Tuning of reset proportional integral compensators with a variable reset ratio and reset band

The PI+CI compensator, given by the parallel connection of a proportional integral (PI) compensator and a Clegg integrator (CI), has been shown to be effective in a number of practical applications, overcoming fundamental limitations of PI compensation. Two key design aspects of PI+CI compensation is the use of the resetting law (zero crossing/reset band) and a (constant/variable) reset ratio; these two design factors have been previously used in control practice, but using heuristic design methods. This work develops a systematic design method for the tuning of reset PI compensators, specifically for first- and second-order plants, obtaining in both cases simple tuning rules. In addition, several detailed examples are developed; therefore, a detailed analysis of cost of feedback and robustness again parametric uncertainty is also given. Finally, an experiment of pH In-Line control is made to show the advantages of the proposed tuning rule.