Topic
Frequency response
About: Frequency response is a research topic. Over the lifetime, 25705 publications have been published within this topic receiving 332249 citations.
Papers published on a yearly basis
Papers
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TL;DR: In this article, a feedback control technique, known as integral resonant control (IRC), is proposed for damping vibrations in collocated flexible structures, and conditions for the stability of the proposed controller are derived, and shown that the set of stabilizing IRCs is convex.
Abstract: A transfer-function is said to be negative imaginary if the corresponding frequency response function has a negative definite imaginary part (on the positively increasing imaginary axis). Negative imaginary transfer-functions can be stabilized using negative imaginary feedback controllers. Flexible structures with compatible collocated sensor/actuator pairs have transfer-functions that are negative imaginary. In this paper a model structure that typically represents a collocated structure is considered. An identification algorithm which enforces the negative imaginary constraint is proposed for estimating the model parameters. A feedback control technique, known as integral resonant control (IRC), is proposed for damping vibrations in collocated flexible structures. Conditions for the stability of the proposed controller are derived, and shown that the set of stabilizing IRCs is convex. Finally, a flexible beam with two pairs of collocated piezoelectric actuators/sensors is considered. The proposed identification scheme is used determining the transfer-function and an IRC is designed for damping the vibrations. The experimental results obtained are reported.
136 citations
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TL;DR: In this paper, the Miller effect model was used to obtain the optimum phase margin condition for a two-pole op amp that is well approximated by a folded-cascode topology.
Abstract: The design considerations for fast-settling operational amplifiers (op amps) are significantly different between sampled-data switched-capacitor (SC) and conventional continuous-time applications. In SC circuits, the shape of the output voltage waveform of an op amp is of no consequence provided that the output settles to within a specified tolerance of its steady-state value prior to the next sampling instant. This feature allows for an optimum op amp frequency shaping to obtain a minimum small-signal settling time. The theory applies to any op amp that is well approximated by a two-pole model, including the conventional two-stage and single-stage folded-cascode topologies. As the commonly used equivalent-circuit Miller-effect model for frequency compensation has generally been improperly applied to two-stage transconductance amplifiers, it does not provide sufficient accuracy to achieve the optimum phase margin condition. Therefore, the use of equivalent-circuit models has been refined to provide greater accuracy and to eliminate some previous misconceptions. >
135 citations
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TL;DR: In this paper, a frequency domain approach was proposed to identify the Hammerstein model in the frequency domain using sampled input-output data, and its convergence was shown for both the linear and nonlinear subsystems in the presence of noise.
Abstract: Discusses Hammerstein model identification in the frequency domain using sampled input-output data. By exploring the fundamental frequency and harmonics generated by the unknown nonlinearity, we propose a frequency domain approach and show its convergence for both the linear and nonlinear subsystems in the presence of noise. No a priori knowledge of the structure of the nonlinearity is required and the linear part can be nonparametric.
135 citations
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01 Jun 1996TL;DR: A preconditioned recycled Krylov-subspace method to accelerate a recently developed approach for ac and noise analysis of linear periodically-varying communication circuits and is shown to be up to forty times faster than the standard optimized direct methods.
Abstract: In this paper we present a preconditioned recycled Krylov-subspace method to accelerate a recently developed approach for ac and noise analysis of linear periodically-varying communication circuits. Examples are given to show that the combined method can be used to analyse switching filter frequency response, mixer 1/f noise frequency translation, and amplifier intermodulation distortion. In addition, it is shown that for large circuits the preconditioned recycled Krylov-subspace method is up to forty times faster than the standard optimized direct methods.
135 citations
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TL;DR: In this paper, the frequency response capability of variable speed wind turbines is evaluated on a test system and the effectiveness of wind turbines' contribution to system inertial response is evaluated in the context of future system requirements.
Abstract: As wind penetration levels on power systems increase worldwide and synchronous generation is displaced, the dynamic characteristics of these systems, and hence the protocols for how they are operated, are changing One issue, of particular concern, is the resulting reduction in system inertia since modern variable speed wind turbines do not inherently contribute to the inertial response of the system Such devices can, however, be fitted with a control loop which provides an active power response to significant frequency deviations, similar to the inertial response of fixed speed wind turbines and synchronous generation Unlike conventional machines, however, the response of variable speed turbines is dependent on local wind speeds and so cannot be quantified deterministically by system operators As a result, it is likely that uncertainty will exist over the inertial response capability of the system at high wind penetration levels In this paper, the frequency response capability is assessed on a test system and the effectiveness of wind turbines' contribution to system inertial response is evaluated in the context of future system requirements
135 citations