Experimental Validation of a Spoke Type Ferrite Permanent Magnet Machine Design for Heavy-Duty Traction Applications

Abstract

Rare earth elements (REEs) are central to the current solutions used for traction applications. However, REEs have fragile supply chains, which exposes them to supply interruptions and price spikes. Research has been focusing on REE-free solutions, either exploring REE-free topologies, such as induction and electromagnetised machines, or investigating the use of alternative hard magnetic materials, such as ferrite permanent magnets (PMs). This paper presents a novel methodology for designing and optimising spoke type permanent magnets synchronous machines (spoke machines) with ferrite PMs. The novelty of the methodology is the unique strategy used to integrate mechanical and demagnetisation constraints. Using this methodology, a novel rotor is optimised using FEM simulations to directly substitute a previous REE-based motor. The optimised design represents a unique rotor, mainly due to its large magnet size, which enables a demagnetisation-safe high-torque motor. A prototype is built and tested to verify the FEM results experimentally. The experimental results show a prototype magnetically resilient to permanent demagnetisation and with higher efficiencies at field weakening when compared with an equivalent REE machine.