Variable-capacitance motors with electrostatic suspension

This paper describes an electrostatically suspended variable-capacitance mo tor (ESVCM). The ESVCM is an electrostatic stepping motor featuring electro static suspension. Thus, the ESVCM possesses the rotating and positioning a bility of an ordinary stepping motor, in addition to providing contactless support by electrostatic suspension. To accomplish these two functions, a f eedback control strategy and the operating principle of an ordinary electro static variable-capacitance motor are used. In this paper, the structure of the ESVCM is described, followed by its operational principle, a linear dy namic model of the suspension system and feedback control strategy. Experim ental results show that the rotor has been rotated with a speed of approxim ately 60 rpm during stable suspension at a gap height of 0.3 mm. (C) 1999 E lsevier Science S.A. All rights reserved.