Search Results (54)

The transition to a low-carbon energy matrix has driven the electrification of vehicles (EVs), yet charging infrastructure—particularly fast direct current (DC) chargers—can negatively impact distribution networks. This study investigates the integration of Battery Energy Storage Systems (BESSs) with the power grid, focusing on the E-Lounge project in Brazil as a strategy to mitigate these impacts. The results demonstrated a 21-fold increase in charging sessions and an energy consumption growth from 0.6 MWh to 10.36 MWh between June 2023 and March 2024. Compared to previous findings, which indicated the need for more robust systems, the integration of a 100 kW/138 kWh BESS with DC fast chargers (60 kW) and AC chargers (22 kW) proved effective in reducing peak demand, optimizing energy management, and enhancing grid stability. These findings confirm the critical role of BESSs in establishing a sustainable EV charging infrastructure, demonstrating improvements in power quality and the mitigation of grid impacts. The results presented in this study stem from a project approved under the Research and Development program of the Brazilian Electricity Regulatory Agency (ANEEL) through strategic call No. 022/2018. This initiative aimed to develop a modular EV charging infrastructure for fleet vehicles in Brazil, ensuring minimal impact on the distribution network. Full article

This study outlines the creation and lab verification of a low-voltage direct current (LVDC) back-to-back (B2B) converter intended as a versatile connection point for low-voltage users. The converter configuration features dual inverters that regulate the power distribution to AC loads and grid connections through a shared DC circuit. This arrangement enables the integration of various DC generation sources, such as photovoltaic systems, as well as DC consumers, like electric vehicle chargers, supported by DC/DC converters. Significant advancements include sensorless current estimation for grid-forming inverters, which removes the necessity for conventional current sensors by employing mathematical models and established system parameters. The experimental findings validate the system’s effectiveness in grid-connected and isolated microgrid modes, demonstrating its ability to sustain energy quality and system stability under different conditions. Our results highlight the considerable potential of integrating grid-forming functionalities in inverters to improve microgrid operations. Full article

Automotive-grade GaN power switches have recently been made available in the market from a growing number of semiconductor suppliers. The exploitation of this technology enables the development of very efficient power converters operating at much higher switching frequencies with respect to components implemented with silicon power devices. Thus, a new generation of automotive power components with an increased power density is expected to replace silicon-based products in the development of higher-performance electric and hybrid vehicles. 650 V GaN-on-silicon power switches are particularly suitable for the development of 3–7 kW on-board battery chargers (OBCs) for electric cars and motorcycles with a 400 V nominal voltage battery pack. This paper describes the design and implementation of a 6.6 kW OBC for electric vehicles using automotive-grade, 650 V, 25 mΩ, discrete GaN switches. The OBC allows bi-directional power flow, since it is composed of a bridgeless, interleaved, totem-pole PFC AC/DC active front end, followed by a dual active bridge (DAB) DC-DC converter. The OBC can operate from a single-phase 90–264 Vrms AC grid to a 200–450 V high-voltage (HV) battery and also integrates an auxiliary 1 kW DC-DC converter to connect the HV battery to the 12 V battery of the vehicle. The auxiliary DC-DC converter is a center-tapped phase-shifted full-bridge (PSFB) converter with synchronous rectification. At the low-voltage side of the auxiliary converter, 100 V GaN power switches are used. The entire OBC is liquid-cooled. The first prototype of the OBC exhibited a 96% efficiency and 2.2 kW/L power density (including the cooling system) at a 60 °C ambient temperature. Full article

This paper presents a groundbreaking control strategy for a bidirectional battery charger that allows power to be injected into the smart grid while simultaneously compensating for the grid’s reactive power using an electric vehicle battery. An artificial neural network (ANN) controller is utilized for precise design to ensure optimal performance with minimal error. The ANN technique is applied to generate sinusoidal pulse width modulation (SPWM) for a bidirectional AC–DC inverter, with the entire algorithm simulated in MATLAB Simulink.The core innovation of this study is the creation of the ANN algorithm, which supports grid compensation using electric vehicle batteries, an approach termed “vehicle-for-grid”. Additionally, the paper details the PCB circuit design of the system controlled by the DSP F28379D board, which was tested on a three-phase motor. The total harmonic distortion (THD) of the proposed ANN algorithm is approximately $1.85\%$, compared to the MPC algorithm’s THD of about $2.85\%$. This indicates that the proposed algorithm is more effective in terms of the quality of the power injected into the grid. Furthermore, it demonstrates effective grid compensation, with the reactive power effectively neutralized to $0\mathrm{KVAR}$ in the vehicle-for-grid mode. Full article

