Permanent Magnet-Assisted Synchronous Reluctance Motor Employing a Hybrid Star-Delta Winding for High Speed Applications

Synchronous Reluctance Motors (SynRMs) with or without ferrite Permanent Magnets (PMs) are promising candidates for several industrial applications e.g. traction applications, in which a wide constant power to speed ratio is mandatory. This paper introduces a comparison between the conventional SynRM with and without ferrite PMs in the rotor, and a SynRM employing a hybrid star-delta connection in the stator and with and without PMs as well for a wide speed range. It is found that the output torque of a SynRM employing a hybrid star-delta winding in the stator and ferrite PMs in the rotor corresponds to an increase of about 141.31 % compared to the conventional SynRM without PMs at rated current and three times rated speed. Consequently, a wide constant power to speed range is obtained. Moreover, the amount of increase in the torque varies with current and speed. In order to validate the theoretical analysis provided in this article, two stators having different windings and two rotors with and without ferrite PMs are manufactured. Eventually, experimental results on four prototypes are obtained.