OBSERVER OF FLUX LINKAGE OF ROTOR WITH CIRCUIT PARAMETRIC FEEDBACK

In vector control systems for squirrel-cage induction machines, rotor flux linkage reference vector observers are widely used. Observers can be open-ended but then they become sensitive to changes in their internal parameters and their accuracy in determining the coordinates of the flux linkage reference vector decreases. The greatest sensitivity of the rotor flux linkage observer is to changes in the active resistance of the rotor phases. In this case to increase the accuracy of flux linkage vector identification closed observers are synthesized, introduce various feedbacks. You can use feedback signals based on deviations of the calculated current values ​​from their measured values. Relations for the choice of signs and values ​​of feedback coefficients are obtained based on Lyapunov’s second theorem on motion stability. In this way parametric disturbances in an asynchronous machine are compensated by adding coordinate feedback. We can use a different approach. Determine the parameters most susceptible to change and synthesize parametric feedback loops designed to identify these parameters during operation of the electric drive. This article uses exactly this approach. The sum of squared deviations of currents or their degrees is taken as the objective function. To close the feedback you need to calculate the gradient of the objective function over the parameter and apply it to the input of a standard controller. In this case the output of the controller will be the parameter estimation value which is used to calculate the gains and time constants of the flux linkage observer. To calculate the gradient over a parameter the values ​​of the sensitivity functions are required which are found as a result of solving the differential equations of the sensitivity model in real time. All specified elements of an analytical self-tuning system that create parametric feedback are presented in the article. The performance of the control system and the increase in its accuracy using a closed-loop rotor flux linkage observer have been proven by mathematical modeling.