Coupled Electromagnetic-Thermal Analysis of Propulsion Motor for Fully Electric Ships With System-Level Design Approach

The concept of a removable-battery-powered fully electric ship (RBP-FES) addresses challenges such as high investment and maintenance costs of large batteries. As the primary energy consumer in an electric ship system, the propulsion motor must be designed to meet the requirements of various propulsion system components, ensuring high efficiency. Permanent magnet synchronous motors (PMSMs) are favored due to their high efficiency, power density, and compact size. However, PMSMs exhibit temperature-dependent performance, requiring simultaneous consideration of electromagnetic and thermal aspects. This study presents a system-level design and coupled electromagnetic-thermal analysis of a 500 kW Interior PMSM (IPMSM) for RBP-FES applications. The design process includes load design (hull, propeller, and gear) and explores the relationship between the C-rate levels of the battery system and the propulsion motor in determining initial physical parameters. A coupled analysis integrating electromagnetic finite element analysis (FEAs) and thermal networks is developed, and its results are discussed. The prototype is built and tested to validate the design and analysis outcomes. The experimental results show that the IPMSM reached an efficiency of 98.3% at rated power. Furthermore, the temperature rise test results match well with coupled analysis, with a deviation of less than 2 °C.