Nonlinear observer design for a Greitzer compressor model

In this paper two different observers for a nonlinear compressor model have been developed and compared: A nonlinear observer based on a circle criterion design and an Extended Kalman Filter. Both of these observers were implemented together with linear control strategies in order to (surge-)control the nonlinear Greitzer compressor model. The newly developed nonlinear observer is a full state observer providing local asymptotic stability results. Compared to the Extended Kalman Filter, the nonlinear observer showed itself at least equivalent, even superior for open-loop estimation.