Design and implementation of an 85-kHz Bidirectional Wireless Charger

Bidirectional wireless chargers will facilitate the seamless adoption of the V2G technology. When compared with unidirectional systems, developing a bidirectional wireless charger for an EV poses some new challenges. This paper presents some of the technological challenges (mainly related to the power converters) that we have addressed when building a bidirectional wireless charger. In particular, we have built a 3.7 kW bidirectional prototype working at 85 kHz. Experimental results for both power flows demonstrate the validity of the design.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Power Factor Corrector Design applied to an 85-kHz Wireless Charger

Wireless charging technology extends the battery autonomy by allowing more flexible and practical ways of recharging it even when the electric vehicle is on move. The frequency conversion, which is required to generate a kHz-ranged magnetic field, also leads to considerable harmonics. As a result, the power factor and the corresponding efficiency decrement. This paper proposes a Power Factor Corrector which overcomes this drawback. The most relevant feature of the designed Power Factor Corrector is that it does not need any electrical signal from the secondary side to adjust its operation properly. The simulation results show the ability of the proposed scheme to increment the system efficiency for different State-Of-Charge in the Battery.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Sensitivity Analysis of a Bidirectional Wireless Charger for EV

Bidirectional chargers are required to fully integrate Electric Vehicle (EV) into the smart grids. Additionally, wireless chargers ease the charge/discharge process of the EV batteries so that they are becoming more popular to fulfill a V2G scenario. When considering the load of wireless chargers, it is a requirement to know the real output power that these systems offer. The designed output power may differ from the real one as components suffer from tolerance. This paper defines six sensitivity factors to model the severity of the effects of tolerance into the output power. To do so, an electric circuit analysis is used and a mathematical formulation is derived. The six sensitivity factors are computed for a laboratory prototype.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

OCPP in the spotlight: threats and countermeasures for electric vehicle charging infrastructures 4.0

Undoubtedly, Industry 4.0 in the energy sector improves the conditions for automation, generation and distribution of energy, increasing the rate of electric vehicle manufacturing in recent years. As a result, more grid-connected charging infrastructures are being installed, whose charging stations (CSs) can follow standardized architectures, such as the one proposed by the open charge point protocol (OCPP). The most recent version of this protocol is v.2.0.1, which includes new security measures at device and communication level to cover those security issues identified in previous versions. Therefore, this paper analyzes OCPP-v2.0.1 to determine whether the new functions may still be susceptible to specific cyber and physical threats, and especially when CSs may be connected to microgrids. To formalize the study, we first adapted the well-known threat analysis methodology, STRIDE, to identify and classify threats in terms of control and energy, and subsequently we combine it with DREAD for risk assessment. The analyses indicate that, although OCPP-v2.0.1 has evolved, potential security risks still remain, requiring greater protection in the future.Funding for open access publishing: Universidad Málaga/CBUA

Impact of Coil Misalignment in Data Transmission over the Inductive Link of an EV Wireless Charger

The penetration rate of electric vehicles (EVs) will experience a relative increment in the future, so easy to use ways to recharge will be demanded. In this sense, wireless charging represents a safe charging method that minimises user intervention. In a similar way to conductive charge, wireless charging requires some information exchange between the charger primary side and secondary side (battery) for safety and operational reasons. Thus, wireless chargers depend on a communication system for their controlled and correct operation. This paper analysed the communication performance of a wireless EV charger in which the communiction device is part of the wireless power transfer system. Particularly, this work studies how the communication system reacts to power coil displacements, which commonly occur in their conventional performance. The results show that the compensation topology selected to ensure the resonant operation clearly impacts on the communication performance. In particular, the theoretical model and the simulation results demonstrate that the asymmetrical compensation topologies are more stable in terms of the wireless communication channel capacity

Distributed Model Predictive Control for voltage coordination of large-scale wind power plants

This paper presents a Distributed Model Predictive Control (DMPC)-based algorithm for distributed and coordinated voltage control of wind power plants. Under the proposed approach, voltage magnitude at the point of connection of wind power plants is optimally controlled to meet voltage requirements. In a conventional centralized approach, each wind power farm tracks the control signals set by the Transmission System Operator but DMPC responds locally to mitigate the voltage deviations without the central commands. The problem is cast as one of optimal control, which is solved at every time step by a distributed optimization. A dual decomposition scheme is proposed to solve the distributed optimization problem where the voltages magnitude of the common nodes are used as a consensus term for the coordination. In order to extend the applicability of this control, the proposed DMPC is carefully designed in such a way that it does not require any change in the inner control of the electrical machines, controls or compensators. The algorithm has been tested on an IEEE 9-bus system with two wind power plants and on an IEEE 14-bus system with three power plants. In both cases, the plants are not directly connected. Following an analysis of the achievable performance and the computational resources consumed by the local algorithm, the results of the simulations confirm that the proposed control approach is suitable for the voltage coordination of wind power plants with acceptable scalable results.This work has been partially funded by the Spanish Ministerio de Ciencia e Innovacion (MICINN) by project PID2019-110531-RA-I00 from the “Proyectos de IDi - RTI Tipo A” programme and by the Consejería de Transformación Económica, Industria, Conocimiento Universidades (Junta de Andalucía) through project P20-01164. The research network RIEMOV “Red Iberoamericana de Investigación en Electromovilidad’, which was founded by Asociación Universitaria Iberoamericana de Postgrado (AUIP), has promoted the collaboration of the authors. Funding for open access charge: Universidad de Málaga/CBUA

