Llado J., Sanchez B., Martinez A., Martín del Rio B., Vicuña J.

Switched reluctance Motors( SRMs) are considered as viable substitutes for AC motors in a variety of applications, because they offer many advantages such as simple mechanical construction, high-speed operation and greater reliance on sophistication in the controller. However, despite these excellent attributes, high levels of torque ripple and audible noise caused by SRMs remains as an open problem that appears to be particularly important, when introducing SRM technology for domestic products. As sound and vibrations are function of geometry, material properties and rotational speed of the motor, the knowledge of the mode shapes, the mode frequencies, and the noise spectrum can be effectively used to develop SRMs with minimal noise through design modifications. The existing research on acoustic noise of a SRM mostly deals with the radial vibration of the stator due to the radial magnetic force, but to characterize the acoustic noise emitted by a SRM it is necessary to know the dynamic behaviour of the rotor. This paper presents the acoustic characterization of a flat shaped SRM designed as a direct drive in a domestic washing machine. This SRM follows an 8/6 basic structure repeated three times, it is a four phases with 24 poles in an external stator and 18 poles rotor placed inside. This means that the sound pressure is measured in a test bench, and this spectrum is correlated to the mode shapes and mode frequencies of the rotor and stator, previously obtained by numerical computation. This correlation will let know which element or property, is the responsible for sound emission.