A FEM APPROACH FOR DYNAMIC MOTION AND CONTROL OF ELECTROSTATIC MICROMOTORS

A quasi-static approach based on two-dimensional Finite Element Analysis (FEA) is described to calculate the position and speed of the rotor of Variable Capacitance Micromotor (VCM). FEA is performed to compute the overall capacitance of the rotor-stator combination when the stator is excited symmetrically. A continuous curve is fit to energy-angle ‎points by the spline interpolation technique that is very effective for data fitting. Thus the energy vs. angle function is obtained and the torque is calculated by the ‎partial derivative of energy vs. angular displacement. A quasi-static approach is then adopted to the operation model of the entire micromotor. Also a new speed control method is presented which the rotor is rotated based on the torque estimated by extrapolating the earlier FEA result for a single stator pole. It can enable a sufficient fast and accurate way to dynamic simulation and control of VCM.