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Multiphase machines with a prime number of phases (five and seven) have shown better torque density than machines with other phase numbers. Unfortunately, these machines require a special stator design. Hence, this article proposes general rewinding techniques to obtain a five-phase winding from the existing standard three-phase stator frames. The proposed rewinding techniques are applied to construct a five-phase star-connected synchronous reluctance machine (SynRM 1) and a novel combined star-pentagon winding (SynRM 2). Simple mathematical formulations are introduced to compute the equivalent winding factor. The performance of five-phase SynRMs is analyzed using two-dimensional Ansys Maxwell transient simulations under the same copper volume for both healthy and faulty cases. SynRM 1 and 2 provide 6.56% and 13.35% higher torque compared to the three-phase SynRM at rated current and at optimal current angle. The torque ripple is decreased by 17% and 30%, respectively. Moreover, SynRM 1 and 2 offer a better performance at the faulty case; e.g., at one phase opened, the average torque of SynRM 1 and 2 is 82% and 108% higher compared to the three-phase SynRM. In addition, the torque ripple is reduced by about 63% and 81%. Finally, experimental results are done to validate the proposed winding techniques. [ABSTRACT FROM AUTHOR]

This paper investigates the performance of synchronous reluctance motors when the stator is equipped with a combined star–delta winding layout. The conventional star winding is used as a benchmark in this study to compare different possible single-layer winding layouts. Among these different winding layouts, those which maximize the fundamental magneto-motive force component are selected. A simple mathematical formula is then derived to calculate the equivalent winding factor for different shares between star and delta subwindings. It has been proved that for the same copper volume and line current magnitude, the star–delta connection can offer an enhancement in the torque density of approximately 5.2% over the conventional star case under rated conditions. However, this gain is affected by the employed number of poles and stator slots. On the other hand, the effect of the winding layout on either power factor or core loss can be merely neglected over a wide range of speeds and currents. Nevertheless, the machine efficiency under a combined star–delta connection is relatively improved under light loading as a result to the machine torque/current ratio enhancement. The theoretical findings are experimentally validated using two identical 5.5 kW prototype machines, having star and combined star–delta winding connections. [ABSTRACT FROM AUTHOR]

This paper analyzes and compares the synchronous reluctance motor (SynRM) performance for a conventional star winding and for a combined star-delta connected winding under healthy and faulty conditions. The finite element method is used to simulate the SynRM characteristics in case of normal star and in case of combined star-delta connected windings. For the healthy case, it was found that for the same current, the SynRM output power increased by about 5% for the star-delta connected windings compared with the conventional star connection. Moreover, the efficiency increased slightly by 0.20%. Probably the strongest advantage of the combined star-delta winding is observed when a phase fault occurs. When one phase is missing, for the same current, the star-delta connected motor keeps 80% of the rated torque in the healthy case, while the star connected motor only keeps 40%. Furthermore, the torque ripple of the star wound machine is extremely high in case of a missing phase, compared to the star-delta wound machine. Simulation results were validated by experimental results to show the effectiveness of the star-delta connected windings on the SynRM. [ABSTRACT FROM PUBLISHER]

The rotor design of Synchronous Reluctance Motors (SynRMs) has a large effect on their efficiency, torque density and torque ripple. In order to achieve a good compromise between these three goals, an optimized rotor geometry is necessary. A finite element method (FEM) is a good tool for the optimization. However, the computation time is an obstacle as there are many geometrical parameters to be optimized. The flux-barrier widths and angles are the two most crucial parameters for the SynRM output torque and torque ripple. This paper proposes an easy-to-use set of parametrized equations to select appropriate values for these two rotor parameters. With these equations, the reader can design a SynRM of distributed windings with a low torque ripple and with a better average torque. The methodology is valid for a wide range of SynRMs. To check the validity of the proposed equations, the sensitivity analysis for the variation of these two parameters on the SynRM torque and torque ripple is carried out. In addition, the analysis in this paper gives insight into the behavior of the machine as a function of these two parameters. Furthermore, the torque and torque ripple of SynRMs having a rotor with three, four and five flux-barriers are compared with three literature approaches. The comparison shows that the proposed equations are effective in choosing the flux-barrier angles and widths for low torque ripple and better average torque. Experimental results have been obtained to confirm the FEM results and to validate the methodology for choosing the rotor parameters. [ABSTRACT FROM AUTHOR]