In this era of fast-moving technology, new paradigm of Internet of Everything (IoE)—the intelligent connection between people, processes, data, and things—will be accompanied by dramatic changes in modern life that...

Flexible Solid-state Hybrid Supercapacitors for the Internet of Everything (IoE)

Microgrid deployments are expanding around the world as the most suitable solution to integrate distributed renewable energy sources to meet the increasing load demands and to power-up the remote areas. The installation of DC microgrid can improve system efficiency and reduces the cost of electrical infrastructure compared to the AC microgrid. However, the main challenge of implementing DC microgrid is the existing structure of the AC distribution system. In addition to the previous researches performed on DC microgrids, this paper proposes a framework to assess the technical and financial benefits of implementing the AC and DC microgrids. The power loss, voltage drop and system efficiency have been investigated for the AC and DC microgrids during the steady-state condition. Furthermore, the dynamic behaviors of AC and DC microgrids have been analyzed when each system subjected to disturbance such as short-circuit fault, aiming to evaluate the system response. In the next stage, techno-economic analysis has been carried out to determine the optimal size of solar PV system connected to each AC or DC microgrid with its energy storage, according to the meteorological and load profile data of the selected remote area in Sarawak (Malaysia). The study presented in this paper justifies that DC microgrid is potentially more beneficial than AC microgrid. However, the stability of the system during fault condition is the main problem in the DC microgrid. Therefore, it can be concluded that the protection and control of DC microgrids should be the key areas of future researches.

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Assessment of technical and financial benefits of AC and DC microgrids based on solar photovoltaic

Nowadays, the energy storage systems based on lithium-ion batteries, fuel cells (FCs) and super capacitors (SCs) are playing a key role in several applications such as power generation, electric vehicles, computers, house-hold, wireless charging and industrial drives systems. Moreover, lithium-ion batteries and FCs are superior in terms of high energy density (ED) as compared to the SCs. But, the down-side associated with them is the low power density (PD). On the other hand, this high PD feature is essential for the enhancement of dynamic performance of the system. Therefore, the SCs are well utilized due to their dominant features such as high specific power, rapid charging-discharging rate and superior cycling life. Hence, this paper mainly focuses on the advancements of various types of SCs along with their performance improvement methods. The important properties and selection of the electrode and electrolyte materials are described in detail. The commercially available SCs are enumerated with much more emphasis on their Figure of Merits (FOMs). Furthermore, the prominent role of SCs is highlighted with respect to the aforementioned applications. Finally, the future challenges associated with the SCs are presented. This review paper gives insightness for the design engineers and researchers in order to fill the research gaps associated with the SCs. 

Super capacitors for energy storage: Progress, applications and challenges

Supercapacitor (SC), or electric double-layer capacitor (EDLC), technology has matured well during the past two decades into three commercial variations with capacitance values ranging between 1 and 50,000 F Compared to electrolytic or film-type capacitors with the same canister size, they offer capacitance that is more than 1 million times larger, with a one to two order smaller equivalent series resistance (ESR) A smaller ESR means a very high current charge or discharge capability without excessive heating of the device One major limitation is the lower dc voltage ratings of less than 5 V

Supercapacitor-Based Long Time-Constant Circuits: A Unique Design Opportunity for New Power Electronic Circuit Topologies

Approximate efficiency of a linear regulator is given by the ratio of regulated output voltage to input voltage. Higher voltage difference between the input and the output means a lower efficiency due to heavy losses in the series power semiconductor. Supercapacitor-assisted low dropout regulator (SCALDO) is an emerging linear DC-DC converter technique, where a supercapacitor (SC) is used to reduce the voltage drop across the series transistor in a linear regulator where the SC acts as a lossless dropper. The circuit operates at a very low frequency decided by the size of the SC. An efficiency multiplication factor such as 1.33, 2, or 3 is achieved depending on the configuration. This study presents the essentials of its generalised theory, few prototype implementations, and a discussion on SCALDO properties. Typical efficiencies of 12-5 and 5-1.2 V linear regulators are around 42 and 24%, respectively. When SCALDO prototypes are built, the authors achieve respective end-to-end efficiencies of 79-81 and 58-73%. A loss analysis summary and further developments of the novel technique are also provided, in addition to a discussion to indicate that this is not a variation of the switched capacitor converters.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-pel.2017.0093

Supercapacitor-assisted low dropout regulator technique: a new design approach to achieve high-efficiency linear DC–DC converters

