An Adaptive Control for Rotating Stall and Surge of Jet Engines - A Function Approximation Approach

Compressor instabilities such as surge and rotating stall are highly unwanted phenomena in operation of jet engines. This is because these two instabilities reduce the performance and cause damage to aircraft engines. In this study, we design a model reference adaptive controller based on the function approximation technique to stabilize these two instabilities. Based upon this scheme, the controller parameters neither are restricted to be constant nor the bounds should be available a priori. The functions of the controller parameters are assumed to be piecewise continuous and satisfy the Dirichlet’s conditions. Furthermore expressing these controller parameters in a finite-term Fourier series, they can be estimated by updating the corresponding Fourier coefficients. A Lyapunov stability approach is implemented to provide the update laws for the estimation of those time-invariant coefficients and guarantees the output error convergence. Therefore, the adaptive controller requires less model information and maintains consistent performance for the system when some controller parameters are disturbed.