Harmonics Analysis of Air-Gap Magnetic Field of Induction Motors With Stator Inter-Turn Fault

The space–time distribution characteristics of the air-gap magnetic field (AGMF) determine the electromagnetic performance of the motor. This article studies the influence of the inter-turn fault (ITF) on space and time harmonics of the AGMF, and the relevant fault characteristics are obtained through analysis and experiments. First, a theoretical analysis is deduced to compare the components of AGMF before and after the fault, and all space and time harmonics are obtained. Then, according to the parameters of the prototype, the distortion and components of space and time harmonics are analyzed. Also, the influence of rotor slot harmonics is considered to analyze the variations of time harmonics. Finally, a detection wire method that can directly measure the AGMF is proposed, and the spectrum results of the measured signals prove the correctness of the research in this article. A fault feature can be extracted based on the frequency band analysis, and it is not affected by load variations. The results obtained through analytical analysis, simulation, and experiment further improve the AGMF research of induction motors with ITF.