METHOD AND APPARATUS OF CONTROLLING ELECTRIC ACTUATOR

PROBLEM TO BE SOLVED: To enable to easily stably control a stepping motor without any trouble in a low speed range and a medium/high speed range with a simple circuit configuration and a simple algorithm, in order to economically realize stable control of a mechanical body of an electric actuator. SOLUTION: In the control method of the electric actuator, the speed of the stepping motor 20 is determined into a medium/high speed range and a low speed range. A slip angle θ is obtained as a phase difference between a vector phase angle θi of a phase current of A, B two phases of the stepping motor 20 and a phase angle θm of a rotor shaft to be acquired from an encoder 21. In the low speed range, when the slip angle θ is not more than 30°, the phase current is changed in several steps at a predetermined rated proportion, if it is 30-90°, the phase current is changed in several steps while rated current is maintained, and the phase current is changed in several steps at not less than a predetermined rated proportion when it is not less than 90°. In the medium/high speed range, an excitation magnetic angle for deciding phase current of two phases is forward-controlled until the slip angle θ becomes 90° for a power drive unit. COPYRIGHT: (C)2007,JPO&INPIT