The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Electric vehicles (EV), including Battery Electric Vehicle (BEV), Hybrid Electric Vehicle (HEV), Plug-in Hybrid Electric Vehicle (PHEV), Fuel Cell Electric Vehicle (FCEV), are becoming more commonplace in the transportation sector in recent times. As the present trend suggests, this mode of transport is likely to replace internal combustion engine (ICE) vehicles in the near future. Each of the main EV components has a number of technologies that are currently in use or can become prominent in the future. EVs can cause significant impacts on the environment, power system, and other related sectors. The present power system could face huge instabilities with enough EV penetration, but with proper management and coordination, EVs can be turned into a major contributor to the successful implementation of the smart grid concept. There are possibilities of immense environmental benefits as well, as the EVs can extensively reduce the greenhouse gas emissions produced by the transportation sector. However, there are some major obstacles for EVs to overcome before totally replacing ICE vehicles. This paper is focused on reviewing all the useful data available on EV configurations, battery energy sources, electrical machines, charging techniques, optimization techniques, impacts, trends, and possible directions of future developments. Its objective is to provide an overall picture of the current EV technology and ways of future development to assist in future researches in this sector.

https://www.preprints.org/manuscript/201705.0090/v1/download

A Comprehensive Study of Key Electric Vehicle (EV) Components, Technologies, Challenges, Impacts, and Future Direction of Development

In this paper, a new non-isolated Interleaved dc/dc converter with high-voltage conversion ratio is presented. The proposed converter combined with interleaved converter techniques and volt...

High step-up interleaved dc/dc converter with high efficiency

With growing concern on climate change, widespread adoption of electric vehicles (EVs) is important. One of the main barriers to EV acceptance is range anxiety, which can be alleviated by fast charging (FC). The main technology constraints for enabling FC consist of high-charging-rate batteries, high-power-charging infrastructure, and grid impacts. Although these technical aspects have been studied in literature individually, there is no comprehensive review on FC involving all the perspectives. Moreover, the power quality (PQ) problems of fast charging stations (FCSs) and the mitigation of these problems are not clearly summarized in the literature. In this paper, the state-of-the-art technology, standards for FC (CHAdeMO, GB/T, CCS, and Tesla), power quality issues, IEEE and IEC PQ standards, and mitigation measures of FCSs are systematically reviewed.

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Grid Impact of Electric Vehicle Fast Charging Stations: Trends, Standards, Issues and Mitigation Measures - An Overview

Traction inverter, as a critical component in electrified transportation, has been the subject of many research projects in terms of topologies, modulation, and control schemes. Recently, some of the well-known electric vehicle manufacturers have utilized higher-voltage batteries to benefit from lower current, higher power density, and faster charging times. With the ongoing trend toward higher DC-link voltage in electric vehicles, some multilevel structures have been investigated as a feasible and efficient option for replacing the two-level inverters. Higher efficiency, higher power density, better waveform quality, and inherent fault-tolerance are the foremost advantages of multilevel inverters which make them an attractive solution for this application. This paper presents an investigation of the advantages and disadvantages of higher DC-link voltage in traction inverters, as well as a review of the recent research on multilevel inverter topologies for electrified transportation applications. A comparison of multilevel inverters with their two-level counterpart is conducted in terms of efficiency, cost, power density, power quality, reliability, and fault tolerance. Additionally, a comprehensive comparison of different topologies of multilevel inverters is conducted based on the most important criteria in transportation electrification. Future trends and possible research areas are also discussed.

/pdf/a-review-of-multilevel-inverter-topologies-in-electric-3qi0zx52ns.pdf

A Review of Multilevel Inverter Topologies in Electric Vehicles: Current Status and Future Trends

This paper intends to establish an overall up-to-date review on Fast Charging methods for Battery Electric Vehicles (BEV). This study starts from basic concepts involving single battery cell charging, current and future charging standards. Then, some popular power converter topologies employed for this application are introduced, and finally a summary of the industrial solutions available on the market are presented, as well as the ongoing projects related to the extreme fast charging (XFC) network expansion. Practical insights, considering the current BEV scenario, are employed to get a better understanding of this topic. Special attention is given to the modular design approach, analyzing its advantages and some of the factors that influence the number and size of modules that conform a fast charger solution

