Research On Diagnosis Scheme For Switch Fault Of Five-phase Two-stage Matrix Converter

With the development of power electronics technology,the motor drive system has broken through the constraints of the traditional three-phase power supply,and is developing in the direction of into multiphase.Compared with three-phase motors,multi-phase motor drive systems have many advantages,such as small torque ripple,large output power,and ability of fault tolerance.Two-stage matrix converter(TSMC)has the advantages of no intermediate energy storage components and compact structure.The five phase TSMC is a multiphase matrix converter developed on the basis of TSMC and is a potential member of multi-phase power converters.The reliability and safety of power converters are critical to any power electronics system.In power converters,the power switch is the most vulnerable part of the fault.Therefore,it is important to study the power switch fault diagnosis strategy to ensure the high reliability of the five-phase TSMC system.Firstly,the operational principle of five-phase TSMC and dual space vector modulation strategy are studied in detail.Furthermore,the five-phase TSMC operating mode and voltage characteristics of the inverter and rectifier power switch faults are analyzed and summarized.laying a theoretical foundation for the follow-up diagnosis strategy.Secondly,the voltage characteristics of lower switches under switch fault are analyzed and summarized.On the basis of these,a fault diagnosis method based on error voltage of lower switches is proposed.The proposed method established a correspondence between the error-voltages and the fault arms,which simplified the algorithm,and any single open-switch fault or several open-switches faults in inverter stage can be diagnosed.Thirdly,the characteristics of the five-phase TSMC output line voltage under inverter and rectifier switch faults are studied in detail.Then,a diagnosis method is put forward according to the line voltage characteristics when large vector and zero vector action.The proposed method has many advantages,such as fast detection,low diagnosis cost,not affected by the way the power is connected,and the algorithm is simpler than the existing line voltage method.Finally,an experimental platform of is built according to the proposed diagnostic strategy,and the design of hardware circuit is introduced in detail.The software system with DSP and CPLD is designed to realize the modulation strategy and diagnostic algorithm of five-phase TSMC.The experimental results verify the correctness of the diagnosis strategy.