Comparison of rare‐earth and hybrid‐magnet mover configurations for a permanent magnet synchronous linear motor

Abstract

Force ripple and cost reduction are two of the main challenges in optimising the design and increasing the market uptake of permanent magnet synchronous linear motors (PMSLM). Two mover configurations are compared in depth; one made entirely from rare-earth materials while another consisting of a hybrid (rare-earth/ferrite) magnet layout. First, the rare-earth PMSLM is optimised and designed. Based on the same design and simulation methods, a hybrid PM materials with structure PMSLM is then proposed, optimised and designed using NdFeB at the centre pole-section and ferrite at the edges. The two configurations of the PMSLM and their relative merits/demerits are compared using the simulation results of the flux density distribution in the air gap, back electromotive force (EMF), and cogging force. The hybrid-magnet structure PMLSM has a better magnetic performance, and the force ripple is reduced by around 1%. Furthermore, the magnet material cost of the hybrid-magnet PMLSM is reduced by nearly 25% compared with the original PMLSM. Finally, a prototype of the rare-earth and hybridmagnet PMSLM is manufactured and tested to validate the modelling techniques and the results. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Optimal control of maximum torque current ratio for synchronous reluctance motor based on virtual signal injection algorithm

“…It utilized the simulation results of air gap magnetic flux density distribution, back electromotive force, and cogging force to compare their configurations and their relative advantages and disadvantages. The hybrid magnet structure PMSLM had better magnetic properties, and compared to traditional machine structures, the cost of magnet materials had been reduced by nearly 25% [12].…”

“…When modeling a SynRM, the magnetic saturation of the motor is an important consideration [20,21]. Due to magnetic saturation, the motor's parameters will undergo non-linear changes before and after virtual signal injection, leading to reduced model accuracy and adversely affecting the control algorithm's accuracy [22].…”

Design and analysis of a novel spoke‐type motor to reduce the use of rare‐earth magnet materials

“…Consequently, researchers face a great challenge to produce ferrite PM motors with high torque density, improved magnetic flux weakening, and improved demagnetisation. To reduce the consumption of rare-earth materials while maintaining high torque density, a hybrid configuration is often applied to PM motors, in which two types of magnets are used together [13][14][15][16][17][18][19][20]. The use and placement of two different types of PM can significantly affect the electromagnetic performance of a motor.…”