Topic
Fundamental frequency
About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.
Papers published on a yearly basis
Papers
More filters
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TL;DR: In this article, a hybrid active/passive topology and control strategy appropriate for removing harmonics caused by unbalanced nonlinear loads is investigated, where harmonic sequence components are used to detect both balanced and unbalanced components and reduce both harmonic components to zero.
Abstract: This paper investigates a hybrid active/passive topology and control strategy appropriate for removing harmonics caused by unbalanced nonlinear loads. Unbalanced loads such as railway traction loads may use static compensators to balance the fundamental frequency components. The harmonic currents produced by this combination are unlikely to be balanced. Purely passive structures are not sensitive to this harmonic imbalance, however some active structures are. Controllers aimed at balanced three phase loads using synchronous transformations will not remove all of the harmonic components. The controller presented in this paper uses harmonic sequence components to detect both balanced and unbalanced components and reduce both harmonic components to zero.
73 citations
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TL;DR: In this paper, the second harmonic response of a microwave distributed bandstop filter has been shown to have upper passband widths of up to six times the fundamental bandstop center frequency, due to the use of compound resonators having shorter electrical length.
Abstract: Previous microwave distributed bandstop filters have had their second harmonic response centered at no more than three times the fundamental bandstop mid-band frequency, due to the use of quarter-wave resonators. This limitation has now been removed by the use of compound resonators having shorter electrical length. Some configurations incorporate lumped capacitors, resulting in additional design degrees of freedom and wider passbands. The new theory has been developed to apply to both wide and narrow stopbands. Example filters having upper passband widths of up to six times the fundamental bandstop center frequency are presented
73 citations
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TL;DR: This article proposes a parameter identification method based on the high frequency (HF) equivalent impedance model of permanent magnet synchronous motor with HF signal injection at both the dq-axes, which identifies the resistance and the dQ-axis inductances offline and online, along with the flux linkage online.
Abstract: Existing online motor parameter identification methods mostly depend on the fundamental frequency voltage equations, which lead to the unsatisfactory identification effect at low current and low speed operation. This article proposes a parameter identification method based on the high frequency (HF) equivalent impedance model of permanent magnet synchronous motor with HF signal injection at both the dq -axes. This method identifies the resistance and the dq -axis inductances offline and online, along with the flux linkage online. In order to improve the identification accuracy, the parameter sensitivity analysis-based algorithm is proposed to detect the resistance and the flux linkage. Meanwhile, the inverter nonlinearities and the HF influence on parameter identification are compensated effectively. In order not to affect the normal operation of the motor drive, the selection of the amplitude, and the frequency of the injected signal is investigated. The proposed method is validated on a 2.2-kW motor and confirmed by finite element analysis. The experimental results show the good identification effect in different operation conditions.
73 citations
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TL;DR: In this book, an introduction to pitch estimation is given and a number of statistical methods for pitch estimation are presented, which include both single- and multi-pitch estimators based on statistical approaches, like maximum likelihood and maximum a posteriori methods.
Abstract: Periodic signals can be decomposed into sets of sinusoids having frequencies that are integer multiples of a fundamental frequency. The problem of finding such fundamental frequencies from noisy observations is important in many speech and audio applications, where it is commonly referred to as pitch estimation. These applications include analysis, compression, separation, enhancement, automatic transcription and many more. In this book, an introduction to pitch estimation is given and a number of statistical methods for pitch estimation are presented. The basic signal models and associated estimation theoretical bounds are introduced, and the properties of speech and audio signals are discussed and illustrated. The presented methods include both single- and multi-pitch estimators based on statistical approaches, like maximum likelihood and maximum a posteriori methods, filtering methods based on both static and optimal adaptive designs, and subspace methods based on the principles of subspace orthogonality and shift-invariance. The application of these methods to analysis of speech and audio signals is demonstrated using both real and synthetic signals, and their performance is assessed under various conditions and their properties discussed. Finally, the estimators are compared in terms of computational and statistical efficiency, generalizability and robustness. (Less)
72 citations
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TL;DR: In this article, an optimization study of sandwich structures with cellular cores for minimum noise radiation in a wide frequency band, subject to the constraints on the fundamental frequency and weight, is presented, where sensitivity functions of the radiated acoustic power are used to improve the computational time and accuracy in near optimization.
72 citations