Jorge Garcia

University of Oviedo | UNIOVI · Department of Electrical, Electronic, Computers and Systems Engineering

Gallium nitride (GaN) high electron mobility transistors (HEMTs) show potential for high-efficiency power converters, but as switching frequencies increase, a need arises for analytical models to predict performance and estimate switching losses. This paper presents a precise and straightforward power loss model for high-voltage enhancement-mode Ga...

This paper presents an analysis of an alternative variable inductor structure compared to the ones previously proposed in the literature. The inductor is constructed based on a toroidal core and presents some prosperous advantages, which are: a reduced induced voltage in the DC bias control windings, and a symmetrical operation, while making use of...

Due to the rising trends in the adoption of smart systems such as smart grids, smart homes, and vehicle-to-grid, there has been a lot of research interest in these areas. To manage these complex systems effectively and intelligently, a reliable, high-speed, and secure data communication network is very essential. The key distinguishing feature betw...

Synopsis This article is intended to present the full section VI, entitled Mathematics for Electrical and Electronics Power Engineering, and to put it into context in the full editorial project of the Encyclopedia of Electrical and Electronics Power Engineering. From pure mathematic concepts such as numbers, expressions and equations, formulas and...

In a previous article we studied how to adapt the main control signals of a power converter to make them suitable for an analog-to-digital transformation. However, coupled to these signals, interferences, spikes, or noise generated by electronic devices such as the own operational amplifiers (op amps) of the adaptation stage, can be encountered. Th...

Synopsis In the previous article, the concept of set of numbers, the revision of the main sets of numbers in mathematics and the definition of the set of complex numbers were introduced. Also, the main properties of complex numbers were investigated, together with the statement of the binomial and polar representations, as well as the concept of th...

In electrical and electronic engineering, the physical magnitudes involved in the considered systems and processes are mainly electrical, electronic, magnetic, mechanical and energy magnitudes. Most of the relevant mathematical techniques for modeling and representing these engineering systems make use of a special set of numbers, called complex nu...

The analog-to-digital converter (ADC) is one fundamental block in modern engineering systems, since it interfaces the analog domain of the physical system involved with the digitized signal path used for processing, control and monitoring of the systems themselves. But actually, the ADC is the last block in a series of stages intended to adapt the...

Vertical transportation in buildings (elevators, vertical conveyors, escalators, etc.) moves more than one billion people worldwide every day, accounting for a significant portion of the energy consumption of an average building. This work discusses the operation of an energy management system in a hybrid energy storage system for an elevator in a...

Energy storage systems (ESSs) are gaining a lot of interest due to the trend of increasing the use of renewable energies. This paper reviews the different ESSs in power systems, especially microgrids showing their essential role in enhancing the performance of electrical systems. Therefore, The ESSs classified into various technologies as a functio...

Nowadays, the emission of pollutant particles is a global problem in terms of limiting pollution in industries, as well as greenhouse gases emissions. There are different ways to filter undesired particles, such as carbon air filters, chemical washing, and so on. One of the most popular techniques is the use of electrostatic precipitators: The oper...

This work discusses a novel set of alternate implementations of isolated gate driver circuits for power electronic transistors. The proposed topologies for the driver have been designed specifically for SiC power MOSFET. Three different solutions are discussed, all of them providing the required gate turn-on and turn-off command signal with galvani...

This paper explores the use of a variable inductor as a reactive element for energy transfer in a Dual-Active-Bridge (DAB) converter. By using a controlled variable inductor, the optimal switching region in the operation of the phase-shift DAB can be extended, and thus high efficiencies can be achieved over wider load ranges compared to the traditi...

This paper presents a study to improve the inductance calculation of magnetic components in power converters, of particular interest in the case of applications using variable inductors. In order to increase the accuracy of the estimation of the reluctance paths, several factors have been taken into consideration, such as: the permeability definiti...

This paper proposes and develops a circuit-based model aiming to simulate variable magnetic power elements in power electronic converters. The derived model represents the magnetic element by a reluctance-based equivalent circuit. The model takes into consideration device core losses, with the main emphasis given to hysteresis losses, which are mod...

This work presents a fault ride-through control scheme for a non-isolated power topology used in a hybrid energy storage system designed for DC microgrids. The hybrid system is formed by a lithium-ion battery bank and a supercapacitor module, both coordinated to achieve a high-energy and high-power combined storage system. This hybrid system is con...

This work shows the development of a software tool that provides realistic operation power profiles in elevators for residential and public buildings applications. The implemented tool carries out a kinematic, dynamic and energetic analysis of the system, as a function of operational variables in the system. Therefore, the final load profile is a f...

