The main objective in this thesis is to refurbish existing three-phase SynRMs to obtain reliable and improved performance five-phase SynRMs. The refurbishment is useful for old existing machines, to give them a second life with better performance and reliability. Different rewinding approaches have been proposed to obtain a five-phase SynRM with either star-connected winding or combined star-pentagon winding using the existing off-the-shelf three-phase stator frames. Moreover, another refurbishing method has been introduced. In this refurbishing method, the existing three-phase SynRM is upgraded to a five-phase SynRM by replacing the existing stator by another one, and keeping the existing rotor. The optimal number of stator slots and winding details for the new stator is selected based on the analysis of the MMF and the winding factor of various numbers of stator slots.

The new stator has an integer number of slots per pole per phase (40 and/or 60 slots). The current density, copper and iron volume are kept the same as much as possible as in the existing three-phase SynRM. A multi-objective optimization is applied to obtain the optimal design for the five-phase SynRM. Apart from the machine design, a three-to-five-phase indirect matrix converter is used to feed the five-phase SynRM. Moreover, the proposed drive system has been compared with conventional three-phase drive system in terms of reliability, cost and performance.