1st Iberoamerican Workshop on Electromobility IBEMOB’22

Para los estudios sobre electromovilidad, la colaboración es especialmente positiva ya que los avances en este campo suelen requerir el desarrollo de prototipos y la integración de múltiples técnicas que son difíciles de realizar por un solo grupo. Entre los trabajos realizados por RIEMOV, incluimos el 1er Taller Iberoamericano sobre Electromovilidad, en el que los autores explican algunas actividades de investigación sobre este tema.El horizonte 2020-2050, y la Agenda 2030 en particular, proponen la reducción de las emisiones de CO2 como mecanismo eficaz de adaptación al cambio climático. La Agencia de Protección Ambiental de los Estados Unidos estimó que el 28% de las emisiones de gases de efecto invernadero provinieron del sector del transporte en 2018. En particular, dentro de este porcentaje, el 60% provino de vehículos livianos. En Europa, el origen también fue similar, en carretera el transporte es responsable del 72% de las emisiones. Por tanto, si no se introducen modelos de movilidad sostenible, el problema medioambiental se agravará significativamente ya que se estima que aumentarán los desplazamientos urbanos en un 70% para 2050. Los viajes más habituales serán los que se realicen en zonas densamente pobladas, e Iberoamérica concentrará gran parte de esta población. En concreto, según ONU Hábitat, casi el 80% de la población vive en ciudades de Iberoamérica y el número de ciudades se ha multiplicado por seis en los últimos 50 años. En cuanto a las tarifas de transporte, ésta también ha experimentado un notable incremento, con la conclusión de que el parque vehicular de la región se triplicará en los próximos 25 años, llegando a más de 200 millones unidades en 2050. En abril de 2021, se financió la red de investigación RIEMOV (Red Iberoamericana de Investigación en Electromovilidad) gracias a la AUIP (Asociación Universitaria Iberoamericana de Postgrado). Desde entonces, ha sido una herramienta útil para la colaboración de 18 grupos de investigación de 13 países diferentes de Iberoamérica

Evaluation of losses in a bidirectional wireless power transfer system for electric vehicles

Inductively power transfer systems are becoming increasingly popular in modern applications like electric vehicles. In order to make this technology attractive, its transfer efficiency must be considerably high. Most works in the literature define the efficiency of the wireless charger as the one associated to the inverter, the coupled coils and the compensation networks. Therefore, they usually omit the study of the losses occurring in other parts of the system such as in the secondary rectifier. This paper evaluates the losses in a complete wireless charger, built and designed to provide V2G functionalities. The experimental evaluation based on the waveform analysis is contrasted with a theoretical model, which relies on the non-idealities of the components. The evaluation reveals that measurement error greatly impact on the power losses derived by the two approachesUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Independent primary-side controller applied to wireless chargers for electric vehicles

Electric vehicles rely on batteries that need to be frequently recharged. As an alternative to conductive charging, wireless chargers provide a higher reliability to pollution and electric failures and they also extend the situations and places where the recharge could be available without user’s intervention (e.g. parking spaces, on-road). In order to optimize the performance of a wireless charger, its configuration should be dynamically adapted to the varying battery’s electrical features. Towards this goal, controllers are incorporated into the system to modify the behavior of some switching devices belonging to the power electronics blocks. This paper presents a controller that acts in the DC/DC structure placed in the primary side. As a novelty, the controller infers the instantaneous battery power demands by exclusively measuring voltage and current in the primary side. In this way, there is no need for communicating (via wired or wireless links) the primary and the secondary sides. The simulation results show the ability of the controller to adapt to different battery states.Universidad de Málaga. Campus de Excelencia Internacional Andalucia Tec

Sensitivity analysis of Component's Tolerance in Inductively Coupled Power Transfer System

ICPT systems help drivers to recharge their electrical vehicles via wireless. The core of the system is a pair of coils and two reactive structures. In order to predict the performance of a practical implementation, it is necessary to study the impact of using real components which suffer from variations in their nominal values. Basing on the performed study, we conclude that the components on the side where the inductance is in series with the capacitance should be carefully selected as variations in their values greatly affect the system performance. A 50 kW system has been evaluated in terms of efficiency and load voltage.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech