Stabilization of compressor surge in systems with uncertain equilibrium flow.

The adaptive correction of uncertain equilibrium states in feedback controlled systems is studied in this paper, with application to the active control of compressor surge with uncertainty in the characteristic curves. Adaptive compensation methods are introduced to correct for the uncertainty in the equilibrium state in both the state and the output feedback control cases, using information from the feedback control signal to determine the true equilibrium of the nonlinear plant. In particular, our proposed solutions overcome the odd-number condition, or parity condition, which appears as a recurring limitation in comparable solutions reported in the literature. Conditions for the existence of the adaptive solutions are presented, and the stability of the closed-loop system is demonstrated. The effectiveness of the proposed adaptation mechanism is verified using a high fidelity mathematical model of a compression system, commissioned to test active surge control methods by active magnetic bearings.