Control of deep-hysteresis aeroengine compressors. I. A Moore-Greitzer type model

While the famous Moore-Greitzer cubic model (MG3) provides a good qualitative description of open-loop dynamic behavior of an axial compressor, it does not capture the main difficulties for control design. In particular, it fails to exhibit the so-called "right-skew" property which distinguishes the deep hysteresis observed on high-performance axial compressors from a small hysteresis present in the MG3 model. We study fundamental feedback control problems associated with deep-hysteresis compressors. We derive a modification of the MG3 model which exhibits the right skew property. Our approach is based on representing the compressor characteristic as a convex combination of a usual cubic polynomial and a nonpolynomial term carefully chosen so that an entire family of right-skew compressors can be spanned using a single parameter /spl epsiv/. We present bifurcation diagrams which show that our model matches experimental data well with a three-state Moore-Greitzer type ODE model.