Research On Fault Diagnosis And Fault Tolerant Control Of Indirect Matrix Converter

Indirect Matrix Converter（IMC）is derived from Direct Matrix Converter（DMC）,and has a series of compact circuit structure,high power density,adjustable input power factor,safe and reliable commutation strategy,etc.Excellent characteristics,with its excellent performance,are widely used in the industrial field.The complex working environment in the industrial field puts forward strict requirements on the stability and reliability of the IMC.Therefore,it is of great significance to study the fault diagnosis technology and fault-tolerant control strategy of IMC to improve the stability and reliability of the system.However,the current academic literature on fault diagnosis and fault-tolerant control strategies of IMC is limited,and there is still a lot of research space.Based on the review and analysis of the existing literature,this paper takes the representative 18-switch IMC topology as the research object,and mainly conducts in-depth research on the fault diagnosis method and fault-tolerant control strategy of the IMC power switch.Based on the detailed description of the working principle and modulation strategy of the IMC,this paper analyzes and summarizes the characteristics of the SVPWM strategy,and studies the corresponding relationship between the IMC rectifier stage power switch and the rectifier stage interval.Through the analysis of the IMC operation mode and the application of the hybrid system theory,the hybrid logic dynamic mathematical model of the IMC is established.The state residual characteristics and the change trend of the DC bus voltage when the switch fails,and the corresponding relationship between the inverter stage power switch and the state residual is established on the basis of the above.In order to describe the influence of the power switch failure on the DC bus voltage and to realize the detection and location of the rectifier-level faulty power switch,a trend percentage function is defined.By detecting the change of the state residual and identifying the change trend of the DC bus voltage in the rectification interval,the detection and location of the fault switch are realized,and the construction of the fault diagnosis system is completed.In order to solve the problem of how to maintain the continuous and stable operation of the system after the failure of the IMC power switch,this paper proposes an IMC fault-tolerant control strategy based on redundant switches.From the perspective of redundant topology,this strategy improves and expands on the basis of phase redundant fault-tolerant topology,and designs an IMC fault-tolerant topology structure based on redundant switches.According to the characteristics of different types of faults of the IMC power switch,combined with the characteristics of the fault-tolerant topology,a control strategy is designed.The system will control the conduction of the triac and the position of the moving head of the SPDT switch in an orderly manner when the power switch fails to switch the fault power.The switch signal of the switch is sent to the corresponding redundant switch to realize the task of fault-tolerant reconstruction.Under the premise of not changing the original modulation strategy and not reducing the output power of the system,this strategy can achieve effective fault tolerance for four types of faults: single-tube open-circuit fault,double-tube open-circuit fault,single-tube short-circuit fault and double-tube short-circuit fault.Finally,the simulation circuit model of the IMC is built on the Matlab/Simulink platform,and the fault diagnosis system and fault-tolerant control system of the IMC are built by using the M language programming,and the simulation experiments are carried out to verify.The simulation results verify the correctness and feasibility of the proposed fault diagnosis method and fault-tolerant control strategy.