Battery energy storage systems are increasingly used to stabilize and balance energy supply systems. For stationary applications, as UPS, electrochemical battery modules are often used, being Li - Ion and lead acid the most popular choice mostly due to power ranges, energy capacity and reversible capability. The present paper is focused in the desi...

A novel implementation of an isolated gate driver for power switches is proposed in this study. The driver is bespoke designed for SiC power mosfet s. The proposal achieves the main driver characteristics—isolation capability, gate switching command, and power transfer to the secondary side by using a unique magnetic transformer. The resulting si...

In this paper, the optimization of the power and control stages of a previously proposed topology for an off-line LED electronic driver is presented. The full system avoids the use of electrolytic capacitors at the D C link, therefore increasing the lifespan and reliability of the driver. As a consequence of having a relatively small capacitance, t...

Energy management control is essential to microgrids (MGs), especially to single-phase ones. To handle the variety of distributed generators (DGs) that can be found in a MG, e.g., renewable energy sources (RESs) and energy storage systems (ESSs), a coordinated power regulation is required. The latter are generally battery-based systems whose lifeti...

This paper deals with the AC and DC dynamic voltage control in a hybrid DC/AC Microgrid (MG) with central and distributed Battery Energy Storage Systems (BESSs), applying a power sharing mechanism between the different devices in the MG. The MG is composed by a multiport transformation center and two fixed frequency 3 phase AC Nanogrids (NGs) coupl...

This paper deals with the dynamic control of the DC bus voltage and the AC voltage magnitude and frequency in a hybrid DC/AC Microgrid (MG). In order to allow a high penetration of renewable energies, provide an increased system reliability during islanding and reduce the dependency on the mains, Energy Storage Systems (ESSs) are included in both t...

In this work, an in-depth investigation was performed on the properties of the half-bridge current-source (HBCS) bidirectional direct current (DC)-to-DC converter, used to interface two DC-link voltage sources with a high-voltage-rating mismatch. The intended implementation is particularly suitable for the interfacing of a supercapacitor (SC) modul...

This paper is focused on determining the efficiency dependency on the switching frequency for a solid state transformer (SST) with one of the ports connected to an energy storage device (Lithium-Ion battery). Some contributions for measuring the efficiency/losses for different power converter structures for energy storage applications can be found...

This paper is focused on the control strategies for non-isolated Hybrid Energy Storage Systems in power support applications for microgrids and nanogrids. The hybrid storage system under analysis consists of two storage units with significantly different ratings and characteristics. These units are interfaced to the main system through dedicated po...

This work proposes a solution for implementing an isolated gate driver for GaN HEMTs based on the previous topology for SiC power MOSFETs. The isolation of the gate driver is realised by the single transformer topology with double winding in the secondary side. The Bi-level HF Amplitude Modulation scheme is retained to avoid the core saturation as...

This work carries out a comparison of non-isolated topologies for power electronic converters applied to Hybrid Energy Storage Systems. At the considered application, several options for three-port circuits are evaluated when interfacing a DC link with two distinct electrical energy storage units. This work demonstrates how the proposed structure,...

In this paper, a full model to simulate variable magnetic elements in power electronic converters is developed. The derived model is based on the reluctance equivalent circuit of magnetic systems. Specifically, the model considers core losses, determined through Jiles-Atherton hysteresis model, and Eddy current losses obtained using Dowell empirica...

This paper addresses the estimation of the grid impedance and the control of grid-tied converters by combining pulsed-signal injection and observer based techniques. A Luenberger based observer is used for controlling the grid-side current of an LCL filter by only measuring the converter-side currents and the grid-side voltage. This configuration m...

This paper proposes a novel solution for transient frequency compensation in weak 3-phase Microgrids (MGs) based on a Luenberger observer and a transient frequency detector. Unlike in conventional grids, the low inertia of the generators coupled to a MG could make their rotor speeds to be affected by load changes, varying the grid frequency and com...

This paper deals with the AC and DC dynamic voltage control in a hybrid DC/AC Microgrid (MG) with central and distributed Battery Energy Storage Systems (BESSs), applying a power sharing mechanism between the different devices in the MG. The MG is composed by a multiport transformation center and two fixed frequency 3 phase AC Nanogrids (NGs) coupl...

The present work proposes a solution for an isolated gate driver suitable for SiC MOSFETs. The driver is implemented by means of two small magnetic transformers, to provide the turn-on and turn-off gate signals, as well as the power required for an adequate gate control. The operation is based on the modulation of the PWM pulses with a high frequen...

