Operation of Dual Excitation Multiphase Electrostatic Drive by Amplitude Modulated AC Voltage

Abstract

Dual Excitation Multiphase Electrostatic Drive (DEMED)is a synchronous motor that is driven by electrostatic force. Because of its light weightiness, thinness and large power per weight ratio, it is expected as small-size motor and high-power motor in the future. Among three types of driving method that had been formerly developed for the motor, single frequency method is the most useful since it needs the least number of phases (three) of power supply. However, when the method drives the motor at such a very low speed as 10μm/s, the force generation decreases, and transformer camot be used to obtain high vo1tage for the motor drive. In order to solve these problems, this paper proposes a novel supplemental operation method. In the new method that is named as “modulation drive,” a3-phase ac signal is amplitude-modulated with higher frequency carrier signal and applied to the electrodes. Being applied tO the single frequency method, the modulation driVe successfully drove the motor with typical audio power operational amplifiers that were boosted by transformers with ferrite core, and eliminated the force degradation at low driving speed. Additionally, the force generation of the modulation drive was analyzed, and the result agreed very well with experimental result. © 1998, The Institute of Electrical Engineers of Japan. All rights reserved.