Research and innovation in power electronics systems applied to energy management

The Power Electronics Systems Group (GSEP) at University Carlos III de Madrid (Spain) offers its wide experience and background in consultancy, R&D projects with private and public funding and pre-industrial prototype building in four main topics: energy conversion (design, modelling and prototyping of equipments and systems), magnetic components modelling and design, photovoltaic systems and electromagnetic compatibility (EMC)

Investigación e innovación en sistemas electrónicos aplicados a la gestión de la energía

El Grupo de Sistemas Electrónicos de Potencia (GSEP) de la Universidad Carlos III de Madrid (España) ofrece su experiencia en servicios de consultoría, asesoría, proyectos I+D de financiación pública o privada y construcción de prototipos pre-industriales, en cuatro líneas de trabajo fundamentales: conversión de energía (diseño, modelado y construcción de equipos y sistemas), diseño y modelado de componentes magnéticos, sistemas fotovoltaicos y compatibilidad electromagnética

Estudio, desarrollo y modelado de nuevas topologías de convertidores CC/CC de múltiples salidas basadas en el control por modulación de anchura de pulso-retardo de pulso (PWM-PD)

Most of the electronic systems need several voltages with different values to work. This supposes an important market demand of reliable, cheap and robust power supply with several output voltages. The specifications of these systems are very different and variable, for this reason a big number of solutions have been developed to supply the market. Nowadays, the main design tendencies in electronic systems are going towards higher power, ‘smaller size, lower voltages (3.3V, 1.5V, 0.9V), and, therefore, higher currents. These requirements penalize the use of classical multiple output converters, since only an output voltage is fully regulated by means of a specific loop control. Consequently, the multiple output converters with all the outputs fully regulated are being more and more used. For this reason, the multiple output converters based on postregulation have had an important expansion. Generally, most of the multiple output converters with postregulation are more expensive than classical solutions, specially, in medium and high power. Therefore, new topologies and strategies are needed to get cheaper multiple output converters fully regulated, and, in any case, to get new alternatives to the nowadays used. For these reasons, in this thesis an original and extensive family of converters is proposed. This new family is composed of converters with and without transformer, and, with and without postregulation. The converters belonging to this new family are named “PWM-PD Multiple output converters”, since they are based 011 the novel “PWM-PD Control” (Pulse Width Modulation-Pulse Delay). The PWM-PD control is presented in this document. Furthermore, several new topologies, a general design method, and a set of accurate small-signal models are proposed. Finally, several prototypes have been built to test both, the circuits and the models developed. These prototypes have corroborated the good operation of this new family of converters.Programa de Doctorado en Tecnologías Industriales por la Universidad Carlos III de MadridPedro M. Martínez Martínez.- Vocales: Joan Peracaula, Salvador Martínez García, Javier Sebastián Zúñiga.- Vocal secretario: Luis Alfonso Entrena Arronte

Comparison of different large signal measurement setups for high frequency inductors

This article belongs to the Special Issue High-Frequency Power Converters.The growing interest of miniaturized power converters has pushed the development of high frequency inductors integrated in Power Supply on Chip or Power Supply in Package. The proper characterization of inductor impedance is a challenge due to the dependence of the impedance on the current, the high quality factor (Q) and the high frequency range where these devices operate. In this paper, we present a comparison of different measuring methods to characterize high frequency and high Q inductors. The comparison is based on a systematic analysis of the measurement process, quantifying the influence of the parameters that affect the measurement result. Four common measurement setups are analyzed and compared. To validate the calculations, the resistance of a high frequency, high-Q inductor is characterized using every presented setup. The good match between calculations, simulation and measurement validates the analysis and the conclusions extracted.This research was founded by the Spanish Ministry of Ciencia, Innovación y Universidades and FEDER funds through the research project EPIIOT under Grant DPI2017-88062-R, and by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M26), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)

Nonparametric frequency response identification for Dc-Dc converters based on spectral analysis with automatic determination of the perturbation amplitude

