Wireless Electric Vehicle Research Articles

Optimal Design of Fully Integrated Magnetic Structure for Wireless Charging of Electric Vehicles

Optimal design of a fully integrated magnetic structure for electric vehicle (EV) wireless charging is proposed in this article. The proposed approach helps save ferrite material, reduce the implementation cost, shrink the size of the converter, and improve the cost and power density. Typically, in a wireless charging system, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> resonant network and the receiver dc–dc converter are used, which require a bulky inductor in their structures. The integration of resonant inductor with the transmitter-side coil has been studied in the literature to reduce the overall cost and improve the power density of an EV wireless charger. The integration of the dc–dc inductor with the vehicle-side receiver coil is also introduced in the literature. However, the full integration of both resonant inductor and dc–dc inductor into the transmitter and receiver coils of the wireless charging system creates new design challenges that have not been addressed before. In this article, the proposed fully integrated magnetic structure and its design challenges are studied in detail. A procedure for achieving the optimal design of the fully integrated structure is presented. An optimization problem is defined to design the best magnetic structure and select the best values for the resonant elements and dc–dc inductor. The outcome of this integration is an all-integrated magnetic structure, compact converter, and efficient wireless charger. A 2.2-kW/85-kHz system is built to verify the feasibility of the proposed integrated wireless charging system, and its performance is evaluated through the experiment.

New Structure Design of Ferrite Cores for Wireless Electric Vehicle Charging by Machine Learning

In this article, a machine learning algorithm is applied for the first time in inductive power transfer (IPT) to find a ferrite core structure with high magnetic coupling between transmitting (Tx) and receiving (Rx) coils for an electric vehicle (EV) wireless charging system. Since formula-based theoretical design is not available due to the nonlinear magnetic field distortion stemming from the presence of the ferrite core in an IPT system, the proposed core structure design has been achieved through finite-element analysis simulation-based data learning. The proposed design methods are so general that they can be applied to any conventional IPT coil design. Furthermore, it can optimize the core structures for high coupling coefficient, mutual inductance, desired magnetic flux density in the specific area, etc. By training only 0.011% data out of the total possible cases, it is verified by simulation and experiment that the ferrite core structure obtained by the proposed method has a mutual inductance that is 0.6% higher than that of the conventional design level in the case of 15 cm distance between the Tx and Rx coils, even though the volume of the ferrite cores are reduced to 90%. Also, a prototype 3.0 kW stationary EV wireless charging system was implemented and showed fairly better performance than a conventional case.

Triple-Coil-Structure-Based Coil Positioning System for Wireless EV Charger

In this article, a triple-coil-based coil positioning approach is proposed for the wireless electric vehicle charger to realize the accurate coil positioning with low electromagnetic field. Based on the working principle of the proposed triple-coil architecture and the discussion of the sensing-coil configuration, the received signal strength (RSS) equations are derived, revealing the way of enhancing the positioning signals by taking advantage of the quality factor (Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</sub> ). Thereafter, an RSS fingerprint positioning algorithm is proposed for obtaining coordinates in x-, y-, and z-direction. Specific considerations are also given for designing the exciting frequency and the coil parameters. Finally, the proposed positioning system is tested on a 3.3-kW wireless charger. The RSS of the proposed positioning system has been proved to be 3.2 times as that of the state-of-the-art one, whereas the excitation current is reduced by more than half. A number of positioning cases, with the targeted coil placed in an area of 32 cm × 32 cm, are tested in the lab. The experimental results show that more than 95% of these test cases have been well positioned with test errors less than 1.5 cm.

