Design of External Rotor Ferrite-Assisted Synchronous Reluctance Motor for High Power Density

Abstract

The rare-earth (RE) permanent magnets (PM) have been increasingly adopted in traction motor application. However, the RE PM is expensive, less abundant, and has cost uncertainties due to limited market suppliers. This paper presents a new design of a RE-free five-phase ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with the external rotor architecture with a high saliency ratio. In such architecture, the low magnetic coercivity and demagnetization risk of the ferrite PM is the challenge. This limits the number of flux barriers, saliency ratio, and reluctance torque. A precise analytical design procedure of rotor and stator configuration is presented with differential evolution numerical optimizations by utilizing a lumped parameter model. A 3.7 kW prototype is fabricated to validate the proposed idea.

Flux-Barrier Design and Torque Performance Analysis of Synchronous Reluctance Motor with Low Torque Ripple

“…As far as the motor industry is concerned, the highefficiency motor has become the focus of attention. Permanent magnet synchronous motor (PMSM) is widely studied and used for its high efficiency [2][3][4]. However, PMSM needs permanent magnets affected by critical minerals such as rare earth and are a scarce resource with relatively high cost.…”

Design of Outer-Rotor Permanent-Magnet-Assisted Synchronous Reluctance Motor for Electric Vehicles

“…A SynRM with or without PM for traction applications in electric vehicles was analyzed and the effect of rotor design on SynRM performance with experimental test results was demonstrated in [17]. In [18], a new five-phase external rotor ferrite permanent magnet-assisted synchronous reluctance motor (Fe-PMaSynRM) with a high saliency ratio was designed.…”