Azimuth Thruster PMSM Optimization using Symbiotic Organisms Search Algorithm

The azimuth thruster is widely used in electric propulsion ships due to its excellent performance in contrast to their mechanical counterparts which present an inherent drawback regarding to maintenance needs, high costs and overall system deficiency. At the same time, according to up-to-date manufacturers' reports, permanent magnet motors make azimuth thrusters more compact, lighter and more efficient compared to other types of motors. Thus, the replacement of a conventional drive with a properly designed low-speed permanent magnet synchronous motor (PMSM) directly coupled to the thruster propeller, provides an attractive alternative. This paper, based on authors' previous work on low-speed surface mounted PMSM design for azimuth thruster application, presents and proposes here an optimization procedure using a meta-heuristic population based technique namely the symbiotic organism search (SOS) algorithm. The results obtained reveal that the SOS algorithm provides effectively the required design solutions and performance.