Research On PWM Modulation Method For The Matrix Converter

The.matrix converter composed of bidirectional switches is a novel AC/AC power converter with a new topology,and it has the advantages of high efficiency,high power density,and high reliability.It can provide sinusoidal output and input current.The input power factor and output frequency can be regulated freely and the energy can flow on bi-direction.The matrix converter is a "green" power converter because it greatly reduces the harmonic and reactive pollution for the power grid,and it has a good prospect.This paper focus on modulation algorithm,commutation strategy,input filter design and other key technologies of the matrix converter.Firstly,its topology and a proper mathematical model of the switching function for any modulation algorithm is analyzed,and several feasible topologies of bidirectional switches are presented and studied.Then,it is the space vector modulation(SVM)that is specially analyzed.Accompanied by the introduction of the virtual DC link,the matrix of low-frequency transfer function can be divided into two through mathematical derivation and transform.By given the equivalent AC/DC/AC topology of matrix converter,SVM is used on the part of equivalent virtual source inverter(VSI)and virtual source rectifier(VSR).On the base of this,the indirect space vector modulation and switching state combinations are obtained.By using typical bilateral modulation switch-mode,switching times are optimized and the switching state combinations of the thirty-six sectors with minimize commutation times are obtained.Then,under the SVM algorithm,a four-step commutation strategy based on output current direction detection and a four-step commutation strategy based on voltage detection are given.This paper simulates the introduced modulation and commutation strategies,and establishes the MATLAB simulation model,which is composed of the main circuit module and the control circuit module.The input and output performances under the introduced modulation strategy are analyzed without the input filter.Then,this paper designs and simulates the input LC filter.It has been found that the THD of input current is merely 2.63%.The result certificates that the introduced modulation and commutation strategies are correct and feasible.