Wireless Charging Research Articles

Improving efficiency of wireless charging system in electric vehicle using a hybrid ultracapacitor-battery energy storage approach

This research aims to enhance the efficiency of wireless charging systems in electric vehicles by integrating a hybrid ultracapacitor-battery energy storage solution. Traditional standalone battery-based energy storage systems in wireless charging often face sub-optimal charging efficiency, resulting in extended charging times and reduced energy transfer efficiency. To address this limitation, we propose a hybrid approach that combines the rapid charging capability of ultracapacitor (supercapacitor) with the long-term storage capacity of batteries. The optimal charging range is 0 cm to 2 cm, and the combined output voltage and current are 5 V to 12 V and 0.63 A, respectively. This hybrid energy storage system will significantly boost electric vehicles (EVs) charging efficiency. Our research involves experimental evaluation and data analysis to assess crucial parameters, including charging efficiency, energy transfer efficiency, and charging time. The experimental results are validated and compared against existing battery-only systems, shedding light on the advantages and limitations of the hybrid approach. This study contributes to the optimization of wireless charging systems, enhancing energy transfer efficiency, and promoting the broader adoption of wireless charging technology in electric vehicles.

Energy-Efficient Trajectory Optimization With Wireless Charging in UAV-Assisted MEC Based on Multi-Objective Reinforcement Learning

Energy-Efficient Trajectory Optimization With Wireless Charging in UAV-Assisted MEC Based on Multi-Objective Reinforcement Learning

Reliability Estimation of Wired and Wireless Fast Electric Vehicle Charging Systems

Reliability Estimation of Wired and Wireless Fast Electric Vehicle Charging Systems

A Misalignment-Insensitive Hybrid Reconfigurable Wireless Charging System for Constant-Voltage and Constant-Current Outputs Based on a Novel Bipolar Coil Symmetrical to Two Perpendicular Directions

A Misalignment-Insensitive Hybrid Reconfigurable Wireless Charging System for Constant-Voltage and Constant-Current Outputs Based on a Novel Bipolar Coil Symmetrical to Two Perpendicular Directions

High-entropy alloys as magnetic shielding materials in low-frequency wireless power transmission

Soft magnetic materials are required to exhibit high saturation magnetization and low coercivity. Iron-based metal alloys, such as FeMnZn, are commonly used commercial soft magnetic materials with electromagnetic shielding functions. However, these alloys generally exhibit low saturation magnetization, poor high-temperature stability, and significant magnetic losses. In recent years, many research groups have highlighted the excellent soft magnetic properties of high-entropy alloys (HEAs). This study develops new HEA powders with superior soft magnetic characteristics for applications in low-frequency magnetic shielding components. The research found that the FeCoNiSiCuNb HEA, under appropriate ball-milling and annealing conditions, exhibits high saturation magnetization and excellent high-temperature properties, retaining over 50% of its magnetism even at 700K. At an operating frequency of 100 kHz, compared to FeMnZn, the real permeability of the FeCoNiSiCuNb HEA is increased by 2.25 times. Preparing this HEA material as a magnetic shielding material can lead to higher inductance, a coupling coefficient increased to 0.84, and a transmission efficiency improvement of 19%, demonstrating the potential of high-entropy alloys in wireless charging applications.

A Wide-Range Global Optimal Control Strategy for Wireless Charging Systems in Electric Vehicles

A Wide-Range Global Optimal Control Strategy for Wireless Charging Systems in Electric Vehicles

Novel Designs of Magnetic Coupled Structure With 360° Rotation Misalignment Tolerance for AUVs’ Wireless Charging System

Novel Designs of Magnetic Coupled Structure With 360° Rotation Misalignment Tolerance for AUVs’ Wireless Charging System

Intelligent Wireless Charging Path Optimization for Critical Nodes in Internet of Things-Integrated Renewable Sensor Networks

Intelligent Wireless Charging Path Optimization for Critical Nodes in Internet of Things-Integrated Renewable Sensor Networks

Anisotropic Heat Transfer in a Fibrous Membrane with Hierarchically Assembled 2D Materials.

Effective heat redistribution in specific directions is vital for advanced thermal management, significantly enhancing device performance by optimizing spatial heat configurations. We have designed and fabricated a hierarchical fibrous membrane that enables precise heat directing. By integrating hierarchical structure design with the anisotropic thermal conductivity of two-dimensional (2D) materials, we developed a fibrous membrane for anisotropic heat transfer. Such a structure is fabricated by aligning a 1D structured fiber in the 2D plane to achieve anisotropy at each scale level. The fiber units, where 2D nanosheets circumferentially and axially aligned, achieved a high axial thermal conductivity of 16.8 W·m-1·K-1 and advanced heat directing ability, confirmed by characterizations and simulations. The assembled membrane demonstrated an exceptional tensile strength (365 MPa) and high thermal conductivity (10.5 W·m-1·K-1) along the fiber axis. Our membranes are seen as a refined model for thermal management materials, combining the benefits of heat spreaders and thermal interface materials, thus being proficient in directing heat along programmed pathways. A practical wireless charging cooling demonstration illustrated this. Our methodology also proved versatile with different 2D fillers and various geometries. This research presents a method to achieve precise heat directing at the material's level, facilitating the systematic design of thermal management in electronics.

