Space Vector Over-modulation Strategy Of Matrix Converter

As an advanced topological structure that can realize AC-AC direct conversion,the matrix converter has the advantages of large power density,high conversion efficiency and bidirectional energy flow et al.,which has a huge market prospect in the power conversion field.The matrix converter has accumulated a great deal of research results in the past forty years.Although the research on matrix converter is significant,and some commercial prototypes have been launched in many fields,the maximum voltage transfer ratio of 0.866 still limits the wider application of matrix converter.In this paper,a series of researches are conducted on the problems such as the lack of research on voltage transfer ratio in overmodulation area and the lack of high voltage transfer ratio overmodulation strategy in matrix converter.The specific principle and modulation process of the space-vector modulation strategy of the matrix converter are analyzed.Based on the space-vector modulation strategy,the functional relationship of instantaneous voltage transfer ratio is deduced and the behavior of instantaneous voltage ratio is further analyzed.Double Fourier analysis is performed on output voltage,based on which a unified maximum voltage transfer ratio under over-modulation with minimum phase error and minimum amplitude error are obtained for convetntional matrix converter,which provides an important theoretical supplement for the design of over-modulation strategies.Through the further analysis of the space vector modulation of the matrix converter based on the equivalent relation between direct matrix converter and indirect matrix converter,five synthesis modes of output voltage at the rectifier stage are obtained for the analysis of the synthesis methods of the DC-link voltage.Furthermore,the output voltage characteristics of the inverter stage are analyzed by using the Fourier transform method.According to the analysis of the inverter output voltage,combined with the concept of over-modulation area dipartition,the division of over-modulation modes at the inverter stage is carried out.Based on the analysis of the specific modulation modes of rectification stage and inverter stage,a novel over-modulation strategy for both direct matrix converter and indirect matrix converter is proposed,which can improve the output voltage transfer ratio and reduce the actual output voltage error.In the process of constructing the over-modulation strategy,this paper uses Matlab/Simulink to build the simulation model of over-modulation for matrix converter and makes a specific comparison study with existing strategies under the same simulation conditions.Simulation results confirm the effectiveness of the modulation strategy.In addition,the over-modulation strategy is verified by practical experiment that using the prototype of a matrix converter system.Experimental results demonstrate the feasibility and effectiveness of the over-modulation strategy proposed in this paper.