Javier Uceda

• PhD in a Electrical Engineering
• Managing Director at Universidad Politécnica de Madrid

Due to the increasing presence of DC-DC power electronic converters in power distribution systems, having accurate models is essential for the analysis and design process. Black-box modeling approaches offer a convenient solution when the available information is limited, which is typically the case for commercial converters. Moreover, converters a...

Power electronic converters are envisaged to be key enablers of modern electric power distribution systems. Grid-connected three-phase inverters are widely used in smart grids and microgrids, but also in standard grids. They provide controllability and dynamic decoupling capabilities, which are fundamental in the integration of renewable sources an...

Membraneless micro redox flow batteries are an incipient technology that has been shown to extend some properties of traditional redox flow batteries. Due to their microfluidic scale and the absence of membrane, the fluid dynamics operation is critical in the electrical response. In this work, an electrical model is established to evaluate the infl...

Membraneless micro redox flow batteries are a promising technology that can improve traditional redox flow batteries performance. However, a precise modeling and control of the microfluidic dynamics is a complex task for which only open loop control strategies can be found in the literature. In this work, a strategy for the adaptive modeling of the...

The proliferation of renewable energy sources is promoting the use of dc-dc power electronic converters in power distribution systems. It is well-known that the interconnection of power electronic converters can be a source of instabilities. Traditionally, impedance-based stability analyses are performed using either the analytical description or t...

At present, it is safe to say that the future belongs to sustainable technologies. Electric vehicles are one of the most representative sustainable solutions for mobility. Some of the many advantages they offer are a clean operation, a profit gain from a possible power return to the grid in vehicle to grid applications, grid power support, etc. As...

DC electric power distribution is becoming popular due to the proliferation of renewable sources and storage elements in applications such as electric vehicles, ships, aircrafts, microgrids, etc. These systems are characterized by a high integration of power electronic converters. From a system-level perspective, it would be desirable to design thi...

Modern electric power distribution systems are progressively integrating electronic power converters. However, the design of electronic-power-converter-based systems is not a straightforward task, as the interactions among the different converters can lead to dynamic degradation or instabilities. In addition, electric power distribution systems are...

Maritime applications have found in the integration of the electric power system a way to further improve efficiency and reduce the weight of new electric ships. This movement has led scientists to integrate smart management systems to optimize the overall behavior of the grid. In this context, power electronics play a key role in linking the diffe...

DC microgrids are envisioned to be EPDS (Electronic Power Distribution Systems) composed of COTS (Commercial- Off-The-Shelf) converters. Naturally, these converters will determine the dynamic behavior of the system. Besides, unlike classic EPDS, microgrids are highly variable due to the intermittent behavior of the renewable sources and customer co...

EPCs (Electronic Power Converters) are the key elements of the smart dc microgrid architectures. In order to enhance the controllability of the system, most of the elements are envisioned to be connected to the different buses through EPCs. Therefore, power flow, stability, and dynamic response in the microgrid are function of the behavior of the E...

During the last few decades power converter-based systems have become a very interesting solution for electric power distribution in many applications. They have been successfully implemented in ships and “more electric aircrafts”, replacing some of the mechanical and hydraulic systems for power converters in order to optimize the efficiency and re...

A power electronics circuit allows the generation of high frequency magnetic field that can be used to increase the temperature of cancer cells previously invaded with magnetic nanoparticles. The circuit designed for this purpose is a high frequency phase-shift inverter implemented with SiC devices and natural Zero Voltage Switching (ZVS). The indu...

This paper shows an example of collaboration of people of different areas working together and achieving a promising result. In this case, a power electronics circuit allows the generation of high frequency magnetic field that can be used to increase the temperature of cancer cells previously invaded with magnetic nanoparticles. Although the resear...

“El deporte inclusivo trasciende fronteras”: éste fue el lema de la II Semana del Deporte Inclusivo (SDI), celebrada los días 17 a 20 octubre de 2011, tras la exitosa celebración de su primera edición en 2010. Si la primera edición recabó un inusitado interés a nivel nacional, la II SDI, celebrada en octubre de 2011 vino a confirmar el interés y la...

