Research On Stator Current Analysis Method Of Asynchronous Motor For The Local Fault Diagnosis Of Gear

The gear transmission mechanism is accurate and reliable,it and can transmit a large range of power and speed,so it has been widely used in many fields.As a key part of transmission system,gear has attracted much attention in recent years.The common fault forms of gear are various,and there are also many fault diagnosis methods.The vibration diagnosis method is one of the most widely used fault diagnosis methods so far,but the same time,it is expensive,inconvenient to install and easily affected by environment and noise.Motor Current Signature Analysis is a fault diagnosis technique based on stator current of motor.It can diagnose mechanical faults such as gears directly through the electrical signals of the system,which is also called sensorless fault diagnosis method.First of all,a dynamic model of gear transmission system is established to study the generation mechanism of modulated signal.The principle of stator current detection of gear fault and the stator current characteristic of gear in normal and fault state are studied theoretically.Secondly,according to the dynamic differential equation of gear transmission system,a fault simulation model of gear transmission system is established under Matlab/Simulink environment to simulate and verify the influence mechanism of gear fault on stator current from the angle of simulation.Then,combining the existing conditions of the laboratory and the simulation model of the gear transmission system,a gear fault simulation test bench is built.The stator current signal of motor and the vibration signal of the gear system are collected under normal and simulated gear partial fault conditions,then analysis and comparison of collected signals using Wavelet transform and Hilbert transform.The results show that the local fault of the gear can cause the change of the stator current of the motor.Combining the advantages of wavelet transform and Hilbert transform in signal processing,the fault characteristic frequency and related frequency of the gear are extracted successfully in the stator current.The comparison between the stator current signal and the vibration signal also proves the feasibility and superiority of the stator current method in gear fault diagnosis,and it shows that the continuous progress and perfection of stator current analysis method will provide powerful technical support for the development of mechanical fault monitoring and diagnosis.