Electroquasistatic induction micromotors

The steady-state operation of the electroquasistatic induction micromotor (IM) is investigated. A rotary pancake IM compatible with surface micromachining serves as an example. A model is developed to predict the electric potential, field, and free charge within the IM. The model also predicts the motive torque and transverse force of electric origin acting on its rotor. The torque is balanced against bushing friction and windage to determine rotor velocity; the bushing friction is modeled as a function of the transverse force acting on the rotor. The model is used to study IM performance and its dependence on IM dimensions and material properties. For example, IM performance is predicted to be a complex function of axial IM dimensions and a strong function of rotor conductivity. The study also reveals that IM performance can differ significantly from that of the variable-capacitance micromotor. For example, the dependence of motive torque and transverse force on velocity and the excitation and control requirements can all be significantly different