On active surge control of compressors using a mass flow observer

A globally exponentially stable (GES) observer for the mass flow in a compression system is proposed. Further, a previously proposed active surge control scheme is shown to be GES. This nonlinear control scheme employs the drive torque of the compressors drive unit as the control variable in an active surge control system. The controller is based on feedback from mass flow. It is desirable to avoid this measurement as it is both inaccurate and expensive. Using a nonlinear separation principle, the total system is shown to be globally asymptotically stable (GAS). The results are supported by simulations.