| Electrostatic induction motors are analogous to magnetic induction motors. Mathematical models of them can be constructed by using this analogy. There are two types of electrostatic induction motors. The attraction induction motor uses charges of opposite sign to produce forces and is a direct analog of the familiar Tesla magnetic induction machine. The repulsion induction motor uses charges of the same sign to produce forces and does not appear to have a direct magnetic analog. The latter has unusual behavior. For example, it can operate as a dc motor without mechanical commutation.; A complete theory based on Maxwell's equations is derived for a motor with a solid rotor and a rotor-stator gap and also for the electrohydrodynamic (EHD) pump, which is a linear electrostatic induction motor and which can have a single continuous fluid "rotor" with no gap. Both space and time harmonics are included. In addition, a steady-state per-phase equivalent circuit is derived in detail. Charge and corona motors are shown to be well-modelled as repulsion induction motors.; Experiments were performed using a generalized electrostatic motor wired for induction operation and for a corona motor, both of which were excited by a high-voltage waveform generator. The results were unusually good for experiments in electrostatics, with good quantitative agreement between the theory and the induction motor operation. The three stable operating modes of the corona motor (supersynchronous forward and backward modes and a low-speed mode resembling typical induction motor behavior) could be predicted qualitatively using a repulsion motor model with harmonics.; This work is intended to be of help in the design of any device which uses electrostatic induction forces. Future work will test the EHD pump model and use the theory as an aid in building more effective devices. |
