Dual Output Power Management Unit for PV-Battery Hybrid Energy System

The tremendous evolution in the electronics industry has provided high performance portable devices. However, the high power demand and the limited capacity of batteries, prevent the devices from operating for a long time without the need of a power outlet. The ease of deploying Photovoltaic (PV) cells close to the device enables the user to harvest energy on the go, and get rid of the conventional power outlets. However, applying the PV power to the electronic devices is not as easy as the plug and play model, due to the unstable output voltage and power of the PV cells. In this thesis, a power management unit is proposed to provide dual regulated outputs using a PV module and a rechargeable battery. The main components of the unit are a Dual Input Multiple Output (DIMO) DC-DC converter and a digital controller. The converter is used to interface the battery and the PV module with the loads. Moreover, the proposed converter has the ability to step up or step down the input voltage. The controller maximizes the PV power using the fractional open circuit voltage Maximum Power Point Tracking (MPPT) method. Furthermore, the controller manages the amount of power supplied to or from the battery in order to satisfy the load demand and regulate the outputs at the required levels. The controller has been implemented and synthesized using VHDL. A prototype has been implemented using an FPGA and off the shelf components. The functionality of the system has been tested and verified under varying environmental conditions

Power management using photovoltaic cells for implantable devices

This paper presents a novel inductor-less switched capacitor (SC) DC-DC converter, which generates simultaneous dual-output voltages for implantable electronic devices. Present dual output converters are limited to fixed ratio gain, which degrade conversion efficiency when the input voltage changes. The proposed power converter offers both step-up and step-down conversion with 4-phase reconfigurable logic. With an input voltage of 1 V provided by photovoltaic (PV) cells, the proposed converter achieves step-up, step-down and synchronised voltage conversions in four gain modes. These are 1.5 V and 0.5 V for Normal mode, 2 V and 1 V for High mode, 2 V for Double Boost mode, as well as 3 V and 2 V for Super Boost mode with the ripple variation of 14-59 mV. The converter circuit has been simulated in standard 0.18 μm CMOS technology and the results agree with state-of-the-art SC converters. However, our proposed monolithically integrated PV powered circuit achieves a conversion efficiency of 85.26% and provides extra flexibility in terms of gain, which is advantageous for future implantable applications that have a range of inputs. This research is therefore an important step in achieving truly autonomous implantable electronic devices

Multiple-output DC–DC converters: applications and solutions

Multiple-output DC–DC converters are essential in a multitude of applications where different DC output voltages are required. The interest and importance of this type of multiport configuration is also reflected in that many electronics manufacturers currently develop integrated solutions. Traditionally, the different output voltages required are obtained by means of a transformer with several windings, which are in addition to providing electrical isolation. However, the current trend in the development of multiple-output DC–DC converters follows general aspects, such as low losses, high-power density, and high efficiency, as well as the development of new architectures and control strategies. Certainly, simple structures with a reduced number of components and power switches will be one of the new trends, especially to reduce the size. In this sense, the incorporation of devices with a Wide Band Gap (WBG), particularly Gallium Nitride (GaN) and Silicon Carbide (SiC), will establish future trends, advantages, and disadvantages in the development and applications of multiple-output DC–DC converters. In this paper, we present a review of the most important topics related to multiple-output DC–DC converters based on their main topologies and configurations, applications, solutions, and trends. A wide variety of configurations and topologies of multiple-output DC–DC converters are shown (more than 30), isolated and non-isolated, single and multiple switches, and based on soft and hard switching techniques, which are used in many different applications and solutions.info:eu-repo/semantics/publishedVersio