Novel Electrical Modeling, Design and Comparative Control Techniques for Wireless Electric Vehicle Battery Charging

Dynamic wireless power systems are an effective way to supply electric vehicles (EVs) with the required power while moving and to overcome the problems of low mileage and extensive charging times. This paper targets modeling and control for future dynamic wireless charging using magnetic resonance coupling because of the latter’s efficiency. We present a 3D model of transmitter and receiver coils for EV charging with magnetic resonance wireless power developed using ANSYS Maxwell. This model was incorporated into the physical design of the magnetic resonance coupling using ANSYS Simplorer in order to optimize the power. The estimated efficiency was around 92.1%. The transient analysis of the proposed circuit was investigated. A closed-loop three-level cascaded PI controller- was utilized for wireless charging of an EV battery. The controller was designed to eliminate the voltage variation resulting from the variation in the space existing between coils. A single-level PI controller was used to benchmark the proposed system’s performance. Furthermore, solar-powered wireless power transfer with a maximum power point tracker was used to simulate the wireless charging of an electric vehicle. The simulation results indicated that the EV battery could be charged with a regulated power of 12 V and 5 A through wireless power transfer. Fuzzy logic and neuro-fuzzy controllers were employed for more robustness in the performance of the output. The neuro-fuzzy controller showed the best performance in comparison with the other designs. All the proposed systems were checked and validated using the OPAL Real-Time simulator. The stability analysis of the DC–DC converter inside the closed-loop system was investigated.

Electrical Interoperability Evaluating of Wireless Electric Vehicle Charging Systems Based on Impedance Space

In the commercialization process of wireless electric vehicle charging (WEVC), it is essential to ensure the interoperability between diverse WEVC systems due to the wide application of various coil configurations and compensation topologies. This paper proposes a novel electrical interoperability evaluation method based on impedance indices and corresponding feasible space in the complex plane. Firstly, the electromagnetic description of the coil system is introduced to reveal the energy flow process of WEVC system. Further, two key impedance indices and their feasible space are derived and verified. Interoperability evaluation results show that the reference devices in Chinese WEVC standard GB/T 38775.6 and GB/T 38775.7 are able to achieve the requirements of power capability. Moreover, it is necessary to reduce the duty cycle of rectifier when the battery voltage rises so as to narrow down the variation of load resistance and avoid dangerous working conditions. The proposed method can effectively evaluate the electrical interoperability of WEVC systems from different manufacturers under different power or distance levels before conducting experiments.

Wireless Charging Efficiency Optimization Method Based on Adaptive Robust Control

This paper designs, analyzes and optimizes the electric vehicle wireless charging system and its control method. Compared with the traditional plug-in conduction charging, wireless charging is more convenient, safe, reliable and has better environmental adaptability. Inductive power transmission technology (IPT) is the main technology for wireless charging of electric vehicles and plug-in hybrid vehicles. Based on the fundamental approximation method, the critical self inductance of the primary or secondary coil is derived in this paper. This critical value reflects the power transmission capacity and control performance of the two chargers when they are interoperable. Compared with the non integrated structure, the magnetically integrated LCC compensated wireless charging system can transmit the same power with smaller compensation inductance. Based on the voltage dependent dynamic state space model, four working modes of magnetically integrated LCC compensated wireless charging system are studied in this paper. Simulation and experimental results show that the voltage dependent equivalent circuit model can be effectively applied to the basic characteristic analysis of wireless charging system. The voltage dependent dynamic state space model is more accurate and realistic. In addition to reflecting the basic characteristics of the wireless charging system, it can also reflect the working mode of the wireless charging system.

An Optimized Design of an Electric Vehicle Wireless Charging Coupling Coil

With the development of electric vehicle wireless charging technology, the transmission power and transmission efficiency of electric vehicle wireless charging system have become the focus of current research. The transmission power and efficiency of wireless charging system largely depend on the energy loss of two resonant coupling coils. The energy loss is mainly related to the structural parameters of the coupling coil and the coupling coefficient of the two coils. On this basis, the structure of the coupling coil is designed and optimized by using the finite element analysis software Maxwell, and a new combined transmitting coil structure is designed. Experiments and verification show that the coil design meets the requirements of transmission efficiency, which can provide a reference for the design of wireless charging coil of electric vehicle in the future.

