Research On Double Line Voltage Modulation Strategy Of Three-to-five Phase Matrix Converter

In recent decades,power electronics has been developing rapidly,power electronic converters occupied an important and even core position in various equipments.Among them,matrix converter has received deep and extensive research as an outstanding power converter.With the continuous development of AC speed control system,the multiphase AC speed control system provided a new approach for improving the performance and reliability of the system,correspondingly,multiphase power converter including multiphase matrix converter has also drawn great attention.Since there are few reaearches on double line voltage modulation strategy of three-to-five phase matrix converter,it is studied in this thesis,which lays a foundation for further study and practical application of multiphase matrix converter and double line voltage modulation strategy.Firstly,the circuit topology and working principle of the three-to-five phase matrix converter,as well as the principle of the double line voltage modulation strategy are briefly introduced.And on this basis,the implementation of double line voltage modulation strategy for three-to-five phase matrix converter is studied in detail,the duty ratio of each switch is deduced,the calculation formula of duty ratio under different interval combinations are analyzed,and the combinations are summarized into two cases according to the polarity of input and output voltages,the calaulation process is simplified,adjustment of input power factor is realized by the adoption of reference input voltages.Besides,the output voltage and input current under unbalanced input voltages,as well as the improvement of input currents are analyzed,the input currents are improved by the modification of reference input voltages.In order to reduce the common mode voltage of matrix converter,the cause of common mode voltage and the value of it under different switching states are analyzed,the maximum value is reduced by changing part of the switching states.Furthermore,switching sequence is studied,the common mode voltage can be reduced without increasing the switching times by optimizing switching sequence,so that the output performance of matrix converter will not be affected.Furthermore,in order to make the implementation of modulation strategy more convenient,a carrier based implementation method is studied,modulation signals of each switches under original and improved strategy are derived,pulse signals of each switches can be obtained by comparing modulation signals with the carrier,some logic operations are also necessary,so that the complex pulse distribution process is avoided,which is helpful to the efficient operation of the controller in practical application.Finally,an experimental platform controlled by DSP and FPGA was designed and built,hardware circuit and software program are introduced in detail,the modulation strategy is experimentally verified and the experimental results are analyzed.Experimental results show that the experimental prototype of three-to-five phase matrix converter has good performance,and the hardware and program design of the matrix converter are reasonable.The correctness and feasibility of modulation strategy is proved,it provides a reference and basis for further research and practical application of multiphase matrix converter.