Smaller is better? [micromotors and electric drives]

Some fundamental constraints on the performance of micromotor technology have been discussed. Several aspects of performance were explored, including energy density, force density, size, constraints on motor-drive circuitry, motor topologies, and friction. Analysis shows that electrostatic machines have advantages as microfabrication processes achieve finer resolution, and, in fact, can exceed the energy and force density capabilities of conventional magnetic machines at small enough scales. Major thrusts for electric drive theory to be applied are in control, topology optimization, and machine testing.