Comparison of the No-Load Features of IPM and Consequent Pole Tubular-Linear PM Synchronous Machines

The paper is aimed at the design and sizing of a consequent pole tubular-linear PM synchronous machine (T-LSM) as well as the comparison of its no-load features with the ones exhibited by an IPM T-LSM equipped with ferrite PMs. To start with, a FEA-based investigation of the no-load features of the IPM T-LSM versus the opening of the PM to the pole pitch ratio, is carried out. In order to reduce the mover mass, one PM among the two of a pole pair is removed, yielding the consequent pole T-LSM. It is found that this latter has lower performance than the IPM T-LSM. An approach to overcome this limitation, consisting in substituting the ferrite PMs by rare earth ones, is proposed. A sizing procedure aimed at the investigation of the no-load features versus the PM geometry is implemented. It is shown that, compared to the IPM T-LSM equipped with ferrite PMs, the consequent pole one allows a reduction of 42.4% of the mover mass.