Resonant Charging Research Articles

Wireless Charging System for Electric Vehicles

This paper presents a comprehensive review of wireless electric vehicle (EV) charging technologies, focusing on the advancements, challenges, and prospects in this domain. With the increasing adoption of electric vehicles globally, the demand for efficient and convenient charging solutions has grown significantly. Wireless charging offers promising opportunities to enhance the user experience by eliminating the need for physical connections between the charger and the vehicle. This review discusses the underlying principles of various wireless charging technologies, including inductive charging, resonant charging, and capacitive charging. Furthermore, it examines the key components and system architectures involved in wireless EV charging systems. The paper also addresses the technical challenges such as efficiency, alignment, safety, and interoperability that must be overcome to realize the widespread deployment of wireless charging infrastructure. Additionally, the regulatory and standardization efforts governing wireless EV charging are discussed, along with their implications for market adoption. Finally, the review provides insights into future research directions and potential applications of wireless EV charging technology, including dynamic charging systems and integration with smart grid networks. Overall, this paper serves as a valuable resource for researchers, engineers, and policymakers interested in understanding the current state and future prospects of wireless electric vehicle charging.

Development of method for frequency regulation of output current in high-voltage transformerless resonant chargers of capacitive energy storage devices

The object of research is high-voltage systems of electric discharge installations for various technological purposes. The work reports solving the problem of enabling the rate of charging of a capacitive energy storage, set by the requirements of a certain high-voltage technology. The quantitative characteristics of the deviation of the output current of the resonant inverter from the set stabilized value when changing the switching frequency of inverter switches in the range of output voltage change from 0 to 20 kV were determined. Using the Fourier transform of the rectangular input voltage, the frequency regulation possibility of the output current of the charger for capacitive energy storage devices was analyzed. Estimation dependences of the output current of resonant inverter on the load resistance and frequency deviation from resonant frequency were derived. These dependences could be used to implement frequency control over the switching inverter transistors, with the help of which the given effective value of the output current of the resonant inverter is obtained. A method of frequency regulation of the output current in high-voltage transformerless resonant charging devices of capacitive energy storage devices has been developed. Special feature of this method is that it is based on the frequency dependence of reactive resistances of the inductance and capacitance of the resonant circuit connected in series. Owing to that, it makes it possible to adjust the switching frequency of the inverter’s power switches depending on the relative resistance of the load and the specified growth rate of the capacitive energy storage voltage. The results reported here could be used in the design of benches for testing the electrical strength of high-voltage cables, as well as for the construction of high-voltage transformerless chargers in systems of electric discharge impulse processing of materials

ARKADIEV-MARKS CIRCUIT WITH RESONANT CHARGING OF CAPACITIVE ENERGY STORAGE IN MAGNETIC-PULSE INSTALLATIONS

The effective use of Arkadiev-Marx scheme with a resonant charging of capacitive storages in magnetic-pulse installa-tions, as power sources, in technologies using the electromagnetic field energy is proposed and substantiated. It is found that during charging the maximum voltage amplitude at capacitor increases by number times equal to the quality factor of the charging circuit at the fundamental frequency of the harmonic expansion of exciting signal, but by ~34% less than possible maximum. The calculations of the characteristics of magnetic-pulse complex intended for the repair of damaged car bodies show the high efficiency of using the Arkadiev-Marx circuit with the resonant charging of ca-pacitive storage. It is found that during the time of ~0.45 s the battery of 10 capacitors connected in parallel with total capacitance of ~100 μF can be charged up to voltage of ~7500 V with stored energy of ~2.8 kJ. The results of the work allow us to give recommendations on the practical increase in the efficiency of magnetic-pulse metal processing. Refer-ences 16, figures 4.

Fixed-Frequency LCC Resonant Battery Charger With Inherent CC-CV Operation for Electric Vehicles

Fixed-Frequency LCC Resonant Battery Charger With Inherent CC-CV Operation for Electric Vehicles

Electromagnetic Detection System with Magnetic Dipole Source for Near-Surface Detection.

