Fault Diagnosis In Voltage Source Inverter For Induction Motor Drives With Space Vector PWM Control

Motors are widely used in many respects such as industry,agriculture,marine,aerospace,national defense and so on for their broad applicability and superior performance.Because induction motors are economic,durable,reliable and suitable for many kind of mechanical transmission,also able to meet the requirements of intelligent control,induction motors are very concerned by people among many types of motors.The control system of motor drives is prone to failure in running process for various reasons,and will greatly affect the factories,enterprises,individuals,even the national interest and security,so many scholars,home and abroad,put more and more attentions on fault diagnosis of the system of induction motor drives.The power electronic device of inverter play an important role in the whole drives system.And they are sensitive segments prone to the fault due to their high switching frequencies and quickly changing currents.So,conducting research on fault diagnosis of inverter for induction motors to improve the reliability of induction motors in the whole working process has important theoretic and realistic significance.For fault diagnosis,the most important thing is to extract features of signal by signal processing and then diagnosis the fault by some certain rules.In this paper,Discrete Wavelet Transform and signal similarity are used as the foundational theory,and diagnosis opencircuit fault of inverter in induction motor controlled by Space Vector Pulse Width Modulation.Features on multi-resolution of Discrete Wavelet Transform are used to pretreatment three-phase currents of motor in this paper.Energy function is constructed to extract features and to avoid current disturbance and parameter variation.Similarity degrees between every two of three-phase currents are distinguished through the similarity principle Finally,fault type can be accurately obtained.Based on analyzing the operational principle of vector controlled induction motor and failure mechanism,a novel method is proposed for diagnosing single and multiple inverter fault in one leg.Processing of current signal simplifier the complexity of the flow-up data calculation,and choosing correct fault feature reduce the disturbance of motor parameters.With the help of similarity theory,detecting and locating the fault can be fast and accurate.Simulation and experimental results both show high accuracy and robustness in the fault diagnosis strategy mentioned in this paper.