The transportation sector is characterized by a high consumption of fossil fuels and a strong environmental impact. Promoting electric vehicles is an alternative to reduce and limit them move towards the sustainability of the automobile sector. In a short period of time, world car manufacturers have built, marketed and sold a million electric vehicles, and a million drivers got used to these new low carbon advanced technologies. Comparatively, this figure represents approximately the average annual sales of conventional vehicles in Spain. The main problem is the battery autonomy, since its maximum range does not exceed 250 km, a restriction that limits the trip. Spain belongs to the group of countries which have longest trip average around 80 km. Then the problem is how to understand electric mobility, for that the types and modes of charging, the types of electric vehicles, and the available charging systems all interact with one another in the charging systems for electric vehicles, which will be specifically analysed. Alternative charging methods are also presented, and the agents involved in the charging process in accordance with applicable regulations are identified. The objective of this article is to analyse the charging of electric vehicles in Spain and to assess the current situation to be able to propose potential improvements or implementation strategies. This paper determines that it is necessary to develop public policies for a structured implementation of charging stations in public places and in common-use areas within large shared spaces, such as parking areas and residential areas in order to improve electric mobility in Spain. This paper also illustrates the need to legislate standards for charging electric vehicles to maximize their implementation in Spain, with the goal of implementing electric vehicles on a larger scale and ultimately allowing society to benefit from the advantages of this technology.

Electric vehicles in Spain: An overview of charging systems

Two of the main challenges for electric vehicle (EV) adoption include limited range and long recharge times. Ultrafast charging can help to mitigate both these concerns. However, for typical 400-V battery EVs (BEVs), the charging rate is limited by the practical cable size required to carry the charging current. To reach ultrahigh charge rates of 350 or 400 kW, 800-V BEVs are a promising alternative. However, the design of an 800-V EV requires careful new considerations for all electrical systems. This article reviews the current state of 800-V vehicle powertrain electrical design and performs an analysis of benefits, challenges, and future trends regarding multiple vehicle powertrain components. Specifically, detailed benefits and challenges related to the battery, propulsion motor, inverter, auxiliary power unit, and on- and off-board chargers are discussed.

800-V Electric Vehicle Powertrains: Review and Analysis of Benefits, Challenges, and Future Trends

Wireless power transfer (WPT) technology has been widely applied to automobile industries, household electronics and medical devices because of its many advantages. The hybrid battery charging scheme, which combines constant voltage (CV) and constant current (CC), is considered to be quite reasonable in view of the limitations of the conventional CC/CV implementation scheme. In this study, based on the inductance and double capacitances-series (LCC-S) compensation topology, a switching hybrid topology is proposed for CC/CV electric vehicle (EV) battery charging. The topology parameters are designed according to the specified CV and zero phase angle (ZPA). In the CC charging mode, two additional capacitances are added to the topology for CC and ZPA implementation. Based on the proposed weak communication, the CC and CV charging mode can be converted via two AC switches (ACSs). The proposed hybrid system provides a simple structure, easy controllability, and stable output. A 2.5-kW experimental prototype is configured to verify the proposed hybrid charger. The maximum DC efficiencies (at 2.5-kW) of the CC and CV charging modes are 89.28% and 88.33%, respectively.

A Switching Hybrid LCC-S Compensation Topology for Constant Current/Voltage EV Wireless Charging

Bidirectional DC-DC converters allow transfer of power between two dc sources, in either direction Due to their ability to reverse the direction of flow of power, Dey are being increasingly used in many applications such as battery charge/dischargers, do uninterruptible power supplies, electrical vehicle motor drives, aerospace power systems, telecom power supplies, etc This Paper Proposes a new bidirectional Sepic/Zeta converter It has low switching loss and low conduction loss due to auxiliary communicated circuit and synchronous rectifier operation, respectively Because of positive and buck/boost-like DC voltage transfer function(M=D/1-D), the proposed converter is very desirable for use in distributed power system The proposed converter also has both transformer-less version and transformer one

New Bidirectional ZVS PWM Sepic/Zeta DC-DC Converter

To maintain a stable output voltage under various operating conditions without introducing extra dc/dc converters, phase-shift (PS) control is usually adopted for wireless power transfer (WPT) systems. By using this method, however, zero-voltage switching (ZVS) operation cannot be guaranteed, especially in light-load conditions. To achieve high efficiency and reduce electromagnetic interference, it is significant for WPT systems to achieve ZVS operation of all switching devices in the whole operation range. In this article, an auxiliary variable inductor, of which the equivalent inductance can be controlled by adjusting the dc current in its auxiliary winding, is designed for series–series-compensated WPT systems under PS control to mitigate the loss arising from hard switching. As a result, a wide ZVS operation range of all switching devices can be achieved. A laboratory prototype is built to verify the theoretical analysis. The experimental results show that, under load and magnetic coupling variations, ZVS operation at fixed operation frequency as well as a constant dc output voltage can be maintained. Compared to the conventional method with only PS control, the proposed WPT can achieve higher overall efficiency in a wider load range owing to the wide ZVS operation range.

