Examinando por Autor "Martinez-Salamero, Luis"
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- PublicaciónSólo datosA Single-Phase Transformer-Based Cascaded Asymmetric Multilevel Inverter With Balanced Power Distribution(IEEE Access, 2019-07-22) Lopez-Santos, Oswaldo; Jacanamejoy-Jamioy, Carlos A.; Salazar-D’Antonio, Diego F.; Corredor-Ramírez, Julian R.; García, Germain; Martinez-Salamero, LuisThis paper introduces a method to enforce balanced power distribution between the stages of a single-phase transformer-based cascaded multilevel inverter using the new asymmetric ratio 6:7:8:9 between stages. Since the inverter is fed by a single DC source, asymmetry is enforced by means of the transformer turns ratio providing multiple redundant switching patterns to synthesize an output signal of until 35 levels. As it is developed in the paper, optimum switching patterns for the proposed ratio allow reducing typical power unbalance produced by commonly used ratios in four stage multilevel inverters (1:2:4:8 and 1:3:9:27). The proposed method consists on determining off-line the best switching patterns for minimizing deviation error, and then, storing them as lock-up tables in the digital device controlling the inverter. By permanently reproducing the selected switching patterns, balanced power distribution is achieved. A closed-loop control approach to regulate the RMS value of the output voltage compatible with the proposed method is also developed. The experimental results using a laboratory prototype are presented validating the entire approach.
- PublicaciónSólo datosA Unified Approach for the Control of Power Electronics Converters. Part II: Tracking(Applied Sciences (Switzerland), 2021-08-19) Garcia, Germain; Lopez-Santos, Oswaldo; Martinez-Salamero, LuisThis paper extends the results recently proposed in Part I of this research work focused on the stabilization of power electronic converters. This second part is devoted to cases in which the underlying control problems can be translated into tracking control problems. This is the case for DC-AC converters whose output must track a sinusoidal reference signal. The idea is to tackle the problem in a unified manner in order to avoid as much as possible the use of approximations and to exploit all the mathematical properties of the corresponding switched models. The case in which measurable or non-measurable perturbations are present is considered. The proposed techniques are illustrated for two particular DC-AC converters simulated using the PSIM software.
- PublicaciónSólo datosAnalysis, Design and Implementation of a Static Conductance-Based MPPT Method(IEEE, 2018-05-15) López-Santos, Oswaldo; García, Germain; Martinez-Salamero, Luis; Giral, Roberto; Vidal-Idiarte, Enric; Merchán-Riveros, María C.; Moreno-Guzman, YamelThis paper introduces a maximum power point tracking (MPPT) method based on a power (P) versus static conductance (G) curve of a photovoltaic (PV) array. The maximum power point (MPP) is tracked by comparing the PV array instantaneous power to a varying power reference generated by the MPPT algorithm. The comparison error is used to reduce or increase the conductance at which the PV array is forced to operate until the MPP is reached. Simultaneously, the error is used to change the power reference until the trajectory of this reference in the P-G curve enters a limit cycle around the MPP. The P-G curve is derived from a piecewise linear approximation of the current versus voltage (I-V) curve, which facilitates the analytical description of the tracking operation. The technique reported can also be implemented by means of simple analog or digital circuitry and requires two sensors to measure the instantaneous PV array current and voltage. It uses only four tuning parameters, which are selected depending on the maximum value of the derivative of the power with respect to the conductance. The theoretical predictions are verified with simulations and experimental results. The latter show that the procedure performs well enough to be favorably compared with the most efficient MPPT methods.
- PublicaciónSólo datosSliding Mode Control of the Isolated Bridgeless SEPIC High Power Factor Rectifier Interfacing an AC Source with a LVDC Distribution Bus(Energies, 2019-09-07) López-Santos, Oswaldo; Cabeza-Cabeza, Alejandro J.; García, Germain; Martinez-Salamero, LuisThis paper deals with the analysis and design of a sliding mode-based controller to obtain high power factor (HPF) in the bridgeless isolated version of the single ended primary inductor converter (SEPIC) operating as a single-phase rectifier. In the work reported here, the converter is used as a unidirectional isolated interface between an AC source and a low voltage direct current (LVDC) distribution bus. The sliding-mode control is used to ensure the tracking of a high quality current reference at the input side, which is obtained from a sine waveform generator synchronized with the grid. The feasibility of the proposal is validated using simulation and experimental results, both of them confirming a reliable operation and showing good static and dynamic performances.