Yes / The single-stage flyback Photovoltaic (PV) micro-inverter is considered as a simple and small in size topology but requires expensive digital microcontrollers such as Field-Programmable Gate Array (FPGA) or Digital Signal Processor (DSP) to increase the system efficiency, this would increase the cost of the overall system. To solve this problem, based on a single-stage flyback structure, this paper proposed a low cost and simple analog-digital control scheme. This control scheme is implemented using a low cost ATMega microcontroller built in the Arduino Uno board and some analog operational amplifiers. First, the single-stage flyback topology is analyzed theoretically and then the design consideration is obtained. Second, a 120 W prototype was developed in the laboratory to validate the proposed control. To prove the effectiveness of this control, we compared the cost price, overall system efficiency, and THD values of the proposed results with the results obtained by the literature. So, a low system component, single power stage, cheap control scheme, and decent efficiency are achieved by the proposed system. Finally, the experimental results present that the proposed system has a maximum efficiency of 91%, with good values of the total harmonic distortion (THD) compared to the results of other authors / This work was supported in-part by Innovate UK GCRF Energy Catalyst PiCREST project under Grant number 41358, in-part by British Academy GCRF COMPENSE project under Grant GCRFNGR3\1541

Charge imbalance may happen to series-connected batteries during charging or discharging due to the discrepancies among batteries. The charge imbalance will cause some batteries being over-charged or over-discharged and is harmful to the battery cycle-life. Moreover, the storage capacity of the battery bank will not be effectively utilized. This thesis brings forth first the concept of charge equalization on discharging for battery banks. Various control strategies are implemented on a flyback converter with a multi-input transformer to provide the balance discharging function as well as output voltage regulation. Each battery of the battery bank is connected to a primary winding of the transformer via an active power switch. The batteries transfer their energy to load according to the residual energy in each battery. Meanwhile, by continually monitoring battery voltages, exhausted batteries can be disconnected to avoid being over-discharged. A battery bank with four series-connected lead-acid batteries is used as an example to illustrate the operation of the balance discharging circuit. The complicated calculations and precise control are accomplished by a digital signal processor (DSP). The experimental results advocate the applicability of the discharging circuit and control strategies.

This paper design a Digital-Singal-Processor based which cooperating with the technique of switching power supply to implement the Brushless DC motor driver for electric vehicle ,and use the asymmetry pulse-width modulation theorem in sinusoidal PWM switch to increase motion efficiency of motor and decrease the power depletion ,thus can improve the current- spike from analog controller effectively ,and prove the feasibility of the system.

In the thesis, an LED driver circuit that is applied in low power lighting LED with constant output current and Power Factor Correction (PFC) is presented. The insulated Flyback converter is used for the LED driver. Power Factor Correction is realized with both the method of Voltage Follower Approach Control under Discontinuous Conduction Mode and the method of Boundary Conduction Control under Boundary Conduction Mode. Compared with Voltage Follower Approach Control, Boundary Conduction Control needs only output current feedback. Moreover, it possesses lesser magnetize inductance current, lesser electrical stress of elements, more flexible choice of elements specification, smaller output current ripples, and higher power factor under light load. The circuit design is expounded, and verified by IsSpice simulation and experiment result.

abstract: As residential photovoltaic (PV) systems become more and more common and widespread, their system architectures are being developed to maximize power extraction while keeping the cost of associated electronics to a minimum. An architecture that has become popular in recent years is the "DC optimizer" architecture, wherein one DC-DC converter is connected to the output of each PV module. The DC optimizer architecture has the advantage of performing maximum power-point tracking (MPPT) at the module level, without the high cost of using an inverter on each module (the "microinverter" architecture). This work details the design of a proposed DC optimizer. The design incorporates a series-input parallel-output topology to implement MPPT at the sub-module level. This topology has some advantages over the more common series-output DC optimizer, including relaxed requirements for the system's inverter. An autonomous control scheme is proposed for the series-connected converters, so that no external control signals are needed for the system to operate, other than sunlight. The DC optimizer in this work is designed with an emphasis on efficiency, and to that end it uses GaN FETs and an active clamp technique to reduce switching and conduction losses. As with any parallel-output converter, phase interleaving is essential to minimize output RMS current losses. This work proposes a novel phase-locked loop (PLL) technique to achieve interleaving among the series-input converters. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2014

This dissertation describes the design and implementation of an emergency lighting system using Light Emitting Diodes (LED s). The system is composed by two integrated converters working as battery charger and LED s supplying. Power LED s were used, due to their high luminous flux and opening angle of 160°. System control and management are done through a microcontroller. The features of light emitting diodes are discussed in this work. The system is based on both Brazilian and international current emergency lighting systems standards, NBR10898, 1999 and IEEE Std 446, 1995, respectively / Esta dissertação descreve o projeto e implementação de um sistema de iluminação de emergência utilizando Diodos Emissores de Luz (LED s). O sistema é composto por dois conversores integrados que possuem as funções de recarga da bateria e acionamento dos LED s. Os LED s utilizados nesta proposta são os LED s de potência, que tem um fluxo luminoso superior aos demais, e apresenta um ângulo de abertura de aproximadamente 160º. O controle e supervisão do sistema são realizados através de um microcontrolador. As características dos diodos emissores de luz são analisadas neste trabalho. O sistema é baseado nas normas para sistema de Iluminação de emergência ABNT, NBR 10898, 1999, norma brasileira e IEEE Std 446, 1995, norma internacional

This master’s thesis deals with design and construction of experimental flyback converter with utilization of novel lossless clamp circuit for switching transistor and with utilization of silicon carbide devices. The issue of flyback converter for higher power and possible control strategies are discussed. The thesis also describes power and control circuits design, design of PCB, construction of the converter and measured waveforms. End of the thesis contains technical documentation of designed board. Designed converter was successfully built and tested.

