Teixeira singularities in 3D switched feedback control systems

Abstract: This paper is concerned with the analysis of a singularity that can occur in threedimensional discontinuous feedback control systems. The singularity is the two-fold – a tangency of orbits to both sides of a switching manifold. Particular attention is placed on the Teixeira singularity, which previous literature suggests as a mechanism for dynamical transitions in this class of systems. We show that such a singularity cannot occur in classical single-input single-output systems in the Lur’e form. It is, however, a potentially dangerous phenomenon in multiple-input multiple-output switched control systems.The theoretical derivation is illustrated by means of a representative example

Bifurcation Boundary Conditions for Switching DC-DC Converters Under Constant On-Time Control

Sampled-data analysis and harmonic balance analysis are applied to analyze switching DC-DC converters under constant on-time control. Design-oriented boundary conditions for the period-doubling bifurcation and the saddle-node bifurcation are derived. The required ramp slope to avoid the bifurcations and the assigned pole locations associated with the ramp are also derived. The derived boundary conditions are more general and accurate than those recently obtained. Those recently obtained boundary conditions become special cases under the general modeling approach presented in this paper. Different analyses give different perspectives on the system dynamics and complement each other. Under the sampled-data analysis, the boundary conditions are expressed in terms of signal slopes and the ramp slope. Under the harmonic balance analysis, the boundary conditions are expressed in terms of signal harmonics. The derived boundary conditions are useful for a designer to design a converter to avoid the occurrence of the period-doubling bifurcation and the saddle-node bifurcation.Comment: Submitted to International Journal of Circuit Theory and Applications on August 10, 2011; Manuscript ID: CTA-11-016

Stick-slip oscillations in resonant power converters

The paper presents evidence of the existence of stick-slip oscillations, usually found in mechanical systems with friction, in a class of resonant power converters. It is shown that these converters can exhibit periodic solutions characterized by segments of sliding motion (associated to theoretically infinitely many switchings). Also, numerical and analytical evidence of the occurrence of sliding bifurcations is given. These phenomena have recently been presented in the literature and the paper reports their occurrence in power electronics for the first time

Nonlinear development of matrix-converter instabilities

Matrix converters convert a three-phase alternating-current power supply to a power supply of a different peak voltage and frequency, and are an emerging technology in a wide variety of applications. However, they are susceptible to an instability, whose behaviour is examined herein. The desired “steady-state” mode of operation of the matrix converter becomes unstable in a Hopf bifurcation as the output/input voltage transfer ratio, q, is increased through some threshold value, qc. Through weakly nonlinear analysis and direct numerical simulation of an averaged model, we show that this bifurcation is subcritical for typical parameter values, leading to hysteresis in the transition to the oscillatory state: there may thus be undesirable large-amplitude oscillations in the output voltages even when q is below the linear stability threshold value qc

Two-fold singularity in nonsmooth electrical systems

This paper reviews some recent results on the analysis of a little known phenomenon in PWS systems: two-fold singularities. Such singularities were shown to be present in Filippov systems when the boundaries of the sliding region intersect transversally. After briefly describing a two-fold singularity and its associated dynamics into a generic Filippov vector field, we present its occurrence in two representative nonsmooth electrical systems