The rising Greenhouse Gas (GHG) emissions stemming from the extensive use of automobiles across the globe represent a critical environmental challenge, contributing significantly to phenomena such as global warming and the deterioration of air quality. To address these challenges, there is a critical need for research and development in electric vehicles (EVs) and their associated charging infrastructure, including off-board and on-board chargers (OBCs). This paper aims to bridge the gaps in existing review literature by offering a comprehensive review of both integrated and non-integrated OBCs for EVs, based on the authors’ knowledge at the time of writing. The paper begins by outlining trends in the EV market, including voltage levels, power ratings, and relevant standards. It then provides a detailed analysis of two-level and multi-level power converter topologies, covering AC-DC power factor correction (PFC) and isolated DC-DC topologies. Subsequently, it discusses single-stage and two-stage non-integrated OBC solutions. Additionally, various categories of integrated OBCs (iOBCs) are explored, accompanied by relevant examples. The paper also includes comparison tables containing technical specifications and key characteristics for reference and analysis. Full article

To solve the problems of large switching losses and the need for large-capacity electrolytic capacitances in three-phase DC/AC on-board chargers for vehicle-to-grid (V2G) applications, this paper proposes a single-stage bidirectional high-frequency isolated converter that eliminates the need for large-capacity capacitances. Combined with the proposed modulation scheme, it can theoretically reduce the switching loss by about two-thirds with the three-phase converter compared with the conventional modulation scheme, improving the converter’s operating efficiency and power density. Firstly, based on the characteristics of the proposed topology, a hybrid modulation scheme is proposed, which combines a phase-shift modulation scheme based on double modulation waves and a sawtooth carrier with a 1/3 modulation scheme, and the theoretical feasibility of the hybrid modulation scheme is verified using a mathematical modeling equation. Secondly, this paper provides a detailed analysis of the four operating modes of the two full-bridge circuits and the commutation process of the three-phase converter within 1/6 of the fundamental frequency cycle (P₁ modulation interval). Then, the control strategy is given for the constant-current and constant-voltage charging and constant-current discharging for electric vehicle batteries. Finally, simulation results verify the correctness of the proposed topology and modulation scheme in vehicle–grid interaction. Full article

The application of electrochemical cells as a source unit of electrical energy is rapidly growing—used in electric vehicles and other electric mobility devices, as well as in energy supply systems—as energy storage, often together with renewable energy sources. The key element of such systems is the power electronic converter used for DC energy storage and AC grid interfacing. It should be bidirectional to charge and discharge the battery when it is necessary. Two-stage battery interface converters are the most common; their DC-DC stage controls the battery current and adjusts voltage, but the DC-AC stage (inverter or frontend) controls the current in the grid. The use of unfolding inverters in two-stage battery interfaces can have some advantages. In this case, the DC-DC converter produces half-sinewave pulsating voltages and currents, but the unfolding circuit changes the polarity of the voltages and currents and produces no switching losses. Another trend of modern power electronics is the principle of partial power processing. In this case, power electronic converters deal only with a part of the total power; therefore, losses in such converters are reduced. This paper considers combining unfolding frontends with partial power DC-DC converters that enable the further reduction in losses. In this paper, it is shown that such implementation of the partial power conversion principle in semi-DC-AC systems is really possible based on the real-time matching of the voltage of the partial-power DC-DC converter, battery voltage (which depends on its state of charge) and the rectified instantaneous voltage of the AC grid. Full article

