Flux concentrated doubly salient linear permanent magnet machine

Abstract

Different topologies of Vernier permanent magnet (PM) machines have been proposed for direct drive low-speed applications due to their high thrust and power density. However, this type of machine can suffer from low power factor (PF). In this study, a flux concentrated doubly salient linear permanent magnet machine with V-shape PM arrays is proposed and compared to a consequent pole (CP) type machine. Using the configuration of V-shaped PMs allows the flux to be concentrated in iron spacers located between two pieces of PMs. This feature is shown to result in an improvement of the airgap flux density, which allows a reduction in electrical loading and hence an improvement in power factor. In order to achieve a fair comparison, two doubly salient linear permanent magnet machines with different PMs’ configurations have been analysed and compared using transient FEA. The investigated machines have the same overall machine and, crucially, magnet volume. The results confirm that the proposed V-shape machine is capable of higher thrust force, higher no-load back EMF and can achieve a higher PF of 42% compared to the consequent pole machine, while it consumes the same amount of the PM material.