A Comprehensive Analysis of the Acoustic Noise in an Interior Permanent Magnet Traction Motor

Modeling and analysis of acoustic noise is one of the important design phases for a traction motor in the noise-sensitive applications, such as hybrid electric vehicles. This paper presents a comprehensive analysis on the acoustic noise and the radial force density harmonics in a 48/8 interior permanent magnet (IPM) traction motor designed for an electrified powertrain. Detailed acoustic modeling and analysis based on the numerical method is presented. The techniques on improving the simulation accuracy and reducing the computation cost of the numerical modeling is also analyzed. The effect of the two-step skewed rotor on the radial force density harmonics is discussed. The sound pressure level waterfall diagram and the analysis of the radial force density harmonics confirm the dominant vibration mode and the dominant harmonics of the radial force density. The acoustic noise analysis process presented in this paper develops the basis for the acoustic noise reduction by optimizing the rotor stepped skew angles.