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Droplet Size Impact on Efficacy of a Dicamba-plus-Glyphosate Mixture

WEED TECHNOLOGY 2019年第1期33卷 66-74页

作者： Butts, Thomas R. Samples, Chase A. Franca, Lucas X. Dodds, Darrin M. Reynolds, Daniel B. Adams, Jason W. Zollinger, Richard K. Howatt, Kirk A. Fritz, Bradley K. Hoffmann, W. Clint Luck, Joe D. Kruger, Greg R. Univ Arkansas Syst Div Agr 2001 Highway 70 E Lonoke AR 72086 USA Univ Nebraska Lincoln Dept Agron & Hort 402 West State Farm Rd North Platte NE USA Mississippi State Univ Dept Plant & Soli Sci POB 9555 Mississippi State MS 39762 USA North Dakota State Univ Dept Plant Sci POB 6050 Fargo ND USA USDA ARS Aerial Applicat Technol Res Unit 3103 F&B Rd College Stn TX USA Univ Nebraska Dept Biol Syst Engn POB 830726 Lincoln NE USA

Chemical weed control remains a widely used component of integrated weed management strategies because of its cost-effectiveness and rapid removal of crop pests. Additionally, dicamba-plus-glyphosate mixtures are a commonly recommended herbicide combination to combat herbicide resistance, specifically in recently commercially released dicamba-tolerant soybean and cotton. However, increased spray drift concerns and antagonistic interactions require that the application process be optimized to maximize biological efficacy while minimizing environmental contamination potential. Field research was conducted in 2016, 2017, and 2018 across three locations (Mississippi, Nebraska, and North Dakota) for a total of six site-years. The objectives were to characterize the efficacy of a range of droplet sizes [150 mu m (Fine) to 900 mu m (Ultra Coarse)] using a dicamba-plus-glyphosate mixture and to create novel weed management recommendations utilizing pulse-width modulation (PWM) sprayer technology. Results across pooled site-years indicated that a droplet size of 395 mu m (Coarse) maximized weed mortality from a dicamba-plus-glyphosate mixture at 94 L ha(-1). However, droplet size could be increased to 620 mu m (Extremely Coarse) to maintain 90% of the maximum weed mortality while further mitigating particle drift potential. Although generalized droplet size recommendations could be created across site-years, optimum droplet sizes within each site-year varied considerably and may be dependent on weed species, geographic location, weather conditions, and herbicide resistance(s) present in the field. The precise, site-specific application of a dicamba-plus-glyphosate mixture using the results of this research will allow applicators to more effectively utilize PWM sprayers, reduce particle drift potential, maintain biological efficacy, and reduce the selection pressure for the evolution of herbicide-resistant weeds.

关键词： Kevin Bradley, University of Missouri Dicamba glyphosate Application optimization precision agriculture pulse-width modulation site-specific weed management weed control

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Adaptive neural networks for AC voltage sensorless control of three-phase PWM rectifiers

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INTERNATIONAL JOURNAL OF MODELLING IDENTIFICATION AND CONTROL 2019年第2期31卷 139-151页

作者： Rahoui, Adel Seddiki, Hamid Bechouche, Ali Abdeslam, Djaffar Ould Mouloud Mammeri Univ Lab L2CSP BP 17 RP Tizi Ouzou 15000 Algeria Univ Haute Alsace MIPS Lab 61 Rue Albert Camus F-68093 Mulhouse France

In this paper, a new adaptive grid voltages estimator for AC voltage sensorless control of three-phase pulse-width modulation (PWM) rectifier is proposed. This method is based on a simple adaptive neural network (ANN) to estimate online the grid voltages. Its main advantages are the simplicity and low computational cost requirements. The proposed ANN estimator is inserted in voltage-oriented control (VOC) to perform an AC voltage sensorless control scheme. As the start-up is a common problem in case of sensorless control, a new start-up process is also proposed for estimating initial values of the grid voltages. Experimental tests are carried out to verify the feasibility and robustness of the proposed ANN estimator. Obtained results show good performances of the proposed AC voltage sensorless control scheme in normal and severe grid voltage conditions.

