Mitigation techniques for acoustic noise and vibration in switched reluctance drives

Abstract

Switched reluctance machines (SRM) have become an attractive rotating electrical machine in many applications because they have no permanent magnets, have robust structures and high fault tolerance. However, the crucial drawback of the SRM that limits the range of applications, is the acoustic noise and vibration often associated with this technology. The major source of vibration comes from the high deformation of the SRM stator stack, caused primarily by high radial magnetic forces. Vibration behaviour of di erent SRM topologies is analyzed by using nite element software to calculate the magnitude, mode shape and the resonant frequencies of the SRM. This includes determination of the generating magnetic force characteristic for each topology. To improve the accuracy of the vibration model of the SRM stator, which is built from laminated steel sheet, calculation of the mechanical material properties of the stator are developed for structural simulations. The simulation and testing results of the resonant frequency of the SRM are compared to determine the accuracy of the simulation model. There are two main strategies for reducing the vibration in an SRM. I) structural design and II) control technique. In this thesis, the structural design of six types of SRM segmented stator, each shrink- tted into an aluminium housing, are investigated, both in terms of the structural sti ness and resonant frequency. The impact of varying temperature on the resonant frequency of the stator is tested to show the rate of change of the resonant frequency and damping ratio of the stator structure. Furthermore, the control technique of the SRM has also been shown to have a signi cant impact on the vibration produced in the SRM. Improvement of the control technique based on an active vibration cancellation (AVC) method is implemented under load conditions with di erent operating speeds of the SRM and compared with the conventional control method.