La Semana del Deporte Inclusivo (SDI) es un evento que combina sesiones técnicas en el INEF (UPM) con exhibiciones prácticas de deporte inclusivo en diferentes entornos de la ciudad de Madrid. Desde 2010, primer año de desarrollo del Centro de Estudios de Deporte Inclusivo (CEDI) y de la Alianza Estratégica por el Deporte Inclusivo 2010-2015 lidera...

This paper summarizes some of the current solutions to fulfil the requirements of the new low voltage power systems. On one hand, microelectronics evolution demands lower supply voltage. On the other hand, the portability of the new communication systems demands lighter and smaller power electronics. The improvement of the performance of low power...

Engineering is changing as a consequence of scientific and technological evolution and society needs and demands. Engineers need to understand the structure and behaviour of matter from nanoscale to extremely complex systems. Convergence of scientific and technological disciplines requires also an interdisciplinary approach in education. In this pr...

The 21 papers in this special section focus on uninterruptible power supply (UPS) systems. They are organized according to the following six topics: control of parallel UPS systems; UPS inverter control; double-conversion UPS; line-interactive UPS; battery management; and dynamic UPC. The papers are summarized here.

In the last years, the use of distributed uninterruptible power supply (UPS) systems has been growing into the market, becoming an alternative to large conventional UPS systems. In addition, with the increasing interest in renewable energy integration and distributed generation, distributed UPS systems can be a suitable solution for storage energy...

The energy consumption in mobile systems has become a big challenge that limits high performance and autonomy in mobile systems. The dynamic voltage scaling (DVS) is a recent technique that reduces energy consumption varying dynamically the supply voltage of the system accordingly to the clock frequency. The Buck topology is a good candidate to sup...

This paper presents a magnetic component equivalent circuit as well as a methodology to extract its parameters by using a finite- element analysis tool. The model is valid for any kind of magnetic component-transformers and gapped and nongapped inductors-and takes into account frequency and geometry effects such as skin, proximity, interleaving, ga...

Nowadays, uninterruptible power supply (UPS) systems are in use throughout the world, helping to supply a wide variety of critical loads, in situations of power outage or anomalies of the mains. This article describes the most common line problems and the relationship between these and the different existing kinds of UPS, showing their operation mo...

Functional validation plays an important role in the design cycle of digital integrated circuits. The generation of good test benches is required for checking the complete circuit behaviour. Early location of design errors could highly reduce the development time and cost for these circuits. There are several initiatives for the development of meth...

Magnetic integration and magnetic coupling are very promising concepts to be applied in multiphase converters. Tight magnetic coupling allows energy transfer among phases. Ideally the magnetic component can act as a voltage source, with very low output impedance and with a perfect sharing of output current ripple. The main advantages provided by ma...

Supplying power to mobile equipment is one of today's trends in power electronics research. In this paper we review this problem from the perspective of four applications with very different specifications.

Next future vehicles will change battery voltage front 14 to 42 V. As a consequence, new converters are being developed to cover the needs of the electrical circuits. In the meantime, vehicles will have dual battery system (14 and 42 V). A 1 kW bidirectional 14-42V DC-DC converter has been built and tested for these vehicles. The goodness of the di...

Digital controllers are becoming an important alternative to the traditional analog solutions employed for controlling switching power converters. Among digital controllers, microprocessor-based implementations (such as DSPs) are the most usual ones. However, custom hardware implementations (FPGAs and ASICs) are obtaining special attention for thei...

This paper shows the goodness of the multiphase half bridge topology (two phases) for high input voltage (48 V), low output voltage (2 V) and high efficiency applications. The power stage is designed with a high current speed capability (20 A/μs) to reduce the size and cost of the output capacitors. The strong influence of the dynamics specs on the...

Piezoelectric transformers (PTs) provide several advantages compared to magnetic components that are higher power density, lower radiated noise and higher voltage isolation capability. PT must be properly designed to benefit the power converter with the advantages aforementioned. In this paper, a step by step procedure to determine the electrode ar...

