ADAPTIVE FREQUENCY OBSERVERS FOR TWO-PHASE AND SINGLE-PHASE HARMONIC SIGNALS

An adaptive observer for frequency and magnitude of two-phase symmetrical sinusoidal signal is presented. It is de-signed based on control concept of internal model approach. The observer guarantees global exponential estimation and high performance. If the information about one of the two-phase signal components is missing, a modified structure of the observer is proposed. This case is equivalent to the measurement of a single-phase sinusoidal signal. The proper-ties of local exponential stability of single-phase signal observer are proved using Lyapunov’s conversion theorem for disturbed systems. The robustness of the two-phase signal observer with respect to additive disturbances (high-frequency noise, varying frequency) is confirmed by simulation results. It is shown that the observer estimation speed can be arbitrarily increased by increasing the feedback gains. A method for single-phase harmonic signal frequency observer tuning is developed, which ensures the expansion of the stability region. References 14, figures 7.