Fredy Edimer Hoyos Velasco

Bio: Fredy Edimer Hoyos Velasco is an academic researcher from National University of Colombia. The author has contributed to research in topics: Buck converter & Boost converter. The author has an hindex of 5, co-authored 27 publications receiving 71 citations.

Dynamic Analysis of a Permanent Magnet DC Motor Using a Buck Converter Controlled by ZAD-FPIC

Abstract: This paper presents the dynamic analysis of a permanent magnet DC motor using a buck converter controlled by zero average dynamics (ZADs) and fixed-point inducting control (FPIC). Initially, the steady-state behavior of the closed-loop system was observed and then transient behavior analyzed while maintaining a fixed ZAD control parameter and changing the FPIC parameter. Other behaviors were studied when the value of the ZAD control parameter changed and the FPIC parameter was maintained at the initial value. Besides, bifurcation diagrams were built with one and two delay periods by changing the control parameter of the FPIC and maintaining fixed ZAD parameters while some disturbances were carried out in the electric source. The results show that the ZAD-FPIC controller allowed good regulation of the speed for different reference values. The ZAD-FPIC control technique is effective for controlling the buck converter with the motor, even with two delay periods. The robustness of the system was checked by changing the voltage of the source. It was shown that the system used a fixed switching frequency because the duty cycle was not saturated for certain ranges of the control parameters shown in the research. This technique can be used for higher order systems with experimental phenomena such as quantization effects, time delays, and variations in the input signal.

Adaptive Control for Buck Power Converter Using Fixed Point Inducting Control and Zero Average Dynamics Strategies

Abstract: In this paper, the output voltage of a buck power converter is controlled by means of a quasi-sliding scheme. The Fixed Point Inducting Control (FPIC) technique is used for the control design, based on the Zero Average Dynamics (ZAD) strategy, including load estimation by means of the Least Mean Squares (LMS) method. The control scheme is tested in a Rapid Control Prototyping (RCP) system based on Digital Signal Processing (DSP) for dSPACE platform. The closed loop system shows adequate performance. The experimental and simulation results match. The main contribution of this paper is to introduce the load estimator by means of LMS, to make ZAD and FPIC control feasible in load variation conditions. In addition, comparison results for controlled buck converter with SMC, PID and ZAD–FPIC control techniques are shown.

Period Addition Phenomenon and Chaos Control in a ZAD Controlled Boost Converter

Abstract: In this paper, we present an analytical, numerical, and experimental description of the period addition phenomenon in a dynamical system arising from a boost converter controlled by ZAD strategy. T...

Performance evaluation of a DC-AC inverter controlled with ZAD-FPIC

Abstract: Introduction: Power converters are used in microgrids to transfer power to the load with a regulated voltage. However, the DC-AC converters present distortions in the waveform that can be improved with the help of real-time controllers.Objective: Evaluate the response in alternating current of the buck converter controlled using ZAD-FPIC technique.Methodology: Based on the differential equations that describe the buck power converter, the ZAD and FPIC controllers are designed, simulations of the complete controlled system are made in Simulink of MATLAB, the system is implemented experimentally, and the controller is executed in real-time with the help of a DS1104 from dSPACE. In the end, several tests are carried out to check the effectiveness of the controller.Results: The results show that the controller allows good stability against different variations in the system and in the load.Conclusions: The ZAD-FPIC technique controls the variable and tracks changes in the waveform, magnitude, and frequency of the reference signal. The controller presents good stability to different tests, tracking the reference signal after each event.

Rapid Control Prototyping of a permanent magnet DC motor using non-linear sliding control ZAD and FPIC

Abstract: This paper shows the behavior of the buck power converter — DC-motor coupled system. The controller is designed using Zero Average Dynamic (ZAD) and Fixed Point Inducting Control (FPIC) techniques. The variable to be controlled is the motor speed. The designs have been tested in a Rapid Control Prototyping (RCP) system based on Digital Signal Processing (DSP) for dSPACE platform. The results show that the speed motor has very good performance when it is controlled with these techniques. The robustness of the system is proven by varying a constant of the controller. Experimental and simulations results agree only when quantization effects are considered in simulations. After this consideration, numerical and experimental bifurcations diagrams agree in stable zone as well as in transition to chaos.

Adaptive Control

Abstract: This book, written by two major figures in adaptive control, provides a wealth of material for researchers, practitioners, and students. While some researchers in adaptive control may note the absence of a particular topic, the book‘s scope represents a high-gain instrument. It can be used by designers of control systems to enhance their work through the information on many new theoretical developments, and can be used by mathematical control theory specialists to adapt their research to practical needs. The book is strongly recommended to anyone interested in adaptive control.

Hydrodynamics of vertical subsurface flow constructed wetlands: tracer tests with Rhodamine WT and numerical modelling

Abstract: Abstract Typical unsteady unsaturated conditions can profoundly affect the hydrodynamics of vertical subsurface flow constructed wetlands. In this study we analyzed the hydrodynamics of a 33 m2 vertical flow pilot plant, treating municipal secondary effluents. Three different saturation conditions were analyzed under several constant flux regimes: complete saturation, partial saturation with the free water table 20 cm over the bottom of the bed, and complete drainage. Tracer tests were performed in steady state conditions by dosing rhodamine WT as square input signals. Breakthrough curves were analyzed by means of both a classical residence time distribution analysis and an originally developed numerical plug-flow model with longitudinal dispersion adapted to the unsaturated conditions. We found that the degree of global mixing in the vertical flow constructed wetland increased as the water content increased; this effect was controlled by the hydraulic residence time of the system. Conversely, the degree of local mixing was inversely affected by water content; the dispersivity was 4.5, 10, and 14 cm for fully saturated, partially saturated and draining conditions, respectively. We explain the dependency of dispersivity on water content in physical terms; however, further studies are needed to mathematically include this relationship in numerical models that describe the behaviour of vertical flow constructed wetlands.

Sensorless Tracking Control for a “Full-Bridge Buck Inverter–DC Motor” System: Passivity and Flatness-Based Design

Abstract: A sensorless control based on the exact tracking error dynamics passive output feedback (ETEDPOF) methodology is proposed for executing the angular velocity trajectory tracking task on the “full-bridge Buck inverter–DC motor” system. When such a methodology is applied to the system, the tracking task is achieved by considering only the current sensing and by using some reference trajectories for the system. The reference trajectories are obtained by exploiting the flatness property associated with the mathematical model of the “full-bridge Buck inverter–DC motor” system. Experimental tests are developed for different desired angular velocity trajectories. With the aim of obtaining the experimental results in closed-loop, a “full-bridge Buck inverter–DC motor” prototype, Matlab-Simulink, and a DS1104 board from dSPACE are employed. The experimental results show the effectiveness of the proposed control.