Piezoelectric transformer (PT) design requires finite element analysis (FEA) tools, because its performance depends strongly on its shape (2D/3D effect). The main drawback of these tools is that they do not provide the electrical model needed to design the power converter. Nevertheless, the existing electrical models only take into account the main...

Since the temperature rise is one of the key parameters in the design of magnetic components, thermal models are commonly applied in order to calculate the temperature value. Finite element analysis (FEA) tools are typically used to visualize thermal distributions but not for obtaining a model from the field calculation. This work presents a new th...

Analytical magnetic models are used when the winding strategy and the geometry of the magnetic component produces an 1D magnetic field distribution. Additionally, analytical thermal models can be used when thermal distribution, the geometries of the windings and the core produce an 1D heat flux distribution. This work shows how both thermal and mag...

Interleaved converters are an interesting alternative for many applications due to their advantage in terms of dynamic response, output ripple cancellation, EMI reduction, thermal management and optimized design. In this paper, the benefits of interleaving from the point of view of size and losses reduction of the passive components are quantified....

The use of magnetic components containing winding as in different core legs is a common practice in order to integrate a transformer and an inductor in the same magnetic core (integrated magnetics). The use of a model for these components is a helpful tool to aid the designer in order to select the adequate winding strategy. This work presents a fu...

Increasing the input voltage of voltage regulator modules provides very attractive advantages to the system, reducing the distribution losses and improving the system stability. This paper analyzes how the increment of the input voltage affects the VRM itself. Several multiphase buck and multiphase half bridge solutions are designed, tested and com...

Switched converters are a source of EMI due to the hard switching and abrupt edges in the current and voltage waveforms. Interleaved converters can reduce the EMI at the source, minimizing the generation of conducted EMI, without changing the normal operation of the circuit. Input filter can be reduced, radiated EMI is lower and internal EMI proble...

1D thermal models are often used in the design of magnetic components in order to obtain an optimum design for a specific application. These thermal resistor-based models usually consider a thermal network based on the analogy between electricity and heat transfer equations. These models consider heat transfer in axial or radial direction using dif...

A resonant topology based on class-E is presented as the power supply of a cochlear implant. This topology has the important advantage of a small number of components and a grounded single switch. Zero voltage switching can be achieved, which significantly reduces switching losses and improves efficiency. A circuit has been designed, built and test...

Multiphase converters based on buck topology are very good candidates for voltage regulator modules that convert from 5 V or 12 V down to 1.5 V. However, their applicability is very restricted at higher input voltages (24 V, 48 V). In those applications where a fast dynamic on-board DC/DC converter with a high input voltage (24 V, 48 V) is required...

New recommendations and future standards have increased the interest in power factor correction circuits. There are multiple solutions in which line current is sinusoidal. In addition, a great number of circuits have been proposed with nonsinusoidal line current. In this paper, a review of the most interesting solutions for single phase and low pow...

A new strategy to accomplish low-frequency Regulation EN 61000-3-2 at system level is proposed in this paper. By means of a simple converter, connected in parallel with the loads, the harmonic currents generated by them are greatly reduced, it being unnecessary to include additional power-factor-correction converters. This approach is based on the...

This paper presents a very simple step-down DC/DC low power converter based on piezoelectric transformers (PTs) without any magnetic component. PTs become very interesting in this kind of applications comparing with magnetic transformers due to the higher power density. It is important to highlight that the PT has been specifically designed to avoi...

In this paper several techniques for integration of magnetic components in interleaved converters are analyzed. Magnetic components define the way the energy is transformed. Several opposite approaches can be considered: from decoupled integrated inductors to tightly coupled inductors. The integration of inductors in the same core for multiphase co...

The magnetic field in many magnetic components, namely toroids and EE cores, has a three-dimensional (3-D) distribution. Energy and losses calculation in these particular structures makes necessary the use of 3-D techniques that accounts for all 3-D effects. The calculation of the energy and losses is needed in order to obtain any transformer model...

Nowadays, most digital controls for power converters are based on DSPs. This paper presents a field programmable gate array (FPGA) based digital control for a power factor correction (PFC) flyback AC/DC converter. The main difference from DSP-based solutions is that FPGAs allow concurrent operation (simultaneous execution of all control procedures)...

