Sequential model predictive control of three-phase direct matrix converter

© 2019 by the authors. The matrix converter (MC) is a promising converter that performs the direct AC-to-AC conversion. Model predictive control (MPC) is a simple and powerful tool for power electronic converters, including the MC. However, weighting factor design and heavy computational burden impose significant challenges for this control strategy. This paper investigates the generalized sequential MPC (SMPC) for a three-phase direct MC. In this control strategy, each control objective has an individual cost function and these cost functions are evaluated sequentially based on priority. The complex weighting factor design process is not required. Compared with the standard MPC, the computation burden is reduced because only the pre-selected switch states are evaluated in the second and subsequent sequential cost functions. In addition, the prediction model computation for the following cost functions is also reduced. Specifying the priority for control objectives can be achieved. A comparative study with traditional MPC is carried out both in simulation and an experiment. Comparable control performance to the traditional MPC is achieved. This controller is suitable for the MC because of the reduced computational burden. Simulation and experimental results verify the effectiveness of the proposed strategy

Investigation of Grid-Connected and Islanded Direct Matrix Converter for Renewable Microgrid Applications with Model Predictive Control

© 2018 IEEE. The direct matrix converter has been proposed for many potential applications. However, it remains unexplored within the context of microgrids and distributed generation. This paper investigates the application of the direct matrix converter to these areas. Both the grid-connected and islanded operation modes are explored. Model predictive control is employed to achieve flexible active and reactive power regulation in the grid-connected mode, and stable sinusoidal voltage control in the islanded mode. It is also used to achieve grid voltage synchronization prior to grid connection. Simulation and experimental results verify the feasibility and effectiveness of the direct matrix converter when used in grid-connected and islanded microgrids. When used in the matrix converter-connected microgrid, model predictive control is effective in regulating the voltage and the power exchange with the grid

Sequential model predictive control of direct matrix converter without weighting factors

© 2018 IEEE. The direct matrix converter (MC) is a promising converter that performs direct AC-to-AC conversion. Model predictive control (MPC) is a simple and powerful control strategy for power electronic converters including the MC. However, weighting factor design and heavy computational burden impose significant challenges for this control strategy. This paper investigates the sequential MPC (SMPC) for a three-phase direct MC. In this control strategy, each control objective has an individual cost function and these cost functions are evaluated sequentially based on priority. The complex weighting factor design process is not required and the computational burden can be reduced. In addition, specifying the priority for control objectives can be achieved. A comparative simulation study with standard MPC is carried out in Matlab/Simulink. Control performance is compared to the standard MPC and found to be comparable. Simulation results verify the effectiveness of the proposed strategy

Predictive Voltage Control of Direct Matrix Converters with Improved Output Voltage for Renewable Distributed Generation

© 2013 IEEE. This paper proposes a predictive voltage control strategy for a direct matrix converter used in a renewable energy distributed generation (DG) system. A direct matrix converter with LC filters is controlled in order to work as a stable voltage supply for loads. This is especially relevant for the stand-alone operation of a renewable DG where a stable sinusoidal voltage, with desired amplitude and frequency under various load conditions, is the main control objective. The model predictive control is employed to regulate the matrix converter so that it produces stable sinusoidal voltages for different loads. With predictive control, many other control objectives, e.g., input power factor, common-mode voltage, and switching frequency, can be achieved depending on the application. To reduce the number of required measurements and sensors, this paper utilizes observers and makes the use of the switch matrices. In addition, the voltage transfer ratio can be improved with the proposed strategy. The controller is tested under various conditions including intermittent disturbance, nonlinear loads, and unbalanced loads. The proposed controller is effective, simple, and easy to implement. The simulation and experimental results verify the effectiveness of the proposed scheme and control strategy. This proposed scheme can be potentially used in microgrid applications

AtUTr1, a UDP-glucose/UDP-galactose transporter from Arabidopsis thaliana, is located in the endoplasmic reticulum and up-regulated by the unfolded protein response

