Abstract
This paper compares four prototype Synchronous Reluctance Motors (SynRMs) having an identical geometry of iron lamination stacks in the stator and rotor. Two different stator winding layouts are employed: a conventional three-phase star connection and a combined star–delta winding. In addition, two rotors are considered: a conventional rotor without magnets and a rotor with ferrite magnets. The performance of the four SynRMs is evaluated using a two-dimensional (2D) Finite Element Model (FEM). For the same copper volume and current, the combined star–delta-connected stator with Permanent Magnets (PMs) in the rotor corresponds to an approximately 22% increase in the output torque at rated current and speed compared to the conventional machine. This improvement is mainly thanks to adding ferrite PMs in the rotor as well as to the improved winding factor of the combined star–delta winding. The torque gain increases up to 150% for low current. Moreover, the rated efficiency is 93.60% compared to 92.10% for the conventional machine. On the other hand, the impact on the power factor and losses of SynRM when using the star–delta windings instead of the star windings is merely negligible. The theoretical results are experimentally validated using four identical prototype machines with identical lamination stacks but different rotors and winding layouts.
Highlights
In the literature, several types of Synchronous alternating current (AC) machines can be found, e.g., Interior and Surface Permanent Magnet Motors (IPMs and SPMs) and Synchronous ReluctanceMotors (SynRMs) [1,2,3,4,5]
The prototype of a combined star–delta winding in the stator and ferrite permanent magnets (PMs) in the rotor could be a very promising candidate for several industrial applications, e.g., PV pumping applications and electric vehicle traction
For full-rated current, it is clear from Figure 5 that the output torque of the Sd, S-PM, and Sd-PM machines is higher than the S
Summary
Several types of Synchronous alternating current (AC) machines can be found, e.g., Interior and Surface Permanent Magnet Motors (IPMs and SPMs) and Synchronous Reluctance. In order to improve the power factor and to enhance the torque density and efficiency of SynRMs, permanent magnets (PMs) are inserted into the rotor flux-barriers, resulting in a PM-assisted SynRM (PMaSynRM) [9]. It is found that the SynRM’s output torque increased by about 5% at the rated conditions compared to the conventional star connection This is because of the improved winding factor of the star–delta connection. The work presented compares the performance of four prototype SynRMs having an identical geometry of iron lamination stacks in the stator and rotor; two rotors (with and without PMs) and two stator winding connections (star and combined star–delta) are considered. The prototype of a combined star–delta winding in the stator and ferrite PMs in the rotor could be a very promising candidate for several industrial applications, e.g., PV pumping applications and electric vehicle traction
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