Study of Induction Motor Inter-Turn Fault Part II: Online Model-Based Fault Diagnosis Method

Seong-Hwan Im,Bon-Gwan Gu

doi:10.3390/en15030977

Abstract

This paper (Part II) is a follow-up paper to our previous work on developing induction motor inter-turn fault (ITF) models (Part I). In this paper, an online ITF diagnosis method of induction motors is proposed by utilizing the negative sequence current as a fault signal based on the fault model of the previous study in part I. The relationships among fault parameters, negative sequence current, and fault copper loss are analyzed with the ITF model. The analyses show that the fault severity index, a function of fault parameters, is directly related to the negative sequence and the copper loss. Therefore, the proposed model-based fault diagnosis method estimates the fault severity index from the negative sequence current and recognizes the ITF. With the estimated fault severity index, the fault copper loss by the ITF, causing thermal degradation, can be calculated. Finally, experiments were performed in various fault conditions to verify the proposed fault diagnosis method.

Highlights

Induction motors are commonly used as industrial drives due to their cost, reliability, and self-starting advantages
They are composed of many mechanical parts such as stator windings, slots, rotor bars, shafts, and bearings that might occur in machine faults
The relationships between the severity of the inter-turn faults (ITF) and additional negative sequence currents and copper loss generated in the fault spot are analyzed with the induction motor ITF model presented in part I [27]

Summary

Introduction

Induction motors are commonly used as industrial drives due to their cost, reliability, and self-starting advantages. The relationships between the severity of the ITF and additional negative sequence currents and copper loss generated in the fault spot are analyzed with the induction motor ITF model presented in part I [27]. The ITF diagnosis and fault severity estimation method are proposed based on the analyzed negative sequence current deviation. If the additional copper loss by the ITF is defined by fxR not the respective fault parameters, the fault effects on the neighboring winding could be calculated using estimated fxR. The entire copper loss generated in the ITF circuit can be divided into the main stator path with i f and the shorted circuit with ia − i f , and derived as (6) using the calculated fault current if. When the fault count is over a certa z, it is judged as the ITF, and at this time, the fault degree f is estim f { idqs(ITF) } of Figure 3

Experimental Results

Inter-Turn Fault Diagnosis Method

Conclusions