An Energy Harvesting Solution for IoT Sensors Using MEMS Technology

The significant development of IoT sensors will play a critical role in a large number of applications. It is predicted that billions of IoT sensors will be used worldwide by 2020 [1]. Batteries are commonly utilized to power on sensors, but they are depleted and they require maintenance and replacement. Battery replacement for billions of sensors is a daunting task and battery disposal for IoT sensors can become an environmental problem. Energy harvesting from ambient sources presents a viable solution to overcome these problems. Among all energy sources, light is considered as one of the best sources due to its high energy density and availability in both indoor and outdoor environments. In order to make an energy harvesting system efficient, many methods have been proposed in the literature to extract the maximum energy while minimizing the power consumption by the energy harvesting circuitry. In this work, a boost converter circuit is designed using MEMS-based switches to reduce the leakage current and power loss caused by conventional transistor-based switches. A light energy harvesting method is also proposed utilizing available components of a typical IoT sensor. The reuse of available components in the proposed solution reduces the overall power consumption and the area overhead of the energy harvesting solution

Power management systems based on switched-capacitor DC-DC converter for low-power wearable applications

The highly efficient ultra-low-power management unit is essential in powering low-power wearable electronics. Such devices are powered by a single input source, either by a battery or with the help of a renewable energy source. Thus, there is a demand for an energy conversion unit, in this case, a DC-DC converter, which can perform either step-up or step-down conversions to provide the required voltage at the load. Energy scavenging with a boost converter is an intriguing choice since it removes the necessity of bulky batteries and considerably extends the battery life. Wearable devices are typically powered by a monolithic battery. The commonly available battery such as Alkaline or Lithium-ion, degrade over time due to their life spans as it is limited by the number of charge cycles- which depend highly on the environmental and loading condition. Thus, once it reaches the maximum number of life cycles, the battery needs to be replaced. The operation of the wearable devices is limited by usable duration, which depends on the energy density of the battery. Once the stored energy is depleted, the operation of wearable devices is also affected, and hence it needs to be recharged. The energy harvesters- which gather the available energy from the surroundings, however, have no limitation on operating life. The application can become battery-less given that harvestable energy is sufficiently powering the low-power devices. Although the energy harvester may not completely replace the battery source, it ensures the maximum duration of use and assists to become autonomous and self-sustain devices. The photovoltaic (PV) cell is a promising candidate as a hypothetical input supply source among the energy harvesters due to its smaller area and high power density over other harvesters. Solar energy use PV harvester can convert ambient light energy into electrical energy and keep it in the storage device. The harvested output of PV cannot directly connect to wearable loads for two main reasons. Depending on the incoming light, the harvested current result in varying open-circuit voltage. It requires the power management circuit to deal with unregulated input variation. Second, depending on the PV cell's material type and an effective area, the I-V characteristic's performance varies, resulting in a variation of the output power. There are several works of maximum power point tracking (MPPT) methods that allow the solar energy harvester to achieve optimal harvested power. Therefore, the harvested power depends on the size and usually small area cell is sufficient for micro-watt loads low-powered applications. The available harvested voltage, however, is generally very low-voltage range between 0.4-0.6 V. The voltage ratings of electronics in standard wearable applications operate in 1.8-3 V voltages as described in introduction’s application example section. It is higher than the supply source can offer. The overcome the mismatch voltage between source and supply circuit, a DC-DC boost converter is necessary. The switch-mode converters are favoured over the linear converters due to their highly efficient and small area overhead. The inductive converter in the switch-mode converter is common due to its high-efficiency performance. However, the integration of the inductor in the miniaturised integrated on-chip design tends to be bulky. Therefore, the switched-capacitor approach DC-DC converters will be explored in this research. In the switched-capacitor converter universe, there is plenty of work for single-output designs for various topologies. Most converters are reconfigurable to the different DC voltage levels apart from Dickson and cross-coupled charge pump topologies due to their boosting power stage architecture through a number of stages. However, existing multi-output converters are limited to the fixed gain ratio. This work explores the reconfigurable dual-output converter with adjustable gain to compromise the research gap. The thesis's primary focus is to present the inductor-less, switched-capacitor-based DC-DC converter power management system (PMS) supplied by a varying input of PV energy harvester input source. The PMS should deliver highly efficient regulated voltage conversion ratio (VCR) outputs to low-power wearable electronic devices that constitute multi-function building blocks

