Research On Fault Diagnosis Strategy For Two-stage Matrix Converter

The two-stage matrix converter(TSMC)has many advantages,such as adjustable power factor,good performance of input and output,bidirectional flow of energy and compact structure,and it has great application prospect in the field of power system and electric drive,these applications require the system to run stably and reliably for a long time.However,due to the large number of power switches and complex working environment,the probability of fault is larger in TSMC,which hinders the application of TSMC.Therefore,it is of great significance to study the fault diagnosis of TSMC,which can be used to protect the TSMC in time.In this paper,the voltage method is used to study the fault of TSMC power switch.The research contents of this paper are as follows:Firstly,the background and significance of the research is introduced in this paper,and the fault diagnosis methods of conventional matrix converter(CMC)and TSMC based on current method and voltage method are analyzed in detail.The topology structure of TSMC and the function relation between input and output is introduced,and the working principle of TSMC is analyzed under the double space vector modulation of rectifier stage and inverter stage.Secondly,the operation mode of the TSMC is analyzed when the power switch is normal and fault,according to the load current flows after the fault,the fault characteristics of the TSMC output phase voltage are obtained after the open circuit fault of power switch,and the similarities and differences between the two faults are summarized.The rectifier stage and inverter stage switch fault sometimes will produce the same output voltage fault,which is difficult to accurately locate the fault switch,combined with the characteristics of inverter space vector modulation,a method to locate the fault switch is put forward in this paper according to the number of switch group error voltage and the switching state when the inverter has two switches on which with the same bridge arm of the fault switch.The proposed method has the advantages of accurate diagnosis,no need to detect DC voltage,fast diagnosis speed and simple realization.The simulation model is built based on the proposed diagnosis method,and the simulation results verify the correctness of the proposed method.Finally,the experimental platform of TSMC fault diagnosis is built.The design method of the main switch,buffer circuit,drive circuit and signal conditioning circuit are introduced in detail;the software system based on TMS320F28335 + EPM570 is designed to realize the fault diagnosis method.The experimental results show that the proposed method is correct and effective.