Les convertisseurs électriques sont présents dans tous les équipements électroniques. Les besoins en alimentations stabilisées des appareils et la variabilité des sources d'énergie imposent l'omniprésence des convertisseurs. Dans un environnement embarqué, la conversion, majoritairement DC/DC, subit de multiples contraintes environnementales dues au milieu dans lequel elle évolue, que ce soit dans un aéronef ou un véhicule terrestre. Les équipements ferroviaires doivent ainsi subir des contraintes vibratoires et volumiques fortes imposant à la fois l'absence de pièces mobiles telles que des ventilateurs, ainsi qu'un volume minimal afin de ne pas empiéter sur l'espace utile des cabines de trains.Une contrainte plus spécifique à l'environnement ferroviaire est la très large plage de tension d'alimentation devant être supportée par le convertisseur. Cette plage de tension, s'étendant de 12 V à 154 V, due à la multiplicité des standards électriques de par le monde représente le principal défi à la conception de convertisseurs DC/DC compacts.Dans ce mémoire, les topologies de convertisseurs existantes sont dans un premier temps analysées en fonction des contraintes du cahier des charges. Les deux structures les plus pertinentes sont ensuite étudiées plus profondément, par des simulations comportementales et des modélisations de pertes, afin de confirmer leur pertinence et d'étudier leurs carences.Dans les deux derniers chapitres de ce mémoire, les stratégies de dimensionnement propres à notre application sont décrites. Finalement, les technique de contrôle élaborées spécifiquement pour notre application sont décrites puis testées sur les prototypes des convertisseurs. Les mesures réalisées sur les prototypes ont permis de confirmer l'apport des techniques de contrôle et de dimensionnement décrites précédemment, améliorant significativement les performances des convertisseurs ainsi que l'encombrement de leurs éléments passifs / Electric converters can be found on almost every electronic device. The need for a stabilized power supply and the variability of the power sources make the power converters unavoidable. In embedded applications, the power conversion, mostly DC/DC conversion, must sustain various constraints due to their environment, airborne or in ground vehicles. Devices for railway applications endure severe constraint on their volume and immunity to vibration. Thus, they have to be built without any mobile part including fans, and to be as small as possible to minimize their impact on the payload capacity of the trains.The most specific constraint in railway application is the wide input voltage range sustained by the power converter. This voltage range, from 12 V to 154 V, is due to the large amount of electric standards worldwide. This characteristic is the main challenge for the design of compact DC/DC converters.In this thesis, in a first time the current converters topologies are analysed under the scope of our specifications. Then, the two most relevant structures are more deeply studied. Behavioural simulations and loss models are described, leading to the confirmation of their relevancy and the study of their lacks.In the last two chapters of this thesis, the sizing strategies used to fit our specifications are described. Then, the control techniques elaborated to meet the specificities of our application are described then tested on prototypes. The measurements made on the prototypes have confirmed the gain due to these control techniques and the sizing strategies previously described. These improvements have led to significant improvements in the performance of the converters and in the volume reduction of their passive elements

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Electrical energy generation with photovoltaic cells is being more utilized. Not only on large scale systems, but also in small ones connected to the grid. Parallel operating with the great generators from power companies, in a non-centralized way of operation, supplying low power, installed in houses, commerce establishments, industry, with the goal to minimize the loss in transmission, for being installed at the same consumption place. This work presents a FPGA device controller of a four transistor flyback inverter for maximum power point in photovoltaic systems. Despite this system has low power it contributes to search simple and low cost alternatives for generating of electrical power in a decentralized manner, which does not use battery banks connected parallel to network of energy near to consumers. / Geração de energia elétrica a partir de painéis fotovoltaicos vem sendo cada vez mais utilizada, não somente em sistemas fotovoltaicos de grande porte, como também em pequenos sistemas conectados a rede CA. Interligada paralelamente aos grandes geradores da concessionária de energia de forma descentralizada em sistemas de pequeno porte e baixas potências, instalados em residências, estabelecimentos comerciais, indústria, com o objetivo de minimizar perdas por transmissão por estarem instalados nos próprios locais. Este trabalho apresenta um controle num dispositivo FPGA de um inversor flyback a quatro transistores para máxima potência em sistemas fotovoltaicos. Apesar da baixa potência este contribui para a busca de alternativas simples e de baixo custo para geração de energia elétrica de forma descentralizada, não utilizando bancos de bateria conectados paralelamente a rede de energia próxima aos consumidores. / Mestre em Ciências

This thesis mainly presents the design and implementation of a flyback converter with single-stage power factor correction. In the beginning, we propose different power factor collection (PFC) techniques referring to the inductor current of converter under three kinds of operation modes. In the continuous mode, we adopt the nonlinear-carrier control (NLC). Then, in the discontinuous mode and boundary mode, voltage-follower control (VFC) and transition mode technique control (TM) are adopted respectively. As to the converter analysis, we derive and verify the results of a small-signal model and perform equivalent circuit analysis by state-space averaging method, loss-free resistor (LFR) model, averaging method for two-time-scale system (AM), and current injected equivalent circuit approach (CIECA). Results derived from the above-mentioned models are compared and verified to be accurate of the system model. Furthermore, the control function and element design are implemented by simulation. We perform a PI controller to achieve better power factor based on results of analysis of the time and frequency domains analysis. Finally, three sets of different hardware are fabricated and verified depending on measured result and theoretical simulation.