F. Segura

Analog Current Control Techniques for Power Control in PEM Fuel-Cell Hybrid Systems: A Critical Review and a Practical Application

This paper presents a prototype of a proton exchange membrane (PEM) fuel-cell hybrid system, with a bus connection set by a dc battery bank and all the power electronics and control needed to manage the system. The system power control is based on analog current control. To choose the topology of the controller, a critical review of all the topologies of analog current controllers for dc/dc converters has been done. This review was necessary because there is no literature found that shows a similar compilation. In the experimental part, the proper functioning of the controlled hybrid system is reflected on one hand and the way to solve the known problem of starvation on the other hand. A very important aspect of the system is its scalability. It can be developed in parallel to implement a whole system that handles power levels higher than the rate power of each single fuel-cell system.

An application of interleaved DC-DC converters to obtain I-V characteristic curves of photovoltaic modules

The basic operation of a solar cell, module or photovoltaic generator under different irradiation and temperature conditions is characterized by its I-V characteristic curve. Only the experimental measurement of the I-V curve allows us to know the electrical parameters of a photovoltaic cell, module or array. This measure provides very relevant information for the design, installation and maintenance of photovoltaic systems. Currently, the I-V characteristic curve is obtained by connecting a variable charge to the panel terminals in order to achieve that the current of the terminals ranges from zero to the short circuit current. In this paper, a new experimental methodology to measure this characteristic curve by using several SEPIC converters in parallel connection operating in interleaved mode is proposed. This methodology provides two fundamental advantages for this application as regards the use of a single converter: (1) It allows to reproduce I-V curves of higher power (2) It allows to obtain these curves with lower ripple.

A New, Scalable and Low Cost Multi-Channel Monitoring System for Polymer Electrolyte Fuel Cells

In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level.In this work a new, scalable and low cost multi-channel monitoring system for Polymer Electrolyte Fuel Cells (PEFCs) has been designed, constructed and experimentally validated. This developed monitoring system performs non-intrusive voltage measurement of each individual cell of a PEFC stack and it is scalable, in the sense that it is capable to carry out measurements in stacks from 1 to 120 cells (from watts to kilowatts). The developed system comprises two main subsystems: hardware devoted to data acquisition (DAQ) and software devoted to real-time monitoring. The DAQ subsystem is based on the low-cost open-source platform Arduino and the real-time monitoring subsystem has been developed using the high-level graphical language NI LabVIEW. Such integration can be considered a novelty in scientific literature for PEFC monitoring systems. An original amplifying and multiplexing board has been designed to increase the Arduino input port availability. Data storage and real-time monitoring have been performed with an easy-to-use interface. Graphical and numerical visualization allows a continuous tracking of cell voltage. Scalability, flexibility, easy-to-use, versatility and low cost are the main features of the proposed approach. The system is described and experimental results are presented. These results demonstrate its suitability to monitor the voltage in a PEFC at cell level.

An approach to obtain the V-I characteristic of fuel cells by means of DC-DC converters

This paper proposes a new approach to test and evaluate V-I characteristics of fuel cells stacks based on DC-DC converters, which features are simple structure, scalability, fast response and low cost. The measurement of the desired characteristic of fuel cells includes high speed of response, high fidelity and low cost. The obtained results show that all DC-DC topologies are not capable of reproducing this characteristic and that SEPIC (Single-Ended Primary Inductance Converter) converter is optimal for this application. Experimental results show the usefulness of the proposed method.

Hardware/Software Data Acquisition System for Real Time Cell Temperature Monitoring in Air-Cooled Polymer Electrolyte Fuel Cells

This work presents a hardware/software data acquisition system developed for monitoring the temperature in real time of the cells in Air-Cooled Polymer Electrolyte Fuel Cells (AC-PEFC). These fuel cells are of great interest because they can carry out, in a single operation, the processes of oxidation and refrigeration. This allows reduction of weight, volume, cost and complexity of the control system in the AC-PEFC. In this type of PEFC (and in general in any PEFC), the reliable monitoring of temperature along the entire surface of the stack is fundamental, since a suitable temperature and a regular distribution thereof, are key for a better performance of the stack and a longer lifetime under the best operating conditions. The developed data acquisition (DAQ) system can perform non-intrusive temperature measurements of each individual cell of an AC-PEFC stack of any power (from watts to kilowatts). The stack power is related to the temperature gradient; i.e., a higher power corresponds to a higher stack surface, and consequently higher temperature difference between the coldest and the hottest point. The developed DAQ system has been implemented with the low-cost open-source platform Arduino, and it is completed with a modular virtual instrument that has been developed using NI LabVIEW. Temperature vs time evolution of all the cells of an AC-PEFC both together and individually can be registered and supervised. The paper explains comprehensively the developed DAQ system together with experimental results that demonstrate the suitability of the system.

A review of bop configurations for PEFCs. Experimental study of a suitable topology

This paper presents first a comprehensive review about Balance of Plant (BoP) configurations applied to polymer electrolyte stacks. Taking into account this review, a suitable topology (from our point of view the best) is chosen and analyzed experimentally following a standardized procedure, not only how the stack voltage responds to load current changes (upward and downward) but also to hydrogen pressure, hydrogen flow, stack temperature, stoichiometric rate, fan performance and stack power.

Study of a renewable energy sources-based smart grid. requirements, targets and solutions

More and more often governments around the world drive their efforts on displacing their actual electricity production models which consist on large power plants based on fossil fuels, towards other ones based on renewable energy source, usually smaller and geographically distributed. Two main reasons justify this movement: 1-the increasingly environmental problem derived from the use of fossil fuels and 2-the long distances they must be overcome to transport the electricity from the production point to consumption area. In this paper authors propose a distributed power generation system with interconnected loads (microgrid), made up by solar panels (PV), wind turbines (WT), a batteries bank (BAT) and a modular fuel cell system. In addition, an electrolyzer (load) will convert the electrical energy into chemical energy with the use of hydrogen like energy vector. To put in work this microgrid, it is needed a proper energy management strategy which takes into account both technical and economical parameters (smart grid). This paper analyses the hierarchical structure of the proposed smart grid, starting from primary sources, and finishing with the whole plant. Furthermore it is proposed and tested an energy management strategy which satisfies smart grid requirements at time that accomplishes the fixed targets.