关键词： adaptive neural network ANN adaptive neural filter ANF pulse-width modulation PWM rectifier diode rectifier grid voltages estimation voltage-oriented control VOC sensorless control start-up process experimental verification stability

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Real-Time Selective Harmonic Mitigation Technique for Power Converters Based on the Exchange Market Algorithm

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ENERGIES 2020年第7期13卷 1659-1659页

作者： Marquez, Abraham Leon, Jose I. Laguna, Marta Gonzalez-Rodriguez, Francisco Portillo, Ramon Zafra-Ratia, Eduardo Vazquez, Sergio Franquelo, Leopoldo G. Bayhan, Sertac Abu-Rub, Haitham Univ Seville Dept Elect Engn Seville 41004 Spain Harbin Inst Technol Dept Control Sci & Engn Harbin 150001 Peoples R China Qatar Environm & Energy Res Inst Doha Qatar Texas A&M Univ Qatar Doha Qatar

Hand-in-hand with the smart-grid paradigm development, power converters used in high-power applications are facing important challenges related to efficiency and power quality. To overcome these issues, the pre-programmed pulse-width modulation (PWM) methods have been extensively applied to reduce the harmonic distortion with very low power switching losses for high-power converters. Among the pre-programmed PWM techniques, Selective Harmonic Elimination (SHE) has been the prevailing solution, but recently, Selective Harmonic Mitigation (SHM) stands as a superior alternative to provide further control of the harmonic spectrum with similar losses. However, the large computational burden required by the SHM method to find a solution confines it as an off-line application, where the switching set valid solutions are pre-computed and stored in a memory. In this paper, for the first time, a real-time implementation of SHM using an off-the-shelf mid-range microcontroller is presented and tested. The Exchange Market Algorithm (EMA), initially focused on optimizing financial transactions, is considered and executed to achieve the SHM targets. The performance of the EMA-based SHM is presented showing experimental results considering a reduced number of switching angles applied to a specific three-level converter, but the method can be extrapolated to any other three-level converter topology.

关键词： power converters harmonic distortion pulse-width modulation metaheuristic search algorithms

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Heat Dissipation Balancing in a Switched Reluctance Drive by Combined Use of Active and Passive Thermal Control Methods 20

Heat Dissipation Balancing in a Switched Reluctance Drive by...

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20th International Symposium on Power Electronics (Ee)

作者： Anuchin, Alecksey Briz, Fernando Gulyaev, Igor Zharkov, Alexandr Gulyaeva, Maria Popova, Viktoriya Moscow Power Engn Inst Dept Elect Drives Moscow Russia Univ Oviedo Dept Elect Elect Comp & Syst Engn Gijon Spain Ogarev Mordova State Univ Elect & Nanoelect Dept Saransk Russia

ISBN: (纸本)9781728150673

Air-cooled heatsinks for electric drives often suffer from unbalances in the heat dissipation capability when several power modules are mounted on the same heatsink, eventually limiting the output power that dictated by the hottest module. This paper discusses the options for the placement of the power modules on the heatsink for the particular case of switched reluctance drives. Combined with active thermal control methods, this reduces the temperature dispersion, and therefore allows to increase the maximum output power of the converter.

关键词： active thermal control pulse-width modulation switching losses voltage source inverters switched reluctance drive

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Univariate equation-based SHE-PWM for multilevel inverter

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SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES 2019年第5期44卷 1-5页

作者： Kamani, Piyush L. Mulla, Mahmadasraf A. Sardar Vallabhbhai Natl Inst Technol Dept Elect Engn Surat 395009 India

This article presents a selective harmonic elimination-pulse-width modulation (SHE-PWM) method for cascaded H-bridge multilevel inverters. The concept of volt-second area balancing is applied to estimate the voltage ratings of the dc sources, which provides different voltage ratings of each dc source. The control of output voltage is achieved by varying switching notch created at the centre of each level. This method calculates switching angles in real time easily owing to the usage of univariate equations. A comparison study shows that the proposed method eliminates more harmonics compared with the conventional SHE-PWM methods. Simulation and experimental studies are conducted to validate the performance of the proposed SHE-PWM method.

关键词： Multilevel inverter pulse-width modulation selective harmonic elimination

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Distributed control of multi-agent systems with pulse-width-modulated controllers

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AUTOMATICA 2020年 119卷 109020-109020页

作者： Liu, Tengfei Jiang, Zhong-Ping Northeastern Univ State Key Lab Synthet Automat Proc Ind Shenyang 110004 Peoples R China NYU Dept Elect & Comp Engn 370 Jay St Brooklyn NY 11201 USA

This paper studies the distributed control of multi-agent systems with pulse-width-modulated (PWM) control inputs. A necessary and sufficient condition on the PWM control laws is given for uniform asymptotic state agreement with directed and switched information exchange topologies. The methodology is validated by a computer-based simulation. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： pulse-width modulation Multi-agent systems Switched topologies State agreement

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Analysis and Verification of a Wide Input Voltage PWM Converter with Variable Windings

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ENERGIES 2020年第7期13卷 1634页

作者： Lin, Bor-Ren Chang, Ji-Wei Natl Yunlin Univ Sci & Technol Dept Elect Engn Touliu 640 Yunlin Taiwan

