Normalization-based approach to electric motor BVR related capacitances computation

J. Ahola, A. Muetze, M. Niemela, A. Romanenko

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review


Electrical discharge machining (EDM) bearing currents that may occur within electric machines of variable-speed-driven motor systems have been recognized for a long time. One important factor of influence, the capacitive voltage divider 'bearing-voltage-ratio' BVR of the machine strongly depends on the rotor-to-frame and the stator winding-to-rotor capacitances which are, in turn, affected by the design of the machine's stator slot. This paper presents an approach to improve the accuracy with which these capacitances can be estimated. It is based on the well-known plate capacitance equation which is then corrected by normalization functions. The functions are defined by extensive parameter studies using electrostatic FEM simulations. The final expressions not only allow relatively accurately predicting the stator-winding-to-rotor and rotor-to-frame capacitances. They are also easily applicable, so as to, for example, easily study the sensitivity of the BVR towards changes of the different stator slot parameters.

Original languageEnglish
Title of host publicationAPEC 2018 - 33rd Annual IEEE Applied Power Electronics Conference and Exposition
PublisherInstitute of Electrical and Electronics Engineers
Number of pages7
ISBN (Electronic)9781538611807
Publication statusPublished - 18 Apr 2018
Event33rd Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2018 - San Antonio, United States
Duration: 4 Mar 20188 Mar 2018


Conference33rd Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2018
Country/TerritoryUnited States
CitySan Antonio


  • Bearing currents
  • Electric machine
  • Modelling
  • Variable speed drive

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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