Fast and Ultra-Fast Charging for Battery Electric Vehicles – A Review

Interleaved dc–dc converters with integrated magnetic components capable to achieve high power density have recently gained attention in automotive applications for eco-friendly transportation. These circuits may contribute to the downsizing of powertrains for electric vehicles (EVs) and hybrid electric vehicles (HEVs) using close-coupled inductors (CCIs) and loosely coupled inductors (LCIs). In this study, a novel core model for size and loss calculation of the interleaved converter with integrated winding coupled inductors (IWCIs) is proposed to assess the size of magnetic components. This assessment was carried out using the parameters of a 1-kW circuit. As a result, interleaved converters with IWCIs proved to be more effective than the converters with LCIs and CCIs for downsizing the magnetic components. In contrast, it was also found that the interleaved converter with LCIs achieved downsizing of the magnetic component at a duty ratio close to 50%. Finally, the effectiveness of the calculation model was validated through experimental tests.

Downsizing Effects of Integrated Magnetic Components in High Power Density DC–DC Converters for EV and HEV Applications

A novel integrated magnetic structure suitable for the transformer-linked interleaved boost chopper circuit is proposed in this paper. The coupled inductor is known to be effective for miniaturization in high coupling area because the DC flux in the core can be canceled and the inductor current ripple become to high frequency. However, coupled inductor with E-E core and E-I core are realistically difficult to obtain necessary leakage inductance in high coupling area. The cause is fringing effect and the effects leads to complication of magnetic design. To solve this problem, novel integrated magnetic structure with reduction of fringing flux and high frequency ripple current performance, is proposed. Furthermore, the design method for novel integrated magnetic structure suitable for coupled inductor is proposed from analyzing of the magnetic circuit model. Finally, effectiveness of reduction of fringing flux and design method for novel coupled inductor are discussed from experimental point of view.

A Novel Integrated Magnetic Core Structure Suitable for Transformer-Linked Interleaved Boost Chopper Circuit

Currently, driving power circuits at high switching frequency is performed in order to downsize and lighten switching power supplies. Along with it, wide band gap semiconductor devices, GaN and SiC, have attracted attention. However, there is a great constrain related to the false turn-on phenomenon produced by gate noise because these wide band gap semiconductor devices have low threshold voltage. If the false turn-on phenomenon occurs, the efficiency of the power supply decreases. Therefore, this paper analyzes the gate noise performance using simulation and experimental tests focusing on the parasitic inductance of the power devices terminals. As a result, it was found that the gate noises can be related to the recovery current of the body diodes. Additionally, this analysis was theorized by the comparison between the experimental results and the theoretical equation using an equivalent circuit.

An analysis of false turn-on mechanism on power devices

A new implementation of an iron-loss model for laminated magnetic cores in the MATLAB/Simulink environment is proposed in this paper. The model is based on numerically solving a one-dimensional diffusion problem for the eddy currents in the core lamination and applying an accurate hysteresis model as the constitutive law. An excess loss model is also considered. The model is identified merely based on the catalog data provided by the core material manufacturer. The implementation is validated with analytical and finite-element models and experimentally in the case of a toroidal inductor supplied from a GaN FET full-bridge inverter with 5–500 kHz switching frequencies and a deadtime of 300 ns. Despite the simple identification, a good correspondence is observed between the simulated and measured iron losses, the average difference being 3.3% over the wide switching frequency range. It is shown that accounting for the skin effect in the laminations is significant, in order to correctly model the iron losses at different switching frequencies. Some differences between the measured and simulated results at high switching frequencies are also discussed. The model is concluded to be applicable for designing and analyzing laminated magnetic cores in combination with power-electronics circuits. The Simulink models are openly available.

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Wilmar Martinez

Papers

Fast and Ultra-Fast Charging for Battery Electric Vehicles – A Review

Downsizing Effects of Integrated Magnetic Components in High Power Density DC–DC Converters for EV and HEV Applications

A Novel Integrated Magnetic Core Structure Suitable for Transformer-Linked Interleaved Boost Chopper Circuit

An analysis of false turn-on mechanism on power devices

Simulink Model for PWM-Supplied Laminated Magnetic Cores Including Hysteresis, Eddy-Current, and Excess Losses