Research on Metal Foreign Object Detection of Electric Vehicle Wireless Charging System Based on Detection Coil

Due to the open structure of wireless charging systems, foreign objects are inevitably involved. In the process of energy transfer, the intervention of metal foreign objects will cause the system to deviate from the normal operating point and even cause safety accidents. Therefore, metal foreign objects detection (MOD) technology is of considerable importance. In this paper, a metal foreign object detection system of a wireless power transfer (WPT) system based on the symmetrical detection coil was designed, and a MOD method based on frequency scanning is proposed. The coil size of the WPT system was designed based on SAE-J2954 standard. In addition, the suitable detection coil was installed at the transmitting coil. The system model was established in ANSYS simulation software, and 5 cm × 5 cm copper sheet and iron sheet were used as the metal to be detected. The result shows that the self-induction of the detection coil at the position of the foreign object can achieve a fluctuation of 52.46% and −34.72%, and the resonant frequency of the detection system is offset by 24.7% and −18.82%, respectively. Finally, the experimental platform of MOD system was built, and the effectiveness of the system was verified.

Authentication and Billing for Dynamic Wireless EV Charging in an Internet of Electric Vehicles

Dynamic wireless charging (DWC) is a promising technology to charge Electric Vehicles (EV) using on-road charging segments (CS), also known as DWC pads. In order to ensure effective utilization of this on-the-road charging service, communication and coordination need to be established between the EVs and the different network entities, thereby forming an Internet of Electric Vehicles (IoEV). In an IoEV, EVs can utilize different V2X communication modes to enable charging scheduling, load management, and reliable authentication and billing services. Yet, designing an authentication scheme for dynamic EV charging presents significant challenges given the mobility of the EVs and the short contact time between the EVs and the charging segments. Accordingly, this work proposes a fast, secure and lightweight authentication scheme that allows only authentic EVs with valid credentials to charge their batteries while ensuring secure and fair payments. The presented scheme starts with a key pre-distribution phase between the charging service company (CSC) and the charging pad owner (PO), followed by a hash chain and digital signature-based registration and authentication phase between the EV and the CSC, before the EV reaches the beginning of the charging lane. These preliminary authentication phases allow the authentication between the EVs and the charging segments to be performed using simple hash key verification operations prior to charging activation, which reduces the computational cost of the EVs and the CS. Symmetric and asymmetric key cryptography are utilized to secure the communication between the different network entities. Analysis of the computational and transmission time requirements of the proposed authentication scheme shows that, for an EV traveling at 60 km/h to start charging at the beginning of the charging lane, the authentication process must be initiated at least 1.35 m ahead of the starting point of the lane as it requires ≃81 ms to be completed.

An Si MOSFET-Based High-Power Wireless EV Charger With a Wide ZVS Operating Range

This article proposes a new digitized modulation scheme suitable for a high-power wireless electric vehicle charger employing an integrated boost multilevel converter (IBMC) as its primary-side converter. Using the proposed modulation scheme, an IBMC can generate a boosted square-wave-shaped ac voltage with a controllable amplitude, enabling it to regulate the power efficiently over a wide load and/or coupling range while achieving zero voltage switching for all switches. This article focuses on the steady-state operating principles of the proposed digitized modulation scheme. Key practical considerations, such as capacitor voltage balancing and semiconductor device selection, are highlighted. To verify the benefits of the proposed modulation scheme, an SAE J2954 WPT2/Z2 compliant wireless EV charger prototype that uses an IBMC as the primary converter is designed and built. 200 V Si MOSFETs are employed in the 12 submodules (SMs) that compose the IBMC. The secondary side employs a passive rectifier, and the power flow is controlled using only the IBMC. This system maintains an efficiency between 90% and 93% when regulating power transfer at 7.7 kW under a 220% variation in coupling factor (i.e., 0.14–0.31) and a 150% variation in battery voltage (i.e., 280–420 V).

