Morphing Switched-Capacitor Converters with Variable Conversion Ratio

High-voltage-gain and wide-input-range dc-dc converters are widely used in various electronics and industrial products such as portable devices, telecommunication, automotive, and aerospace systems. The two-stage converter is a widely adopted architecture for such applications, and it is proven to have a higher efficiency as compared with that of the single-stage converter. This paper presents a modular-cell-based morphing switched-capacitor (SC) converter for application as a front-end converter of the two-stage converter. The conversion ratio of this converter is flexible and variable and can be freely extended by increasing more SC modules. The varying conversion ratio is achieved through the morphing of the converter's structure corresponding to the amplitude of the input voltage. This converter is light and compact, and is highly efficient over a very wide range of input voltage and load conditions. Experimental work on a 25-W, 6-30-V input, 3.5-8.5-V output prototype, is performed. For a single SC module, the efficiency over the entire input voltage range is higher than 98%. Applied into the two-stage converter, the overall efficiency achievable over the entire operating range is 80% including the driver's loss

Isolated Single-stage Power Electronic Building Blocks Using Medium Voltage Series-stacked Wide-bandgap Switches

The demand for efficient power conversion systems that can process the energy at high power and voltage levels is increasing every day. These systems are to be used in microgrid applications. Wide-bandgap semiconductor devices (i.e. Silicon Carbide (SiC) and Gallium Nitride (GaN) devices) are very promising candidates due to their lower conduction and switching losses compared to the state-of-the-art Silicon (Si) devices. The main challenge for these devices is that their breakdown voltages are relatively lower compared to their Si counterpart. In addition, the high frequency operation of the wide-bandgap devices are impeded in many cases by the magnetic core losses of the magnetic coupling components (i.e. coupled inductors and/or high frequency transformers) utilized in the power converter circuit. Six new dc-dc converter topologies are propose. The converters have reduced voltage stresses on the switches. Three of them are unidirectional step-up converters with universal input voltage which make them excellent candidates for photovoltaic and fuel cell applications. The other three converters are bidirectional dc-dc converters with wide voltage conversion ratios. These converters are very good candidates for the applications that require bidirectional power flow capability. In addition, the wide voltage conversion ratios of these converters can be utilized for applications such as energy storage systems with wide voltage swings

Dual Output and High Voltage Gain DC-DC Converter for PV and Fuel Cell Generators Connected to DC Bipolar Microgrids

This paper introduces a new topology for a DC-DC converter with bipolar output and high voltage gain. The topology was designed with the aim to use only one active power switch. Besides the bipolar multiport output and high voltage gain this converter has another important feature, namely, it has a continuous input current. Due to the self-balancing bipolar outputs, the proposed topology is suitable for bipolar DC microgrids. Indeed, the topology balancing capability can achieve the two symmetrical voltage poles of bipolar DC microgrids. Furthermore, it is possible to create a midpoint in the output of the converter that can be directly connected to the ground of the DC power supply, avoiding common-mode leakage currents in critical applications such as transformerless grid-connect PV systems. The operating principle of the proposed topology will be supported by mathematical analysis. To validate and verify the characteristics of the presented topology, several experimental results are shown.info:eu-repo/semantics/publishedVersio

