108 research outputs found

    Development of controllers using FPGA for fuel cells in standalone and utility applications

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    In the recent years, increase in consumption of energy, instability of crude oil price and global climate change has forced researchers to focus more on renewable energy sources.Though there are different renewable energy sources available (such as photovoltaic and wind energy), they have some major limitations. The potential techniques which can provide renewable energy are fuel cell technology which is better than other renewable sources of energy. Solid oxide fuel cell (SOFC) is more efficient, environmental friendly renewable energy source. This dissertation focuses on load/grid connected fuel cell power system (FCPS) which can be used as a backup power source for household and commercial units. This backup power source will be efficient and will provide energy at an affordable per unit cost. Load/grid connected fuel cell power system mainly comprises of a fuel cell module, DCDC converter and DC-AC inverter. This thesis primarily focuses on solid oxide fuel cell (SOFC) modelling, digital control of DC-DC converter and DC-AC inverter. Extensive simulation results are validated by experimental results. Dynamic mathematical model of SOFC is developed to find out output voltage, efficiency, over potential loss and power density of fuel cell stack. The output voltage of fuel cell is fed to a DC-DC converter to step up the output voltage. Conventional Proportional-Integral (PI) controller and FPGA based PI controller is implemented and experimentally validated. The output voltage of DC-DC converter is fed to DC-AC inverter. Different pulse width modulation-voltage source inverter (PWM-VSI) control strategy (such as Hysteresis Current Controller (HCC), Adaptive-HCC, Fuzzy-HCC, Adaptive Fuzzy-HCC, Triangular Carrier Current Controller (TCCC) and Triangular Periodical Current Controller (TPCC)) for DC-AC inverter are investigated and validated through extensive simulations using MATLAB/SIMULINK. This work also focuses on number of fuel cells required for application in real time and remedy strategies when one or few fuel cells are malfunctioning. When the required numbers of fuel cells are not available, DC-DC converter is used to step up the output voltage of fuel cell. When there is a malfunction in fuel cell or shortage of hydrogen then a battery is used to provide backup power

    Applications of Power Electronics:Volume 1

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    Design and test of digitally-controlled power management IPs in advanced CMOS technologies