Indexación: Scopus.The folding of glycoproteins in the endoplasmic reticulum (ER) depends on a quality control mechanism mediated by the calnexin/calreticulin cycle. During this process, continuous glucose trimming and UDP-glucose-dependent re-glucosylation of unfolded glycoproteins takes place. To ensure proper folding, increases in misfolded proteins lead to up-regulation of the components involved in quality control through a process known as the unfolded protein response (UPR). Reglucosylation is catalyzed by the ER lumenal located enzyme UDP-glucose glycoprotein glucosyltransferase, but as UDP-glucose is synthesized in the cytosol, a UDP-glucose transporter is required in the calnexin/calreticulin cycle. Even though such a transporter has been hypothesized, no protein playing this role in the ER yet has been identified. Here we provide evidence that AtUTr1, a UDP-galactose/glucose transporter from Arabidopsis thaliana, responds to stimuli that trigger the UPR increasing its expression around 9-fold. The accumulation of AtUTr1 transcript is accompanied by an increase in the level of the AtUTr1 protein. Moreover, subcellular localization studies indicate that AtUTr1 is localized in the ER of plant cells. We reasoned that an impairment in AtUTr1 expression should perturb the calnexin/calreticulin cycle leading to an increase in misfolded protein and triggering the UPR. Toward that end, we analyzed an AtUTr1 insertional mutant and found an up-regulation of the ER chaperones BiP and calnexin, suggesting that these plants may be constitutively activating the UPR. Thus, we propose that in A. thaliana, AtUTr1 is the UDP-glucose transporter involved in quality control in the ER.https://www.jbc.org/article/S0021-9258(19)56445-6/fulltex

Novel loci and Mapuche genetic ancestry are associated with pubertal growth traits in Chilean boys

Puberty is a complex developmental process that varies considerably among individuals and populations. Genetic factors explain a large proportion of the variability of several pubertal traits. Recent genome-wide association studies (GWAS) have identified hundreds of variants involved in traits that result from body growth, like adult height. However, they do not capture many genetic loci involved in growth changes over distinct growth phases. Further, such GWAS have been mostly performed in Europeans, but it is unknown how these findings relate to other continental populations. In this study, we analyzed the genetic basis of three pubertal traits; namely, peak height velocity (PV), age at PV (APV) and height at APV (HAPV). We analyzed a cohort of 904 admixed Chilean children and adolescents with European and Mapuche Native American ancestries. Height was measured on roughly a 6−month basis from childhood to adolescence between 2006 and 2019. We predict that, in average, HAPV is 4.3 cm higher in European than in Mapuche adolescents (P = 0.042), and APV is 0.73 years later in European compared with Mapuche adolescents (P = 0.023). Further, by performing a GWAS on 774, 433 single-nucleotide polymorphisms, we identified a genetic signal harboring 3 linked variants significantly associated with PV in boys (P <5×10−8). This signal has never been associated with growth-related traits

Caracterizaci\uf3n del holoparasitismo de Orobanche ramosa en tomate bajo condiciones de campo

