Prediction of audible magnetic noise radiated by adjustable speed drive induction machines

This paper presents a fully analytical model of the electromagnetic and vibro-acoustic behavior of variable-speed squirrel-cage induction machines. This model is integrated in a fast simulation tool that can be used to design motors with low magnetic noise level on their whole speed range. Some simulation results at variable speed are favorably compared with experiments at both vibratory (spectrograms) and acoustic levels (sonagrams) on a 700 W laboratory motor and on an industrial 250 kW traction motor. These extensive tests show that the model correctly predicts the main exciting forces, motor natural frequencies and resonances during adjustable-speed drive. The simulation tool, called DIVA, has been successfully applied to design a new low-noise ALSTOM motor.