A three-leg pulse-width modulation converter with auxiliary windings is provided and investigated to realize wide voltage operation and zero voltage switching characteristics on power switches. The presented converter has three converter legs on the input-side and two sets of winding turns on the output-side. Owing to the on/off states of the three converter legs and the two sets of secondary winding turns, the proposed converter can be operated under three different equivalent circuits to have wide input voltage operation from 30V similar to 240V (V-in,V-max = 8V(in,min)). Compared with the multi-stage converters to realize wide input voltage operation, the proposed circuit topology has fewer circuit components and a simple control algorithm. Conventional duty cycle control with phase-shift between each converter leg is adopted to regulate load voltage and also accomplish zero voltage switching on active switches. The presented three-leg converter is tested with a laboratory circuit. Finally, experiments testify to the performance and validity of the presented converter.

关键词： pulse-width modulation zero voltage switching power converters three-leg converters

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Output Perfect Tracking Control for a Plant with PWM-Type Input ⁎

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IFAC-PapersOnLine 2020年第2期53卷 8351-8356页

作者： Kohta Tamekuni Masayasu Suzuki Mitsuo Hirata Utsunomiya University 7-1-2 Yoto Utsunomiya Tochigi 321-8585 Japan

It is a well-established fact that an unstable zero may appear when a minimum-phase continuous-time system is discretized by a zero-order hold. Therefore, a feedforward controller cannot be obtained based on the inverse system; this is because it becomes unstable. Herein, an exact linearization method for a continuous-time system with a pulse-width modulation-type (PWM-type) input has been proposed showing that unstable zeros of the linearized discrete-time system can be moved to the stable region by altering the pulse-centers location. This enables the construction of a stable feedforward controller that achieves an output perfect tracking control. However, the current paper shows a trade-off between the stability of the stabilized zero and the maximum pulse-width. This prevents the unstable zero from moving to a high stability region, and shows some oscillation at the output of the feedforward controller. To address this, a zero-phase error filter has been introduced to reduce the oscillation. Further, a nonlinear deadbeat controller is also proposed, which can be applied to second and higher order systems. The effectiveness of the proposed methods are presented in this paper by performing simulations.

关键词： pulse-width modulation Perfect tracking control Discrete-time unstable zeros Feedforward control

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Simulation of Processes in the Modular Multilevel Inverter

Simulation of Processes in the Modular Multilevel Inverter

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IEEE International Conference on Modern Electrical and Energy Systems (MEES)

作者： Kozakevych, Ihor Siyanko, Roman Kryvyi Rih Natl Univ Dept Automated Electromech Syst Ind & Vehicles Kryvyi Rih Ukraine

ISBN: (纸本)9781728125695

One of the important aspects of improving energy efficiency at the moment is the widespread introduction of a adjustable-speed electric drives for motors with a medium rated voltage. One of the actual ways of development in this direction is to research the methods for controlling a modular multi-level inverter, since it has a number of valuable advantages for the implementation of such a system. The main advantage of this scheme can be the possibility of a modular implementation based on the same types of cells with identical parameters. The disadvantage is that the entire load current of the converter passes through the capacitors of its modules, causing a change in the voltage on them. The paper presents the results of modeling the operation of the circuit at high and low frequency of the output voltage. An analysis of the main dependencies describing the processes in a modular multilevel converter is presented.

关键词： modular multilevel converter pulse-width modulation voltage balancing low-speed drive

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Mixed-Integer Quadratic Program for Predictive Control of a Grid-Connected Power Converter 4

Mixed-Integer Quadratic Program for Predictive Control of a ...

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IEEE 4th Colombian Conference on Automatic Control (CCAC) - Automatic Control as Key Support of Industrial Productivity

作者： Morfin-Magana, Rodrigo Rico-Melgoza, Jesus Ornelas-Tellez, Fernando Vasca, Francesco Cortes-Vega, David Univ Michoacana Fac Elect Engn Morelia Michoacan Mexico Univ Sannio Dept Engn Piazza Roma 21 I-82100 Benevento Italy

ISBN: (纸本)9781538669624

Model predictive control has demonstrated to be an efficient control technique for power electronic systems. In this paper the linear complementarity modeling framework is used for the model predictive control design of a DC-DC boost converter cascaded with a single-phase inverter, a topology usually adopted in microgrids. A linear complementarity model valid for all operating modes of the converter is derived. A mixed-integer quadratic program is formulated for the design of the predictive controller constrained to the dynamic model and implementing a pulse width modulation. Numerical results show the effectiveness of the proposed solution.

关键词： Model Predictive Control Hybrid Systems Power Converters pulse-width modulation Mixed-Integer Quadratic Problem

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