Low-temperature preheating, fast charging, and vehicle-to-grid (V2G) capabilities are important factors for the further development of electric vehicles (EVs). However, for conventional two-stage chargers, the EV charging/discharging instructions and grid instructions cannot be addressed simultaneously for specific requirements, pulse heating and variable-current charging can cause high-frequency power fluctuations at the grid side. Therefore, it is necessary to design a bidirectional grid-friendly charger for EVs operated under pulse-current heating and variable-current charging. The DC bus, which serves as the medium connecting the bidirectional DC–DC and bidirectional DC–AC, typically employs capacitors. This paper analyzes the reasons why the use of capacitors in the DC bus cannot satisfy the grid and EV requirements, and it proposes a new DC bus configuration that utilizes energy storage batteries instead of capacitors. Due to the voltage-source characteristics of the energy storage batteries, EV instructions and grid instructions can be flexibly and smoothly scheduled by using phase-shift control and adaptive virtual synchronous generator (VSG) control, respectively. In addition, the stability of the control strategy is demonstrated using small signal modeling. Finally, typical operating conditions (such as EV pulse preheating, fast charging with variable current, and grid peak shaving and valley filling) are selected for validation. The results show that in the proposed charger, the grid scheduling instructions and EV charging/discharging instructions do not interfere with each other, and different commands between EVs also do not interfere with each other under a charging pile with dual guns. Without affecting the requirements of EVs, the grid can change the proportion of energy supply based on actual scenarios and can also obtain energy from either EVs or energy storage batteries. For the novel charger, the pulse modulation time for EVs consistently achieves a steady state within 0.1 s; thus, the pulse modulation speed is as much as two times faster than that of conventional chargers with identical parameters. Full article

Catalyzed by the increasing interest in bi-directional electric vehicles, this paper delves into their significance and the challenges they encounter. Bi-directional electric vehicles not only serve as transportation but also function as essential electricity resources. Central to this energy revolution are On-Board Chargers (OBCs), which are pivotal in converting alternating (AC) energy into direct (DC) energy and vice versa. In this context, we explore the various circuit architectures of OBCs employed in bi-directional electric vehicles. We delve into the intricacies of rectifiers, switching converters, and the application of advanced control and filtering technologies. Our analysis extends to the implications of these circuit architectures on aspects such as voltage regulation capability, energy efficiency, and thermal management. Furthermore, we address the broader significance of these developments in the integration of bidirectional systems, which are driving advances in circuit architectures to better harness the energy flexibility of electric vehicles. We emphasize the critical role of bi-directional electric vehicles in the transition toward a smart and sustainable energy grid. To enhance accessibility for a diverse readership, we will provide concise definitions or explanations for technical terms used throughout the paper, ensuring that our work is approachable even for those who may not be experts in the field. Full article

In this study, a model predictive control (MPC) technique is applied to a packed-u-cell (PUC)-based dual-output bidirectional electric vehicle (EV) battery charger. The investigated topology is a 5-level PUC-based power factor correction (PFC) rectifier allowing the generation of two levels of DC output voltages. The optimization of the MPC cost function is performed by reducing the errors on the capacitors’ voltages (DC output voltages) and the grid (input) current. Moreover, the desired capacitors’ voltages and peak value of the input current are considered within the designed cost function to normalize the errors. In addition, an external PI controller is used to generate the amplitude of the grid current reference based on the computed errors on the capacitors’ voltages. The presented simulation and experimental results recorded using a 1 kW laboratory prototype demonstrate the high performance of the proposed approach in rectifying the AC source at different levels (dual rectifier), while drawing a sinusoidal current from the grid with low THD (around 4%) and ensuring a unity power factor operation. Full article

This work presents the experimental validation of a 40 kW electric vehicle (EV) charger. The proposed system comprises two 20 kW modules connected in parallel at the input and output. Each module has two stages—as a grid converter Vienna Rectifier (VR) was chosen, and as an isolated DC/DC stage, two Series-Resonant Dual-Active-Bridges (SRDABs) in input-series-output-parallel (ISOP) configurations were applied. The AC/DC and DC/DC stages were enclosed in 2U rack standard housing. A bipolar DC-link with ±400 V DC voltage was employed to connect both stages of the charger module while the charger’s output is dedicated to serving 800 V batteries. VRs operated at 66 kHz switching frequency and the SRDABs operated at 100 kHz. The converters used in the charger structure were based on silicon carbide (SiC) power devices. The description and parameters of the built hardware prototypes of both—AC/DC and DC/DC—converters are provided. Moreover, the experimental validation of each stage and the whole charging system, including oscilloscope waveforms and power analyzer measurements at nominal power, are included. Such a configuration enables energy conversion with high efficiency without a negative impact on the grid and high-quality grid waveforms. Full article