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    Les technologies avancées de semi-conducteur permettent de mettre en œuvre un contrôleur numérique dédié aux convertisseurs à découpage, de faible puissance et de fréquence de découpage élevée sur FPGA et ASIC. Cette thèse vise à proposer des contrôleurs numériques des performances élevées, de faible consommation énergétique et qui peuvent être implémentés facilement. En plus des contrôleurs numériques existants comme PID, RST, tri-mode et par mode de glissement, un nouveau contrôleur numérique (DDP) pour le convertisseur abaisseur de tension est proposé sur le principe de la commande prédictive: il introduit une nouvelle variable de contrôle qui est la position de la largeur d'impulsion permettant de contrôler de façon simultanée le courant dans l'inductance et la tension de sortie. La solution permet une dynamique très rapide en transitoire, aussi bien pour la variation de la charge que pour les changements de tension de référence. Les résultats expérimentaux sur FPGA vérifient les performances de ce contrôleur jusqu'à la fréquence de découpage de 4MHz. Un contrôleur numérique nécessite une modulation numérique de largeur d'impulsion (DPWM). L'approche Sigma-Delta de la DPWM est un bon candidat en ce qui concerne le compromis entre la complexité et les performances. Un guide de conception d'étage Sigma-Delta pour le DPWM est présenté. Une architecture améliorée de traditionnelles 1-1 MASH Sigma-Delta DPWM est synthétisée sans détérioration de la stabilité en boucle fermée ainsi qu'en préservant un coût raisonnable en ressources matérielles. Les résultats expérimentaux sur FPGA vérifient les performances des DPWM proposées en régimes stationnaire et transitoire. Deux ASICs sont portés en CMOS 0,35 m: le contrôleur en tri-mode pour le convertisseur abaisseur de tension et la commande par mode de glissement pour les convertisseurs abaisseur et élévateur de tension. Les bancs de test sont conçus pour conduire à un modèle d'évaluation de consommation énergétique. Pour le contrôleur en tri-mode, la consommation de puissance mesurée est seulement de 24,56mW/MHz lorsque le ratio de temps en régime de repos (stand-by) est 0,7. Les consommations de puissance de command par mode de glissement pour les convertisseurs abaisseur et élévateur de tension sont respectivement de 4,46mW/MHz et 4,79mW/MHz. En utilisant le modèle de puissance, une consommation de la puissance estimée inférieure à 1mW/MHz est envisageable dans des technologies CMOS plus avancées. Comparé aux contrôlés homologues analogiques de l'état de l'art, les prototypes ASICs illustrent la possibilité d'atteindre un rendement comparable pour les applications de faible et de moyen puissance mais avec l'avantage d'une meilleure précision et une meilleure flexibilité.Owing to the development of modern semiconductor technology, it is possible to implement a digital controller for low-power high switching frequency DC-DC power converter in FPGA and ASIC. This thesis is intended to propose digital controllers with high performance, low power consumption and simple implementation architecture. Besides existing digital control-laws, such as PID, RST, tri-mode and sliding-mode (SM), a novel digital control-law, direct control with dual-state-variable prediction (DDP control), for the buck converter is proposed based on the principle of predictive control. Compared to traditional current-mode predictive control, the predictions of the inductor current and the output voltage are performed at the same time by adding a control variable to the DPWM signal. DDP control exhibits very high dynamic transient performances under both load variations and reference changes. Experimental results in FPGA verify the performances at switching frequency up to 4MHz. For the boost converter exhibiting more serious nonlinearity, linear PID and nonlinear SM controllers are designed and implemented in FPGA to verify the performances. A digital control requires a DPWM. Sigma-Delta DPWM is therefore a good candidate regarding the implementation complexity and performances. An idle-tone free condition for Sigma-Delta DPWM is considered to reduce the inherent tone-noise under DC-excitation compared to the classic approach. A guideline for Sigma-Delta DPWM helps to satisfy proposed condition. In addition, an 1-1 MASH Sigma-Delta DPWM with a feasible dither generation module is proposed to further restrain the idle-tone effect without deteriorating the closed-loop stability as well as to preserve a reasonable cost in hardware resources. The FPGA-based experimental results verify the performances of proposed DPWM in steady-state and transient-state. Two ASICs in 0.35 m CMOS process are implemented including the tri-mode controller for buck converter and the PID and SM controllers for the buck and boost converters respectively. The lab-scale tests are designed to lead to a power assessment model suggesting feasible applications. For the tri-mode controller, the measured power consumption is only 24.56mW/MHz when the time ratio of stand-by operation mode is 0.7. As specific power optimization strategies in RTL and system-level are applied to the latter chip, the measured power consumptions of the SM controllers for buck converter and boost converter are 4.46mW/MHz and 4.79mW/MHz respectively. The power consumption is foreseen as less than 1mW/MHz when the process scales down to nanometer technologies based on the power-scaling model. Compared to the state-of-the-art analog counterpart, the prototype ICs are proven to achieve comparable or even higher power efficiency for low-to-medium power applications with the benefit of better accuracy and better flexibility.VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF

    Design and Control of Power Converters 2019

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    In this book, 20 papers focused on different fields of power electronics are gathered. Approximately half of the papers are focused on different control issues and techniques, ranging from the computer-aided design of digital compensators to more specific approaches such as fuzzy or sliding control techniques. The rest of the papers are focused on the design of novel topologies. The fields in which these controls and topologies are applied are varied: MMCs, photovoltaic systems, supercapacitors and traction systems, LEDs, wireless power transfer, etc