Digital control for high switching frequency converter enables new features on DC-DC power conversion for a minimum cost. Frequency response identification is one such enabled functionality used in auto tunning, measurement of components to assess the converter’s state of health, or system stability monitoring. High accuracy, flexibility to operate in open or closed loop, and minimum impact in the converter’s regular operation are the frequency response identification system’s goals. We propose in this paper a nonparametric identification system addressing these main goals. First, it can autoadjust the perturbation size to reduce the perturbation’s impact on the converter’s output quantities. Second, as it is based on spectral analysis, it is suitable for open and closed-loop operation. Third, we demonstrate the identification system’s high accuracy, achieving a very low difference between the experimental measurements and the discrete model used as reference.This research was founded by the Spanish Ministry of Ciencia, Innovacióon y Universidades and FEDER funds through the research project EPIIOT under Grant DPI2017-88062-R, and by the Madrid Government (Comunidad de Madrid-Spain) under the Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M26), and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)

Numerical and Experimental Evaluation and Heat Transfer Characteristics of a Soft Magnetic Transformer Built from Laminated Steel Plates

The present work evaluates, both experimentally and numerically, the heat transfer characteristics of a 5 kW three-phase transformer built from laminated steel sheets. The transformer is operated at different powers, and its temperature distribution is monitored using 108 thermocouples. The experimental measurements are used firstly to determine the heat dissipated at the core and the windings of the transformer. This information is used as an input for a finite element numerical model, which evaluates the heat transfer characteristics of the transformer. The model proposed in this work simply solves the diffusion equation inside the transformer, accounting for the anisotropic thermal conductivity of the different components of the transformer, together with well-known correlations at its boundaries. The results reveal that the proposed numerical model can correctly reproduce the maximum temperature, the temperature distribution, and the time-evolution of the temperature at specific points of the transformer measured during the experimental campaign. These results are of great use for the subsequent development of transformers of the same type in lab-scale or industrial-scale size and reveal the applicability of simplified numerical models to accurately predict the heat transfer characteristics of this kind of transformers.Eduardo Cano-Pleite acknowledges support from the CONEX-Plus programme funded by Universidad Carlos III de Madrid and the European Union’s Horizon 2020 programme under the Marie Sklodowska-Curie grant agreement No. 801538.Publicad

General parameter identification procedure and comparative study of Li-Ion battery models

Accurate and robust battery models are required for the proper design and operation of battery-powered systems. However, the parametric identification of these models requires extensive and sophisticated methods to achieve enough accuracy. This article shows a general and straightforward procedure, based on Simulink and Simscape of Matlab, to build and parameterize Li-ion battery models. The model parameters are identified with the Optimization Toolbox of Matlab, by means of an iterative process to minimize the sum of the squared errors. In addition, this procedure is applied to a selection of five different models available in the literature for electric vehicle applications, obtaining a comparative study between them. Also, the performance of each battery model is evaluated through two current profiles from two driven profiles known as the Urban Driving Cycle (ECE-15 or UDC) and the Hybrid Pulse Power Characterization (HPPC). The experimental results obtained from a Li-ion polymer battery have been compared with the data provided by the models, confirming the effectiveness of the proposed procedure, and also, the application field of each model as a function of the required accuracy.This work was supported by the Ministry of Economy and Competitiveness and FEDER funds through the research project “Storage and Energy Management for Hybrid Electric Vehicles based on Fuel Cell, Battery, and Supercapacitors”—ELECTRICAR-AG-(DPI2014- 53685-C2-1-R)

Step-by-step small-signal modeling and control of a light hybrid electric vehicle propulsion system

