A systematic approach toward studying noise and vibration in switched reluctance machines: preliminary results

A systematic approach is taken to investigate the noise and vibration of switched reluctance motor (SRM). Although it has been shown that SRM are well within the noise specifications for most applications, there is significant interest in applying this technology in applications with stringent noise requirements. This paper describes the calculation of magnetically-induced forces, and the dynamic response of the motor structure to those forces. Unlike previous studies, a step-by-step approach is taken in the construction of a finite element (FE) model of the mechanical system. Each component is modeled and analyzed, and the results compared with experimental measurements. In this way the model is calibrated against the real motor at the component level, the sub-assembly level, and as a complete motor. This approach yields a reliable model of the mechanical system without accumulated errors from its component parts. The model, together with experimental measurements, allows the accuracy of different methods of electromagnetic-force prediction (which is otherwise unmeasurable) to be compared. The study yields a complete and accurate magnetic and mechanical model of the system which can be used to predict motor vibration under any operating condition. In addition, a much simplified and computationally faster mechanical analysis is presented. This is intended to give the machine designer an indication of noise and vibration levels without resorting to more complicated FE analysis.