Renewable energy driven on-road wireless charging infrastructure for electric vehicles in smart cities: A prototype design and analysis

The adoption of electrical vehicles (EVs) has increased due to the increasing concerns about fossil fuel shortages, rising costs, and environmental impacts. This increasing adoption of EVs significantly increase power demand on utility grids. Moreover the EVs require more time for charging compared to fossil fuel vehicles. To address these challenges, this study proposes a renewable energy-based on-road wireless charging (ORWC) infrastructureto reducing charging time and utilizing renewable energy within a smart city framework. This study develops a prototype of the ORWC system and examines its techno-economic and environmental benefits. Moreover, the study also evaluates annualized energy share, energy economics, and cost-effectiveness. The results of the proposed study indicate that the ORWC system in combination with RERs, effectively reduces the cost of energy from $0.112/kWh to $0.30/kWh and lowers carbon emissions from 76.9 tons/year to 29.5 tons/year. Furthermore, the results also reveals optimal energy distribution among different energy resources PV, BESS, and the grid. These results highlight that ORWC infrastructure can reduce peak load demand on existing grids and enhance the power density of EV charging systems. This has potential implications for future-oriented fast charging stations and policy development to support the widespread adoption of EVs.

Unobstructive and safe-to-wear watt-level wireless charger

A wearable microgrid that centralizes and distributes harvested energy across different body regions can optimize power utilization and reduce overall battery weight. This setup underscores the importance of developing cable-free wireless power transfer (WPT) systems for mobile and portable devices to eliminate the risks posed by wired connections, especially in dynamic and hazardous environments. We introduce a thin, stretchable, and safe hand band capable of watt-level wireless charging through the widely adopted Qi protocol operating at 130 kHz. The implementation of non-adhesive fabric encapsulation serves to protect the 50-μm-thin spiral copper antenna from mechanical strain, ensuring an overall hand band stretchability of 50%. We also create a stretchable “Ferrofabric”, characterized by a magnetic permeability of 11.3 and a tensile modulus of 75.3 kPa, that provides magnetic shielding for the antenna without compromising wearability. The “Ferrofabric” improves the coil inductance but induces core loss in AC application. By fully understanding and managing loss mechanisms such as the skin effect, proximity effect, core loss, and joule heating, we achieve a wireless charging efficiency of 71% and power delivery of 3.81 W in the kHz frequency range. Our WPT hand band is unobstructive to hand motion and can charge a handheld smartphone as fast as a desktop charger or power a battery-free chest-laminated e-tattoo sensor, with well-managed thermal and electromagnetic safety. Through a holistic electromagnetic, structural, and thermal design, our device culminates in a safe, rugged, and versatile solution for wearable WPT systems.

Modeling EV dynamic wireless charging loads and constructing risk constrained operating strategy for associated distribution systems

Dynamic wireless charging (DWC) is an emerging technology that enables the charging of electric vehicles (EVs) while they are in motion. However, previous load modeling methods have not thoroughly explored the detailed analysis of DWC load characteristics. Existing research only considers the single-node supply mode for dynamic wireless charging roads (DWCRs), and the assessment of operational risks arising from the uncertain DWC loads has not been addressed. This paper begins by conducting an equivalent circuit analysis of a typical EV DWC system with multiple segmented coils. We present a more accurate trapezoidal power model for a single EV. Subsequently, we model the aggregated EV DWC load, accounting for traffic flow and headway using Poisson and negative exponential distribution functions, respectively. In the operation process, we consider a multi-node supply mode for DWCRs. To address the inaccuracy of long-term predictions, we propose a rolling optimization model to coordinate DWC and renewables with heterogeneous uncertainties by introducing a risk metric to manage potential uncertain risks. The proposed optimization model is transformed into a mixed-integer second-order cone programming (MISOCP) problem after convex relaxation. Finally, we conduct case studies to validate the proposed methods.

