Nonlinear PI regulators

This paper introduces a simple modification to classic PI controllers to achieve the ideal behaviour of the regulator where the proportional component is used to get close to the reference signal, and the integral component to achieve zero steady-state error. As a consequence, the control effort is reduced and overshoots/wind-up phenomena are mitigated, while performance and simplicity of the PI controller are preserved. The proposed nonlinear PI is extensively compared with similar controllers from the literature to validate the theoretical expectations.