Influence of constructive parameters and power signals on sound quality and airborne noise radiated by inverter-fed induction motors

• We have developed a novel approach based on sound quality parameters.
• We establish the noise emitted by a powered three-phase induction motor.
• The results show differences using psychoacoustic analysis instead noise emission.

This work presents the result of a study of the acoustic quality of noise emitted by a three-phase, induction motor fed with various modulation techniques (Pulse Width Modulation, PWM). It complements the classical study of noise emitted by rotating electrical machines, based on acoustic emission levels. For this, the psychoacoustic parameters of Specific and Total Loudness, as well as Total Roughness were used. These were applied to the noise emitted by a 4-speed, Dahlander-type motor to identify their contribution to the acoustic quality of distinct pole-number configurations as well as the different control-parameter values of each of the studied techniques. The modulation techniques employed have been analyzed in previous research in which was determined their contribution to the noise levels emitted by a machine of similar characteristics as that employed here. Results are checked experimentally and compared to the sound-pressure level; showing the noise emitted and the sound quality do not coincide for a given combination of parameters. Moreover, the choice of the best modulation strategy changes depending on if the aim to achieve is less harmonic distortion (HIPWM-FMTC), less heating of associated electronics (SLPWM) or a lower acoustic emission level (HIPWM-FMTC2). Finally, with the present study an attempt is made to compliment and corroborate the results obtained up until now, as well as initiate a new focus of analysis that can serve as the basis for future research of other operation forms and regimes, and also other kinds of rotating electrical machines.