Multipurpose Flexible Positioning Device Based on Electromagnetic Balance for EVs Wireless Charging

The electric vehicles (EVs) have played an important role in people's traveling due to the clean energy and friendly environment. Considering the endurance issue of EVs, wireless charging is regarded as a convenient and effective solution. However, the charging power and the efficiency would be greatly affected when the transmitting coil (TC) and the receiving coils are nonaligned. In this article, we present a flexible and high-accuracy positioning device based on electromagnetic balance, which could automatically achieve wireless charging and two-level positioning without communication between TC and EVs during the location. Besides, a six-coil cross-coupled circuit model has been built to optimize the key parameters that affect the positioning accuracy. The theoretical analysis and experimental results show that the proposed structures and location method have certain advantages in positioning accuracy, operation complexity, and practicability. Within the range of first-level positioning, the accuracy could achieve 1 cm. There is a high fitting performance between the simulation and experimental results, which verify the correctness of the theoretical analysis and the validity of the structures. Moreover, an additional comparative experiment has been designed to verify the correctness of the proposed method used in the wireless charging positioning system with ferrite cores and a magnetic shielding layer.

Magnetic Force Calculation of Movable YBCO Superconducting Helical Coils Applicable to Electric Vehicles Wireless Power Transfer

Background and Objectives: Today, replacing gasoline-powered vehicles with electric vehicles (EVs) and connecting them to an electric power source have made the optimal usage of energy-saving resources. Therefore, wireless Power Transfer (WPT) outstands as an alternative technology to improve the user perception about the charging process of the EVs. Superconducting coils (SCs) with high-temperature have an applied feature in decreasing losses of wireless power transmission (WPT). The Magnetic force has effects of overall deformation modes between two current carrier superconducting coils, i.e. axial extension, torsion, and bending. Coil misalignment is a fundamental problem and its impact on wireless power transmission efficiency is very complex. The analysis of a magnetic force which is presented in this paper are beneficially for the design and application of the WPT systems. Here, a fast analytical solution is presented to obtain the magnetic force between the transmitter and receiver helical superconducting coils in different positions.Methods: In this paper, a new method applied to solve the numerically magnetic force solutions in different superconducting coils mismatch states for WPT. Finally, for improvement of efficiency, the WPT system has been designed on the basis of mutual inductance changes which receiving helical coil was moved inside the transmitting helical coil. Hence, the magnetic force calculation of movable YBCO superconducting helical coils inside each other is presented. These models have been compared with the FEM.Results: Results show that the presented equations are reliable as well. According to the comparing the analysis and FEM data, the obtained results indicated the errors with less than 0.0064%. Also, results show an excellent agreement with respect to the finite element method.Conclusion: In this paper, the numerical solutions of magnetic force in different superconducting coils mismatch states were solved by a new method. The magnetic force analysis basics introduced in this paper are useful to develop and apply for wireless power transmission system. The simulation results show that only by applying some constraints, the efficiency of the transmitted wireless power will be optimized. Then, analytical models have been presented which make it possible to calculate the axial force which was exerted between two axially Helical magnetized and two thin coils in air. Also, the analytical stiffness calculation applied between these distributions of magnetic source has been presented. These models have been compared with the FEM to show an appropriate consistency.

Analysis of Dual Input Buck-Boost Converter for Solar PV Integration with Wireless Electric Vehicle Charger

Investigation of on-board renewable solar PV and wireless EV chargingstation integration is studied in this paper. Integration of on-board solar PVpower with EV charger power will reduce the stress on the grid without theneed for extra ground for solar plant installation. A dual-input buck-boostconverter (DIBBC) is used to integrate the two power sources and chargethe EV battery. A small-signal model of the converter is used to design thecontroller for three switches of the DIBBC. The simulation model of the inte-grated solar PV system and wireless power transfer (WPT) system is designedfor charging a battery of 120V/165Ah at 130V. The hardware prototype ofthe proposed EV battery charging system is designed for 1.5kW to verify thesimulation results. WPT system is developed for circular spiral-shaped coils,which are series-series compensated for 85kHz resonance frequency. SolarPV is replaced by a solar simulator programmed to operate with the samespecifications used in the simulation. Results and analysis of the DIBBCbased charger with charging voltage 130V showed higher efficiency up to 92% when both the sources are supplying power to DIBBC. The proposedcharging system gives better efficiency with higher source voltages and whenthe difference in power supplied by the two sources is less. Thus, highervoltage sources are beneficial for improving the efficiency of the integratedcharging system. Further, loss analysis in major components of the converteris discussed.

