Induction rim-drive for a marine propulsor

The design of a line-start rim-driven induction motor specifically for use in a marine propulsor/thruster is described. This paper explores the use of a hybrid ‘canned’ induction rotor design in which a conventional ‘deep-bar’ cage is replaced by a simple cage with a low radial depth, along with a series of air-gap cans to provide environmental shielding, and a conducting rotor can to simplify the rotor design. An overview of the design process to the ‘final’ design for the proposed induction rim-drive is explained, along with details of the two-dimensional finite element models and simulation results. An appraisal of the merits of the rim-driven design, compared to a benchmark industrial induction motor, is also discussed.