The energy consumption in notebooks and multimedia terminals limits autonomy, high performance and further reduction of size. The DVS represents an alternative solution to current techniques that dramatically reduces energy consumption in digital systems. The power supply becomes a very important part of the system as it enables the voltage scaling...

The heterogeneity of sensor interfaces has caused the creation of the IEEE 1451.2 standard. This standard proposes a common digital interface for all sensors and a set of instructions to communicate with them. Following this standard, smart networked sensors can become a reality. In addition to the interface functions, an electronic data sheet is i...

This work presents a summary about the state of the art in thermal modeling for magnetic components. The thermal problem is formulated in terms of physical concepts and mathematical equations and the procedures for carrying out the analysis of the problem are outlined. Different magnetic thermal models are studied according to the thermal effects t...

When a physical connection cannot exist between the power source and the load, a transformer is usually used as a power link to transfer the energy. Primary and secondary windings of this transformer are usually separated a distance that is quite large compared to its own size. This means that coupling is low and leakage inductance is higher or com...

Switched mode power supplies are widely used due to their advantages on efficiency, size and weight. However, it is necessary to include an EMI filter that is not always considered, but affects the overall volume. This paper quantifies the advantages of the interleaved converters from the point of view of EMI generation. Clear benefits are obtained...

In this paper, a simple single-stage AC/DC converter based on the flyback topology is presented. With a single switch, a fast-regulated output voltage is achieved and, although the line current is not sinusoidal, the converter complies with the Standard IEC 1000-3-2 about low frequency harmonies for a medium power range (50-500 W). The major advant...

The goal of this paper is to design and test a "universal" low power (10 W) converter that can be fed from a very wide input voltage range (36 V-373 V), being possible to plug it in different power systems. Flyback with Active Clamp shows very good performance for this application and is used to test a 150 kHz, 5 V, 10 W prototype that operates eve...

Single-stage AC/DC power converters are an advisable solution to meet the regulations for low frequency harmonics (such as EN61000-3-2) at lower cost compared with the two-stage approach. The main challenge is the use of this type of converter in universal line voltage applications. In this paper, a single-stage AC/DC power converter capable of ope...

Usually, the performance of piezoelectric transformers (PTs) is optimum when they are sinusoidally driven. The PT can also be driven with a quasi-square voltage waveform. Although PT performance is not optimized with a squared driving, corresponding topologies can be simpler and the whole converter can be improved. Those alternatives that keep an i...

The time domain control theory and the root-locus analysis are applied to the design of the PWM buck controller. A method that focuses on the optimization of the close-loop output impedance when a step load occurs is proposed. It accounts for duty cycle saturation. The best transient response achievable by a power stage is obtained. Analytical resu...

Nowadays, most digital controls for power converters are based on DSPs. This paper presents a field programmable gate array (FPGA) based digital control for a power factor correction (PFC) flyback AC/DC converter. The main difference is that FPGAs allow concurrent operation (simultaneous execution of all control procedures), enabling high performan...

This work presents a new modeling strategy to account for the energy stored in the volume around the air gap in gapped magnetic components. The approach is based on the Schwarz-Christoffel transformation, which has been extended to axisymmetrical magnetic components. The results have been validated by means of comparisons with analytical expression...

Low power AC/DC adapters require a small size to be competitive. Among their components, the bulk capacitor is one of the largest because it should keep the input voltage with low ripple. Also, the size of this capacitor is penalized due to the universal line voltage application. A smaller size AC/DC adapter is proposed in this paper. Based on a to...

The goal of this paper is to show and quantify the advantages and drawbacks of flex foil technology and its application field in manufacturing flat HF transformers. A comparison between three different winding technologies (wires, PCB type and flex-foil) based both on experimental and simulation results is presented. Three multiwinding transformers...

A model for coreless magnetic components based on finite element analysis (FEA) is proposed. The lack of a nonlinear magnetic core is an advantage in terms of modelling. The characteristic of linearity makes these transformers perfectly suitable for modelling using FEA. A model based only on finite element analysis is proposed in this paper. This m...

