Abstract
A magneto-electric composite element of two functional materials: giant magnetostrictive (GMM) and piezoelectric materials, is developed for coil-less magnetic force control. This force control is based on the inverse magnetostrictive effect of GMM and realized by composing a closed parallel magnetic circuit with a permanent magnet in magnetic yoke. The magnetic force between two yokes can be adjusted by controlling the strain in the magnetostrictive rod. For the purpose of efficiently controlling the strain of the GMM rod, a magnetp-electric composite element is constructed, in which the two functional materials: a giant magnetostrictive rod and a stack piezoelectric actuator, are mechanically coupled via strain. The magnetization in the GMM rod can be controlled by adjusting the voltage of the piezoelectric actuator. It is confirmed that this element works to adjust magnetic force and has wide frequency bandwidth. As an application of this element, a magnetic levitation system is proposed and the movable yoke was levitated by simple PD control. This system has advantages of low power consumptions and low heat generation cpmpared with a conventional system with electromagnetic coils.
