Tuning of robust fractional-order phase-lead compensators using pole placement and pole-zero ratio minimization

Abstract

This paper deals with the tuning of robust fractional-order phase-lead compensators to provide desired time-domain specifications. A simple analytical design technique, which is based on minimization of a compensator’s pole-zero ratio subject to pole placement requirements, is developed. The necessary and sufficient conditions for the feasibility of the problem and determination of optimal compensator parameters are provided. To have a robust compensator, a desired maximum sensitivity is provided by properly choosing the compensator’s fractional-order in the acceptable range. Finally, illustrative examples are presented to evaluate the performance and effectiveness of the proposed method.