Geometry Optimization of an Interior Permanent Magnet Machine for Minimal Life Cycle Cost in City, Rural and Highway Driving

This paper presents Interior Permanent Magnet Machine (IPM) geometries that are customized for city, rural and highway driving in an electric car, using an optimization work-flow that minimizes the Life Cycle Cost (LCC) of the IPM and its feeding inverter. The work-flow includes scaling of electromagnetic finite element results to identify which size and current rating of each geometry that gives lowest LCC while meeting, thermal and mechanical constraints. The different driving types are considered either as single drive cycles or as distributions of logged driving. The IPMs optimized for city, rural or highway driving are compared to an IPM optimized for mixed driving, showing that IPM customization reduced the LCC by 7% in a city cycle and by 1% in a highway cycle. However, most of the driving scenarios, including all types based on logged driving, were found to be well met with an IPM optimized for mixed driving.