Investigation on Noise and Vibration of Rare-Earth Free High-Speed Carbon Composite Wrapped IPM

This study examines the noise and vibration characteristics of a rare-earth-free, high-speed, carbon composite-wrapped Interior Permanent Magnet (IPM) motor, focusing on the impact of the carbon composite sleeve on air-gap force density and vibration modes. Through the analytical calculation of radial electromagnetic (EM) forces and subsequent finite element analysis (FEA), the research establishes vibration modes on the stator outer surface, enabling the calculation of equivalent radiated power and sound pressure level. FEA is also utilized to identify bending frequency modes and critical rotational speeds in an undamped condition, with a parametric analysis of bearing stiffness, shaft length, and diameter elucidating their influence. By comparing with a conventional IPM rotor, the study quantifies the effects of the carbon composite and further evaluates allowable vibration modes under unbalanced mass conditions, ensuring they remain within air-gap clearance limits.