Miniature Drive

an electric drive in which the actuating electric motor has a power of up to about 500 watts. It is used in automatic equipment, motion-picture and radio apparatus, and household electrical appliances. A distinction is made between AC and DC miniature drives. In DC drives, magnetic and transistor amplifiers are used as regulators, and in reversible drives, push-pull magnetic amplifiers with internal feedback are used.

In AC drives the actuating electric motor is controlled by magnetic and magnetic-semiconductor amplifiers, and also by transistor and thyristor frequency converters. In this case the speed of the electric motor is regulated by changing the amplitude and frequency of the voltage on the stator winding. The required stiffness of the electric motor’s speed-torque characteristic is obtained by the introduction of feedback for the rate of rotation.