TECHNIQUE FOR FINDING THE OPTIMUM GEOMETRY OF ELECTROSTATIC MICROMOTORS

This paper presents a computer-based method for finding the optimum ge ometry of very small electrostatic motors based on the variable capaci tance principle. Not only is the geometry taken into account, but diff erent excitation schemes are studied, in order to find the maximum ave rage output torque and / or the minimum vibration component in the out put torque. Different combinations of stator and rotor poles are treat ed. The most important part of this optimization is automation of the procedure. For the actual calculation of the electrostatic field distr ibution, the finite-element method is used. The mesh generation for th e machine as a function of the rotor position and the design parameter s is automated. The extraction of the torque and capacitance values is done in batch procedure, constructed around a commercial finite-eleme nt CAD package. This automation makes the system into an optimization tool of an otherwise very tedious technique.