Investigation of a Surface Mounted PM Machine Concept with 3D-Flux Paths, Modular Stator and Amorphous Material

Abstract

This paper deals with the design and investigation of a surface mounted machine concept targeted at the efficient recycling of rare-earth materials used in permanent magnets. The proposed machine has an outer rotor, single phase and a modular stator. In addition, the use of laminated iron based amorphous material is investigated. The implementation of this type of material in electrical machines is of interest due to their performance in terms of reduced losses when compared with standard electrical steel. However, the widespread use of amorphous materials is limited mainly due to their hardness and brittleness that make their processing (i.e. cutting and punching) a challenging task. Hence, an alternative for the use of such material is proposed in this paper, with the combination of both laminated C-shaped amorphous cores and a modular stator. 3D-FEM calculations of various parameters such as back-EMF, torque, inductance and losses, were validated with measurements performed on a demonstrator.

Design and Experimental Investigation of a Hybrid Rotor Permanent Magnet Modular Machine with 3D Flux Paths Accounting for Recyclability of Permanent Magnet Material

“…The main advantage of having a hybrid rotor is that the PM is protected from the variations of permeance in the air-gap, due to the salient structure of the modular stator. Therefore, the losses in the PM may be reduced significantly, while, for a rotor structure with surface-mounted PMs, the PM losses were increasing with approximately the square of the frequency [12], which is not convenient in a machine with a large number of poles or running at a high speed, or both.…”

“…However, an excitation assistance coil is added to the rotor structure, which increases the complexity of such topology. Finally, a single stack C-shaped core is investigated in [12], where the use of laminated amorphous materials is also evaluated. As a conclusion, having a single stack of C-shaped cores might have negative effects on the performance of the machine.…”

“…That is, the recycling of PMs of the machine is addressed in conjunction with the use of non-traditional materials (e.g., grain oriented electrical sheet, amorphous laminated material, SMC, etc.). In this regard, the use of non-traditional materials in a structure with a modular stator was investigated in [12]. Iron based amorphous laminated C-shaped cores were used in a proof of concept of a surface-mounted outer rotor machine.…”

“…Therefore, in order to allow an efficient recycling of the PMs, the rotor structure proposed in this work is conceived in such fashion that the use of glue is not required for holding the PMs on place. Additionally, the modular stator structure proposed in [12] is expected to facilitate the extraction of the rotor. Furthermore, as it was demonstrated, it allows the use of materials that are not commonly used in rotating electrical machines.…”