Magnetic Circuit Design Method for Magnetic Force Control Systems Using Inverse Magnetostrictive Effect

Examination of Energy Conversion Efficiency Depending on ΔE Effect

Abstract

A new magnetic force control method using giant magnetostrictive material (GMM) was proposed and its feasibility was confirmed in the former studies by the authors. This new method is based on the inverse magnetostrictive effect and the magnetic force is controlled by changing the stress or strain in the magnetostrictive material. This method was expected to have lower heat generation and higher energy conversion efficiency compared to traditional methods since constant magnetic force can be maintained by only applying constant stress. In this study, the energy conversion efficiency of this method is investigated experimentally using a universal test machine. The input elastic energy was calculated from the stress-strain loading curve and the converted magnetic energy was estimated from the generated magnetic field. Since the elastic energy is strongly dependant on history of strain-stress loading curve, and the loading curve is affected by the applied magnetic field in the magnetostrictive material, it is important to optimize the bias magnetic field for maximum energy conversion efficiency. The relationships between Young's modulus and magnetic field were measured experimentally and the results show that a bias magnetic field must be carefully chosen to obtain high efficiency of energy conversion.