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This paper presents the development and practical implementation of a four-switch buck-boost converter for variable input voltage. The circuit operates in buck or boost mode when the input values are higher or lower than the output. For voltages near the required level, the traditional buck-boost mode is replaced by modes A and B consisting in the combination of some periods working in buck mode with others working in boost mode. The sequence and duty cycle assignment of these transition modes are defined according to an approach based on steady-state analysis and discrete-time models. The digital system is completed by the addition of a voltage control loop that regulates the output under possible perturbations. Experimental results show that the proposed modes A and B present less ripple and appreciable less losses than the buck-boost counterpart. Thus, the prototype achieves efficiencies above 95% for all the input range and nominal load. Fil: Ceci, Martin Federico. Invap S. E.; Argentina Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentina

Population models are particularly helpful for understanding long-term changes in the weed dynamics associated with integrated weed management (IWM) strategies. IWM practices for controlling L. rigidum are of high importance, mainly due to its widespread resistance that precludes chemical control as a single management method. The objective of this contribution is to simulate different IWM scenarios with special emphasis on the impact of different levels of barley sowing densities on L. rigidum control. To this effect, a weed–crop population model for both L. rigidum and barley life cycles was developed. Our results point out: (i) the necessity of achieving high control efficiencies (>99%), (ii) that the increase of twice the standard sowing density of barley resulted in a reduction of 23.7% of the weed density, (iii) non-herbicide-based individual methods, such as delayed sowing and weed seed removal at harvest, proved to be inefficient for reducing drastically weed population, (iv) the implementation of at least three control tactics (seed removal, delay sowing and herbicides) is required for weed infestation eradication independently of the sowing rate, and (v) the effect of an increase in the sowing density is diluted as a more demanding weed control is reached. Future research should aim to disentangle the effect of different weed resistance levels on L. rigidum population dynamics and the required efficiencies for more sustainable IWM programs., This research was funded by Secretaría General de Ciencia y Tecnología de la Universidad Nacional del Sur, grant numbers PGI 24/K087 and 24/A225. J.L.G.-A. was supported by FEDER (European Regional Development Funds) and the Spanish Ministry of Science, Innovation and Universities funds (grant PID2019-103929RB-I00).

En este trabajo se presenta un convertidor boost alimentado con un panel fotovoltaico, operando en modo de conduccion critica (MCCr), mediante corriente programada, permitiendo el seguimiento del punto de maxima potencia (PMP). La accion de comando del convertidor modula de forma continua y natural la frecuencia de conmutacion en funcion de la potencia. A mayor radiacion solar menor es la frecuencia de conmutacion, teniendo como objetivo aumentar la eficiencia de conversion. A partir de la corriente de corto circuito del panel y midiendo su tension, se calcula la corriente de programacion para operar en MCCr y en PMP. Mediante simulacion se muestran los resultados para carga resistiva o con una bateria a la salida.

The large-signal averaged model of a coupled-inductor double-boost converter is developed and analysed in this paper. Due to the large current fluctuations, the differential system is deduced by averaging the circuit equations of the operation modes over a switching period. Generic expressions that permit to calculate the current commutation intervals as function of the averaged state variables are also found to complete the model. Resistive losses are introduced into an equivalent averaged circuit leading to a more realistic scenario. The proposed state-space model is used for studying voltage conversion ratios, transients and frequency-domain responses of the converter as well as for designing a control loop that regulates the output voltage. Numerical simulations and experimental measurements corroborate the obtained results., Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señales

Annual ryegrass is a weed species that produces considerable yield losses on winter crops around the world. The population-based model derived from the life-cycle of L. rigidum has demonstrated to be useful for predicting its dynamics and proposing alternative management strategies. The aim of this paper is to analyse the behaviour of ryegrass when a cancellation control law is implemented. The controlled system develops transcritical and period doubling bifurcations if parameters deviates from their exact values. The critical curves of these non linear phenomena define acceptable operation regions where the weed population could be eradicated or maintained at sufficiently low infestation levels.

An averaged state-space model of the coupled inductor double boost converter (C2B) operating in discontinuous conduction mode and without considering losses is presented in this paper. Differential equations depend on the time intervals lasted by the interchange of energy between the magnetic elements. Thus, expressions that permit to estimate those values as a function of the averaged states are proposed. A condition to determine the conduction mode of the circuit according to the load current and the duty cycle of the switch is also developed. Finally, transient and steady-state responses given by the model are compared to those obtained by simulating the converter.

