Abstract: A generalized force approach is used to model the instability of magnetic microactuators.The reluctance of the magnetic core is considered.The critical value of applied current,beyond which the dynamic response of the small gain model becomes unstable,is investigated and the Pull-in equation is derived.Then a generalized energy approach is used to model the same problem.The results of the two approaches are identical.Finally,a case of the magnetic microactuator,illustrating the use of the Pull-in parameters,is presented.

Key words: magnetic,  microactuator,  Pull-in