Stability Improvement of Dynamic EV Wireless Charging System with Receiver-Side Control Considering Coupling Disturbance

Receiver-side control has been a reliable practice for regulating the transferred energy to the batteries in the electric vehicle (EV) wireless power transfer (WPT) systems. Nonetheless, the unpredictable fluctuation of the mutual inductance in dynamic wireless charging brings extreme instability to the charging process. This overshoot that appears in instant vibrations may largely increase the voltage/current stress of the system, and even cause catastrophic failure in the battery load. In addition, the speed of the vehicles may lead to untraceable steady-state operation. However, existing solutions to the above two issues suffer from either long communication time delay or significantly compromised output regulation. In this paper, the slow dynamics and the overshoot issues of the WPT system are elaborated in theory, and the small-signal model mainly considering mutual inductance disturbance is established. A simple feedforward control is proposed for overshoot damping and fast system dynamics. Experimental results validate that the overshoot can be reduced by 13% and the settling time is improved by 50% in vehicle braking or acceleration. In constant speed driving, the battery charging ripple is decreased by 12% and ensures better system stability.

Design and Performance Analysis of Misalignment Tolerant Charging Coils for Wireless Electric Vehicle Charging Systems

In order to design a high efficiency Wireless Electric Vehicle Charging (WEVC) system, the design of the different system components needs to be optimized, particularly the design of a high-coupling, misalignment-tolerant inductive link (IL), comprising primary and secondary charging coils. Different coil geometries can be utilized for the primary and the secondary sides, each with a set of advantages and drawbacks in terms of weight, cost, coupling at perfect alignment and coupling at lateral misalignments. In this work, a Finite Element Method (FEM)-based systematic approach for the design of double-D (DD) charging coils is presented in detail. In particular, this paper studies the effect of different coil parameters, namely the number of turns and the turn-to-turn spacing, on the coupling performance of the IL at perfect alignment and at ±200 mm lateral misalignment, given a set of space constraints. The proposed design is verified by an experimental prototype to validate the accuracy of the FEM model and the simulation results. Accordingly, FEM simulations are utilized to compare the performance of rectangular, DD and DDQ coils. The FEM results prove the importance of utilizing an additional quadrature coil on the secondary side, despite the added weight and cost, to further improve the misalignment tolerance of the proposed inductive link design.

Ultrawideband (UWB)-based precise short-range localization for wireless power transfer to electric vehicles in parking environments.

As the necessity of wireless charging to support the popularization of electric vehicles (EVs) emerges, the development of a wireless power transfer (WPT) system for EV wireless charging is rapidly progressing. The WPT system requires alignment between the transmitter coils installed on the parking lot floor and the receiver coils in the vehicle. To automatically align the two sets of coils, the WPT system needs a localization technology that can precisely estimate the vehicle’s pose in real time. This paper proposes a novel short-range precise localization method based on ultrawideband (UWB) modules for application to WPT systems. The UWB module is widely used as a localization sensor because it has a high accuracy while using low power. In this paper, the minimum number of UWB modules consisting of two UWB anchors and two UWB tags that can determine the vehicle’s pose is derived through mathematical analysis. The proposed localization algorithm determines the vehicle’s initial pose by globally optimizing the collected UWB distance measurements and estimates the vehicle’s pose by fusing the vehicle’s wheel odometry data and the UWB distance measurements. To verify the performance of the proposed UWB-based localization method, we perform various simulations and real vehicle-based experiments.

