Low voltage and high current are typical requirements for the input source of the new family of microprocessors; therefore there is the need to develop new topologies and control strategies that can meet such requirements. A narrow duty ratio has limited the application of the conventional buck converter for wider step-down DC–DC conversion. An interesting option is to consider the quadratic buck converter; however, there is still the problem to obtain a wider step-down conversion. In this study, a switched-capacitor quadratic buck converter is proposed such that a wider conversion ratio is obtained for lower-output voltages. The converter consists of a quadratic buck converter with an array of capacitors and diodes, also referred as a voltage multiplier. To illustrate the behaviour of the proposed converter, experimental results are shown for a conversion from 36 to 1.5 V and an output power of 30 W. The efficiency of the proposed converter can be effectively increased when soft-switching and synchronous rectification are implemented.

Switched-capacitor quadratic buck converter for wider conversion ratios

This paper presents the technological advancements of the electric vehicles (EVs) all over the world. The first emphasis is on the various types of the EVs along with the energy management strategies (EMSs). The EVs are equipped with different energy storage elements such as lithium-ion batteries, super capacitors (SCs) and fuel cells (FCs). Hence, it is important to optimize the power split between the various energy storage systems (ESSs) under the complex driving conditions. The second imperative aspect is the utilization of the energy efficient wide bandgap (WBG) semiconductor technology. The WBG materials present the superior properties like wide bandgap, high saturated drift velocity and high critical breakdown field. This has led a path for the development of SiC and GaN based power semiconductor devices (PSDs). However, this paper mainly focuses on the utilization of the SiC devices for the EV applications. The substantial features of the various SiC devices are presented along with the performance aggrandization methods. Furthermore, this paper presents the updated survey and various performance measures of the SiC based power converter topologies. It also emphasizes the necessity of energy optimization for the EV charging systems. On the other hand, the burning issues associated with the SiC power modules other than the power converters are explored in detail. This extensive literature survey provides insightness for the design and research engineers in view of fulfilling the research gaps between the current and the desired targets. 

A review on energy efficient technologies for electric vehicle applications

As the number and range of electric vehicles in use increases, and the size of batteries in those vehicles increases, the demand for fast and ultra-fast charging infrastructure is also expected to increase. The growth in the fast charging infrastructure raises a number of challenges to be addressed; primarily, high peak loads and their impacts on the electricity network. This paper reviews fast and ultra-fast charging technology and systems from a number of perspectives, including the following: current and expected trends in fast charging demand; the particular temporal and spatial characteristics of electricity demand associated with fast charging; the devices and circuit technologies commonly used in fast chargers; the potential system impacts of fast charging on the electricity distribution network and methods for managing those impacts; methods for long-term planning of fast charging facilities; finally, expected future developments in fast charging technology and systems.

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Review of Fast Charging for Electrified Transport: Demand, Technology, Systems, and Planning

Triboelectric-nanogenerator-inspired light-emitting diode-in-capacitors for flexible operation in high-voltage and wireless drive modes

Modelling, simulation and control of a fuel cell-powered laptop computer voltage regulator module

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

Advancements in energy efficient GaN power devices and power modules for electric vehicle applications: a review

The switched-mode power supplies are widely used in very low voltage and high-power applications where large conversion ratios are required. In such cases, the quadratic buck converter is the suitable one compared to buck, cascaded buck and multi-phase choppers, because of their limitations in switching frequency and losses. This paper presents mathematical analysis, design and simulation of a quadratic buck converter using fixed frequency Pulse-Width Modulation (PWM)-based Sliding-Mode (SM) controller in order to obtain fast dynamic performance. The design aspects include choice of sliding surface, deriving existing and stability conditions, control parameter selection and their analysis. The performance of the proposed converter is compared with the conventional Average Current-Mode (ACM) controller. In average current mode, the tuning of the PI controller for the inner current loop and outer voltage loop is done using bode plots. The simulation results for the two types of controllers are represented for analysing dynamic performance, as well as line and load regulations.

Anuradha Kotapati

Papers

Super capacitors for energy storage: Progress, applications and challenges

A review on energy efficient technologies for electric vehicle applications

Advancements in energy efficient GaN power devices and power modules for electric vehicle applications: a review

A fast-response sliding-mode controller for quadratic buck converter

An overview of energy efficient solid state LED driver topologies