Research On Two-level Fault-tolerant Inverter Based On IGBT Failure Analysis

Aviation communication power supply requires extremely high equipment reliability to ensure its safety during operation.Therefore,it is particularly important to study the reliability of the power electronic converter which is the most easily damaged.Most of the previous research was conducted on a certain level,such as the reliability of the device,the reliability of the converter,etc.,and very few people combined the reliability of the device level with the entire converter for research.Moreover,most of the fault-tolerant methods proposed for the reliability of converters are realized at the cost of reducing output power,increasing switching losses,increasing design costs,and reducing reliability indicators.In this paper,the two levels of research are combined.First,the device level is studied,and then based on the research results,a device-level fault-tolerant model is proposed that does not reduce the reliability index,does not change the control strategy,and does not increase the cost.Inverter structure.Firstly,taking the basic reliability model of power electronic power devices as the basic unit,by constructing a general reliability model of two-level(2-Level,hereinafter referred to as 2L)inverter,a qualitative reliability analysis method of "relative" quantification is realized.Make the theoretical basis for the device-level fault-tolerant inverter proposed later.And because the content of this chapter is expansible,this method is applied to 3-level(hereinafter referred to as 3L)and 5-level(hereinafter referred to as 5L)ANPC inverters on the basis of the established 2L model.The internal fault tolerance and the influence mechanism of the failover mode on the reliability of the multi-level inverter before and after the fault are compared and analyzed by the way of the unit structure.Theoretically,qualitative and quantitative comparison of "overall" reliability is carried out to prove the reliability and fault tolerance of the system.Then,start with the failure of the switching device(IGBT)with the most inverter failures,and take the overcurrent short circuit failure that has the greatest impact on the performance of the IGBT as the starting point,carry out the transient short circuit damage test of the IGBT bridge arm in two different packaging forms,and analyze Effect of overcurrent short circuit damage on IGBT performance.In the two cases with and without overcurrent protection,the failure mode and mechanism of transient short circuit are analyzed and clarified from the micro level.On this basis,combined with the comparative analysis of various electrical parameters,the failure mechanism and failure mode of the IGBT short circuit are clarified,and the dynamic/static analysis of the failure impedance is carried out,which will provide a reliable application for the subsequent IGBT bridge arm(establish a device-level fault-tolerant type inverter structure)provides the necessary device basis.Finally,a device-level fault-tolerant inverter structure based on device failure characteristics and the evolution law of electrical parameters is established to achieve the coexistence of safety,availability and economy.Finally,through the verification of the devicelevel fault-tolerant inverter test platform,it has achieved "seamless" switching before and after short-circuit faults,full-power long-term time stable output.