Novel Output Regulation Method for Three-Phase Three-Level Wireless EV Charging System

Three-phase wireless power transfer (WPT) systems have compact coil structures, canceled triplen harmonics, and less dc -link current ripple, which are suitable for wireless electric vehicle (EV) charging systems. Most three-phase WPT systems are based on two-level inverters. Alternately, three-level (TL) inverters have the potential to further promote the performance of EV chargers by reducing the electromagnetic interference (EMI) and the voltage stress of power switches. However, the unbalance of the neutral point (NP) voltage is a problem for traditional TL inverters. This article proposes a TL three-phase WPT system for EV wireless charging, which is based on a T-type neutral point clamp (TNPC) inverter. The modeling, coil structure, and switching pattern of the proposed system are analyzed in detail. Furthermore, a novel output regulation method based on vector control is proposed for the WPT system. Also, a NP voltage balance strategy is proposed to enhance the reliability of the TL inverter. Both simulations and an experimental prototype based on SIC- MOSFET are given to verify the effectiveness of the proposed three-phase WPT system and control method.

Retraction: A smart AIS based portable wireless electric charging vehicles (J. Phys.: Conf. Ser. 1916 012145)

This article (and all articles in the proceedings volume relating to the same conference) has been retracted by IOP Publishing following an extensive investigation in line with the COPE guidelines. This investigation has uncovered evidence of systematic manipulation of the publication process and considerable citation manipulation.IOP Publishing respectfully requests that readers consider all work within this volume potentially unreliable, as the volume has not been through a credible peer review process.IOP Publishing regrets that our usual quality checks did not identify these issues before publication, and have since put additional measures in place to try to prevent these issues from reoccurring. IOP Publishing wishes to credit anonymous whistleblowers and the Problematic Paper Screener [1] for bringing some of the above issues to our attention, prompting us to investigate further.[1] Cabanac G, Labbé C and Magazinov A 2021 arXiv:2107.06751v1 Retraction published: 23 February 2022

A smart AIS based portable wireless electric charging vehicles

As the production of electric vehicle has scaled up in the recent years in order to meet the objective of lowering the carbon footprint and eco-friendly transportation. The raise in the production of electric vehicles in accordance with hike in the price of petroleum and diesel has shifted the huge market share of the automobile industry from ICE engines to the battery powered engines. The shift in turn pushes the demand for installation of charging stations for electric vehicles at most locations. But the installation of such EV charging base stations requires high capital and sophisticated spatial infrastructure in densely populated area. Therefore, the paper proposes the AIS based mobile wireless charging system for electric vehicles which is cost effective and reliable. The system is best suited for densely populated areas, parking arenas at theatres, malls, parks etc., The Wireless Sensor Network is implemented to effectuate adaptive intelligent system, therefore leading to better accuracy and modularity.

Optimization of Ferrites Structure by Using a New Core-Less Design Algorithm for Electric Vehicle Wireless Power Transfer

In order to improve the customers’ continuous usage of electrical vehicles (EVs) and reduce the weight of the energy storage devices, wireless charging technology has been widely studied, updated, and commercialized in recent decades, regarding to its distinct superiority of great convenience and low risk. A higher coupling coefficient is the key factor that impacts the transmission efficiency, thus in most medium-power (hundreds of watts) to high-power (several kilowatts) wireless charging systems, ferrites are used to guide the magnetic flux and intensify the magnetic density. However, the weight of the ferrite itself puts an extra burden on the system, and the core loss during operation also reduces the total efficiency and output power. This paper proposes an optimized design algorithm based on a core-less method for the magnetic core, where the core loss and the coupling coefficient are consequently balanced, and the overall weight and efficiency of the system can be optimized. The iteration procedure is applied on the basis of removed ferrite length and thickness in the algorithm. In the simulation, a square coupler with a total volume of 300 mm × 150 mm, a circular coupler of 150 mm × 150 mm and a Double-D (DD) coupler of 300 mm × 150 mm are used to verify the advantages of the proposed method. The optimized ferrite structures are specific for each coupler shape, and the improvement is proved to be universal in current scale by means of 3-D finite element analysis.