A dynamic model for saturated induction machines with closed rotor slots and deep bars

Eemeli Mölsä, Seppo E. Saarakkala, Marko Hinkkanen, Antero Arkkio, Mikko Routimo

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
259 Downloads (Pure)


This paper deals with a dynamic model for three-phase induction machines equipped with closed rotor slots and deep rotor bars. The thin bridges closing the rotor slots saturate highly as a function of the rotor current. The impedance of the rotor bars also varies much as a function of the rotor current frequency. An extended dynamic model, which takes into account the slot-bridge saturation and the deep-bar effect, is developed. The model extensions can be plugged into a standard machine model and parametrized easily. The proposed model can be applied to time-domain simulations, real-time control, and identification. The model is validated by means of finite-element analysis and experiments using a four-pole 5.6-kW induction machine. The results show that the accuracy of the proposed model is superior to the standard model, particularly under transient excitation typically used in standstill self-commissioning tests of induction motor drives.
Original languageEnglish
Article number8889405
Pages (from-to)157-165
Number of pages9
JournalIEEE Transactions on Energy Conversion
Issue number1
Early online date31 Oct 2019
Publication statusPublished - Mar 2020
MoE publication typeA1 Journal article-refereed


  • Closed rotor slots
  • Deep-bar effect
  • Dynamic model
  • Induction motor
  • Magnetic saturation
  • Standstill identification


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