Nine-Phase Six-Terminal Induction Machine Modeling Using Vector Space Decomposition

Ayman S. Abdel-Khalik*, Ahmed M. Massoud, Shehab Ahmed

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The nine-phase six-terminal induction machine (IM) has been recently proposed as a promising contender to the conventional asymmetrical six-phase type in terms of torque density, stator winding simplicity, and fault-tolerant capability. The stator is composed of nine phases, which are connected in a fashion to only provide six stator terminals. Therefore, this connection combines the high performance of a nine-phase winding with the terminal behavior of a six-phase machine. This paper introduces the machine mathematical model based on the vector space decomposition (VSD) modeling approach. The required current and voltage sequence transformation matrices are derived such that the machine is mathematically regarded as an equivalent six-phase IM with only three decoupled subspaces. This way, the same VSD-based controller structures conventionally applied to six-phase-based systems can be preserved. A 1.5-hp prototype IM is used to experimentally validate the machine model under both healthy and open-phase conditions.

Original languageEnglish (US)
Article number8353710
Pages (from-to)988-1000
Number of pages13
JournalIEEE Transactions on Industrial Electronics
Issue number2
StatePublished - Feb 2019


  • Asymmetrical six-phase winding
  • dynamic modeling
  • fault-tolerant operation
  • high-power machines
  • nine-phase machine
  • vector space decomposition (VSD)

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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