Practical anti-windup control via saturation feedback in fuzzy-PI diesel engine speed regulation

Abstract

Anti-windup control is a critical auxiliary for PID regulator. It is designed to address integral saturation when PID regulator’s output is constrained. In this study an anti-windup control via saturation feedback is proposed. It is built with a feedback path, which transfers output constraint and overwrites cumulative term of PID regulator with the constraint value during integral saturation period. Satisfactory anti-windup control performance can be obtained consequently, since any excessive cumulation by integral effect will be reset. Besides, the proposed algorithm is simple enough for practical implementation, because no coefficients are required. The algorithm is utilized in fuzzy-PI diesel engine speed regulation for validation. Simulation experiments are conducted first, where cases of integral saturation at upper boundary and lower boundary are performed respectively. For the former case integral saturation results in 3.4% engine speed overshoot ( $n_{\mathrm{os}}$ ) and 0.2 s time lag of injected fuel mass adjustment ( $t_{\mathrm{lag}}$ ) with saturation feedback, for the latter case 1.5% $n_{\mathrm{os}}$ and 0.1 s $t_{\mathrm{lag}}$ are achieved, demonstrating a good anti-windup performance. Road test is subsequently conducted for further validation. The result shows 0.28 s $t_{\mathrm{lag}}$ after integral saturation, which substantiates the satisfactory performance of saturation feedback in practical application.