems,the realization method of common SVPWM for general multiphase motor zero-sequence voltage injection is derived.Taking a five-phase induction motor as an example,the uniform SVPWM voltage utilization rate of five-phase asynchronous motor was analyzed.A speed sensorless method based on full order observer of five-phase induction motor was deduced.Based on the fivephase motor low power platform,The experimental results show that the proposed SVPWM method can improve the voltage efficiency.The speed sensorless control of multiphase motor based on full order observer can estimate the motor speed without speed sensor control.This method can be used as a traction speed sensorless method for multiphase motors.PMSM has the advantages of high power density,high efficiency and low cost.Combined with the advantages of permanent magnet synchronous motor and multiphase motor,the multiphase permanent magnet synchronous motor has become the mainstream of current research at home and abroad.As the model predictive control method has the advantages of simple realization,no modulation link and direct control of the motor torque and flux linkage,it has certain advantages for the application of locomotive electric traction.This paper studies a five-phase permanent magnet synchronous motor model predictive control method.Based on the model predictive control of fivephase permanent magnet synchronous motor,the torque and current control of the model predictive five-phase permanent magnet synchronous motor are optimized.The harmonic voltage elimination method and the quadratic selection method are proposed.The two methods respectively eliminate and optimize the harmonic voltage and the 32 voltage vectors in the model predictive control.Simulation and experimental results show that the proposed method The model can be used to predict the current and torque of five-phase PMSM.The proposed method can be used in locomotive electric traction converter based on the unmodulated module to exert the advantages of model predictive control and multiphase motor.