Study and design for large line-start permanent magnet synchronous motors

The design of large three-phase line start permanent magnet synchronous motors (LS-PMSM) with buried permanent magnets in the rotor below a squirrel cage is studied in this paper. Difficult problems such as rotor structure and ventilation have been solved during design of a 4 pole 1120 kW LS-PMSM. The leakage magnetic flux and magnet bridge strength is calculated with finite element method (FEM). The verified characteristic of manufactured LS-PMSM is very good agree to the calculated effect by FEM.