Resource efficient synchronous motor in flux barrier design with enlarged air gap

To date, the induction motor (IM) and increasingly the synchronous reluctance motor (SynRM) are well established as energy efficient standard motors in general applications as pumping systems or compressors. However, for many applications with special requirements it is necessary to leave the common motor design. One consequence may be the enlargement of the motor air gap, e.g. in slim long motors or in motors with encapsulated rotor. An enlarged air gap is highly problematic for the torque density of both motor types, which leads to the use of resource critical rare earth permanent magnet motors in many applications. This paper first discusses the need of new motor design with enlarged air gap for different applications. After that the influence of the air gap width on the performance of SynRM is shown analytically and in a parameter study based on numerical finite element method (FEM). Finally, a particularly resource efficient motor design to compensate the performance losses is presented and discussed.