Finite-element analysis of rotor stability in an axial-drive micromotor

Abstract

The effect of axial electrostatic forces on the rotor deflection of an axial-drive double-stator micromotor is studied with respect to the limits of stability against elastic rotor collapse using the finite-element method (FEM). Forces obtained from an electrostatic FE model have been applied to a structural FE model using the indirect coupled-field analysis approach. This technique may be applied to other MEMS structures with conducting components. A technical description is given of the design and the fabrication process of the axial-drive double-stator micromotor investigated. Two different axial rotor supports (bearing and bushing) are investigated. The results are discussed as a function of the applied voltage and rotor thickness considering polysilicon and aluminium as possible rotor materials. The effects on the stability of the rotor of supporting the rotor with an additional bushing, and of increasing the rotor thickness, are investigated quantitatively.

VHDL–AMS modelling and simulation of a planar electrostatic micromotor

“…Their use, however, requires a substantial understanding of the underlying physical behaviour and are computationally intensive since most of them are based on finite element analysis (FEA) methods [4][5][6]. In the context of this paper, tools based on these methods have successfully been used in 0960-1317/03/050580+11$30.00 © 2003 IOP Publishing Ltd Printed in the UK VC electrostatic motor modelling [7,8] whereby electrostatic forces [9], static torque [10,11] and frictional parameters [12] have been calculated from FEA simulations.…”

Optimization of the geometry of electrostatic micromotors using only analytical equations

“…Two types of electrostatic micromotors have already been studied and built: dielectric variable reluctance micromotors (radial gap [10], axial gap [11], and wobble motor [12]) and electric induction micromotors [13,14]. Since the electrostatic motor has been studied less than the electromagnetic one, this article presents a method that allows optimization of the structure of radial gap dielectric variable reluctance micromotors in order to maximize the average torque and minimize the torque ripple.…”