Synchronous reluctance machines: Performance evaluation with and without ferrite magnets

Nowadays, a great interest in the efficiency and the cost of electrical machines has been noticed. Therefore, Synchronous Reluctance Motors (SynRMs) have become more attractive alternative for induction and permanent magnet (PM) synchronous machines in several industrial applications. This is because they do not use rare-earth magnets, windings and cages in their rotor. Consequently, the cost and efficiency are improved. Nevertheless, a major problem of the SynRMs is the low power factor. To improve the power factor as well as the torque density and efficiency, the cheap ferrite PM can be inserted in the rotor, resulting in the so called 'PM assisted SynRM'. The rotor design of SynRMs with and without permanent magnets (PMs) has a huge effect on the motor efficiency, torque density and power factor. This paper introduces an evaluation for the performance of SynRMs with and without PMs in terms of efficiency, torque and power factor maps as a consequence of different rotor designs. Three different rotor designs for the same machine stator have been compared. For one machine, the experimental measurements are obtained and the validation of the simulation results are confirmed. A preprint of this work is available under: https://biblio.ugent.be/publication/8515429. © Published under licence by IOP Publishing Ltd