Papers by javier sebastian reyes muñoz
2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), 2018
In this work a study of a 27-level asymmetric multilevel current source inverter is developed. Th... more In this work a study of a 27-level asymmetric multilevel current source inverter is developed. The presented structure is composed by three current source inverters that together are in a 9:3:1 ratio to produce a current waveform with multiple levels. A model predictive control scheme is developed for tracking the references for the output AC voltages, and to keep the asymmetric ratio between the DC currents even during transient conditions. Furthermore, an extra control goal is included in order to reduce the commutations of the inverter, and therefore reduce the power losses. In order to apply the predictive controller, the equations of the model to be analyzed are obtained systematically for continuous and discrete time domains. Simulations are carried out to validate the proposal and the integrity of the predictive control strategy.
Energies, 2021
Several control strategies have been proposed with the aim to get a desired behavior in the power... more Several control strategies have been proposed with the aim to get a desired behavior in the power converter variables. The most employed control techniques are linear control, nonlinear control based on linear and nonlinear feedback, and predictive control. The controllers associated with linear and nonlinear algorithms usually have a fixed switching frequency, featuring a defined spectrum given by the pulse width modulation (PWM) or space vector modulation (SVM) time period. On the other hand, finite set model predictive control (FS-MPC) is known to present a variable switching frequency that results too high for high power applications, increasing losses, reducing the switches lifetime and, therefore, limiting its application. This paper proposes a predictive control approach using a very low sampling frequency, allowing the use of predictive control in high power applications. The proposed method is straightforward to understand, is simple to implement, and can be computed with o...
2017 IEEE Southern Power Electronics Conference (SPEC), 2017
In this paper a 7-Level Asymmetric Multilevel Current Source Inverter is presented. The topology ... more In this paper a 7-Level Asymmetric Multilevel Current Source Inverter is presented. The topology considers two Current Source Inverters that follow a 1:2 ratio to generate the multilevel current waveform. A Model Predictive Control is used to track the internal current and voltage references as well as to keep the asymmetric ratio between the DC currents even during transient conditions. To properly use the predictive algorithm, the modelling equations of the presented topology are systematically obtained in continuous and discrete time domains, considering the characteristic constraints of a Current Source Inverter. Simulated dynamic tests are presented in order to prove the feasibility of the asymmetric approach and the properness of the predictive control technique.
Energies, 2021
Power converters have turned into a critical and every-day solution for electric power systems. I... more Power converters have turned into a critical and every-day solution for electric power systems. In fact, the incorporation of renewable energies has led towards the constant improvement of power converter topologies and their controls. In this context, over the last 10 years, model predictive control (MPC) is positioned as one the most studied and promising alternatives for power converter control. In voltage source inverters (VSI), MPC has only been applied in the inner current control loop, accelerating and improving its dynamic response, but as mentioned, has been limited only to the current control loop. The fastest of the MPC techniques is the Deadbeat (DB) control, and in this paper, it is proposed to employ DB control on the entire system, therefore accelerating the time response not only for the current loops, but also for voltage loops. At the same time, this avoids overshoots and overpower in order to protect the power converter, leading to the fastest dynamic response acc...
2019 IEEE CHILEAN Conference on Electrical, Electronics Engineering, Information and Communication Technologies (CHILECON), 2019
The single-phase matrix converter is an AC-AC power topology which consists of six bidirectional ... more The single-phase matrix converter is an AC-AC power topology which consists of six bidirectional switches and it is considered the key unit in cascade or multilevel configurations. In this paper, a comparison between two control techniques is presented, one based on a proportional-integral-derivative control module with a pulse width modulator, and the other known as finite-state model predictive control. Simulation and experimental results are presented and discussed to demonstrate the feasibility and performance of both techniques.
Cancers, 2021
Simple Summary Liver resection is the best treatment for liver tumors; its clinical applicability... more Simple Summary Liver resection is the best treatment for liver tumors; its clinical applicability, however, is limited by the mass and quality of the remnant liver. In this study, hepatic resections were performed in a pig model to define changes associated with sufficient and insufficient liver remnants. As well, somatostatin, a naturally occurring peptide hormone that exerts numerous largely inhibitory effects, was given in order to improve outcomes. We observed that extended major hepatectomy is associated with immediate changes in portal pressure leading to injury, stellate cell activation, collagen deposition, and cell death, all of which were improved with somatostatin therapy. This is one of few studies (potentially the first) describing collagen deposition as early as 24 h after extended major hepatectomy and implicating liver resection as potential cause for chronic liver injury. Abstract Liver resection treats primary and secondary liver tumors, though clinical applicabili...
We present a new task in educational NLP, recommend the best interventions to help special needs ... more We present a new task in educational NLP, recommend the best interventions to help special needs education professionals to work with students with different disabilities. We use the professionals’ observations of the students together with the students diagnosis and other chosen interventions to predict the best interventions for Chilean special needs students.
