Date of Award

Spring 2008

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Electrical and Computer Engineering

First Advisor

Demerdash, Nabeel A. O.

Second Advisor

Yaz, Edwin E.

Third Advisor

Mirafzal, Behrooz


The Conventional standard three-phase induction motors have an inherent drawback in so far as performance under loss of phase conditions. The two-phase operation of a three-phase induction motor doesn't provide the necessary performance such as torque and output power under applications which require high reliability such as in electric traction applications, electric ship propulsion, etc. Therefore one of the means to overcome this drawback is by the addition of more phases, which forms the main focus of this thesis. The objective of this thesis is to develop a unique design for an induction motor which can function in both the three-phase and six-phase modes thus obtaining a reversible three-phase to six-phase operation. The functionality of this motor serves the purpose of a reliable operation in the case of loss of phase or phases. In this thesis, a case-study 3-phase, 5-hp squirrel cage, 60 hz, 6-pole, induction motor was tested and modeled using time-stepping finite-element simulation. This motor was redesigned in this work for a six-phase stator winding configuration. This redesigned motor was simulated under different types of phase loss scenarios using a time-stepping finite-element technique. A comparative analysis of the various phase loss conditions of the six-phase configuration with respect to the healthy six-phase case is presented. The analysis of the torque-ripple content with the help of current-space vector concepts was introduced. The ripple content in the torque is shown to improve with the reversible three-phase to six-phase design under loss of phase conditions. There are some thermal issues with regard to performance under loss of phase conditions which emerged in light of the values of the stator phase currents under such faults.



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