Research On Common Mode Voltage Suppression Strategy For The Two-stage Matrix Converter

As an AC-AC power converter,matrix converters have received wide attention due to their excellent characteristics,such as good input and output performance,bidirectional energy flow,simple topology,and high power density.Among them,compared with the direct matrix converter(DMC),the two-stage matrix converter(TSMC)becomes an AC-AC converter with more development potential due to its simpler modulation strategy,commutation method and clamping circuit.Therefore,the two-stage matrix converter is taken as the research object and the common mode voltage suppression of the system is studied based on dual space vector modulation strategy and model predictive control strategy respectively in this dissertation.In this dissertation,the basic principle of the traditional TSMC topology is introduced firstly,and a mathematical model is established according to its topology structure to analyze the input-output relationship between different all levels.Then the Dual Space Vector Modulation(DSVM)strategy of TSMC is introduced in detail through three parts: modulation principle of rectifier stage,modulation principle of inverter stage and the cooperative control mode between two stages.Afterwards,the experimental platform of TSMC is briefly introduced from the main circuit and control structure of the prototype.Secondly,in view of the problem that the existence of zero voltage vector in the inverter stage leads to a large peak of common mode voltage in the system,a new TSMC topology is designed in this dissertation.Based on this new topology,two improved DSVM strategies are proposed to effectively suppress the common mode voltage while retaining the advantages of good input and output performance and zero current commutation of the rectifier stage.Among them,the improved DSVM strategy 1 can effectively suppress the common mode voltage of the system to 0.577 times that of the traditional DSVM.Although the improved DSVM strategy 2 is only applicable to the occasions where the voltage transfer ratio is less than 0.5,it can achieve the deep suppression of common mode voltage,that is,the common mode voltage is suppressed to 0.371 times that of the traditional DSVM.Finally,aiming at the model predictive control strategy of TSMC.In order to improve the input and output steady state performance of the system,this dissertation proposes a modulated model predictive control strategy based on virtual vector(VV-M2PC),which can achieve better steady state control performance without affecting the dynamic performance of the system and the calculation burden of the controller.Then,combined with the proposed improved DSVM strategy 1,a common mode voltage suppression strategy based on VV-M2 PC is implemented,which includes the advantages of VV-M2 PC and the improved DSVM strategy 1.All the above research contents have been verified by simulation and experiment.There are 72 fugures,10 tables and 86 references in this dissertation.