The development and implementation of electric vehicles have significantly increased and are profoundly reshaping the automotive sector. However, long charging times, limited driving range, and difficulties as to suitable charger converter design are the main limitations of the adoption of EV technology. DC fast-chargers offer the best solution for mitigating the charging time problems of EVs. This paper provides an extensive review of the status of the technical development of fast-charging infrastructure architectures and standards, and a classification of fast-charging methods. Key power electronic converter topologies for fast-charging systems, with their advantages and comparisons, are also addressed. Full article

With the widespread use of electric vehicles (EVs), the potential to utilize them as flexible resources has increased. However, the existing vehicle-to-grid (V2G) studies have focused on V2G operation methods. The operational performance is limited by the amount of availability resources, which represents the flexibility. This study proposes a data-driven modeling method to estimate the V2G flexibility. A charging station is a control point connected to a power grid for V2G operation. Therefore, the charging stations’ statuses were analyzed by applying the basic queuing model with a dataset of 1008 chargers (785 AC chargers and 223 DC chargers) from 500 charging stations recorded in Korea. The basic queuing model obtained the long-term average status values of the stations over the entire time period. To estimate the V2G flexibility over time, a charging station status modeling method was proposed within a time interval. In the proposed method, the arrival rate and service time were modified according to the time interval, and the station status was expressed in a propagated form that considered the current and previous time slots. The simulation results showed that the proposed method effectively estimated the actual value within a 10% mean absolute percentage error. Moreover, the determination of V2G flexibility based on the charging station status is discussed herein. According to the results, the charging station status in the next time slot, as well as that in the current time slot, is affected by the V2G. Therefore, to estimate the V2G flexibility, the propagation effect must be considered. Full article

The wide-scale adoption and accelerated growth of electric vehicle (EV) use and increasing demand for faster charging necessitate the research and development of power electronic converters to achieve high-power, compact, and reliable EV charging solutions. Although the fast charging concept is often associated with off-board DC chargers, the importance of on-board AC fast charging is undeniable with the increasing battery capacities. This article comprehensively reviews gallium nitride (GaN) semiconductor-based bidirectional on-board charger (OBC) topologies used in both 400 V and 800 V EV applications. Moreover, comparative evaluations of GaN-based bi-directional OBC topologies regarding power conversion losses (conduction loss and soft switching capabilities), power density, implementation considerations, power quality, electromagnetic interference, and reliability aspects have been presented. The status of commercially available GaN power modules, advancements in GaN technology, applicable industry standards, and application requirements for OBCs have been also included in this study. Finally, in light of forthcoming advancements in GaN power transistor technology, this study highlights potential areas of research related to the reviewed topologies. Such research can aid researchers and designers in improving the performance and user experience of electric vehicles, ultimately supporting the widespread adoption of EVs. Full article

Regarding DC fast chargers, various studies, such as the charge scheduling, have been conducted. On the other hand, research on AC slow chargers has rarely been conducted due to the predictable and simple usage pattern. Despite the long charging times of AC slow chargers, which use the existing electric outlets with relatively low supplied power, these chargers are suitable for daily home charging of electric vehicles (EVs) during the night. Due to their low installation costs, they are likely to be the dominant type of charging equipment. In this paper, the EV charging process based on AC slow chargers, which supply a maximum power of 3 kW from an AC 220 V outlet, is analyzed by constructing a simple charging model. The charging time and fees are statistically derived and investigated. Furthermore, power load curves for charging EVs with the 3 kW charger are observed. From the statistical analyses, we conclude that daily charging of EVs can be an appropriate scenario in using the AC slow chargers, and the power load can be spread without employing any demand response schemes. Full article