Magnetic component models based on 1D field distribution assumption are widely used. They rely on the transformation of every layer of conductors into an equivalent foil layer. This paper presents a study of different approaches to obtain this equivalent layer, providing a physical insight on the scope and limitations of each approach. Some improve...

The proposed laboratory for teaching power electronics combines experimenting with a real prototype and using a simulator. In this case the teaching laboratory is focused on the switched DC/DC converters. Students can learn by their own and without professor assistance not only the theory about switched DC/DC converters, but also the differences be...

Piezoelectric transformers (PT) have become interesting for miniaturizing low power AC/DC or DC/DC converters. In this paper, interleaving of primary and secondary electrodes of the PT is analyzed in order to optimize the converter solutions based on PT. One of the problems to achieve a competitive PT converter is the additional magnetic components...

In this paper, the authors present a methodology that allows them to accommodate the conducted electromagnetic interference (EMI) generated by power factor correctors to international standards in the design step. EMI filter design considerations and EMI predictive procedures are presented. The predictive procedures are based in a family of curves...

A new scheme for driving the synchronous rectifiers in the output side of DC/DC converters has the output current always flowing through a low-resistance switch, even when the input-side switch(es) are not conducting. The gate-source voltage of the synchronous-rectifier switches is independent of (instead of proportional to) the dc input voltage, t...

Commonly, the magnetic component designer focuses the design on the performance of the magnetic component without a detailed analysis of the whole circuit. However, a complete design process should cover different stages, from the analytical design to the circuit simulation using accurate models. This paper presents a design example where it is hig...

The introduction of Regulation EN61000-3-2 a few years ago has forced power supply engineers to design AC/DC power converters that meet the limits imposed by it. As a consequence and considering that unity power factor is not required, many alternatives to the classical two-stage approach have been proposed reducing the cost of the power supply, es...

Distributed measurement and control (DMC) is a current trend in instrumentation systems. In order to enable this kind of systems, smart sensors have to be developed. This paper presents a system for interfacing and controlling a general set of sensors and actuators, making them smart ones. This system is IEEE 1451 compatible and has been developed...

The IEEE Std. 1149.1, also known as JTAG, defines a serial interface to access test-dedicated logic embedded in integrated circuits, although it is also being used as an FPGA programming interface. This paper makes an analysis of the possibilities of reusing this infrastructure in debugging applications implemented in FPGAs while in the prototype v...

Single winding self-driven synchronous rectification (SWSDSR) approach is a new driving circuit that overcomes the limitations of the traditional driving schemes, becoming an interesting alternative to supply new electronic loads such as microprocessors. Traditional self-driven synchronous rectification (SDSR) technique has shown very good performa...

The 48 V DC distribution is considered as a standard in the telecom world while datacom equipment is usually fed from AC mains. This fact has led Alcatel to propose a new power architecture for datacom-telecom applications where the system performance is improved, taking into account the existence of both types of loads. The new system is based on...

A new concept to drive piezoelectric transformers (PT) is presented and validated in this paper. The subharmonic driving consists on applying a voltage waveform to the PT whose fundamental frequency (f _PT/n) contains the resonance harmonic (f_PT) at which the PT transfers the energy. It is important to highlight that this solut...

Piezoelectric transformers (PTs) present an attractive solution compared with magnetic transformers because they have alternative characteristics that are appropriate for particular applications, namely high power density and high isolation levels with low EMI content. The behavior of PTs is very dependent on the material type, geometry and number...

Buck+Half Bridge (d=50%) topology is a very suitable circuit for low output voltage, high output current applications with a wide input voltage range. Its small signal transfer function is very complex and should be considered to optimize the dynamic response, efficiency and size of the power converter. Small signal and large signal behavior of thi...

New recommendations and future standards have increased the interest in power factor correction circuits. There are multiple solutions to this problem to obtain sinusoidal line current and in addition, a great number of circuits have been proposed with nonsinusoidal line current. In this paper, a review of the most interesting solutions for single...

This work presents a procedure valid to solve small signal tests of magnetic components (inductors and multiwinding transformers) by means of analytical expressions. The method is based on the use of the transmission line 1D model of the magnetic component. Since the test can be analytically solved, the procedure allows skipping the use of electric...