Analysis of corona motors and micromotors by means of effective gap conductivity

Corona motors are of possible interest in miniature applications because of their insensitivity to material properties and their ability to produce torque with DC excitation. These motors act through repulsive forces, and can be built in self-levitating arrangements to minimize friction. The nonlinear electrical characteristics are modeled through Fourier analysis of the stator input voltage and current waveforms. An equivalent gap conductivity is defined, and used to provide a linearized model of the charge and field distributions at the rotor surface. The analysis helps explain how a corona motor generates high speeds with DC excitation, and points out the basis for its asynchronous operation. Experimental tests of a macroscopic motor confirm that the model successfully describes the basic behavior of a corona motor. Operation of a small (100 μm) cylindrical motor is considered through simulation. Such a device is expected to be capable of very high speeds with DC input and no special control