Dynamic parameter identification method for wireless charging system of AUV based on multi-strategy nonlinear rime algorithm

Dynamic parameter identification method for wireless charging system of AUV based on multi-strategy nonlinear rime algorithm

Evaluation of practicality of wireless charging for electric vehicles in the next 10 years

As the electric vehicle market is expanding rapidly due to the need for sustainable development; a solution is needed to deal with current problems related to electric vehicles, this includes relatively limited driving range, relatively lack of charging spots during busy season, and the inconveniences of plug-in charging, such as dealing with cables. Therefore, wireless charging technology capable of charging electric vehicles while they are in motion becomes a potential solution. Assessing whether this technology will be mass-applied in the future is crucial. Given the limited current research that evaluates the practicality of wireless charging technology for electric vehicles with a time scale, this article aims to assess the aspects of safety, cost, efficiency, materials, user acceptance and other factors to determine the likelihood of making wireless charging practical for electric vehicles in the next decade. Furthermore, by distributing questionnaires to electric and gasoline car owners to gather participants’ opinions and expectations on wireless charging for electric vehicles, statistical analysis of the questionnaire results; interview with a professor at Shanghai University who is an expert in magnets and electricity, conducting secondary research, this article concludes whether wireless charging technology for electric vehicles can be implemented in the decade or not. As an impact, this article includes a time scale by conducting an evaluation instead of implicitly mentioning the time scale.

Dual‐state and self‐oscillating wireless charging system topology for direct‐drive battery

AbstractThis study proposes a novel topology with bi‐stable controlling for wireless charging system (WCS). The advantage of the proposal is that a desired charging current can be directly output from rectifier without requiring charging current manager, thereby greatly simplifying the structure of the receiver. The proposed topology not only improves the transmission efficiency of system, but also reduces the loss and heat dissipation in the receiver. The principle of the topology is outlined and the circuitry model and control strategy are established and analyzed in detail. The innovation of this method lies in treating the coupler as a current transformer, which enables more direct and simpler controlling of the charging current. The experiment is conducted to verify that when the peak charging current is increased from 5A to 10A, the system efficiency is increased up to 82.0% and the receiver efficiency up to 96.7%. Both computational simulation and experimental validation have confirmed the feasibility of the proposed method. Compared with conventional WCS topology with compensation, the proposed method improves the system efficiency by 3% and the receiver efficiency by 5%, which is more suitable for practical applications where compact and light‐weight receiver is required.

Collaborative Optimization Framework for Coupled Power and Transportation Energy Systems Incorporating Integrated Demand Responses and Electric Vehicle Battery State-of-Charge

The growing adoption of electric vehicles (EVs) and advancements in dynamic wireless charging (DWC) technology have strengthened the interdependence between power distribution networks (PDNs) and electrified transportation networks (ETNs), leading to the emergence of coupled power and transportation energy systems (CPTESs). This development introduces new challenges, particularly as DWC technology shifts EV charging demand from residential plug-in charging to charging-while-driving during commuting hours, causing simultaneous congestion in both ETNs and PDNs during peak times. The present work addresses this issue by developing a collaborative optimization framework for CPTESs that incorporates integrated demand responses (IDRs) and EVs battery state-of-charge (SOC). In the ETN, a multiperiod traffic assignment model with time-shiftable traffic demands (MTA-TSTD) is established to optimize travelers’ routes and departure times while capturing traffic flow distribution. Meanwhile, effective path generation models with EVs battery SOC are proposed to optimize charging energy during driving and construct the effective path sets for MTA-TSTD. In the PDN, a multiperiod optimal power flow model with time-shiftable power demands (MOPF-TSPD) is formulated to schedule local generators and flexible power demands while calculating the power flow distribution. To enhance temporal and spatial coordination in CPTESs, a distributed coordinated operation model considering IDRs is proposed, aiming to optimize energy consumption, alleviate congestion, and ensure system safety. Finally, an adaptive effective path generation algorithm and an ETN–PDN interaction algorithm are devised to efficiently solve these models. Numerical results on two test systems validate the effectiveness of the proposed models and algorithms.

An Energy-Adjustable, Deformable, and Packable Wireless Charging Fiber Supercapacitor.

Wireless charging energy storage devices eliminate bulky wires of wearable electronics. However, rigid shape and specific charging energy restrict their applications in space-limited portable electronics. Herein, an all-carbon fiber supercapacitor is presented that features shape-adjustable, packable, and energy-controllable wireless charging functions. With the unique on-dimensional circuit structure, the maximum energy transfer efficiency from the electrical energy received by the wireless charging unit to the output energy of the fiber supercapacitor can reach up to ≈60.8%, and meanwhile this integrated fiber device exhibits an outstanding area capacity of 803 mF cm-2 and energy density of 1004 µWh cm-2, superior to most of the fiber supercapacitors. Moreover, this unique device can endure significant deformation in shape of circles ranging from 2 to 20cm diameter, and can be packed into narrow spaces, such as smart bracelet and disk-shaped pet global positioning system (GPS). By altering the device shape, the wireless charging current, voltage, and power can be adjusted in the range of 0.5-20mA, 1.4-15.5V, and 0.003-313mW, accommodating the energy requirements for nearly all existing micro-electronics. This work offers unprecedented opportunities for packable, space-confined and energy harvesting controllable wearable electronics.