Extension of ZVS Region of Series–Series WPT Systems by an Auxiliary Variable Inductor for Improving Efficiency

Power conversion systems for electric vehicles (EVs) have been researched to improve power density and efficiency at low cost. To satisfy these needs for EVs, this paper proposes a novel battery charging system that integrates a nonisolated on-board charger (OBC) and low-voltage dc–dc converters (LDCs) by sharing the semiconductor devices and mechanical elements. Thus, the volume of LDCs is reduced dramatically compared with a conventional nonintegrated charging system. The proposed integrated system is configured based on a driving condition that is derived from the analysis of vehicle operating modes. In order to improve system's performance, an asynchronous control algorithm is applied to control the OBC optimally. In the LDC system, two LLC resonant converters are composed by sharing a transformer and secondary-side components. To increase the efficiency of each LDC, which is operated in the wide input and output voltage range, a duty and frequency control algorithm is proposed. The theoretical analysis, operating strategy, and experimental results on a 6.6-kW OBC and 1.9-kW LDC are presented to evaluate the performance of the proposed system; the total volume of LDCs is 1.87 L, and peak efficiencies of OBC and LDC are 97.3% and 93.13%, respectively. Moreover, a comparative analysis is presented to evaluate the performance of the proposed system.

An Integrated Battery Charger With High Power Density and Efficiency for Electric Vehicles

Compensation topologies play an essential role in wireless power transfer systems for electric vehicles. Specifically, the double-sided LCC compensated (DS- LCC ) topology has been widely adopted, owing to its inherent advantages, such as load-independent constant current (CC) output, low sensitivity to load variation, and high freedom in parameter design. However, large resonant devices in the DS- LCC topology lower the system efficiency and increase the complexity of optimal parameter tuning. Therefore, in this article, the parameters of the DS- LCC compensation topology are reconfigured by adjusting the ratios of its two compensation inductances without changing the specified system-level parameters, such as the loosely coupled transformer, operating frequency, and specified CC outputs. The system performance under each case is analyzed and compared in detail, based on which, an asymmetric parameter-design method is proposed to optimize the system efficiency. To verify the reasonability of the proposed tuning method, a 6.6-kW experimental prototype is configured, and comparative experiments are conducted. The experimental results indicate that, compared with the conventional method, the proposed parameter-tuning method improves the system efficiency under overall load conditions, especially under light loads.

An Efficiency Optimization-Based Asymmetric Tuning Method of Double-Sided LCC Compensated WPT System for Electric Vehicles

The use of wireless power transfer technology in unmanned aerial vehicle (UAV) systems is rapidly improving in different application areas. The main limitations of electric-powered UAVs are their charging range and stability in dynamic conditions. To solve these, this article proposes a hybrid control method based on dc-link and switched capacitor control with a fixed operating frequency. The dc-link voltage is regulated by the boost power factor correction converter to smoothen the output voltage, and the switched capacitor is used to dynamically compensate for self-inductance variations under dynamic coupling conditions. The output voltage stabilization and near-unity power factor of the input impedance can be achieved by applying the hybrid control method. Therefore, efficiency improvement can be achieved. Furthermore, the proposed control method can also be applied to systems with large coupling variations. To verify the proposed control method, a 500-W prototype was set up in the laboratory, and the experimental results proved that the control method could ensure a stable output voltage with horizontal and vertical offsets of 200 and 62 mm. respectively. Additionally, the results show that the maximum efficiency of the proposed control method is 91.9%, demonstrating that the proposed method effectively improves the efficiency.

DC-Link and Switched Capacitor Control for Varying Coupling Conditions in Inductive Power Transfer System for Unmanned Aerial Vehicles

In low power energy storage systems, to match the voltage levels of the low-voltage battery side and high-voltage direct current (DC) bus, a high voltage gain converter with bidirectional operation is required. In this system, the cost effectiveness of the design is a critical factor; therefore, the system should be designed using a small number of components. This paper proposes a set of bidirectional converters with high voltage gain range based on the integration of the boost converter with a Cuk converter, single ended primary inductor converter (Sepic), and buck-boost converter. The proposed converters consist of a small number of components with a high voltage gain ratio. Detailed comparisons are made with respect to the operating mode, number of components, voltage, and current ripple and efficiency. The efficiency of proposed converters are higher than the conventional converters in entire power range, and 6% higher efficiency can be achieved in large duty cycle by calculating loss analysis. To verify performances of the proposed converters, three 200-W prototypes of the converters are developed under the same experimental conditions. The results revealed that converter I exhibits the highest efficiency in the boost mode (92%) and buck mode (92.2%). The experimental results are shown to verify the feasibility and performances of the set of converters.

Dong-Hee Kim

Papers

An Integrated Battery Charger With High Power Density and Efficiency for Electric Vehicles

A Switching Hybrid LCC-S Compensation Topology for Constant Current/Voltage EV Wireless Charging

An Efficiency Optimization-Based Asymmetric Tuning Method of Double-Sided LCC Compensated WPT System for Electric Vehicles

DC-Link and Switched Capacitor Control for Varying Coupling Conditions in Inductive Power Transfer System for Unmanned Aerial Vehicles

A Family of Bidirectional DC–DC Converters for Battery Storage System with High Voltage Gain