Real-time Dynamic Eccentricity Detection by Analyzing Harmonic Components of No-load Line-line Voltages in Multi-three-phase PMSMs

Permanent magnet synchronous motors (PMSMs) are widely utilized for many purposes owing to their high efficiency. Such frequent applications require less noise and fewer vibrations. This work focuses on multi-three-phase PMSMs that can independently control the current among winding groups to suppress the vibrations caused by air gap imbalances, which must be detected for suppression control. The representative effects of air gap imbalance include static and dynamic eccentricities. Dynamic eccentricity varies the air gap length in time; therefore, the instantaneous detection of the air gap length condition is necessary for suppression control. We propose a method that instantaneously detects dynamic eccentricity using the fundamental and fourth-order harmonic components of no-load line-line voltages, which are easily measurable in practical manufacturing processes. The proposed real-time detection method is applied to a finite element analysis (FEA) model with dynamic eccentricity, and confirm its detection ability is confirmed experimentally.