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چكيده انگليسي :

The Application of Semistability Theory in Adaptive Notch Filter Ahmadreza Jenabzadeh a jenabzadeh@ec iut ac ir Date of Submission 2013 06 01 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Mohsen Mojiri mohsen mojiri@cc iut ac ir Abstract Frequency estimation is one of the fundamental issue in systems theory and signal processing and has applications in different areas of electrical engineering such as control and system identification biomedical engineering control and power system protection communication and radar In the recent decade researchers have focused on an algorithm of frequency estimation of sinusoidal signals based on notch filtering NF This algorithem which is called multi adaptive NF ANF has been composed of N subfilters signals For this structure three types of stability in cases N K N K N K can be investigated In the in parallel each subfilter estimate one of the component of a quasi periodic signal including K sinusoid case of N K frequencies of quasi periodic signal are isolated equilibrium points of multi ANF and exponential stability of these equilibrium points are investigated and proved In the case of N K multi ANF has a continuum of equilibrium points In this case the concept of semistability has been used and proved that the estimated frequencies of K subfilters converge to frequencies of quasi periodic signal and the after a relatively long time In the case of N K estimated frequencies have bias and variance and ultimate estimated frequency of N K subfilters change slowly and converge to the nearest input signal frequencies boundedness of estimated values under periodic disturbance is investigated Especially when N 1 and the sinusoidal signal is accompanied by undesirable signals has more practical significance These undesirable signals can be harmonic or nonharmonic components of the sinusoidal signal white and colored noise In this thesis besides introducing multi ANF and studing its characteristics the previously mentioned cases for multi ANF are investigated To improve ANF performance in the presence of undesirable signals approachs have been offered The most important approach offered in this thesis is using window function in the frequency estimation loop of ANF The background of using window function goes back to the discrete Fourier transform DFT and its modified forms which improves this algorithm in signal processing The investigations in this thesis shows that window function has favorable effects on estimation of sinusoidal signal parameters by ANF in the presence of undesirable components Keywords Frequency estimation Adaptive notch filter Semistability Ultimate boundedness Harmonics Window function

جناب زاده، احمدرضا

كاربرد نظريه شبه پايداري در فيلتر شكاف دار وفقي

تخمين فركانس , كرانداري نهايي , هارمونيكها , تابع پنجره