    Design and Development of FPGA based Controllers for Photovoltaic Power System

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    In the recent years owing to increased energy consumption and consequent rise in crude oil price and global climatic change have motivated researchers to focus towards harnessing power from renewable energy resources such as photovoltaic (PV), fuel cell, biomass and wind energy systems. Among the different renewable resources, PV technology is one of the fastest growing technologies, because of abundance availability of solar irradiance and it has no adverse environmental impacts. But, the cost of PV energy is higher than the other conventional sources owing to its low PV conversion efficiency. Therefore, research opportunities lie in applying power electronics and control techniques for harvesting PV power at higher efficiencies for appropriate utilization. For simulation, analysis and control design of a PV power system, an accurate model of the PV cell is essential because PV cell is the basic bulding block of a PV power system. To maximise the power generation of a PV system it is necessary that the PV array should be operated at the maximum power point. A maximum power point tracker (MPPT) is required in the PV system to enable it to operate at the MPP. The output current-voltage (I-V) and power-voltage (P-V) characteristics of a PV vell are non-linear and hence its power fluctuates in accordance with the variation in solar irradiance and temperature. During the last decade, a lot of research has been directed to develop efficient MPPT schemes. But, research opportunities are still promising for designing new MPPT algorithms and to address their digital implementation issues. Further, there lies challenge to design MPPTs that can handle partial shading conditions. The thesis first proposes development of new MPPT algorithms and different pulse width modulated-voltage source inverter control strategies for a PV system. Firstly an integral sliding mode MPPT controller (ISMC) has been proposed for achieving an effective MPPT scheme, and then a modified P&O MPPT controller is developed which is implemented using a real-time digital simulator called Opal-RT. The performance of the modified ISMC is compared with that of the conventional proportional integral (PI) MPPT controller using both MATLAB simulation and real-time experimentation. The performance of the modified P&O MPPT controller with fixed step size is compared with that of the conventional incremental conductance (Inc Cond) and P&O MPPT controllers, and these are validated by using Opal-RT and subsequently through FPGA implementation. A modified incremental conductance MPPT controller with variable step size is then proposed for handling partial shading conditions. The tracking performance of the proposed modified Inc Cond MPPT controller is also compared with that of the conventional Inc Cond MPPT controller, from the obtained results by using Opal-RT. Further, an experimental prototype PV set-up is developed in the laboratory to implement the proposed MPPT algorithms on the physical hardware. After having developed efficient parameter extraction algorithms for a PV panel, the thesis subsequently proposes five new MPPT algorithms such as Integral sliding mode MPPT, modified P&O MPPT, modified Inc Cond MPPT, Model predictive MPPT, and modified Inc Cond variable step size MPPT controllers. All these developed MPPT algorithms have been implemented on a Solar array simulator (SAS) PV system, in MATLAB/SIMULINK, OPAL-RT and on a prototype hardware PV set-up. From the obtained results, it is found that these MPPTs adjust the power of a PV system effectively to its maximum power value smoothly with fast response and accuracy whilst reducing the fluctuations in its power. Tracking performance of all these proposed MPPT algorithms are found to be superior to some of the existing MPPTs such as perturb and observe (P&O), incremental conductance (INC), HCC and adaptive HCC. Further more, a PV system is observed to be stable with all these proposed MPPTs. From the results obtained it is also confirmed that the proposed modified P&O MPPT exhibits better MPP tracking performance in terms of quick settling time and least steady state error. Further, less voltage fluctuation and less maximum overshoot are observed in the case of the proposed modified Inc Cond MPPT among all the proposed MPPT algorithms. The proposed controllers are also well suited to all weather conditions. A grid connected PV system involves a power conversion from DC power into AC power. Due to high switching frequencies of this conversion by inverter, there is a power loss. An efficient control scheme needs to be developed for integrating the PV system to the grid. The thesis then proposes a Model Predictive Control (MPC) for integrating a PV system to the grid. The performance of the MPC is compared with conventional hysteresis current controller (HCC) and also with that of an adaptive HCC (AHCC) through a real-time simulatin using the Opal-RT then through FPGA implementations. FPGA implementation of the controllers such as HCC, AHCC and MPC were also performed by using LABVIEW configured with NI-cRIO-9014 platform. For elimination of current harmonic and reactive power of the grid connected PV system, there is a need of designing a filter. The PV system based shunt active power filter (SAPF) with modified incremental conductance MPPT controller with variable step size is then designed. From the MATLAB simulation and real-time digital simulation studies it is envisaged that the proposed PV based SAPF exhibits good harmonics compensation