This work proposes a solution for an isolated gate driver for SiC MOSFETs, based on a magnetic transformer that simultaneously provides to the secondary side the turn-on and turn-off gate signals and the power required for an adequate gate control. This avoids the use of a dedicated DC-DC isolated converter and optocoupler. The original pulse signa...

In this work, a Fault Ride-Through control scheme for a non-isolated power topology for Hybrid Energy Storage Systems in a DC microgrid is presented. The Hybrid System is created from a Lithium-Ion Battery and a Supercapacitor Module coordinated to achieve a high-energy and high-power storage system; it is connected to a DC link to interface to the...

This work proposes a non-isolated power electronic topology to interface two distinct electrical energy storage units to a DC link, resulting in a Hybrid Storage System. The proposed solution, called Series-Parallel Connection, allows for interfacing these three ports in a simple, compact and reliable approach, based on the standard configuration o...

This work focuses on the control strategies for different configurations of Non-Isolated Hybrid Energy Storage Systems. Basic strategies are proposed, studied and compared. Parting from the standard parallel connection of bidirectional boost converter in hybrid storage systems, a comparison with alternate topologies is presented. These alternative...

This work explores the Series-Parallel Connection of a Low Voltage Supercapacitor Module to obtain a Hybrid Energy Storage System for grid support applications. The Hybrid System is formed by the Supercapacitor Module itself, intended to ensure fast performance upon peak power requirements, together with a battery that provides the energy requireme...

This paper deals with the design of a Hybrid Energy Storage System (HESSs) for electric transportation such as Electric/Hybrid Vessel and Electric/Hybrid Train. The association of more than one Energy Storage Systems (ESSs) e.g., batteries which have different dynamics permit to take the advantages of the characteristics of both ESSs obtaining simu...

This paper presents a multifunctional bidirectional converter applied to street lighting and photovoltaic (PV) microgeneration systems. The proposed converter works as an electronic driver supplying a street lighting luminaire based on light emitting diodes (LEDs) at night, from ac single-phase mains with high power factor and reduced harmonic dist...

This paper defines, explains and implements a unified switching pattern for the switches in a bidirectional Discontinuous Conduction Mode (DCM) Flyback converter, used for connecting the individual elements of a street lighting system to the mains facility. In every individual element, the DC bus links the different existing stages, such as lamp dr...

Most common Power Factor Correction (PFC) solutions for low power applications, when galvanic isolation is required, involve the use of discontinuous conduction mode (DCM) dc to dc topologies. The control is generally based on fixed duty ratio operation, or at best, on a classic low-bandwidth duty-ratio control. Considering public lighting systems,...

This paper proposes a solution for the transient grid frequency drift that occurs when active power transients take place in weak grids. Microgrids (MGs) are by definition weak grids, exhibiting a low inertia and high impedance which make them prone to contingencies that compromise the grid quality and stability. Particularly, the low inertia of th...

There is currently a trend in power electronics to avoiding the use of electrolytic capacitors in LED drivers, provided that their expected life span is much lower than that of the LEDs, thus reducing the reliability of the entire LED fixture. This paper presents an optimization study about the determination of the minimal bus capacitance needed fo...

High-frequency copper losses, or copper losses produced during switching in switching-mode power supplies, are very much related to variations of the magnetic field distribution within the core window. When operating at high frequency, the current flowing through the windings of a magnetic component experiences redistribution across the section of...

This work presents a multifunctional bidirectional converter for street lighting systems and grid tie inverter applications. The proposed converter works as grid-tie inverter injecting energy into the main, from photovoltaic panels, during the day, and it operates as an electronic driver supplying a street lighting based on LEDs luminaire during th...

Este artigo apresenta um conversor multifuncional para iluminação pública e injeção de energia na rede elétrica. O conversor proposto funciona no acionamento de uma luminária à LEDs durante a noite, utilizando energia proveniente da rede elétrica com elevado fator de potência e reduzida distorção harmônica. Durante o dia, o mesmo conversor opera in...

This paper presents a new control method and a detailed project methodology for the optimized connection method of two converters, aiming to reduce the redundant power processing, in order to supply high-power light-emitting diodes (LEDs) with reduced capacitance and high efficiency, directly from the ac line. This connection method allows dealing...

