Loss Analysis of a 3-MW High-Temperature Superconducting Ship Propulsion Motor

We developed a 3-MW high-temperature superconducting (HTS) motor for ship propulsion and demonstrated high efficiency, high-output density, and reliability above a certain level. To further promote the commercialization of the HTS motor, it is necessary to enhance its design technology to better satisfy the requirements for ship propulsion. To accomplish this, we need to improve the loss prediction method, as this is essential in the design of a high-efficiency motor. Since there are complicated losses in the 3-MW HTS motor, it is more difficult to deduce the detailed composition within the overall losses of the HTS motor than it is with conventional motors. This paper describes a loss analysis of the 3-MW HTS motor that is used to improve the loss prediction method. The loss at 3 MW operation was broken down in detail using the data obtained from a performance test, an open-circuit test, a short-circuit test, a nonrotating test, and an electromagnetic analysis result. The loss analysis results showed that the Joule heating loss on the armature, the individual wire eddy current loss on the armature, and the rotor cooling loss were comparatively large. The presently obtained results would form a basis for the next stage development study of reducing loss.