This paper develops step-by-step a complete electric model of a light hybrid electric vehicle propulsion system. This model includes the vehicle mass, the radius and mass of the wheels, the aerodynamic profile of the vehicle, the electric motor and the motor drive, among other elements. Each element of the model is represented by a set of equations, which lead to getting an equivalent electric circuit. Based on this model, the outer and inner loop compensators of the motor drive control circuit are designed to provide stability and a fast dynamic response to the system. To achieve this, the steady-state equations and the small-signal model of the equivalent electric circuit are also obtained. Furthermore, as these elements are the main load of the power distribution system of the fully electric and light hybrid electric vehicle, the input impedance model of the set composed of the input filter, the motor drive, the motor, and the vehicle is presented. This input impedance is especially useful to get the system stability of the entire power distribution system.This work has been partially supported by the Spanish Ministry of Economy and Competitiveness and FEDER (ERDF), through the research project "Storage and Energy Management for Hybrid Electric Vehicles based on Fuel Cell, Battery and Supercapacitors" -ELECTRICAR-AG- (DPI2014-53685-C2-1-R

Non-inverting and Non-isolated Magnetically Coupled Buck-Boost Bidirectional DC-DC Converter

A new non-isolated DC-DC converter with non-inverting output and buck-boost operation, named Magnetically Coupled Buck-Boost Bidirectional converter (MCB³), is presented in this paper. The MCB³ passive components arrangement connects the input and output ports getting an equivalent behavior to that of the Dual Active Bridge (DAB) converter, but in a non-isolated topology. This equivalency allows applying Triple Phase Shift (TPS) modulation to MCB³. TPS is known to minimize conduction losses and to achieve soft-switching at any load in the DAB converter. Throughout the paper, the features of the DAB converter are used as a reference to show the main features of the proposed converter. Moreover, other modulation strategies based on TPS modulation are used in MCB³ to operate within the minimum losses path.The multiple operation modes found on the MCB³ under TPS modulation are identified, classified, and used to find the operating points that minimize the switching and conduction losses over the power range. The analysis is shown for the boost mode that is the worst-case design. MCB³ and DAB topologies are designed and simulated for the same specification to validate the theoretical study. Finally, experimental measurements on 460W-prototypes for both topologies corroborate the equivalent operation and the main features of the MCB³.This work was supported in part by the Ministry of Economy and Competitiveness and ERDF funds through the Research Project “Energy Storage and Management System for Hybrid Electric Cars based on Fuel Cell, Battery and Supercapacitors” ELECTRICAR-AG- (DPI2014-53685-C2-1-R), and in part by the Research Projects CONEXPOT (DPI2017-84572-C2-2-R) and EPIIOT (DPI2017-88062-R

Analysis and implementation of the Buck-Boost Modified Series Forward converter applied to photovoltaic systems

The mismatching phenomenon is one of the main issues in photovoltaic (PV) applications. It could reduce the generated power of a string when a PV panel has different performances from the other PV panels connected to the same string. Distributed Maximum Power Point Tracking (DMPPT) architectures are one of the most promising solutions to overcome the drawbacks associated with mismatching phenomena in PV applications. In this kind of architectures, a DC-DC module integrated converter (MIC) manages each PV panel, isolating it from the rest of the PV panels, for harvesting the maximum available power from the Sun. Due to the high number of DCDC converters used in a grid-tied PV installation, the most desired MIC requirements are high efficiency, low cost and the capability of voltage step-up and step-down. This paper proposes the Buck-Boost Modified Forward (BBMSF) converter as a good candidate to be applied in DMPPT architectures. A complete analysis of the BBMSF converter is carried out, including the steady-state analysis as well as the small signal analysis in continuous conduction mode. The main advantages of the BBMSF converter are its step-up and step-down voltage transfer function; a higher simplicity, since it only includes a single controlled switch; the soft switching characteristics in all the diodes and MOSFET, reaching in some cases ZVS and ZCS, and yielding high efficiencies; the use of an autotransformer, with better performances than a typical Forward transformer; and the good dynamic performance, like the Forward converter ones. The theoretical analyses are validated through the experimental results in a 225 W BBMSF prototype designed and built under the requirements of a 100 kW grid-tied PV installation, achieving an efficiency up to 93.6%.This work has been supported by the Ministry of Economy and Competitiveness and FEDER funds through the research project "Storage and Energy Management for Hybrid Electric Vehicles based on Fuel Cell, Battery and Supercapacitors" - ELECTRICAR-AG- (DPI2014-53685-C2-1-R)