A Research On The Fault Diagnosis Methods In Three-Phase Voltage-Source Inverter

The vector control induction is widely used in industrial production and daily life because of superior control performance,and its reliability and stability requirements are getting higher and higher.Nowadays,the state monitoring and fault diagnosis in motor drives has been considered the key to optimizing the operation and improving the reliability level.The power converter in the motor drive system,especially the inverter,they are prone to suffer critical failures due to their complexity and considering that they are often exposed to high stresses.Therefore,the thesis studies a fast and real-time method to enhance the reliability of the system.In this thesis,the working principle and fault mechanism of the inverter are described.Based on the analysis of the fault trajectory of the closed-loop vector control system,a real-time fault diagnosis method is designed with the method of the simple and intuitive variables of the current polarity ratio.This method has the advantages of fast detection speed and strong ability to suppress the system parameters and other noise interference,but it dependent on the threshold for the change of the diagnostic variable during the diagnosis process.Thus,in this thesis,through constructing the normalized current state residual equation,a feature vector is selected and used as the input of fuzzy reasoning,to analyze failure mode,design the membership function,and establish the fuzzy rule base,and consequently another high-performance inverter fault diagnostic method is designed.This method is good for handling extremely extreme or fast transient conditions and can accurately diagnose 21 fault modes.Evaluate the comprehensive performance of similar fault diagnosis methods and proposed methods and its superiority is shown.The validity of the proposed method is proved by a large number of experiments results.Through the speed and load torque changes to assess its motor operating state has a strong robustness.In addition,the design method has the advantages of fast diagnosis time,high precision and low cost.At the same time,the thesis evaluates the comprehensive performance of the similar fault diagnosis method and the proposed method,and shows its superiority.