Topic
Fundamental frequency
About: Fundamental frequency is a research topic. Over the lifetime, 8941 publications have been published within this topic receiving 131583 citations.
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01 Jun 2014
TL;DR: Six switching modes and their complements with opposite power transfer direction are defined with their operational constraints and the presented analysis provides a generalised theory for all phase shift based modulation techniques.
Abstract: Several papers have been published recently on TPS control of dual active bridge (DAB) converter, however, no complete study of the converter operation behaviour exists, that takes into account all switching modes in both charging and discharging (bidirectional) power transfer. In this paper, six switching modes and their complements with opposite power transfer direction are defined with their operational constraints. Exact expressions for power transferred are derived with no fundamental frequency assumptions and range of power transfer for each mode is also defined to characterize mode limitations. Detailed constraints for zero voltage switching (ZVS) are also obtained. A new definition for converter reactive power consumption is introduced. This is based on calculation of inductor apparent power which avoids fundamental frequency approximations as well as the vague negative (back flowing) power definitions in recent papers. All known DAB phase shift modulation techniques including conventional, dual and extended phase shift, represent special cases from triple phase shift, therefore the presented analysis provides a generalised theory for all phase shift based modulation techniques.
61 citations
TL;DR: In this article, a very simple polynomial expression which identically satisfies the boundary conditions is used to solve the title problem, and a variational formulation is then applied to generate an approximate but extremely accurate and simple frequency equation.
61 citations
TL;DR: Initial investigations suggest that the frequency of oscillations of the system is greater by approximately 30% for larger separations than for smaller separations and that the filaments appear to pass through a domain for which the oscillation is possibly quasi-periodic for intermediate values of the mutual separation.
61 citations
TL;DR: In this article, the frequency equation for radial vibrations of a poroelastic cylinder is derived in the form of a determinant involving Bessel functions, which gives the values of the characteristic circular frequency parameters of the first four modes for various geometries.
Abstract: Employing Biot's theory for wave propagation in a porous solid, the frequency equation for radial vibrations of a poroelastic cylinder is obtained. The frequency equation has been derived in the form of a determinant involving Bessel functions. The roots of the frequency equation give the values of the characteristic circular frequency parameters of the first four modes for various geometries. These roots, which correspond to various modes, are numerically calculated and presented graphically. The results indicate that the effects of porosity are very pronounced.
61 citations
TL;DR: In this article, a comb generator based on feeding a single dual-drive Mach-Zehnder modulator with a sinusoidal radio frequency (RF) at one arm and its double frequency at the other arm is demonstrated.
Abstract: A comb generator based on feeding a single dual drive Mach-Zehnder modulator with a sinusoidal radio frequency (RF) at one arm and its double frequency at the other arm is demonstrated. Our comb generator benefits from the superposition of optical subcarriers generated by the fundamental and its second harmonic. We demonstrate flexibility in center wavelength tunability, subcarrier spacing, and subcarrier count. For a fundamental frequency at, e.g., 6.25 GHz, our comb generator can produce 9, 5, 4, or 3 optical subcarriers with a spectral flatness of <; 1.2 dB. We successfully demonstrate to the best of our knowledge, the generation of the largest number of comblines requiring the lowest drive signal with the least components within the field of RF-generated combs.
61 citations