Acoustic noise due to electromagnetic excitations in Asynchronous machines

The audible noise of electrical machines, which contributes to their environmental impact in the same way as their power consumption or recyclability, has become a major criterion during their design phase, both in industrial applications, where exposure to noise has a direct impact on health, and in transport for reasons of acoustic comfort.

The overall noise level of an electrical machine comes from three main sources: mechanical noise (bearings, gears, etc.), aerodynamic or hydrodynamic noise (coolants) and magnetic noise. In open AC machines, magnetic noise can dominate the total noise level at low and medium speeds . It is produced by the currents present in the asynchronous machine and is often characterized by an unpleasant emergence of acoustic lines. This tone is also penalized by the noise limit standard CEI 60034-9 Understanding the phenomenon of magnetic noise is therefore crucial to the design of low-noise machines, or to the diagnosis and resolution of vibro-acoustic problems on existing machines. Magnetic vibrations are also a source of mechanical fatigue, degrading the reliability of electrical machines. Analyzing and minimizing magnetic vibration can therefore help to improve machine life.

Predicting magnetic noise requires multiphysics modeling: it requires both an electromagnetic model of the machine excitation and a vibroacoustic model of the excited structure. What's more, the noise must be simulated in variable regime to take account of resonance phenomena: the use of electro-vibro-acoustic finite element tools in the design phase therefore raises difficulties, both in terms of calculation time and numerical coupling. Analytical electromagnetic, vibratory and acoustic models have therefore been developed . Their speed also enables them to be coupled with a multi-objective optimization algorithm to design machines with low magnetic noise, low torque pulsations and high efficiency