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# Dr. Espinosa-Neira, Eduardo

Nombre de publicación

Dr. Espinosa-Neira, Eduardo

Nombre completo

Espinosa Neira, Eduardo Enrique

Facultad

Email

eespinosa@ucsc.cl

ORCID

10 results

## Research Outputs

Now showing 1 - 10 of 10

- PublicationFCS–MPC with nonlinear control applied to a multicell AFE rectifier(Sensors, 2022)
; ;Espinoza, José ;Melín, Pedro ;Rohten, Jaime ;Rivera, MarcoMuñoz, JavierThe use of controlled power converters has been extended for high power applications, stacking off-the-shelve semiconductors, and allowing the implementation of, among others, AC drives for medium voltages of 2.3 kV to 13.8 kV. For AC drives based on power cells assembled with three-phase diode rectifiers and cascaded H-bridge inverters, a sophisticated input multipulse transformer is required to reduce the grid voltage, provide isolation among the power cells, and compensate for low-frequency current harmonics generated by the diode-based rectifiers. However, this input multipulse transformer is bulky, heavy, and expensive and must be designed according to the number of power cells, not allowing total modularity of the AC drives based on cascade H-bridges. This study proposes and evaluates a control strategy based on a finite control set-model predictive control that emulates the harmonic cancellation performed by an input multipulse transformer in a cascade H-bridge topology. Hence, the proposed method requires conventional input transformers and replaces the three-phase diode rectifiers. As a result, greater modularity than the conventional multicell converter and improved AC overall input current with a THD as low as 2% with a unitary displacement power factor are achieved. In this case, each power cell manages its own DC voltage using a nonlinear control strategy, ensuring stable system operation for passive and regenerative loads. The experimental tests demonstrated the correct performance of the proposed scheme. - PublicationSelective harmonic elimination technique for a 27-Level asymmetric multilevel converterIn this paper, we present an implementation of selective harmonic elimination modulation technique in a 27-Level asymmetric multilevel converter. The main issue in this kind of converters is the generation of the gating patterns to obtain an optimized AC voltage waveform. State-of-the art solutions use deep mathematical analysis in the frequency domain by means of the Fourier series, but they are mainly applied for two-level or symmetric multilevel converters. On the other hand, the modulation for asymmetric multilevel converters is mainly focused on nearest level control or nearest vector control. In this work, we propose a novel modulating technique that takes advantage of the switching angles optimization for a 27-level waveform. In fact, different set of solutions are obtained and presented in order to define the modulation index as well as the value of the switching angles for the multilevel waveform. A modulation index sweep was performed for the entire operating region of the converter, where it can be observed that the number of levels decreases when the modulation index is low, which are calculated in order to minimize the total harmonic distortion (THD) of the resulting voltage waveform. In order to validate the proposal, these results for different modulation indexes values are simulated, obtaining a THD < 5% for a modulation index 0.75 < M < 1.0. Finally, a small scale proof-of-concept prototype is implemented in order to validate the proposal. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
- PublicationStudy of intuitionistic fuzzy super matrices and its application in decision making(Institute of Electrical and Electronics Engineers Inc., 2022)
;Melín, Pedro ;Baier Fuentes, Carlos; ;Riedemann, Javier ;Espinoza C., JoséPeña G., RubénThis work deals with the study of the open-source Arduino DUE board as a digital control platform for three-phase two-level Voltage-Source Converters (VSC) and Current-Source Converters (CSC), including (i) the description of the power topologies, its connection to the load or the ac grid, and the electrical signals required for sensors and power valves, (ii) the description of the Arduino Due board, its features, and its connection with the sensors and power valves in the converter, and (iii) evaluation of the Arduino DUE’s processing time required for typical power converter algorithms, such as modulation, mathematical transforms, and linear controllers typically used in these converters. Experimental results are presented to validate the study, showing that the Arduino DUE is a feasible digital control platform for this type of power converter. - PublicationAnalysis and control strategy for a current-source based D-STATCOM towards minimum losses(International Journal of Electrical Power and Energy Systems, 2020)
