Performances comparison of induction motors and surface mounted PM motor for POD marine propulsion

The overall efficiency of ship propulsion systems equipped with POD, depends considerably on their compactness. Permanent magnet synchronous motors (PMSM) are considered up to 30% more compact than other classical motors. The aim of this paper is to show that an optimized induction machine (IM) may seriously compete an optimized PMSM. Indeed, an EM with lower pole number and an acceptable level of flux density can reach a very high torque density (kN.m/m³). In order to estimate the main performances of IMs, a coupled model taking into account saturation, thermal constraint and space harmonics is developed and validated.