Nine-Phase Six-Terminal Induction Machine Modelling using Vector Space Decomposition

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

Research output: Contribution to journalArticle

4 Citations (Scopus)


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 behaviour of a six-phase machine. This paper introduces the machine mathematical model based on the Vector Space Decomposition (VSD) modelling 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 1.5Hp prototype IM is used to experimentally validate the machine model under both healthy and open-phase conditions.

Original languageEnglish
JournalIEEE Transactions on Industrial Electronics
Publication statusAccepted/In press - 2 May 2018



  • Asymmetrical six-phase winding
  • dynamic modelling
  • fault-tolerant operation
  • high-power machines
  • nine-phase machine
  • vector space decomposition

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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