Bipolar DC output fed grounded DC-AC converter for photovoltaic application

Introduction. In recent years the usage of electricity has increased tremendously as the electrical needs and loads got increased. Hence the researchers focused on the electricity generation from renewable sources in order to promote sustainable green environment. Owing to the lesser cost and more reliable high efficiency system with reduced use of equipments became prominent for the grid connected photovoltaic single phase systems. The novelty of this proposed converters are to reduce total power loss and to analyze the performance of the converter under various modulation index and to have lesser harmonics using sinusoidal pulse width modulation technique for both T-type and F-type inverter. Interest of the work is to merge two DC-DC converters which have same output voltage in order to have transformer less utilization of power. This has given pathway to develop a new DC-DC converter network by merging the common input nodes of CUK and SEPIC converter. Purpose. This similar structure of both converters made it easy to combine the input stages of and to get bipolar output. Methods. Here we can get bipolar output without the utilization of transformer which minimizes the overall size of the proposed system. In this paper, a combined CUK-SEPIC based grid connected transformerless inverter for photovoltaic application is suggested. Results. The suggested converter is simulated using MATLAB and the results were discussed. Further the circuit is extended with a 1 kW F-type inverter to demonstrate grid connection of the converter. Practical value. This converter can be implemented for photovoltaic applications for obtaining the bipolar DC output from the DC source.Вступ. В останні роки використання електроенергії значно зросло, оскільки потреби в електроенергії та навантаження збільшились. Тому дослідники зосередилися на виробництві електроенергії з відновлюваних джерел, щоб сприяти стійкому зеленому середовищу. Через меншу вартість та більш надійну високоефективну систему зі зменшеним використанням обладнання набули популярності фотоелектричні однофазні системи, підключені до мережі. Новизна пропонованих перетворювачів полягає у зниженні загальних втрат потужності та аналізі характеристик перетворювача при різних індексах модуляції, а також у зменшенні гармонік з використанням методу широтно-імпульсної модуляції синусоїдального типу для інверторів як Т-типу, так і F-типу. Інтерес роботи полягає в об'єднанні двох перетворювачів постійного струму з однаковою вихідною напругою, щоб мати менше використання потужності трансформатора. Це дозволило розробити нову мережу перетворювачів постійного струму шляхом об'єднання загальних вхідних вузлів перетворювача CUK та SEPIC. Мета. Подібна структура обох перетворювачів дозволила легко поєднати вхідні каскади та отримати біполярний вихідний сигнал. Методи. Тут ми можемо отримати біполярний вихід без використання трансформатора, що мінімізує загальний розмір пропонованої системи. У цій статті пропонується комбінований безтрансформаторний інвертор на основі CUK-SEPIC, підключений до мережі, для фотоелектричних застосувань. Результати. Пропонований перетворювач моделюється за допомогою MATLAB, результати обговорюються. Далі схема розширена інвертором F-типу потужністю 1 кВт, щоб продемонструвати підключення перетворювача до мережі. Практична цінність. Цей перетворювач може бути реалізований для фотоелектричних застосувань для отримання біполярного виходу постійного струму джерела постійного струму

Bipolar DC output fed grounded DC-AC converter for photovoltaic application

Introduction. In recent years the usage of electricity has increased tremendously as the electrical needs and loads got increased. Hence the researchers focused on the electricity generation from renewable sources in order to promote sustainable green environment. Owing to the lesser cost and more reliable high efficiency system with reduced use of equipments became prominent for the grid connected photovoltaic single phase systems. The novelty of this proposed converters are to reduce total power loss and to analyze the performance of the converter under various modulation index and to have lesser harmonics using sinusoidal pulse width modulation technique for both T-type and F-type inverter. Interest of the work is to merge two DC-DC converters which have same output voltage in order to have transformer less utilization of power. This has given pathway to develop a new DC-DC converter network by merging the common input nodes of CUK and SEPIC converter. Purpose. This similar structure of both converters made it easy to combine the input stages of and to get bipolar output. Methods. Here we can get bipolar output without the utilization of transformer which minimizes the overall size of the proposed system. In this paper, a combined CUK-SEPIC based grid connected transformerless inverter for photovoltaic application is suggested. Results. The suggested converter is simulated using MATLAB and the results were discussed. Further the circuit is extended with a 1 kW F-type inverter to demonstrate grid connection of the converter. Practical value. This converter can be implemented for photovoltaic applications for obtaining the bipolar DC output from the DC source.Вступ. В останні роки використання електроенергії значно зросло, оскільки потреби в електроенергії та навантаження збільшились. Тому дослідники зосередилися на виробництві електроенергії з відновлюваних джерел, щоб сприяти стійкому зеленому середовищу. Через меншу вартість та більш надійну високоефективну систему зі зменшеним використанням обладнання набули популярності фотоелектричні однофазні системи, підключені до мережі. Новизна пропонованих перетворювачів полягає у зниженні загальних втрат потужності та аналізі характеристик перетворювача при різних індексах модуляції, а також у зменшенні гармонік з використанням методу широтно-імпульсної модуляції синусоїдального типу для інверторів як Т-типу, так і F-типу. Інтерес роботи полягає в об'єднанні двох перетворювачів постійного струму з однаковою вихідною напругою, щоб мати менше використання потужності трансформатора. Це дозволило розробити нову мережу перетворювачів постійного струму шляхом об'єднання загальних вхідних вузлів перетворювача CUK та SEPIC. Мета. Подібна структура обох перетворювачів дозволила легко поєднати вхідні каскади та отримати біполярний вихідний сигнал. Методи. Тут ми можемо отримати біполярний вихід без використання трансформатора, що мінімізує загальний розмір пропонованої системи. У цій статті пропонується комбінований безтрансформаторний інвертор на основі CUK-SEPIC, підключений до мережі, для фотоелектричних застосувань. Результати. Пропонований перетворювач моделюється за допомогою MATLAB, результати обговорюються. Далі схема розширена інвертором F-типу потужністю 1 кВт, щоб продемонструвати підключення перетворювача до мережі. Практична цінність. Цей перетворювач може бути реалізований для фотоелектричних застосувань для отримання біполярного виходу постійного струму джерела постійного струму

