Bifurcation Control of Rotating Stall with Actuator Magnitude and Rate Limits

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Yong Wang, Simon Yeung, Richard Murray
Automatica 38(4):597-610 and 611-625

Nonlinear qualitative analysis is performed on the Moore-Greitzer

 model to evaluate the tradeoff of fluid noise, actuator magnitude saturation, 
 bandwidth, rate limits, and the shape of compressor characteristics in active 
 control of rotating stall in axial compressors with bleed valve actuators. Model 
 order reduction is achieved by approximating the dynamics on the invariant manifold 
 that captures the bifurcations and instabilities. Bifurcations and qualitative 
 dynamics are obtained by analyzing the reduced system. The operability enhancement 
 is defined as the extension of operating range for which fully developed rotating 
 stall is avoided. Analytic formulas are derived for the operability enhancement 
 as a function of noise level, actuator saturation limits, and the shape of the 
 compressor characteristic, which is the major nonlinearity in the model. The 
 shape of the compressor characteristic, especially the unstable part, is critical 
 to the rate required for robust operability near the peak for the closed loop 
 system. Experiments are carried out on a single-stage low-speed axial compressor 
 using different level of steady air injections to generate different compressor 
 characteristics. The theoretical formulas give good qualitative estimates to 
 experimental data and simulations using a high fidelity model (37 states).