Power-Saving Drive in 2-Position Control of Giant-Magnetostrictive Actuator

In the fundamental configuration of a giant magnetostrictive linear actuator (GMA), a giant magnetostrictive material (GMM) rod is energized by a coil surrounding it. However, supply of continuous electric power to the coil is necessary to maintain the expansion of the GMA. The electric power consumption is in proportion to the activation interval and becomes larger especially for applications which maintain the expansion of the GMA for long duration. This research developed a new GMA drive method which wasted no electric power during the GMA expanding. Permanent magnet (Al-Ni-Co) rods are located around the GMM rod, which are magnetized and demagnetized by the coil instantaneously. The permanent magnets supply the magnetic field to the GMM rod without electric power consumption in maintaining the expansion of the GMA. It is possible to achieve both the power-saving drive of the GMA and reduction of the thermal expansion.