2018 IEEE International Conference on Electrical Systems for Aircraft, Railway, Ship Propulsion and Road Vehicles & International Transportation Electrification Conference (ESARS-ITEC), 2018
Predictive control has risen as a plausible option in the control of power converters for photovo... more Predictive control has risen as a plausible option in the control of power converters for photovoltaic utilisation. In this work, a predictive control scheme is proposed to obtain the maximum power point in a photovoltaic array coupled directly to a grid-connected DC/AC power converter. The architecture considered avoids the use of the DC/DC stage, reducing the losses related to the inclusion of the boost stage. The introduced control strategy is proved by simulations in Matlab&Simulink, demonstrating flexibility to include the non-linear behaviour of the system and satisfying performance in terms of DC voltage and AC current control.
A combinatorial design is equivalent to a stable set in a suitably chosen Johnson graph, whose ve... more A combinatorial design is equivalent to a stable set in a suitably chosen Johnson graph, whose vertices correspond to all k-sets that could be blocks of the design. In order to find maximum stable sets of a graph G, two ideals are associated with G, one constructed from the Motzkin-Strauss formula and one reported by Lovász in connection with the stability polytope. These ideals are shown to coincide and form the stability ideal of G. Graph stability ideals belong to a class of 0-1 ideals. These ideals are shown to be radical, and therefore have a strong structure. Stability ideals of Johnson graphs provide an algebraic characterization that can be used to generate Steiner triple systems. Two different ideals for the generation of Steiner triple systems, and a third for Kirkman triple systems, are developed. The last of these combines stability and colorings. 2010 Mathematics Subject Classification: 05B07,13P10.
Sustainability, 2021
The high increase of renewable energy sources and the increment of distributed generation in the ... more The high increase of renewable energy sources and the increment of distributed generation in the electrical grid has made them complex and of variable parameters, causing potential stability problems to the PI controllers. In this document, a control strategy for power injection to the electrical system from photovoltaic plants through a voltage source inverter two-level-type (VSI-2L) converter is proposed. The algorithm combines a current-based maximum power point-tracking (Current-Based MPPT) with model predictive control (MPC) strategy, allowing avoidance of the use of PI controllers and lowering of the dependence of high-capacitive value condensers. The sections of this paper describe the parts of the system, control algorithms, and simulated and experimental results that allow observation of the behavior of the proposed strategy.
Sustainability, 2020
This article proposes a 27-level asymmetric cascade H-bridge multilevel topology for photovoltaic... more This article proposes a 27-level asymmetric cascade H-bridge multilevel topology for photovoltaic applications, which considers a predictive control strategy that allows minimization of the commutations of the converter. This proposal ensures a highly sinusoidal and stable photovoltaic injection when there are solar irradiance disturbances, generating a low distortion in the current waveform and low switching losses. To validate the performance of the control and the proposed topology, the dynamic model of the alternating current (AC) and direct current (DC) side system is first obtained, which is checked by computational simulations. Subsequently, the implementation of a master–slave control is carried out, focused on the control of DC voltage and AC current. The proposal is simulated, and the total harmonic distortion (THD) is obtained in the voltage and current waveforms. Undesired commutations, typical of the predictive control, are eliminated in the AC voltage waveform, and a p...
Sensors, 2021
High-order switched DC-DC converters, such as SEPIC, Ćuk and Zeta, are classic energy processing ... more High-order switched DC-DC converters, such as SEPIC, Ćuk and Zeta, are classic energy processing elements, which can be used in a wide variety of applications due to their capacity to step-up and/or step-down voltage characteristic. In this paper, a novel methodology for analyzing the previous converters operating in discontinuous conduction mode (DCM) is applied to obtain full-order dynamic models. The analysis is based on the fact that inductor currents have three differentiated operating sub-intervals characterized by a third one in which both currents become equal, which implies that the current flowing through the diode is zero (DCM). Under a small voltage ripple hypothesis, the currents of all three converters have similar current piecewise linear shapes that allow us to use a graphical method based on the triangular shape of the diode current to obtain the respective non-linear average models. The models’ linearization around their steady-state operating points yields full-or...
Electronics, 2021
This paper presents an optimal design of a surface-based polynomial fitting for tracking the maxi... more This paper presents an optimal design of a surface-based polynomial fitting for tracking the maximum power point (MPPT) of a photovoltaic (PV) system, here named surface-based polynomial fitting (MPPT-SPF). The procedure of the proposed MPPT-SPF strategy is based on a polynomial model to characterize data from the PV module with a global fit. The advantage of using polynomials is that they provide a good fit within a predefined data range even though they can diverge greatly from that range. The MPPT-SPF strategy is integrated with a DC-DC boost converter to verify its performance and its interaction with different control loops. Therefore, the MPPT strategy is applied to the reference outer PI control loop, which in turn provides the current reference to the inner current loop based on a discrete-time sliding current control. A real-time and high-speed simulator (PLECS RT Box 1) and a digital signal controller (DSC) are used to implement the hardware-in-the-loop system to obtain th...
