Alberto M. Pernía

Power Supply for a High-Voltage Application

In this paper, the guidelines to design a high-voltage power converter based on the hybrid series parallel resonant topology, PRC-LCC, with a capacitor as output filter are established. As a consequence of the selection of this topology, transformer ratio, and therefore secondary volume, is reduced. The mathematical analysis provides an original equivalent circuit for the steady-state and dynamical behavior of the topology. A new way to construct high-voltage transformers is also proposed, pointing out the advantages and establishing an original method to evaluate the stray components of the transformer before construction. The way to make compatible the characteristics of both, topology and transformer is illustrated in the frame of a practical application. To demonstrate the feasibility of this solution, a high-voltage, high-power prototype is assembled and tested with good performance and similar behavior to the one predicted by the models. Experimental results are shown on this particular.

Dynamic and Steady-State Models for the PRC-LCC Resonant Topology With a Capacitor as Output Filter

In high-voltage DC power supplies (hundreds of kilovolts), avoiding the inductance in the output filter is an important asset. Thus, a capacitor as a unique component of that filter is preferable. On the other hand, a high-voltage step-up transformer shows a high capacitance in its secondary, which can be included in a resonant stage. Both capacitances, i.e., one from the filter and the other from the transformer, are separated by the output rectifier. When this rectifier is on, they are in parallel; when it is off, they are disconnected. A resonant stage where a very large capacitor appears and disappears several times in one period is not linear and has not been dynamically modeled before. This paper shows two simple models for the parallel-series (LCC-type parallel resonant converter) resonant topology with a capacitor as output filter. Its dynamics and steady state are studied and constitute an important help for any designer.

Intelligent and universal fast charger for Ni-Cd and Ni-MH batteries in portable applications

In this paper, a new fast charger is presented for Ni-Cd and Ni-MH batteries, which are the most frequently used in portable applications. In this charger, the control and supervision of the process has been entrusted to a microcontroller, which provides a powerful and intelligent tool to undertake complex tasks, and reduces the requested circuitry to the microcontroller itself and a few additional components. The resulting charger is able to work out the initial battery state (detecting deteriorated devices), decide the suitable way to charge it (ensuring a long cyclic life), and determine when the charge process must be finished. This way, the state of the battery is always controlled, preventing any damage to it and providing a fully protected operation mode. This paper summarizes the design and construction of the presented charger, as well as shows the experimental results obtained in the prototype tests.

Design and analysis of thick-film integrated inductors for power converters

This paper describes the design procedures followed to obtain a thick-film inductor for its application in DC/DC power microconverters. The main characteristics of the new technology used are commented upon and design equations are given. Results are compared to those obtained by means of finite-element analysis tools. Details of some thick-film inductors developed with this technique (within the framework of the IMPASS Esprit Project (number 23910), financed by the European Community) are also given. The inclusion of one of these inductors in a 5-to-3.3-V DC/DC converter contributes to obtaining a very high power density: 6.25 W/cm/sup 3/.

1D/2D transformer electric model for simulation in power converters

This paper describes two complete electric models that characterize transformer windings. The models have the geometric information of the magnetic component and give accurate results for high frequency simulations. Both models are derived from Maxwell equations and the expressions to calculate the electric parameters directly from the geometry are shown. The models are suitable to be included in any simulation programs having very short generation time. This fact avoids the use of complex finite element analysis (FEA) tools.<<ETX>>

A multiwinding modeling method for high frequency transformers and inductors

This paper presents a method to obtain an electric model for transformers and inductors, including both frequency and geometry effects in the windings, which can be linked with existing core models. One-dimensional distributions for magnetic and electric fields are assumed, and from Maxwells equations an equivalent electric circuit is easily obtained. This equivalent circuit has been included in analog simulators (Spice, AnalogWorkBench, Saber ...), and comparisons between measured and simulated results are shown, both in time domain and in AC sweep, which verify the model accuracy. The model described in this paper allows designers to deal with key issues in the design of high-frequency magnetic components (copper losses, leakage inductance, skin and proximity effects) by using analog simulators, which are usually more familiar to them than finite-element analysis tools.

A modular PV regulator based on microcontroller with maximum power point tracking

We can find many different types of commercial regulators in the market, these devices basically can be divided into two categories according to their operation mode: The first ones modulate the input voltage with PWM (pulse width modulation) to hold the constant voltage in the output necessary to charge the battery. The other ones operate in the MPP (maximum power point) of the PV (photovoltaic) array, tracking it by different ways depending on the type of regulator; these regulators are called MPPTs (maximum power point trackers). The increase of power using a maximum power point tracker can be up to 25%. This paper presents a regulator which can operate in the maximum power point of PV arrays regardless of the meteorological conditions and the effects of them in the dispersion of the PV array characteristics. Parallel connection of this kind of regulators is also proposed, which allows installation without the need to get rid of previous equipment.

Development of a wireless sensor network for individual monitoring of panels in a photovoltaic plant.

With photovoltaic (PV) systems proliferating in the last few years due to the high prices of fossil fuels and pollution issues, among others, it is extremely important to monitor the efficiency of these plants and optimize the energy production process. This will also result in improvements related to the maintenance and security of the installation. In order to do so, the main parameters in the plant must be continuously monitored so that the appropriate actions can be carried out. This monitoring should not only be carried out at a global level, but also at panel-level, so that a better understanding of what is actually happening in the PV plant can be obtained. This paper presents a system based on a wireless sensor network (WSN) that includes all the components required for such monitoring as well as a power supply obtaining the energy required by the sensors from the photovoltaic panels. The system proposed succeeds in identifying all the nodes in the network and provides real-time monitoring while tracking efficiency, features, failures and weaknesses from a single cell up to the whole infrastructure. Thus, the decision-making process is simplified, which contributes to reducing failures, wastes and, consequently, costs.

A Circuit for the Large and Small Signal Dynamic Modeling of the PRC-LCC Resonant Topology with a Capacitor as Output Filter

This paper explains how to obtain and solve with PSpice a simple mathematical model for the series-parallel resonant topology (PRC-LCC) with a capacitor as output filter. The model provides dynamic information useful to calculate any voltage and current in the topology and design the feedback loop. If the extended describing function and the generalized averaging method are applied to the general equations of the topology, five non-linear differential equations are obtained. This five equations constitute the large signal model, which can be solved by numeric calculation or, simpler, with the aid of PSpice. To use PSpice, the large signal model of the topology is translated into an equivalent circuit. As the circuit contains all the information about dynamical behavior of the topology, large and small signal analysis can be carried out. In both cases, PSpice results have been experimentally verified. The paper can also be of use to implement the model in other simulation environments

Up–Down Converter for Energy Recovery in a CDI Desalination System

One of the newest methods for desalinating water is capacitive deionization (CDI). This technology is based on carbon electrodes capable of adsorbing ionic components from water. The aim of this paper is to present the power electronic stage required in a water desalination system that permits recovery of part of the energy involved in the process and its reuse in a high efficient manner. First, the CDI process and the energy recovery are described. Second, a buck-boost converter is designed that allows energy to be recovered while taking into account the large voltage variations at its input and output. The converter is modeled using a mathematical algorithm to study its behavior with large input and output capacitor values. Simulation results are provided as well as experimental data agreeing with them.