;Melin, P.E. ;Guzmán, J.I. ;Hernández, C.R. ;Muñoz, J.A. ;Espinoza, J.R.This work deals with a Distribution Static Synchronous Compensator (D-STATCOM) based on a current-source converter for low and medium voltage distribution systems, specifically small and medium manufactures industries which are fined if the displacement power factor is below given limits. The D-STATCOM is analyzed using its mathematical model, showing the strong relation of the D-STATCOM power losses and its DC current level. Using the operating region of the D-STATCOM, an operating sub-region is defined such that the minimum DC current is used for a required reactive compensation, which leads to reducing the operating losses in the DSTATCOM. Also, Selective Elimination Harmonic is used to modulate the equipment to reduce the switching frequency while ensuring a desired current quality in the D-STATCOM input. As a result, a simple control strategy is proposed that uses a fixed modulation index while a phase control regulates the DC current to the lowest value required for reactive power compensation. Mathematical analysis jointly with simulated and experimental results corroborates the proposal, showing that it is possible to achieve a suitable compensation capability for improving the efficacy of the STATCOM. - PublicationReduction of DC capacitor size in Three-Phase Input/Single-Phase Output power cells of multi-cell converters through Resonant and Predictive Control: A characterization of its impact on the operating region(Mathematics, 2023)
;Ramírez, Roberto ;Baier, Carlos ;Villarroel,Felipe; ;Arevalo, MauricioEspinoza, JoseCascaded H-bridge drives require using a significant-size capacitor on each cell to deal with the oscillatory power generated by the H-bridge inverter in the DC-link. This results in a bulky cell with reduced reliability due to the circulating second harmonic current through the DC-link capacitors. In this article, a control strategy based on a finite control set model predictive control and a proportional-resonant controller is proposed to compensate for the oscillatory power required by the H-bridge inverter through the cell’s input rectifier. With the proposed strategy, a DC-link second harmonic free operation is achieved, allowing for the possibility of reducing the capacitor size and, in consequence, the cell dimensions. The feasibility of the proposed control scheme is verified by experimental results in one cell of a cascade H-bridge inverter achieving an operation with a capacitance 141 times smaller than required by conventional control approaches for the same voltage ripple. - PublicationAn efficiency analysis of 27 level single-phase asymmetric inverter without regeneration(MDPI, 2021)
; ;Melín, Pedro ;Baier, Carlos ;Espinoza, JoséGarcés Hernández, HugoFor medium voltage applications, multilevel inverters are used. One of its classic topologies is the Cascaded H-Bridge, which requires isolated DC voltages to work. Depending on the DC voltage ratio used in the Cascaded H-bridge can be classified into symmetric and asymmetric. In comparison between symmetric and asymmetric inverters, the latter can generate an AC output voltage with more output voltage levels. DC voltage ratio most documented are binary and trinary. The last can generate an AC voltage of 3n = 27 levels is obtained, using n = 3 inverters in cascade and NLM modulation, which generates a flow power of the load to the inverters (regeneration). This work analyzes the semiconductor losses (switching and conduction) and the THD of the AC output voltage in function of index modulation, considering a non-regenerative modulation technique for a 27-level single-phase asymmetric inverter. To confirm the theoretical analyzes, simulation and experimental results are shown. - PublicationCascaded H-Bridge Converter Based on Current-Source Inverter with DC Links Magnetically Coupled to Reduce the DC Inductors ValueThe main drawback of the Cascaded-H Bridge converter based on three-phase/single-phase current-source inverters is the large DC inductors needed to limit the variation of the DC current caused by the single-phase inverter oscillating power. If the oscillating power is some-how compensated, then the DC inductor can be designed just as a function of the semiconductors’ switching frequency, reducing its value. This work explores the use of three-phase/single-phase cells magnetically coupled through their DC links to compensate for the oscillating power among them and, therefore, reduce the DC inductor value. At the same time, front ends controlled by a non-linear control strategy equalize the DC currents among coupled cells to avoid saturating the magnetic core. The effectiveness of the proposal is demonstrated using mathematical analysis and corroborated by computational simulation for a 110 kVA load per phase and experimental tests in a 2 kVA laboratory prototype. The outcomes show that for the tested cases, coupling the DC links by a 1:1 ratio transformer allows reducing the DC inductor value below 20% of the original DC inductor required. The above leads to reducing by 50% the amount of magnetic energy required in the DC link compared to the original topology without oscillating power compensation, keeping the quality of the cell input currents and the load voltage. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.
