Tuning Method for a PID Controller in a Non-minimum Phase System

We propose a simple tuning method for PID controllers in non-minimum phase systems. A non-minimum phase system, which contains zero in its right-half plane, can be approximated as a stable dead-time system. Therefore, its PID controller parameters can be roughly tuned using a two-step tuning method for stable dead-time systems. Subsequently, the parameters of the PID controller can be successfully tuned by adjusting the scale factor <em<α</em<. The undershoot and dead-time caused by the zeros in the right-half plane are thus eliminated. The effectiveness and the robustness of this two-step tuning method have been proven through simulations.