Performance Analysis of a Superconducting Motor for Higher Efficiency Design

The superconducting motor shows several advantages such as smaller size and higher efficiency against conventional motor especially utilized in ship propulsion application. However, this size reduction merit appears in large capacity more than several MW. We are going to develop a 17-MW class synchronous motor with a rotating HTS (high-temperature superconducting) coil that is aimed to be utilized for ship propulsion, therefore it has a slow rotating speed of about 200 rpm. The ship propulsion motor must generate high electromagnetic torque instead of low-speed. Therefore, the rotor (field) coils have to generate large magnetic flux that results in large amounts of expensive HTS conductor for the field coil. In this paper, a 17-MW HTS motor for ship propulsion is designed with smaller manufacturing cost by HTS field coil length reduction because the HTS conductor cost is a critical factor in the construction cost of an HTS motor. Furthermore, the output performance of the machine is simulated based on the equivalent circuit model of the synchronous motor with back electromagnetic field values from three-dimensional magnetic field calculation. The simulation results are used to design higher efficiency motor.