Research On Three-Level Inverter Fault Diagnosis Based On Data-driven

With the rapid development of industry and the substantial increase in social productivity,frequency converters have been widely used in medium-high voltage and high-power equipment for its excellent performance.As one of the key equipments in the mine hoist system,the three-level inverter will seriously affect the safety of the mine hoist and bring uncertainties to mine production.For this reason,this thesis takes the neutral point clamped three-level inverter in the mine hoist system as the research object,and can recognize and locate the open-circuit fault of IGBTs,the core components of the inverter,by data-driven method.Firstly,through the understanding of the structure and characteristics of the mine hoist inverter,the neutral-point clamped three-level inverter is selected as the research object.Its main circuit structure,working principle and SVPWM control technology are analyzed.The cause of the fault and the main fault types are divided and numbered.The fault simulation model of the three-level inverter is established and the features of the fault current waveform are analyzed.The relationship and amplitude change of three-phase current waveform under single and double IGBTs fault are researched.Secondly,the open-circuit fault test-bed for three-level inverters is built to collect the measured data of fault current.Based on the current signal data of two different sources from the simulation and test-bed,the low frequency energy value of the threephase current as fault feature.At the same time,due to the insufficient discrimination of energy value for partial fault types,the positive half-cycle current proportional coefficient is added as auxiliary fault feature to form the fault feature vector of inverters and construct the fault diagnosis model.The fault current data of simulation and testbed are tested separately.The experimental data is analyzed by a variety of classifiers,and the best classification model is determined by comparison to complete the recognition and localization of the three-level inverter failure mode,which achieves good fault classification effect.Finally,the design of recognition and localization algorithm is completed by Matlab,and the fault diagnosis system for three-level inverters is developed by combining SQL Server database and C# language.The real-time monitoring of opencircuit faults is realized.This system has strong data analysis and processing functions.It also has a friendly human-computer interface,and can realize the functions of operation state monitoring,fault history inquiry,fault identification and alarm of three-level inverters.