    Stratégies de commande numérique pour un convertisseur DC/DC SEPIC en vue de l intégration

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    L utilisation des alimentations à découpage (SMPSs : switched mode power supplies) est à présent largement répandue dans des systèmes embarqués en raison de leur rendement. Les exigences technologiques de ces systèmes nécessitent simultanément une très bonne régulation de tension et une forte compacité des composants. SEPIC (Single-Ended Primary Inductor Converter) est un convertisseur à découpage DC/DC qui possède plusieurs avantages par rapport à d autres convertisseurs de structure classique. Du fait de son ordre élevé et de sa forte non linéarité, il reste encore peu exploité. L objectif de ce travail est d une part le développement des stratégies de commande performantes pour un convertisseur SEPIC et d autre part l implémentation efficace des algorithmes de commande développés pour des applications embarquées (FPGA, ASIC) où les contraintes de surface silicium et le facteur de réduction des pertes sont importantes. Pour ce faire, deux commandes non linéaires et deux observateurs augmentés (observateurs d état et de charge) sont exploités : une commande et un observateur fondés sur le principe de mode de glissement, une commande prédictive et un observateur de Kalman étendu. L implémentation des deux lois de commande et l observateur de Kalman étendu sont implémentés sur FPGA. Une modulation de largeur d impulsion (MLI) numérique à 11-bit de résolution a été développée en associant une technique de modulation - de 4-bit, un DCM (Digital Clock Management) segmenté et déphasé de 4-bit, et un compteur-comparateur de 3-bit. L ensemble des approches proposées sont validées expérimentalement et constitue une bonne base pour l intégration des convertisseurs à découpage dans les alimentations embarquées.The use of SMPS (Switched mode power supply) in embedded systems is continuously increasing. The technological requirements of these systems include simultaneously a very good voltage regulation and a strong compactness of components. SEPIC ( Single-Ended Primary Inductor Converter) is a DC/DC switching converter which possesses several advantages with regard to the other classical converters. Due to the difficulty in control of its 4th-order and non linear property, it is still not well-exploited. The objective of this work is the development of successful strategies of control for a SEPIC converter on one hand and on the other hand the effective implementation of the control algorithm developed for embedded applications (FPGA, ASIC) where the constraints of Silicon surface and the loss reduction factor are important. To do it, two non linear controls and two observers of states and load have been studied: a control and an observer based on the principle of sliding mode, a deadbeat predictive control and an Extended Kalman observer. The implementation of both control laws and the Extended Kalman observer are implemented in FPGA. An 11-bit digital PWM has been developed by combining a 4-bit - modulation, a 4-bit segmented DCM (Digital Clock Management) phase-shift and a 3-bit counter-comparator. All the proposed approaches are experimentally validated and constitute a good base for the integration of embedded switching mode convertersVILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF

    Survey of FPGA applications in the period 2000 – 2015 (Technical Report)

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    Romoth J, Porrmann M, Rückert U. Survey of FPGA applications in the period 2000 – 2015 (Technical Report).; 2017.Since their introduction, FPGAs can be seen in more and more different fields of applications. The key advantage is the combination of software-like flexibility with the performance otherwise common to hardware. Nevertheless, every application field introduces special requirements to the used computational architecture. This paper provides an overview of the different topics FPGAs have been used for in the last 15 years of research and why they have been chosen over other processing units like e.g. CPUs

    Applications of Power Electronics:Volume 2

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