Modelling, Analysis, and Design of a Line-Start Permanent Magnet Synchronous Motor

Line-Start Permanent Magnet Motors are a valid alternative to conventional three-phase induction motors and wound-field synchronous machines for fixed-speed applications direct fed by the grid, targeting superior efficiency and high reliability. A general analytical-numerical approach is presented to model SPM type rotors with embedded squirrel cage, aiming to permit completing both a preliminary design and an effective assessment of the starting and synchronisation capabilities. As a case study, the preliminary design of a 8 MW @ 3000 rpm LSPMSM for large compressors is presented, targeting unity power factor as well as low current THD. The electromagnetic design of the machine is validated by means of a Finite Element (FE) model developed on purpose.