The Break-bar Fault Diagnostics Of The Asynchronous Motors Based On Variable Frequency Drives

Asynchronous motors are widely used in industrial and agricultural production as the main energy conversion device. When asynchronous motor break down,not only harming motor itslef, may cause serious production safety accidents.It is necessary to monitor the state of the asynchronous motors and to diagnose the asynchronous motors incipientfault for keeping the asynchronous motors and the loads safe operation.Especially with the policy of the"energy conservation and emission reduction"is advocated,the asynchronous motor power by inverter in variable frequency systems are more widely used.Broken-bars fault is one the common faults to asynchronous motors,at present,the study focus on the broken-bar fault diagnostics of asynchronous motors power by power network.But the research in the broken-bar fault diagnostics of asynchronous motors power by inverter in variable frequency drives system is very few still.So this paper will focus on this areas to do some research on detecting broken-bars fault in invert-fed asynchronous motors.This paper will begin to focus on the broken-bar fault diagnostics of asynchronous motors power by power network.throught analyzing the broken-bar fault feature and common methods of fault diagnosis in this case.Then we will discuss the fault diagnosis method of motor current signature analysis(MCSA),it is common methods of broken-bar fault diagnostics of asynchronous motors.We will try to explore the possibility of the application of this common method in the broken-bar fault diagnostics of asynchronous motors power by inverter in variable frequency drives system.We will find whether or not broken-bars fault frequency (1±2s)f₁exists,once broken rotor bar fault occurred in asynchronous motors power by inverter in the variable frequency systems.Adopting the frequency spectral method to analyze whether or not broken-bars fault frequency (1±2s)f₁exists to detect broken-bars fault in invert-fed asynchronous motors.If application of the fault diagnosis method of MCSA to detect broken-bars fault in invert-fed asynchronous motors,we are going to face a problem.the components of rotor broken-bar fault characteristic frequencies will affected bycomponents of power supply frequency in the stator current spectrum.Sometime components of rotor broken-bar fault characteristic frequencies may be lose.It is hard to detect broken-bars fault.So this paper presents two different novel detection schemes for rotor bar breaking fault.One schemes is Based on digital lowpass filter techniques,self-adaptived filter techniques,ZOOM fast Fourier transform.Two schemes is Based on digital lowpass filter techniques, Hilbert transform, ZOOM fast Fourier transform.We will do the Simulation and experimental verification to validate the feasibility of the two detection schemes.V/F inverter-fed drive systems with rotor bar breaking fault is completed by MATLAB/Simulink.Then we built an experimental motor fault diagnosis platform to simulate moter faults in the laboratory.In order to acquire sample signals,we design a signal acquisition system. And the simulation and experimental results demonstrate that the two detection schemes is effective.We can use the two detection schemes to detect broken-bars fault in invert-fed asynchronous motors.