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Describing function

About: Describing function is a research topic. Over the lifetime, 1742 publications have been published within this topic receiving 26702 citations.


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Journal ArticleDOI
TL;DR: The method of harmonic linearization and describing function method, numerical methods, and applied bifurcation theory together discover new opportunities for analysis of hidden periodic oscillations with basin of attraction which does not contain neighborhoods of equilibria as mentioned in this paper.
Abstract: The method of harmonic linearization and describing function method, numerical methods, and the applied bifurcation theory together discover new opportunities for analysis of hidden periodic oscillations (with basin of attraction which does not contain neighborhoods of equilibria) of control systems. In the present paper new algorithms for construction of counterexamples to Aizerman's conjecture and Kalman's conjecture is suggested.

66 citations

Journal ArticleDOI
TL;DR: In this article, a controllable semi-active squeeze film dampers (SFD) using magneto-rheological fluids is presented, which can suppress unbalanced vibrations in rotor systems, particularly supported by rolling element bearings.
Abstract: Conventional squeeze film dampers (SFDs) have shown their effectiveness in suppressing unbalanced vibrations in rotor systems, particularly supported by rolling element bearings. Recently, there is an increasing demand for 'controllable' SFDs to meet the need of modern rotating machinery, characterized by high operating speed and high load capacity. Thus, this paper presents a controllable semi-active SFD using magneto-rheological (MR) fluids, focusing on its design and modeling. It offers a comprehensive design method and an innovative experimental identification and modeling technique for MR-SFDs. The primary goal of the MR-SFD design is set to maximize its dynamic control bandwidth, and the design method includes the material selection, magnetic circuit analysis and sealing element design. After constructing a prototype MR-SFD based on the final design, this work investigated how some of the critical design parameters affect the performance of the MR-SFD (i.e. its dynamic control bandwidth change). Furthermore, it characterized the damper's dynamic behavior experimentally using a novel excitation method that adopts active magnetic bearing (AMB) units. Unlike conventional methods, the AMB system was able to precisely control the amplitude and frequency of the input excitation, enabling us to obtain the nonlinear dynamic stiffness properties of the MR-SFD with varying input current. In modeling the dynamic behavior of the MR-SFD, this study employed the describing function method. The describing function analysis effectively captured the nonlinear dynamic behavior of the MR-SFD.

65 citations

Journal ArticleDOI
24 Jun 1991
TL;DR: In this article, a simplified approach for determining the control-to-output linearized describing function of time-interval-modulated switched networks using time-varying system theory was proposed.
Abstract: An analysis method for determining the control-to-output linearized describing function of time-interval-modulated switched networks using time-varying system theory was previously proposed by the author. A simplification is now presented which eases the analysis considerably. Use of the simplified approach is demonstrated in the derivation of the control-to-output frequency response of pulse-width-modulated (PWM) DC-to-DC switching power converters operating in discontinuous conduction mode (DCM) and current programmed converters operating in continuous conduction mode (CCM) as well as in DCM. Experimental results are presented which verify the modeling approach. >

65 citations

Proceedings ArticleDOI
29 Jun 1994
TL;DR: In this article, the authors describe studies done at HP Labs on the actuator pivot bearing nonlinearity of a small disk drive and show how the swept-sine/describing function method was used to develop a nonlinear model of the pivot.
Abstract: This paper describes studies done at HP Labs on the actuator pivot bearing nonlinearity of a small disk drive. The nonlinear frictional behavior of the pivot bearing varies with actuator position, from drive to drive, and with time and temperature. This nonlinear behavior has made the traditional linear disk drive models inadequate. The paper shows how the swept-sine/describing function method was used to develop a nonlinear model of the pivot. This model departs from the classical friction models, but does a good job of matching laboratory frequency domain measurements.

65 citations

Proceedings ArticleDOI
04 Jun 2012
TL;DR: Based on the extended describing function concept, the small-signal model of an LLC resonant converter is derived in this paper, which is illustrated so that the corresponding frequency response can be easily obtained by using Is Spice simulation.
Abstract: Due to the advantages of low switching loss and high efficiency, LLC resonant converters have been widely used. Based on the extended describing function concept, the small-signal model of an LLC resonant converter is derived in this paper. The equivalent circuit of small-signal model is illustrated so that the corresponding frequency response can be easily obtained by using Is Spice simulation. The well agreement with experimental measurements has verified the accuracy of the derived small-signal model.

64 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202312
202230
202142
202057
201953
201847