Comparison of electrostatic and electromagnetic motors based on fabrication and performance criteria

It is generally agreed that electrostatic motors have more advantages than electromagnetic motors in devices demanding small sized components. Such comparison is based on an analysis of the energy density using a simple model. The primary goals of our research are to fabricate and evaluate practical micromotors and to characterize the relationship between the torque and scale of both the electromagnetic and electrostatic motors. In this paper, models of the electrostatic and electromagnetic motors are described. The motor torque is calculated by an analytical method using the finite element method (FEM) or conventional-size equations for stepping motors. To verify the models, actual millimeter sized motors were fabricated and evaluated. For both motors, good agreement was found between the calculated and measured values. Based on the results, the relationship between the torque characteristics and the scale of the motors is described