Suppression of Arbitrary Periodical Disturbances in the Design of Digitally Controlled Electrical Drives

This paper outlines the basic concepts for compensation of arbitrary immeasurable periodical external disturbances and/or for the accurate tracking of periodical reference signal without error in the steady-state. The conventional method based upon the application of IMP (internal model principle) is first described briefly and then the more efficient IMPACT (internal model principle and control together) controlling structure is proposed, which completely rejects effects of any periodical disturbance on the steady-state value of controlled variable (system output). Besides the efficient extraction of periodical disturbances, the IMPACT structure enables achievement the higher degree of system robustness. The structure design is illustrated by the extraction of periodical load torque disturbance in a speed-controlled electrical drive with DC motor