Induction motor design considerations for LNG carrier dual fuel electric propulsion

This paper proposes a design procedure of induction motor for Liquefied Natural Gas (LNG) carrier applications, implementing dual fuel electric propulsion system. For the purposes of the analysis, a preliminary motor design stage is performed by using classical analytical formulae and a parameterization of the design is introduced. In a next step, a critical design stage is developed, based on a geometry optimization procedure at nominal operating conditions by using 2D Finite Element (FE) modeling. The optimization criteria are focused on the minimization of motor total losses at nominal load, in order to achieve high efficiency of the propulsion drive system, and the minimization of torque ripple, in order to provide increased reliability. Finally, for the final optimized motor design, the performance and efficiency indexes are evaluated as well as the equivalent circuit parameters for implementation in the drive control model are determined.