A 250 kW Three Phase Induction Motor Design for Electric Bow Thruster

Induction motors are used in various applications because it has the simplest construction and design than other motor types. The applications are not only in industrial applications but also in maritime applications. This paper presents a design process for a 250 kW three-phase asynchronous motor with high torque and low rpm for electric bow thruster application. First, motor capacity is obtained based on the naval architect calculation. The capacity determination is considered ship weight and dimensions. After that, basic calculations for the motor used mathematical approaches. Those mathematical approaches are used to find out major geometries of the motors (for instance: stator coils, rotor bars, stator, and rotor core dimensions, and air gap). In addition, the air gap is one important part in motor geometry calculations. The optimum air gap distance is needed to obtain better motor performances. This paper shows the impact of air gap distance for motor performances. The motor performances are analyzed with MATLAB.