Noise in Electric Motors: A Comprehensive Review

Electric machines are important devices that convert electrical energy into mechanical energy and are extensively used in a wide range of applications. Recent years have seen an increase in applications where electric motors are used. The frequent use of electric motors in noise-sensitive environments increases the requirements placed on electric motors intended for these applications, especially when compared to electric motors commonly used in industrial applications. This paper provides a comprehensive review of electric motor noise. Firstly, a brief introduction to noise is given. Then, the sources of electromagnetic noise and vibration in electric machines, including mechanical, aerodynamic and electromagnetic factors, are presented. Different methods such as analytical, numerical and semi-analytical for calculating electromagnetic force, natural frequencies and noise are also analyzed. Various methods for noise reduction are presented, including skewing, stator and rotor notching and slot opening width. Finally, noise measurement standards and procedures are described.