Field studies were conducted between 1999 and 2002, in Angol, Chile (37\ub045 ' S, 72\ub044 ' W) to determine the phenology of the system Orobanche ramosa \u2013 tomato ( Lycopersicon esculentum Mill.), to characterize the influence of holoparasitism on the growth and development of the host and the productive response at three planting dates (early, normal and delayed). The O. ramosa phenology includes underground and aerial phases, defining a total of six development stages: "a":: nodule; "b": nodule with initial crown roots; "c": shoot bud already visible; "d": shoot bud and crown root developed; "e": shoot development; and "f": shoot emerged from soil surface. The underground phase began with the establishment of the parasite, the first phenological event (stage "a":) being detected between 120 to 250 degree-days (DG), and the aerial phase (stage "f":) began when 550 DG of thermal requirements was surpassed. These phases occurred at flowering and fruit set of the host, respectively. The mean life cycle of the system O. ramosa - tomato was completed with 1,180 DG or 132 days after planting (DDT). Parasitism of O. ramosa altered morphological parameters and the distribution of dry matter in the host before the emergence of O. ramosa, the aerial components being most effected. It translated into important losses of production at the planting dates, which varied between 77 and 81%. Therefore, advancing or delaying the planting date does not constitute an efficient cultural practice for tomato fields to escape O. ramosa parasitism.Se realizaron estudios de campo entre 1999 y 2002, en Angol, Chile (37\ub045' lat. Sur, 72\ub044' long. Oeste) para determinar la fenolog\ueda del complejo orobanque-tomate ( Orobanche ramosa L.- Lycopersicon esculentum Mill.), caracterizar la influencia del holoparasitismo en el crecimiento y desarrollo del hospedero, y la respuesta productiva en tres \ue9pocas de plantaci\uf3n (temprana, normal y tard\ueda). La fenolog\ueda de O. ramosa comprende una fase subterr\ue1nea y otra a\ue9rea, defini\ue9ndose un total de seis estados de desarrollo: "a": n\uf3dulo; "b": n\uf3dulo con ra\uedz de escaso desarrollo; "c": aparici\uf3n de yema; "d": yema y ra\uedz desarrollada; "e": v\ue1stago desarrollado; y "f": v\ue1stago emergiendo sobre la superficie del suelo. La fase subterr\ue1nea se inici\uf3 con el establecimiento del fitopar\ue1sito, detect\ue1ndose el primer evento fenol\uf3gico (estado "a") entre 120 a 250 d\uedas grado (DG), y la fase a\ue9rea (estado "f") comenz\uf3 cuando se super\uf3 los 550 DG de requerimientos t\ue9rmicos. Dichas fases coincidieron con la floraci\uf3n y fructificaci\uf3n del hospedero, respectivamente. El ciclo de vida promedio de O. ramosa se complet\uf3 con 1.180 DG \uf3 132 d\uedas despu\ue9s del trasplante (DDT). El parasitismo alter\uf3 par\ue1metros morfol\uf3gicos y distribuci\uf3n de la materia seca en el hospedero antes de la emergencia de O. ramosa, siendo el componente a\ue9reo (follaje) el m\ue1s afectado. Ello se tradujo en importantes p\ue9rdidas de producci\uf3n en las \ue9pocas de plantaci\uf3n, las que variaron entre 77 y 81%. Por lo tanto, adelantar o retrasar la plantaci\uf3n de tomate no constituye una pr\ue1ctica cultural eficiente para escapar al efecto del parasitismo de O. ramosa

Mitochondrial phylogeography and demographic history of the Vicuña: implications for conservation

The vicuña (Vicugna vicugna; Miller, 1924) is a conservation success story, having recovered from near extinction in the 1960s to current population levels estimated at 275 000. However, lack of information about its demographic history and genetic diversity has limited both our understanding of its recovery and the development of science-based conservation measures. To examine the evolution and recent demographic history of the vicuña across its current range and to assess its genetic variation and population structure, we sequenced mitochondrial DNA from the control region (CR) for 261 individuals from 29 populations across Peru, Chile and Argentina. Our results suggest that populations currently designated as Vicugna vicugna vicugna and Vicugna vicugna mensalis comprise separate mitochondrial lineages. The current population distribution appears to be the result of a recent demographic expansion associated with the last major glacial event of the Pleistocene in the northern (18 to 22°S) dry Andes 14–12 000 years ago and the establishment of an extremely arid belt known as the 'Dry Diagonal' to 29°S. Within the Dry Diagonal, small populations of V. v. vicugna appear to have survived showing the genetic signature of demographic isolation, whereas to the north V. v. mensalis populations underwent a rapid demographic expansion before recent anthropogenic impacts