To overcome short-term input energy fluctuations, and to offer complete 24-h energy solutions based on renewable resources such as solar and wind, energy storage devices are mandatory. A relatively new storage family is the supercapacitor (SC), which were developing rapidly over the last 15 years, and are yet to compete with rechargeable batteries. Today with three different commercially available SC families developing rapidly, with 1–70 000 F per single cell, at least one of them is reaching the specific energy of lead-acid batteries. All new families of SCs have charge/discharge life cycles of several orders larger than rechargeable battery chemistries, and their usage in energy storage systems is rapidly advancing. The SC-assisted converters are a new family of very low-speed converters, where a power electronic building block is combined with an SC bank to achieve high end-to-end efficiency, with the added advantage of dc-uninterruptible power supply (UPS) capability within the converter. This article provides an overview of the new SC-assisted loss management theory applied to SC-assisted converters, with practical examples of implementation useful in renewable energy systems such as SC-assisted low dropout regulator, SC-assisted LED, SC-assisted server rack power architecture, and SC-assisted wide-input inverter. In developing these new converters, useful in renewable energy systems, SCs are considered as a new device family with five to six-order larger capacitance for the same canister size, helping the achievement of the long time constant circuits.

Development of Supercapacitor Technology and Its Potential Impact on New Power Converter Techniques for Renewable Energy

Uninterruptible power supply (UPS) systems are used to buffer against input energy source disconnections. In most UPS systems associated with an AC input energy source, an AC-DC converter feeds an energy storage system such as a battery bank or a supercapacitor bank together with a DC to AC conversion systems to buffer against AC input supply failures. If the critical load is fed by a DC source, DC-UPS designs are introduced with high efficiency, less complexity, low cost and smaller size. Supercapacitor assisted low dropout (SCALDO) regulator is a novel DC-DC converter developed to achieve high efficiency in a linear regulator approach using a supercapacitor as a series dropper element in the series path of a linear regulator such as a LDO. The DC-UPS capability is a novel feature which can be integrated into the SCALDO regulator simply by oversizing the supercapacitor without using any additional hardware. This paper describes the conceptual background followed by experimental results of the DC UPS capability integrated SCALDO regulator using 12–5 V prototype.

Efficiency enhanced linear DC-DC converter topology with integrated DC-UPS capability

All electrical and electronic devices require access to a suitable energy source. In a portable electronic product, such as a cell phone, an energy storage unit drives a complex array of power conversion stages to generate multiple DC voltage rails required. To optimize the overall end-to-end efficiency, these internal power conversions should waste minimal energy and deliver more to the electronic modules. Capacitors are one of the main component families used in electronics, to store and deliver electric charges. Supercapacitors, so called because they provide over a million-fold increase in capacitance relative to a traditional capacitor of the same volume, are enabling a paradigm shift in the design of power electronic converter circuits. Here we show that supercapacitors could function as a lossless voltage-dropping element in the power conversion stages, thereby significantly increasing the power conversion stage efficiency. This approach has numerous secondary benefits: it improves continuity of the supply, suppresses voltage surges, allows the voltage regulation to be electromagnetically silent, and simplifies the design of voltage regulators. The use of supercapacitors allows the development of a novel loss-circumvention theory with applicability to a wide range of supercapacitor-assisted (SCA) techniques. These include low-dropout regulators, transient surge absorbers, LED lighting for DC microgrids, and rapid energy transfer for water heating.

https://www.mdpi.com/2079-9292/10/14/1697/pdf

Supercapacitor-Assisted Techniques and Supercapacitor-Assisted Loss Management Concept: New Design Approaches to Change the Roadmap of Power Conversion Systems

Supercapacitors can store a million times more energy per unit mass or volume compared to electrolytic capacitors. Due to their low internal resistance, they are capable of driving or absorbing pulsative high currents. Over the last quarter, century supercapacitor (SC) manufacturers have developed several families of mass-scale devices with high-power density and a longer cycle life that helped the end-users to improve their energy storage systems and products. Today, there are three common device families, namely, (i) symmetrical double-layer capacitors (EDLCs), (ii) hybrid capacitors with a lithium electrode, and (iii) battery capacitors based on pseudo capacitance concepts. This review paper compares these families and provides an overview of several state-of-the-art applications in electric vehicles (EVs), microgrids, and consumer electronics.

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Kosala Gunawardane

Papers

Supercapacitor-assisted low dropout regulator technique: a new design approach to achieve high-efficiency linear DC–DC converters

Development of Supercapacitor Technology and Its Potential Impact on New Power Converter Techniques for Renewable Energy

Efficiency enhanced linear DC-DC converter topology with integrated DC-UPS capability

Supercapacitor-Assisted Techniques and Supercapacitor-Assisted Loss Management Concept: New Design Approaches to Change the Roadmap of Power Conversion Systems

Modern Supercapacitors Technologies and Their Applicability in Mature Electrical Engineering Applications