Acoustic Noise and Vibration in Electric Machinery
Electromechanical energy conversion can be viewed as an interaction between the tangential and normal components of the flux density within an actuator. Although motional forces are the main intended outcome of this process, a significant portion of the electromagnetic forces are normal to the path of motion and as such originate undesirable vibration of the stator and coils. These tangential and normal vibrations constitute the main origin for the acoustic noise in electric machinery. Introduction of power electronics-based excitation has contributed to the existence of high frequency force components which in turn demonstrate their impact in the acoustic noise spectrum. The severity of the acoustic, and especially the audible noise, for the most part depend on the structural configuration, material used and the assembly, local distribution of the magnetic forces. The inherent flexibility in articulation of the input current allows for mitigation of vibration and acoustic noise. An overall solution, however, requires a comprehensive analysis that can effectively combine the field problems associated with the electromagnetic, structural, and fluid dynamic problems.
At REVT we have developed an Impulse Response method using the concept of convolution theory. This model can precisely and efficiently calculate the vibration in SRMs. An experimental demo can be found on Youtube from this link. This research in modeling and mitigation of acoustic noise and vibration continues to be a research priority in sensitive aerospace, and military vehicles as well as in consumer products and automotive drives where quiet operation is on high demand.