Design and implementation of multi-port DC-DC converters for electrical power systems

The thesis proposes developing, analysing, and verifying these DC-DC converters to improve the current state-of-the-art topology. Four new DC-DC converters for applications like light emitting diode, lighting microgrids DC, PV applications, and electric vehicles are as follows. In this study, the two-input converter is presented. The two-input converter that has been proposed serves as the interface between the two input sources and load. Using two switches and two diodes, the proposed converter minimises switching losses and contains eight components in total, making it compact and low volume. As a result, the highest average efficiency is 92.5%, and the lowest is 89.6%. In this research, the new three-port converter that has been proposed serves as the interface between the input source, a battery, and a load. In addition, the converter is suitable for use in standalone systems or satellite applications. A low-volume converter is designed with three switches and two diodes, thereby minimizing switching losses and ten components in total. Regarding efficiency, the highest average is 92.5%, and the lowest is 90.9%. Also, this study proposes a single-switch high-step-up converter for LED drivers and PV applications. A further benefit of the proposed converter over conventional classical converters is that it utilises only one active switch. These results align with simulation results, and its gain is 6.8 times greater than classical converters. Furthermore, stress across switches and diodes is smaller than the output voltage, approximately 50%. Semiconductor losses were limited with a low duty cycle of 0.7. This makes the highest average efficiency 95% and the lowest 93.9%. The new four-port converter is presented for applications such as microgrid structures and electric vehicles. As part of the integrated converter, two or three converters are combined by sharing some components, such as switches, inductors, and capacitors, to form a single integrated converter. As a result of the four-port converter proposed, battery power can be managed, and output voltage can be regulated simultaneously

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

MPPT battery charge controller with lorawan communication interface

Mestrado de dupla diplomação com Tunisia Private University (ULT Tunisie)Renewable sources, such as Photovoltaic Systems (PV), have been employed for decades to focus on cleaner types of electricity generation. Today, it is a subject of worry as to how to cut costs and enhance efficiency in order to harness and utilise these natural resources in the best way possible. As a result, the concept of Maximum Power Point Tracking Technique (MPPT) evolved, which is essentially a system used by charge controllers for wind turbines and Photovoltaic Systems to use and also give a maximised power output. This thesis is primarily focused with the application of such a system in order to achieve controlled photovoltaic power using the MPPT mechanism. The main goal is to add LoRaWAN capability such as to be able to transmit information regarding the solar charge battery controller internal state A micro-controller, which is part of a larger circuit, such as a solar charge controller, is required for MPPT hardware implementation. The heart of the hardware circuit is the solar charge controller. Furthermore, the system was integrated with a dashboard to provide easier access to data for analysis from anywhere, eliminating the physical work of data collecting.Fontes de energia renovável, como é o caso dos sistemas fotovoltaicos, têm sido vindo a ser cada vez mais utilizadas como alternativas menos impactantes do ponto de vista ambiental. Atualmente, é motivo de preocupação o recurso a métodos e tecnologias que permitam aproveitar os recursos naturais sustentáveis e, ao mesmo tempo, reduzir os custos e aumentar a sua eficiência. Neste contexto, é importante o recurso a técnicas de seguimento de ponto de potência máximo (MPPT), usado por controladores de carga para turbinas eólicas e sistemas fotovoltaicos, de modo a extrair a máxima potência do sistema elétrico de produção de energia. Esta tese assenta no desenvolvimento de um sistema fotovoltaico capaz de regular o processo de carga para baterias de gel, dotada de mecanismo MPPT integrado e com a capacidade de transmitir toda a telemetria associada à operação do regulador usando o protocolo LoRaWAN. Este sistema de controlo de carga é baseado num microcontrolador que implementa o algoritmo MQTT e os dados enviados, via LoRaWAN, são apresentados numa interface gráfica

Non-isolated high-gain triple port DC–DC buck-boost converter with positive output voltage for photovoltaic application

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