The objective of this paper is to investigate the properties of the Half Bride Current Source bidirectional DC to DC converter used to interface supercapacitors with batteries in a hybrid storage system. This work focuses on the benefits of applying synchronous rectification to the switches of the primary and the secondary side, both in terms of ef...

his paper presents the experience of applying project-based learning (PBL) on power electronics in the context of two official Master degree courses. The discussion covers both strategic and implementation topics, from the initial conception of the Master and the subject, to practical implementation issues. The final conclusions show recommendation...

This paper presents a multifunctional bidirectional converter. The proposed converter works as a grid-tied inverter, injecting power coming from a PV subsystem to the AC mains in the daytime hours, but also supplies energy to a LED-based street lighting system at night. The topology is based on the integration of two Flyback converters thus allowin...

This paper deals with the estimation and decoupling of grid impedance and LCL filter parameters variation using signal injection techniques and Luenberger type observer. When integrating a power converter in the AC grid as an interface for any Distributed Generation Systems (DGS) or other grid quality compensator like Active Power Filters (APF) or...

This paper proposes the basic average model and the design of the control system for the Half Bridge Current Source (HBCS) Bidirectional DC to DC Converter. This converter is intended to interface a High Voltage DC link and a Low Voltage DC Storage Device in transportation applications. Firstly, the basics of the converter operation, high-level con...

A novel high pressure sodium (HPS) lamp model is proposed. The proposed model is particularised for 150 W HPS lamps, providing a powerful tool for simulating the behaviour of such lamps operating with low-frequency electromagnetic ballasts or high-frequency switching electronic ballasts. Simulations and experimental results are provided for verific...

Self-supply consists on turning the electrical consumers in prosumers; they produce a part or all the energy that they consume. In Spain, the regulatory frame that affects these kind of facilities has not been published yet. This regulatory gap causes different law interpretations that lead to misunderstandings between prosumers and electrical comp...

Parallel connection of several LED strings is a practical way to reduce the overall lamp voltage when a large number of emitters is needed. However, this connection might lead to high current mismatches between strings due to the dispersion of characteristics that even binned devices feature. Several techniques have been proposed in order to elimin...

Electric vehicles are one of the major keystones on the development of a more sustainable society. However, nowadays there are a number of obstacles for the full development of the Electric Vehicles and their necessary infrastructure. These hurdles tend to slow down the implementation of a technology that from other aspects can be considered as mat...

This work proposes an electronic driver for street lighting systems integrated to renewable energy. In recent lighting applications, the use of micro renewable generators in lighting points makes necessary the use of special electronics to handle the bidirectional energy flow in the ballast. The proposed input stage is a topology based on the integ...

Power regulation of all converter units in a micro-grid should not be only determined by load demand, but also by the available power of each unit, i.e. a converter fed by a battery. Energy management control is essential in order to handle the variety of prime movers which may include different types of renewable energy sources (RES) and energy st...

This paper presents a methodology to improve the line current THD of a distribution line configuration with multiple non-linear loads, by means of a simple algorithm based on sensing only the voltage at the Point of Common Coupling (PCC), thus avoiding the use of line current measurement. Firstly, the effect of conventional low frequency electromag...

This work proposes an electronic driver for street lighting systems integrated to renewable energy. In recent lighting applications, the use of micro renewable generators in lighting points makes necessary the use of special electronics to handle the bidirectional energy flow in the ballast. The proposed input stage is a topology based on the integ...

This paper presents the experience of applying project-based learning (PBL) on power electronics, in the context of two official Master degree courses. The discussion covers both strategic and implementation topics, from the initial conception of the Master and the subject, to practical implementation issues. The final conclusions show recommendati...

This paper proposes an electronic driver for public lighting systems. The input stage is based on the integration of two flyback converters with different polarities, in order to avoid the use of the input diode bridge rectifying stage. The output stage is a boost converter with an output current control. The proposed circuit is introduced and anal...

In the prior literature, the small-signal incremental impedance of fluorescent lamps has been characterized using a single-pole single-zero transfer function. This transfer function provides a good estimation of the lamp dynamics at rated power. However, when this model is used at low power levels, the accuracy is severely reduced, particularly at...

This paper presents an electronic ballast to supply a 70W high pressure sodium lamp. The electronic ballast consists on a single-stage converter that integrates a buck converter to provide power factor correction and two flyback converters to supply the lamp, with low frequency square waveform, in order to avoid the acoustic resonance phenomenon oc...

This paper presents a converter structure applied to supply high power Light Emitting Diodes (LEDs) from the mains in a street lighting system, based on the Reduced Redundant Power Processing (R2P2) principle. To guarantee high power factor and low harmonic injection a buck-boost operating in Discontinuous Conduction Mode (DCM) is employed as Power...