Single-phase inverter with active ripple energy storage

It is well known that conventional energy sources such as coal, oil, and natural gas are decreasing and a growing problem of environmental pollution. The renewable energy sources are becoming the best alternative for a clean and inexhaustible energy source, and solar energy is one of the most popular energy sources. Solar energy has gained more and more attention because of its advantages such as abundance, pollution free, renewability and low maintenance. The solar energy is usually obtained from photovoltaic (PV) cell which transform the solar irradiance into direct current (DC), that is electric energy. Since the majority of the electric devices and the main grid, require AC (alternate current) a power converter is needed to convert the DC electricity coming from the PV cell into AC electricity. The most used electronic converter for that is an inverter. Inverters contains semiconductor switches that are often controlled using the pulse width modulation technique, which yields second-order harmonic currents and corresponding ripple voltages on the DC bus. This double line frequency on the DC bus affect the performance of the photovoltaic system. Bulky DC link electrolytic capacitors are typically employed as transient energy buffer to decouple, or smooth out, the pulsating ac power from constant dc power. However, the use of electrolytic capacitor leads to temperature and aging concerns, and this also result in a low power density. A novel active power decoupling method proposed to add a bidirectional buck and boost converter that can store the ripple energy in its inductor and capacitor. This method can effectively reduce the energy storage in the DC link capacitor. This thesis deals with the design of such as bidirectional DC-DC converter and an inverter. The theoretical work mode of the bidirectional converter together with an inverter is studied. The power stages, inverter and bidirectional converter are studied in steady state to dimension the components. These stages are also modelled in their small signal equivalent model to find their transfer functions need to design the control loops. Different control strategies are studied and implemented to achieve the independent controls of the inverter and DC-DC converter. By using LTspice, the simulation results have verified the proposed power decoupling method.Es bien conocido que las fuentes de energía convencionales como el carbón, petróleo y gas natural están disminuyendo y volviéndose un problema de contaminación ambiental. Las fuentes de energías renovables están llegando a ser la mejor alternativa para a una fuente de energía limpia e inagotable y la energía solar es una de la más popular fuente de energía. La energía solar ha ganado más y más atención por sus ventajas, tales como, abundancia, libre de polución, renovabilidad y poco mantenimiento. La energía solar es normalmente obtenida de una célula fotovoltaica (FV) la cual transforma la irradiancia solar en corriente continua (CC), es decir, en energía eléctrica. Como la mayoría de los dispositivos electrónicos y la red requieren corriente alterna (CA) un convertidor de potencia es necesitado para convertir la electricidad continua proveniente de la célula fotovoltaica en electricidad alterna. El dispositivo más usado para esto es un inversor. Los inversores contienen conmutadores semiconductores que son a menudo controlados usando la técnica de modulación por ancho de pulso la cual produce un armónico de segundo orden en la corriente que da a lugar un rizado en el voltaje del bus de continua. Esta frecuencia de dos veces la frecuencia de línea en el bus de continua afecta el rendimiento del sistema fotovoltaico. Grandes condensadores electrolíticos son típicamente usados como buffer de energía transitoria para desacoplar, o suavizar, la potencia alterna de la potencia continua. Sin embargo, el uso de condensadores electrolíticos da lugar a problemas de temperatura y degeneración y estos además resultan en una baja densidad de potencia. Un método novedoso propone añadir un convertidor elevador reductor, bidireccional, que almacene la energía de rizado en sus inductor y capacitor. Este método puede reducir eficazmente la energía almacenada en el condensador usado en el DC link. Esta tesis trata sobre el diseño de un convertidor CC-CC bidireccional y un inversor. El modo de operación teórico del convertidor bidireccional junto con un inversor es estudiado. Las etapas de potencia, inversor y convertidor bidireccional son estudiadas en estado estacionario para dimensionar los componentes. Estas etapas son también modeladas en su modelo equivalente en pequeña señal para encontrar sus funciones de transferencia necesarias para el diseño de los lazos de control. Diferentes estrategias de control son estudiadas e implementadas para conseguir el control del inversor y del convertidor de continua. Usando LTspice, los resultados de las simulaciones han verificado el método propuesto de desacoplo de potencia.Sutil Ortiz, AM. (2018). Inversor monofásico con corrección activa de rizado. Universitat Politècnica de València. http://hdl.handle.net/10251/103423TFG

Power delivery mechanisms for asynchronous loads in energy harvesting systems

PhD ThesisFor systems depending on methods, a fundamental contradiction in the power delivery chain has existed between conventional to supply it. DC/DC conversion (e.g.) has therefore been an integral part of such systems to resolve this contradiction. be made tolerant to a much wider range of Vdd variance. This may open up opportunities for much more energy efficient methods of power delivery. performance of different power delivery mechanisms driving both asynchronous and synchronous loads directly from a harvester source bypassing bulky energy method, which employs a energy from a EH circuit depending on load and source conditions, is developed. through comprehensive comparative analysis. Based on the novel CBB power delivery method, an asynchronous controller is circuits to work with tasks. The successful asynchronous control design drives a case study that is meant to explore relations between power path and task path. To deal with different tasks with variable harvested power, systems may have a range of operation conditions and thus dynamically call for CBB or SCC type power set of capacitors to form CBB or SCC is implemented with economic system size. This work presents an unconventional way of designing a compact-size, quick- circuit overcome large voltage variation in EH systems and implement smart power management for harsh EH environment. The power delivery mechanisms (SCC, employed to help asynchronous- logic-based chip testing and micro-scale EH system demonstrations

Power Management Circuits for Energy Harvesting Applications

Energy harvesting is the process of converting ambient available energy into usable electrical energy. Multiple types of sources are can be used to harness environmental energy: solar cells, kinetic transducers, thermal energy, and electromagnetic waves. This dissertation proposal focuses on the design of high efficiency, ultra-low power, power management units for DC energy harvesting sources. New architectures and design techniques are introduced to achieve high efficiency and performance while achieving maximum power extraction from the sources. The first part of the dissertation focuses on the application of inductive switching regulators and their use in energy harvesting applications. The second implements capacitive switching regulators to minimize the use of external components and present a minimal footprint solution for energy harvesting power management. Analysis and theoretical background for all switching regulators and linear regulators are described in detail. Both solutions demonstrate how low power, high efficiency design allows for a self-sustaining, operational device which can tackle the two main concerns for energy harvesting: maximum power extraction and voltage regulation. Furthermore, a practical demonstration with an Internet of Things type node is tested and positive results shown by a fully powered device from harvested energy. All systems were designed, implemented and tested to demonstrate proof-of-concept prototypes