Analytical-FE Study of Rotor-Dependent Hairpin Conductor Sizing in High-Performance IPMSMs

Hairpin windings (HWs) are increasingly adopted in Interior Permanent Magnet Synchronous Motors (IPMSMs) for electric vehicles, owing to their high fill factor and ease of manufacturing. This study pursues two main objectives: first, to investigate how changes in rotor design influence the ideal HW dimensions for minimising losses and maximising efficiency, and second, to verify whether simplified analytical models can accurately predict the optimal HW height under varying rotor geometries. A multi-objective finite element (FE) approach is employed to identify optimal rotor-stator configurations, followed by analytical estimations of conductor dimensions. Results show that rotor geometry affects conductor width, while HW height remains relatively constant once the critical height is achieved. Even though the simplified analytical models do not account for non-linearities or end-winding effects, they still provide reliable predictions of HW dimensions for various rotor configurations.