Research Of Control Method For Improving Transmission Ratio Of Matrix Converter

The matrix converter is a new type of power converter topology, it is constructed by a two-wayswitch which positive and negative direction of current can go through,input current of it is sinewave and the power factor can be regulated, it can freely adjust the output frequency and realizebidirectional flow of energy. Because of the above characteristics, the power of non reactive andharmonic pollution has been reduced, it is a kind of green power conversion device. Matrixconverter from concept development today has more than thirty years, has made great progress inthe key technology of modulation strategy, commutation strategy, device development. In practicalapplications, the matrix converter has not realized the fast and safe commutation, the voltagetransfer ratio is limited by the control strategy of maximum can only reach0.866, which limits itsapplication in speed control of AC motor. Therefore, the use of appropriate modulation algorithmsto improve the voltage transfer ratio of matrix converter, finding the right security commutationstrategy has also become a hot research field in the study of matrix converter.This article choose the direct three-phase-three phase matrix converter for the research object,the circuit topology and basic working principle of the matrix converter are analyzed, it’s lowvoltage transfer ratio, safety commutation problem are researched.First, the control strategies of matrix converter were researched, focuses on the mostcommonly used strategy:space vector modulation. First, analyze the equivalent AC-DC-ACstructure of matrix converter by the method of mathematical analysis, and then use the space vectormodulation strategy for the mathematical modeling analysis of the equivalent of both rectifier andinverter, and then synthesized matrix converter space vector modulation strategy, summed switchcombination function based on space vector modulation strategy. Simulation studies were carriedout on the establishment of Matlab/Simulink model based on space vector modulation strategy formatrix converter, analysis the input and output properties of a matrix converter with space vectormodulation strategy, the correctness of the theory of matrix converter are verified. On thisbasis, the over modulation strategy of matrix converter have be researched, the voltage transfer ratioup to0.996by modulation strategy of matrix converter; the over voltage transmission modulationstrategy of matrix converter and the ratio of output characteristics is verified by the use ofMatlab/Simulink simulation.Next, commutation time is too long in traditional four-step commutation strategy wereresearched, according to the different turn-off time of IGBT in the different current sizeimprovements of the strategy are proposed, define the the commutation time interval as2500ns， dramatically reducing the commutation time, improve the waveform distortion caused by thecommutation time is too long. The simulation verified the correctness and effectiveness of thenew strategy.