- PublicationA predictive control scheme for a Single-Phase Grid-Supporting Quasi-Z-Source inverter and its integration with a frequency support strategy(IEEE Access, 2023)
;Baier, Carlos ;Villarroel, Felipe ;Torres, Miguel ;Pérez, Marcelo ;Hernández, JesúsSmall grid-connected inverters are not friendly to the electrical grid, in the sense they do not take any action to support the grid when contingency events occur. For example, because of their relatively low power capacity, small grid-connected inverters are not designed to provide dynamic frequency support to the grid. On the other hand, it is well known that microgrids and weak grids including distributed generation would benefit significantly if all of the grid-connected converters could support and help against grid frequency disturbances. Within the family of small grid-connected converters, single-phase quasi-Z-source inverters (QZSI) have become an attractive topology, because they represent a reliable and economical alternative, and can be very efficient in applications that demand small or medium powers. However, a major disadvantage is that the control strategy must manage both direct current and alternating current variables through the same group of switches. The latter is a challenging task when implementing predictive control schemes. This paper proposes a finite control set model predictive control (FCS-MPC) strategy for a single- phase grid-supporting QZSI. The proposed predictive scheme can be easily integrated with a complementary control block to provide grid frequency support. Experimental results show evidence of the inverter operating under the proposed control strategy and providing grid frequency support, which demonstrates the feasibility of the proposal - PublicationAsymmetrical influence of personality on entrepreneurship(European Journal of International Management, 2023)
;Soria-Barreto, Karla ;Alonso-Dos-Santos, ManuelThe objective of this study is to explore the antecedents of the formation of entrepreneurial intention from a linear, causal and asymmetrical perspective. We have combined the Ajzen model applied to entrepreneurship, including two personality variables (self-confidence and creativity). This study involves a structural equation model based on partial least squares (PLS) and fuzzy set qualitative comparative analysis (fsQCA). All of the hypotheses were supported except for the influence of the variables subjective norms and self-confidence on EI. The PLS model explains 68.7% of the variance of EI. According to the fsQCA results, four models explain 88.1% of the existence of EI. The two models with the greatest degree of coverage are: Self-Confidence × Attitude Towards Entrepreneurial Behaviour × Subjective Norms and Perceived Behaviour Control × Creativity × Subjective Norms. - PublicationAnalysis and design of a multicell topology based on Three-Phase/Single-phase current-source cells(IEEE Transactions on Power Electronics, 2016)
; ;Melin, Pedro ;Rohten, Jaime ;Espinoza, Jose ;Baier, Carlos ;Muñoz, JavierRiedemann, JavierThis work proposes a multicell topology based on current-source cells in order to inherit the advantages of current-source topologies such as reduced load dv/dt voltage and natural bidirectional power flow and to adopt a similar behavior of the multicell topology based on a voltage source converter such as voltage controlled behavior where n C cells are connected in series to feed one load phase. In order to check the technical feasibility and performance of the proposed topology, a mathematical model is introduced and studied and key design guidelines of passive components are defined. The analysis shows the possibility of using components with a lower voltage rating than that of the classic multilevel current source topologies and allows the use of low switching frequencies in both rectifier and inverter stages while at the same time obtaining a high-quality waveform in both load voltage and converter input currents. A case of example is used to corroborate the theoretical analysis and the component design methodology, as well as the performance of the topology using a low-power prototype.