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This paper introduces the design and fabrication progress of a megawatt class 2G high temperature superconductor (HTS) motor for the ship propulsion application at Doosan Heavy Industries and Construction. The purpose of this 2G HTS propulsion motor is to launch the business area for marine applications such as surface ship, submarine, merchant ship etc. The principles and interpretation of the magnetic field for 2G HTS motor and permanent magnet type motors are similar on the basis of 3D design and production. The most important component of an HTS motor is the rotor, which is composed of HTS coil, non-ferrous metal, torque disk, damper, and hollow shaft. A HTS rotor using hastelloy-based 2G HTS coils was designed and built. Open-circuit and short-circuit characteristics of the superconducting motor were investigated and compared with the analysis results at reduced excitation to verify the design. Preliminary testing of a 2G HTS motor has been conducted at a few hundred kilowatts as per the design. Through these results, we anticipate that most of the design criteria can be satisfied. However, we have faced several issues during the testing of the motor and these issues need to be resolved in order to take the design further.

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In recent years, a laminated rotor made of the insulated silicon steel laminates is increasingly adopted in the electrical machineries. While this laminated rotor offers good electrical performances, it is quite complicated to predict its stiffness as it is influenced by various factors such as material properties and shape of the laminates, characteristics of the insulation layer, lamination pressure and method of fitting. As it is difficult to model or define boundary conditions in the case of lamination pressure or fitting, the stiffness of the laminated rotor cannot simply calculated using conventional analytical method. Therefore, quantitative investigation on the influence of lamination pressure upon the stiffness of laminated rotor is highly required. In this study, natural frequency of the rotor is measured under various conditions of lamination pressure to investigate the influence of lamination pressure upon the stiffness of laminated rotor. It is found from the experiment that the natural frequency is increased with lamination pressure, and saturated near the 20% of the difference between the inner and outer diameters of the laminate. It is also found that the natural frequency can be controlled to 4-14% in the range of 1-10 MPa of lamination pressure. The saturated value of the stiffness of laminated rotor is expected to approach to that of shrinkage-fitted cylinder having the same inner and outer diameters under the same assembly condition. It is expected that the results would be helpful to design generators or motors using laminated rotors.

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