Feature Investigation of a Segmented PM Quasi- Halbach T-LSM: Cost-Performance Trade-off

The paper is aimed at an investigation ofthe features of a tubular-linear synchronous quasi-Halbachmachine (T-LSM) where the radially-magnetized PMs aresubstituted by four equal segments with parallel magnetization. Such a substitution is done in an attempt to improve the machine cost-effectiveness which makes it aviable candidate to equip free-piston engine-based serieshybrid propulsion systems. The investigation is initiatedusing a 3D analytical model of the flux density spatialrepartition considering (i) the case of the conventionalquasi-Halbach T-LSM and (ii) the case of the segmentedparallel-magnetized PM one. The comparison between thetwo linear machines is extended to a 3D finite elementanalysis of their no- and on-load features. Following theprototyping of the quasi-Halbach T-LSM with segmentedparallel-magnetized PMs, selected features predicted by 3DFEA are experimentally-validated. It is shown that whilethe PM segmentation slightly affects the back-EMFs andcogging force, it has a remarkable fallout on the machineforce production capability which makes necessary theassessment of the cost-performance trade-off.