This paper focuses on developing a small-signal model of a coupled-inductor boost converter. A circuital representation of the differential equations is also provided. The aim is to bring a tangible way of analyzing the influence of parameters like the coupling factor or the load on the behavior of the converter. Detailed numerical results complete the analytical study.

The response of a digital Zero Average Dynamics ZAD-controlled buck converter under the variation of its intrinsic parameters as well as the pulse-width modulation signal is studied in detail. The multiparameter analysis presented here leads to a complete knowledge of the different dynamical scenarios exhibited by the system. Numerical results indicate that the success of the ZAD-strategy is highly dependent on the parameter and pulse-width modulation PWM combinations. Experiments are included to validate the performance inside the so-called optimum region. Copyright © 2013 John Wiley & Sons, Ltd.

In this paper, the modeling and control of a flyback converter used to dim a LED array is presented. Feedback is designed based on the linearized version of the true averaged state-space model of the converter. The dynamics is analyzed for all operation range and then, the worst case is chosen. Since the driver is part of an integrated circuit, there exist limitations in the type of controller to be implemented and in the desired performance. Nevertheless, commercial specifications are fulfilled for all output current values. The performance of the closed-loop system is corroborated via numerical simulations.

Weed species present high competitive capacity, rapid adaptability and herbicide resistance, hindering their effective control across worldwide cropping regions. Since field-conducted experiments are very time-consuming and usually expensive, mathematical population-based models are valuable tools to test and develop long-term weed management programs. Within this context, the objective of this paper is to formalize analytically the possible seed bank dynamics of the Lolium rigidum, subjected to different control strategies. The first focus is on studying in detail the effects of integrating constant actions, promoting more environmentally and economically sustainable scenarios. From the same perspective, an alternative to applying time-variant programs is introduced. The proposed control guarantees that the weed population is sufficiently small or, alternatively, is kept below a given economic threshold level in a ten-year planning horizon. Furthermore, an optimization criterion is adopted for distributing necessary efficiency into diverse integrated options. Numerical simulations are included to illustrate the analytical findings. Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Calandrini, Guillermo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina. Universidad Nacional del Sur. Departamento de Matemática; Argentina Fil: Gonzáles-Andujar, José Luis. Instituto de Agricultura Sostenible; España Fil: Chantre Balacca, Guillermo Ruben. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina

The first period-doubling bifurcation of a dc–dc buck converter controlled by a zero-average dynamic strategy is studied in detail. Owing to the saturation of the duty cycle, this bifurcation is followed by a border-collision bifurcation, which is the main mechanism to introduce instability and chaos in the circuit. The multiparameter analysis presented here leads to a complete knowledge of the relatioship between these two bifurcations. The results are obtained by using a frequency-domain approach for the study of period-two oscillations in maps. Copyright © 2010 John Wiley & Sons, Ltd. (The ∞-norm of a matrix A is defined as ∥A∥ = maxij|aij|. In particular, |aij|⩽∥A∥ for all i and j.)

Analytical solutions of the period-four orbits exhibited by a classical family of n-dimensionalquadratic maps are presented. Exact expressions are obtained by applying harmonic balance and Grobner bases to a single-input single-output representation of the system. A detailed study of a generalized scalar quadratic map and a well-known delayed logistic model is included for illustration. In the former example, conditions for the existence of bistability phenomenon are also introduced. Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación En Ingeniería Eléctrica; Argentina Fil: Calandrini, Guillermo. Universidad Nacional del Sur. Departamento de Matemática; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Instituto de Investigación en Ingeniería Eléctrica; Argentina

This paper presents an averaged model for a coupled-inductor double-boost converter. Differential equations depend on the time intervals for which diodes are conducting simultaneously. Thus, expressions that permit to estimate those values as a function of the states of the circuit are also proposed. The response of the model is compared with that of the original converter via numerical simulations.

A frequency-analytic methodology for controlling the amplitudes and stability of Neimark-Sacker bifurcations exhibited by discrete-time systems is presented. The proposed controller consists of a nonlinear static feedback law and a highpass filter used to preserve the dynamical behaviors of the system's equilibria. A simple example is included to illustrate the application of the method.

