Star-Drive for a Stepper Motor
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
A technique is described whereby a circuit to drive a four-phase stepper motor is simplified so as to require the use of only four wires from the motor, thereby reducing costs without sacrificing performance. In a four-phase stepper motor, two of its four coils are energized in series when the motor is to be advanced a step. The motor circuit resembles a poly-phase star-connected AC motor, hence the name Star- Drive. The operation of Star-Drive stepper motor 10 can be explained by initially assuming that coil 11 and coil 12 are energized through transistors 13 and 14 actuated by the external signals -SEL A and -SEL C. In the first step thereafter, coil 11 remains energized and coil 12 is de-energized while coil 16 is energized through the -SEL D controls.