Feature Investigation of a Segmented PM Quasi- Halbach Tubular-Linear Synchronous Machine

The paper is aimed at an investigation of the

features of a tubular-linear synchronous quasi-Halbach machine

(T-LSM) where the radially-magnetized PMs are substituted

by four equal segments with parallel magnetization. Such a

substitution is done in an attempt to improve the machine costeffectiveness

which makes it a viable candidate to equip freepiston

engine-based series hybrid propulsion systems. The study

is initiated an analytical formulation of the flux density spatial

repartition considering (i) the case of the conventional quasi-

Halbach T-LSM and (ii) the case of the segmented pole one.

The comparison between the two T-LSMs is extended to a 3D

finite element analysis (FEA)-based investigation of their no- and

on-load features. Following the prototyping of the quasi-Halbach

T-LSM with segmented poles, selected features predicted by 3D

FEA are experimentally-validated. It is shown that while the PM

segmentation slightly affects the back-EMFs and cogging force,

it has a remarkable fallout on the machine force production

capability which makes necessary the assessment of the costperformance

trade-off.