Energies, 2020
Microgrids need control and management at different levels to allow the inclusion of renewable en... more Microgrids need control and management at different levels to allow the inclusion of renewable energy sources. In this paper, a comprehensive literature review is presented to analyse the latest trends in research and development referring to the applications of predictive control in microgrids. As a result of this review, it was found that the application of predictive control techniques on microgrids is performed for the three control levels and with adaptations of the models in order to include uncertainties to improve their performance and dynamics response. In addition, to ensure system stability, but also, at higher control levels, coordinated operation among the microgrid’s components and synchronised and optimised operation with utility grids and electric power markets. Predictive control appears as a very promising control scheme with several advantages for microgrid applications of different control levels.
Sensors, 2021
The use of renewable energies sources is taking great importance due to the high demand for elect... more The use of renewable energies sources is taking great importance due to the high demand for electricity and the decrease in the use of fossil fuels worldwide. In this context, electricity generation through photovoltaic panels is gaining a lot of interest due to the reduction in installation costs and the rapid advance of the development of new technologies. To minimize or reduce the negative impact of partial shading or mismatches of photovoltaic panels, many researchers have proposed four configurations that depend on the power ranges and the application. The microinverter is a promising solution in photovoltaic systems, due to its high efficiency of Maximum Power Point Tracking and high flexibility. However, there are several challenges to improve microinverter’s reliability and conversion efficiency that depend on the proper control design and the power converter design. This paper presents a review of different control strategies in microinverters for different applications. Th...
Sustainability, 2020
Complex control structures are required for the operation of photovoltaic electrical energy syste... more Complex control structures are required for the operation of photovoltaic electrical energy systems. In this paper, a general review of the controllers used for photovoltaic systems is presented. This review is based on the most recent papers presented in the literature. The control architectures considered are complex hybrid systems that combine classical and modern techniques, such as artificial intelligence and statistical models. The main contribution of this paper is the synthesis of a generalized control structure and the identification of the latest trends. The main findings are summarized in the development of increasingly robust controllers for operation with improved efficiency, power quality, stability, safety, and economics.
Journal of Emergency and Critical Care Medicine, 2018
Background: Primary decompressive craniectomy (DC) is increasingly used in certain neurosurgical ... more Background: Primary decompressive craniectomy (DC) is increasingly used in certain neurosurgical pathologies. We have performed a systematic review and meta-analysis to study the results in terms of quality of life (QOL) and survival at 1 year of follow-up of patients undergoing this treatment. Methods: Meta-analysis of randomized controlled trials, cohort and case-control studies. Results: Fifteen studies (1,603 patients) were included (9 ischemic stroke, 3 trauma brain injury, 3 subarachnoid hemorrhage, none cerebral hemorrhage). None of the studies used specific QOL assessments. Eleven studies reported modified Rankin Scale and 4 Extended Glasgow Outcome Scale. DC reduces mortality or vegetative state (OR 0.21; 95% CI, 0.14-0.32) and the combined goal of mortality or moderate-severe disability (OR 0.35; 95% CI, 0.21-0.58) at 12 months in a malignant stroke of the middle cerebral artery (MCA). Patients ≤60 years, with infarctions ≥50% of MCA territory, without contralateral involvement, Glasgow Coma Score ≥6 and without bilateral fixed mydriasis, should be considered for early DC. However, international records indicate that a different population is being treated with DC. Those beneficial effects cannot be demonstrated in the other studied pathologies. As rule, the medical protocols do not include monitoring of oxygenation of brain tissue, cerebral microdialysis or electroencephalogram (EEG)-derived parameters. Conclusions: The only clear current indication refers to certain select cases of malignant MCA infarction. Future studies should incorporate the evaluation of QOL, the institutional coverage and rehabilitation services, economic analysis, and impact of modern neuromonitoring techniques. Also, it seems that we should ensure that real clinical indications conform to those evaluated in clinical trials.
IECON 2016 - 42nd Annual Conference of the IEEE Industrial Electronics Society, 2016
The version presented here may differ from the published version or from the version of record. I... more The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.
2016 IEEE 17th Workshop on Control and Modeling for Power Electronics (COMPEL), 2016
The version presented here may differ from the published version or from the version of record. I... more The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.
IEEE EDUCON 2010 Conference, 2010
This paper describes the design and implementation of a virtual laboratory for photovoltaic power... more This paper describes the design and implementation of a virtual laboratory for photovoltaic power systems based on the Cadence PSpice circuit simulator, which is intended to be a complement to the traditional physical laboratory in undergraduate photovoltaic engineering courses.
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Papers by javier sebastian reyes muñoz