Static Eccentricity Fault Detection for PSH-type Induction Motors Considering High-order Air Gap Permeance Harmonics

Diagnosis of static eccentricity (SE) fault for induction motors (IMs) is essential for the quality control of the machines, especially during their manufacturing process. Principal slot harmonic (PSH) type IMs have special combinations of rotor bar number and pole pair number, and it has been shown in previous works that conventional methods cannot effectively detect SE fault for these machines. Aiming at finding an effective approach for the SE fault detection for PSH-type IMs, this paper presents an analysis of SE-induced line currents in IMs with the higher-order harmonics of the air gap permeance considered. The analysis reveals that the second-order harmonic in the air gap permeance can induce SE-level-related signals in the line current of PSH-type three-phase IMs. The generation mechanism of the signature current signal is validated by simulations with an analytical IM model and a time-stepping finite element model. The signature signal in the motor's current discussed in this paper provides a new method for quantitative detection of SE fault for PSH-type IMs.