Topic
Describing function
About: Describing function is a research topic. Over the lifetime, 1742 publications have been published within this topic receiving 26702 citations.
Papers published on a yearly basis
Papers
More filters
01 Jan 2005
TL;DR: In this article, an extension to Higher Order Describing Functions is realized by introducing the concept of the harmonics generator, which relates the magnitude and phase of the higher harmonics of the periodic response of the system to the magnitude of a sinusoidal excitation.
Abstract: For high precision motion systems, modeling and control design specifically oriented at friction effects is instrumental. The Sinusoidal Input Describing Function theory represents an approximative mathematical framework for analyzing nonlinear system behavior. This theory however limits the description of the nonlinear system behavior to a quasi linear amplitude dependent relation between sinusoidal excitation and sinusoidal response. In this paper an extension to Higher Order Describing Functions is realized by introducing the concept of the harmonics generator. The resulting Higher Order Sinusoidal Input Describing Functions (HOSIDFs) relate the magnitude and phase of the higher harmonics of the periodic response of the system to the magnitude and phase of a sinusoidal excitation. Based on this extension two techniques to measure HOSIDFs are presented. The first technique is FFT based. The second technique is based on IQ (inphase/quadrature-phase) demodulation. In a simulation the measurement techniques have been tested by comparing the simulation results to analytically derived results from a known (backlash) non-linearity. In a subsequent practical case study both techniques are used to measure the changes in dynamic behavior as function of drive level due to friction in an electric motor. Both methodes prove successful for measuring HOSIDFs.
Patent•
11 Sep 2018
TL;DR: In this paper, a cascade DC-DC converter stability analysis method based on a describing function method is proposed to determine the critical stable state of a converter system and effectively improve the accuracy of judgment results.
Abstract: The invention discloses a cascade DC-DC converter stability analysis method based on a describing function method The cascade DC-DC converter stability analysis method includes the following steps: performing linear modeling on a linear part in a single-stage DC-DC converter in a cascade system through a small signal modeling method to obtain a first linear transfer function; performing nonlinear modeling on a switch link of the DC-DC converter through a describing function method to obtain a describing function; performing equivalent processing on a source converter through a converter equivalent method to obtain a second linear transfer function, and determining the stability range of a two-stage cascade DC-DC converter according to a relation between the second linear transfer function and the describing function; and performing equivalent processing on a load converter through the converter equivalent method to obtain a third linear transfer function, and determining the stability range of the two-stage cascade DC-DC converter according to a relation between the third linear transfer function and the describing function The method of the invention can accurately determine the critical stable state of a converter system and effectively improve the accuracy of judgment results