Automated monitoring of airgap eccentricity for inverter-fed induction motors under standstill conditions

Doosoo Hyun, Jongman Hong, Sang Bin Lee, Kwonhee Kim, Ernesto J. Wiedenbrug, Mike Teska, Subhasis Nandi, Ilamparithi Thilumarai Chelvan

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


There are many limitations to applying online spectrum analysis techniques for diagnosis of closed-loop inverter-fed induction motors due to variable load or frequency operation, and the masking effect of the current regulator. In this paper, a new automated approach for testing inverter-fed induction machines for airgap eccentricity is proposed. The main concept is to use the inverter to excite the machine with a pulsating field at multiple angular positions to observe the variation of equivalent impedance due to eccentricity, whenever the motor is stopped. It is shown that the increase in the value of the equivalent (leakage) inductance under standstill excitation can be used as an indicator of increasing airgap eccentricity. Standstill testing can provide reliable assessment of eccentricity that is independent of variations in operating conditions, load interferences, or motor type. An experimental study on a 7.5-hp induction motor verifies that eccentricity can be detected with high sensitivity and reliability without additional hardware.

Original languageEnglish
Article number5728868
Pages (from-to)1257-1266
Number of pages10
JournalIEEE Transactions on Industry Applications
Issue number3
Publication statusPublished - 2011 May


  • AC machine
  • airgap eccentricity
  • condition monitoring
  • diagnostics
  • induction motors
  • inverters
  • offline testing
  • spectrum analysis

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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