Linear Actuator Utilizing Magnetic Shape Memory Material

Magnetic shape memory (MSM) alloys are smart materials that change their shape when exposed to an external magnetic field. MSM technology is being considered increasingly for various actuator applications due to its potential advantages such as fast response times. A further advantage is the possibility to actuate not only magnetically but also thermally; which enables replacing a thermal and a magnetic actuator by a single MSM actuator. This is particularly beneficial in miniature circuit breakers, where currently a thermal actuator is used for overload and a magnetic actuator for short circuit protection. This paper presents a linear MSM actuator comprising a single-turn coil, a magnetic core and an MSM element block. The magnetic and mechanical aspects of the design are explained, and two actuator demonstrators are shown. Experimental results are given to validate the design.