El Aroudi, A.; Al-Numay, M.; Calvente, J.; Rodriguez, E.; Alarcon, E. International journal of electronics Vol. 103, num. 12, p. 2090-2109 DOI: 10.1080/00207217.2016.1178342 Data de publicació: 2016-12 Article en revista
New exact critical conditions for predicting subharmonic instability in switching regulators are approximated by simple design-oriented expressions valid under practical conditions. These simplified expressions contain the ripple and slope information of the feedback control signal. Depending on the converter topology, the controller used and values of parasitic parameters, either the slope or the ripple can be dominant in predicting instability. A discussion on the validity of this interpretation is illustrated through six different examples of switching regulators using the concept of the spectral radius and the relative degree of the system loop. Using this approach, the boundary between the desired stable region and the subharmonic instability can be easily obtained. The theoretical results are validated by means of numerical simulations.
Rodriguez, E.; Guinjoan, F.; Alarcon, E.; El Aroudi, A. IEEE transactions on circuits and systems I: regular papers Vol. 58, num. 1, p. 215-227 DOI: 10.1109/TCSI.2011.2161396 Data de publicació: 2011-12 Article en revista
This paper presents a design-oriented analytical approach for predicting fast-scale instability in power electronics converters under voltage-mode control strategy. This approach is based on the use of the ripple amplitude of the feedback control voltage as an index for predicting subharmonic oscillations in these systems. First, the work revisits the stability analysis technique based on the nonlinear discrete-time model, demonstrating that the ripple amplitude can be included within the expression of the Jacobian matrix of this model, hence giving a mathematical support to extend the ripple index to more complex topologies. A simple but representative buck converter under voltage-mode control is used to illustrate the approach. Using the ripple-based index, closed-form expressions of stability boundaries are derived. Unlike other available results obtained from existing methods, the stability boundary, in this work is expressed analytically in terms of both power stage and controller design parameters. Moreover, one can determine how these parameters are involved in the closed form expressions and, furthermore, how each parameter affects the stability of the system. The approach is validated by numerical simulations from the state equations and also experimentally within a wide range of the design parameter space.
El Aroudi, A.; Rodriguez, E.; Orabi, M.; Alarcon, E. International journal of circuit theory and applications Vol. 39, num. 2, p. 175-193 DOI: 10.1002/cta.627 Data de publicació: 2011-02 Article en revista
In this paper, the dynamical behavior of a full bridge DC–AC buck inverter controlled by fixed frequency and PWM is studied. After showing that the system can undergo both period-doubling and Neimark–Sacker bifurcation at the fast scale (switching period) by using the exact switching model, an exact solution discrete-time model able to predict both instability phenomena is derived. The model is obtained without making the quasi-static approximation and it can be used to obtain the useful operation region in the multi-dimensional design parameter space from time domain simulations in a very fast and accurate manner. Based on the study of the system, some design guidelines are provided.
El Aroudi, A.; Leyva, R.; Rodriguez, E.; Alarcon, E. IEEE transactions on circuits and systems II: express briefs Vol. 57, num. 3, p. 218-222 DOI: 10.1109/TCSII.2010.2041807 Data de publicació: 2010-03 Article en revista
El Aroudi, A.; Alarcon, E.; Rodriguez, E.; Leyva, R. COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering Vol. 29, num. 1, p. 90-108 DOI: 10.1108/03321641011007984 Data de publicació: 2010 Article en revista
Rodriguez, E.; Alarcon, E.; Iu, H.; El Aroudi, A. IEEE International Symposium on Circuits and Systems p. 2928-2931 DOI: 10.1109/ISCAS.2010.5538031 Data de presentació: 2010 Presentació treball a congrés
The purpose of this paper is the synthesis from the frequency domain standpoint of a controller for switching power converters with the aim to eliminate bifurcation and chaotic behavior. Firstly the paper analyzes the frequency response of previous delay-based chaos controllers unveiling that they are based in comb-filtering at multiples of the sub-harmonic half of the switching frequency. Secondly, chaos control is explored by using both a single notch filter and a bandstop filter at half of the switching frequency. It is demonstrated that the latter achieves chaos rejection while being an implementation-aware simplification of delay-based methods.
In this paper a simplified model based on the exact discrete-time map of a buck switching power converter with proportional control, which captures all its dynamics, allows deriving a closed-form stability condition for predicting fast-scale
instability boundary. This condition analytically demonstrates the validity of the recently proposed ripple-based index to
predict fast-scale period-doubling, hitherto based on an a priori hypothesis and simulation validation, thereby demonstrating the use of the ripple index as a design-oriented tool. The equivalence of the ripple index to the condition derived from the discrete-time map endorses its use as a means to characterize the complete design space against fast-scale instabilities.