Optimal Design and Placement of Piezoelectric Actuators using Genetic Algorithm: Application to Switched Reluctance Machine Noise Reduction

Abstract

Thanks to a good robustness, an easy production and high performances, switched reluctance machine (SRM) is an interesting drive for electro vehicular applications (Rahman et al., 2000) (Wang et al., 2005) or high speed applications (Kub et al., 2007). However, noise and vibrations generated by the SRM limit its integration. Previous studies on vibration reduction have considered SRM supplied by a pulsed current source. In this context, many solutions have been successfully applied to this problem such as adapted control schemes (Hong, 2002) and optimized stator design (Blaabjerg et al., 1994). However, these methods are less efficient in high speed operation zones. This chapter deals with the optimal placement and design of piezoelectric actuators used to reduce the noise and vibration generated by a SRM. Piezoelectric actuators are stuck on the SRM stator and controlled in order to reduce the generated vibrations. The design and placement are achieved by a genetic algorithm, NSGA II (Deb et al, 2002), with multi contradictory objectives in order to obtain a set of optimal solutions. Considering the number of actuators and the minimization of final displacement energy as contradictory objectives, a set of optima is found and a solution is chosen in order to be experimentally tested on a SRM. In electrical machines, noise and vibrations are mainly due to aerodynamic (Fiedler et al., 2005), mechanical and magnetic issues. Aerodynamic vibrations are due to air displacement along rotating rotor (laminar flow) and vortices (turbulent flow) on SRM air gaps. These vibrations are located on inner surface of SRM stator. Mechanical vibrations are generated by relative movement between machine part and shock inside ball bearing. These vibrations are un-located on SRM. At last, magnetic vibrations are due to permeability gradient and generated on stator air-gap interface. Such sources can excite mechanical resonances of the structure and then generate vibratory displacement on the structure. Each source of noise