A New Magnetic Coupler with High Misalignment Tolerance and Inherent Constant Current–Constant Voltage for Underground Wireless Charging

In an underground inductive power transfer (IPT), it is inevitable to produce the phenomenon of misalignment between the transmitter and the receiver, which will reduce the output current, voltage and output efficiency of the whole IPT system. Aiming to solve this problem, a universal hybrid coupler is proposed, which can still stabilize the output in the expected range and has the ability of anti-misalignment when the X and Z directions are misaligned. The coupler is composed of a BP coupler and Γ type network. The secondary edge of the coupler introduces a Γ network, which decouples the two main coils on the same side of the receiver from the auxiliary coil and reduces the complexity of the system. The coupler can effectively reduce the coupling fluctuation caused by physical movement between the downhole transmitting end and the receiving end, thereby ensuring the stable output of the coupler. As a widely used IPT system, it can access the rest of the circuit topology whose output is independent of the load and achieve misalignment-tolerant output. Finally, based on the proposed hybrid IPT coupler theory, a 500 W misalignment-tolerant coupler prototype was built, and the compensation topologies were configured as series–series (SS) and series/inductance/capacitance/capacitor (S/LCC) structures. When the X and Z direction is misaligned, the constant current and voltage independent of the load can be output by switching the compensation topology. The experimental results are the same as the theoretical analysis.

A Decoupled Modulation Strategy for Constant Voltage/Current Wireless Charging System Under High Coils Misalignment

ABSTRACTOutput fluctuation and lower transmission efficiency under load and mutual inductance variation are hot concerned in the wireless charging system for power batteries. In this paper, a decoupled tracking strategy is proposed to realize constant voltage (CV) or current (CC) output and high transmission efficiency. The circuit model of series–series compensation network is built, and corresponding transmission characteristics can be derived. First, the load and mutual inductance value can be estimated by measuring the primary electrical information, including the inverter output voltage, current, and the phase error between them. Then load‐independent voltage or current output characteristics under coils misalignment can be maintained by tracking the optimal switching frequency of inverter part. In addition, the value of output voltage or current can be adjusted flexibly for different operation occasions by the employment of pulse‐width modulation. As a result, the load‐independent output characteristics realization and output adjustment can be decoupled. Based on only the primary measuring information, the CV/CC output can be maintained via the proposed hybrid control strategy when the coils misalignment and load variation happen, increasing the robustness of whole wireless power transfer (WPT) system. Furthermore, the soft switching of all power switches in the inverter part can be realized to reduce the switching loss. Compared with previous research, the proposed wireless charging system has a higher power density and a simplified control strategy. Finally, an experimental platform with 60‐V charging voltage and 3.6‐A charging current is built to verify the feasibility of the proposed sys‐tem and control method.

Adaptive output feedback control of a bidirectional AC/DC totem‐pole PFC converter for wireless charging of electric vehicles

AbstractThis paper deals with the control problem of a single‐phase bidirectional alternating current/direct current (AC/DC) totem‐pole power factor correction (PFC) converter intended to be used in wireless power transfer (WPT) chargers for electric vehicles (EVs). The converter is operating as a bridgeless boost rectifier with the PFC functionality during grid to vehicle (G2V) mode and as a PFC inverter during vehicle to grid (V2G) mode. Firstly, the operating principle is presented. Secondly, an overall mathematical model governing all the operating modes of the converter is elaborated. Thirdly, due to the nonlinearity of the studied system, a nonlinear controller–based Lyapunov technique is designed to achieve the following control objectives: (i) unity power factor (UPF) during both power transfer modes G2V and V2G, (ii) regulation of the DC‐link voltage, and (iii) asymptotic stability of the closed‐loop system. Further, as the developed control law requires the measurement of all voltages and currents, an adaptive observer–based Kalman‐like technique is designed to estimate all the required signals and parameters. The performances of the proposed output feedback control technique are validated through several simulation scenarios showing that all control objectives are achieved. It should be noted that the use of the Kalman observer reduces the complexity of the systems as it requires only two measurements (grid voltage and current) making it an advantageous solution over existing solutions where three measurements are generally used. Furthermore, due to the low‐pass filtering behavior of the observer and its susceptibility to estimate the converter's parameters, the robustness of the controller and its insensitivity to the parameter uncertainties are greatly improved.