Research On Fault Diagnosis Strategy Of Isolated AC-DC Matrix Converter

Isolated AC-DC Matrix Converter(IAMC)has the advantages of less power conversion stages,energy flowing in both directions,high power density,and easy modularization.It has become a research focus in the power electronics field.However,during the operation of the converter,problems such as open circuit failure of power devices will inevitably occur,thereby reducing the performance and service life of the converter and even crashing the system.How to research the fast and accurate diagnosis strategy to locate the fault switch is of great significance to improve the operating efficiency and reliability of the converter.This paper takes IAMC as the research object to study the fault diagnosis strategy of its power devices under the condition of open circuit fault.Firstly,this paper introduces the research background and significance of isolated matrix converter.The research status of power switch fault diagnosis methods for Matrix Converter(MC)is described.The bipolar current space vector modulation and phase-shift control strategy of IAMC are described in detail,and the operation modes of IAMC in different situations are analyzed.On this basis,the fault characteristics of three-phase to single-phase matrix converter(3-1MC)in single bidirectional power switch,two bidirectional power switches at the same time and two bidirectional power switches at different times are summarized.On this basis,the fault characteristics of3-1MC in single bidirectional power switch fault,two bidirectional power switches fault at the same time and two bidirectional power switches fault at different time are summarized respectively.At the same time,the fault characteristics of diode or IGBT in H Bridge Converter(HBC)are also analyzed in detail.Then,based on fault characteristics,an error voltage method based on switch state is proposed for 3-1MC.This method uses successively different switching states and combines the relationship between input line voltage and output voltage to locate a faulty power switch.This diagnostic method is not limited by the wiring method of the input power supply,and the voltage sensor is used less,and the diagnostic cost is low.On this basis,a new fault diagnosis method based on the phase voltage of the switch group error voltage is proposed.Compared with the previous method,the cost of this method is relatively increased,but the speed of diagnosis is improved,which is not affected by modulation strategy.Not only the single fault power switch can be diagnosed,but also the two fault power switches can be located.At the same time,theHBC diagnosis method based on the lower switches error voltage is proposed.This diagnosis method can not only diagnose the faulty IGBT,but also the faulty diode in HBC can also be located.The diagnosis principle is simple and easy to realize.Finally,the diagnosis simulation platform of IAMC fault power switch is built by Matlab/Simulink,and the experiment platform is built by DSP and CPLD.The accuracy and feasibility of the proposed fault diagnosis method are verified.