Emerging Converter Topologies and Control for Grid Connected Photovoltaic Systems

Continuous cost reduction of photovoltaic (PV) systems and the rise of power auctions resulted in the establishment of PV power not only as a green energy source but also as a cost-effective solution to the electricity generation market. Various commercial solutions for grid-connected PV systems are available at any power level, ranging from multi-megawatt utility-scale solar farms to sub-kilowatt residential PV installations. Compared to utility-scale systems, the feasibility of small-scale residential PV installations is still limited by existing technologies that have not yet properly address issues like operation in weak grids, opaque and partial shading, etc. New market drivers such as warranty improvement to match the PV module lifespan, operation voltage range extension for application flexibility, and embedded energy storage for load shifting have again put small-scale PV systems in the spotlight. This Special Issue collects the latest developments in the field of power electronic converter topologies, control, design, and optimization for better energy yield, power conversion efficiency, reliability, and longer lifetime of the small-scale PV systems. This Special Issue will serve as a reference and update for academics, researchers, and practicing engineers to inspire new research and developments that pave the way for next-generation PV systems for residential and small commercial applications

High Efficient Module of Boost Converter in PV Module

Within the photovoltaic (PV) power-generation market, the  PV module has shown obvious growth. However, a high voltage gain converter is essential for the module’s grid connection through a dc–ac inverter. This paper proposes a converter that employs a floating active switch to isolate energy from the PV panel when the ac module is OFF; this particular design protects installers and users from electrical hazards. Without extreme duty ratios and the numerous turns-ratios of a coupled inductor, this converter achieves a high step-up voltage-conversion ratio; the leakage inductor energy of the coupled inductor is efficiently recycled to the load. These features explain the module’s high-efficiency performance. The detailed operating principles and steady-state analyses of continuous, discontinuous, and boundary conduction modes are described. A 15V input voltage, 200V output voltage, and 100W output power prototype circuit of the proposed converter has been implemented; its maximum efficiency is up to 95.3% and full-load efficiency is 92.3%.DOI:http://dx.doi.org/10.11591/ijece.v2i6.158

Analysis, design, and implementation of the AFZ converter applied to photovoltaic systems

Grid-tied photovoltaic (PV) installations with Distributed Maximum Power Point Tracking (DMPPT) architectures include a DC-DC Module Integrated Converter (MIC) for managing each PV panel, isolating it from the others, reducing the mismatching effect and maximizing the harvested power. In this paper, the Autotransformer Forward converter with type-Zeta resonant reset (AFZ) is proposed as a DMPPT architecture’s MIC candidate. The main characteristics of the AFZ converter are the high versatility due to its voltage step-up and step-down capability; the use of an optimized autotransformer with only two windings, reducing the complexity and power losses of this component; the good dynamic performances, like the Forward converter ones; the low number of components and the simplicity and high feasibility associated to the use of just one active switch. Besides, soft switching transitions are achieved thanks to the autotransformer type-Zeta resonant reset. The steady-state theoretical analysis, considering the effect of the autotransformer leakage inductance, is presented. The converter is also studied in the frequency domain, obtaining the small-signal transfer functions. A design procedure based on the requirements of a 100 kW grid-tied photovoltaic installation is described, yielding in a 225 W prototype with efficiencies up to 95.6 %. Experimental results validate the theoretical analysis.This work was supported in part by the Spanish 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 under Grant DPI2014-53685-C2-1-R, in part by the research project CONEXPOT under Grant DPI2017-84572-C2-2-R, and in part by the research project EPIIOT under Grant DPI2017-88062-R