A nonlinear digital controller for improving the dynamical behavior of a buck converter operating in discontinuous conduction mode is presented. The aim is the extension of the operating range of the circuit, ameliorating the appearance of period-two orbits when the resistive load or the source voltage are varied. The controlled system is analyzed by using a frequency-domain technique. Numerical and experimental results are included to illustrate the performance of the system.

A frequency domain methodology for the approximation of period doubling bifurcations in discrete-time nonlinear systems is presented. The computation of a stability index, which characterizes the dynamical behavior of the emerging period-two orbit is also derived. The technique is applied to estimate the domain of attraction of the fixed point in an adaptive control system and to improve the dynamical behavior of a buck converter.

The application of the graphical Hopf theorem (GHT) as a tool for detecting invariant cycles in maps is presented. The invariant cycle emerging from the bifurcation is approximated using an analogous version of the GHT for continuous-time systems. This technique is formulated in the so-called frequency domain and it involves the use of the Nyquist stability criterion and the harmonic balance method. Some examples are included for illustration. Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Moiola, Jorge Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

A new network data transmission strategy was proposed in Zhang \& Chen [2005] (arXiv:1405.2404), where the resulting nonlinear system was analyzed and the effectiveness of the transmission strategy was demonstrated via simulations. In this paper, we further generalize the results of Zhang \& Chen [2005] in the following ways: 1) Construct first-return maps of the nonlinear systems formulated in Zhang \& Chen [2005] and derive several existence conditions of periodic orbits and study their properties. 2) Formulate the new system as a hybrid system, which will ease the succeeding analysis. 3) Prove that this type of hybrid systems is not structurally stable based on phase transition which can be applied to higher-dimensional cases effortlessly. 4) Simulate a higher-dimensional model with emphasis on their rich dynamics. 5) Study a class of continuous-time hybrid systems as the counterparts of the discrete-time systems discussed above. 6) Propose new controller design methods based on this network data transmission strategy to improve the performance of each individual system and the whole network. We hope that this research and the problems posed here will rouse interests of researchers in such fields as control, dynamical systems and numerical analysis., 40 pages, 19 figures

This paper presents an alternative method for improving the transient response exhibited by a four-switch buck-boost converter during its mode transitions. The proposed algorithm permits to determinate the combination of buck and boost cycles that has to be implemented in modes A and B to reduce the overshot and overmodulation on the output voltage. The so-called α and β values are deduced by minimizing the mean-square error between the output voltage and the desired level. Nonlinear discrete-time models of buck and boost converters are used to predict the states of the circuit. Finally, three different options for assigning the duty cycles are considered. The performance of the converter is illustrated via numerical simulations.

This paper focuses on the dynamical response of the ZAD-controlled buck converter under the variation of the PWM structure. Numerical analysis shows that the system can exhibit supercritical and subcritical period-doubling bifurcations, depending on the parameter values. This indicates that the ZAD technique can be highly dependent on the PWM composition.

A novel method is presented for controlling the amplitudes and stability of orbits generated from Neimark-Sacker bifurcations in discrete-time systems. The technique es rooted in the frequency-domain approach for the study of bifurcations in maps. Fil: D'amico, Edith Maria Belen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Chen, Guanrong. City University Of Hong Kong; China Fil: Paolini, Eduardo Emilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina Fil: Moiola, Jorge Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; Argentina

[ES] En este trabajo se estudia el comportamiento dinámico de un convertidor dc-dc tipo buck operando en modo de conducción discontinua con control proporcional más integral. El propósito es detectar la aparición de oscilaciones ante variaciones de la resistencia de carga o la tensión de alimentación, empleando técnicas de análisis de bifurcaciones de doble período en el dominio de la frecuencia. La presentación incluye simulaciones computacionales y ensayos experimentales., [EN] The dynamical behavior of a buck converter operating in discontinuous conduction mode is studied in this paper. The aim is the detection of oscillations when the resistive load or the source voltage are varied, by using a frequency-domain approach for the analysis of period doubling bifurcations. The manuscript includes computational simulations and experimental results., Los autores agradecen a la SGCyT de la UNS, a la ANPCyT y al CONICET por el apoyo brindado para la realización de este trabajo.

The application of the Hopf bifurcation theorem (HBT) for maps is presented in this paper. The invariant cycle emerging from the bifurcation is approximated using an analogous version of the graphical Hopf theorem (GHT) for continuous-time systems. This technique is formulated in the so-called frequency domain and it involves the use of the Nyquist stability criterion for discrete-time systems. An application example is included for illustration.