Stability of the solutions of the observation error equations at control of the steel converter process

Consideration was given to the nonlinear observer with the feedback sensitivity function which showed itself well in estimating the carbon and silicon content in the converter melt on the basis of the nonlinear model with time-constant parameters. In the case of controlling the melt temperature by the cooling additives, the plant parameters vary in time, which requires additional studies. For the estimation error under permanent perturbations where the matrix of the linear part is time-dependent, the zero solution of the equation system was proved to be stable.