This paper proposes a nondestructive, separate transmitter-receiver (TX-RX) electromagnetic measurement system for near-surface detection. Different from the traditional dual-coil integrated design, the proposed transient electromagnetic (TEM) system performs shallow subsurface detection using independent TX coil and movable RX coils. This configuration requires a large primary field so that the far-away secondary field is able to generate reliably induced voltages. To achieve this goal, a bipolar current-pulsed power supply (BCPPS) with a late resonant charging strategy is designed to produce a sufficiently large magnetic moment for the exciting coil with low source interference. The magnetic dipole source (MDS) with a large proportion of weight is separated from the field observation device and does not need to be dragged or transported during the detection process. This setup lowers the weight of the scanning device to 3 kg and greatly improves the measurement efficiency. The results of the laboratory test verify the effectiveness of the separate MDS and RX module system. Field experimental detection further demonstrates that the proposed system can realize highly efficient and shallow surface detection within a 200 m range of the MDS device.

Adaptive Wireless Power Transfer via Resonant Laser Beam Over Large Dynamic Range

Wireless power transfer (WPT) via resonant laser beam from a spatially-distributed laser resonator not only benefits the instinct safety, but also has important potential of adaptive operation without positioning and aiming when retroreflectors are used to enable the alignment-free operation of the laser. Despite the intense theoretical modeling and experimental efforts with different laser schemes, the adaptive resonant beam WPT across large dynamic range -including both working distance and field of view (FoV) -has never been demonstrated, due to the absence of true alignment-free laser. In this work, we summarized the requirements on the dynamic range and discussed the optimization criteria of dynamic range and laser safety, including the telescope in the laser resonator, the resonator stability, coupled-resonator scheme, and influences of the optical aberrations. The analysis indicated that loss induced by optical aberrations is the main issue limits the dynamic range. In the experiment, alignment-free laser with large dynamic range for WPT application was demonstrated with improved resonator design and optical design to compensate the aberrations. Efficient multiwatt optical output was obtained across a working distance of 1-5 m, a receiver FoV of ±30∘, and a transmitter FoV of 4.6∘; and over 1.3 W electrical output was obtained via an InGaAs photovoltaic cell, with DC-DC WPT efficiency being 4%. Our work proved the feasibility of large-dynamic-range alignment-free laser with distributed-resonator, which paves the way for practical resonant beam charging and communication applications based on it for the internet of things devices.

An Efficiency Optimization Strategy for Electric Vehicle Wireless Energy Transmission System

Magnetic coupling resonant wireless energy transmission technology has become an important research direction for electric vehicle wireless charging systems. This paper proposes an efficiency optimization strategy for the electric vehicle wireless energy transmission system based on LCL-S topology to improve the efficiency of electric vehicle magnetic coupling resonant wireless charging. This paper analyzes the optimization method of system efficiency based on LCL-S topology, establishes an experimental model in MATLAB/Simulink simulation software, and verifies it with the control variable method. The experiment shows that the efficiency optimization strategy based on the LCL-S topology proposed in this paper can effectively improve the system transmission efficiency and stabilize the transmission efficiency at a higher level faster.

A photovoltaic powered wireless charging system for light-duty electric vehicles with reflective panel analysis

ABSTRACT To reduce the pollution to a large extent in the transportation sector, it is important to charge the Electrical Vehicles (EV) from sustainable sources of electricity, such as solar or wind energy. Building integrated photovoltaic (BIPV) systems have gained popularity over the past 10 years and have been demonstrated to be a practical method of generating renewable energy that can be used to partially power buildings. One of the emerging technologies in EV charging systems is wireless charging technology; we realize that using this technology, fully automatic charging is simple. Compared to a plug-in charging system, wireless charging is free from rust, rain, and other environmental impacts like vandalization and visual pollution. By integrating wireless EV charging with BIPV shading systems, it offers a green and cutting-edge charging option. Building integrated solar panels are affected by different scenarios and causes due to their positioning. The direction of the solar panel, tilted position, and reflected irradiation, these all factors are to be considered in design of BIPV system. In this article, a system designed in way to analyze the effect of white and black color reflectors effect on solar panels (shading system) in different directions. In this work, a 256-W wireless charging system developed for E-bikes utilizing BIPV system. The proposed BIPV-fed resonant inductive charging system achieved efficiency of 95% for simulation and 91.6 for experimental analysis. The experimental analysis is verified by simulation and experimental results.

Modelling of a Resonant Charging Circuit for a Solid-State Marx Generator

For the pulsed electric field treatment of plant material on an industrial scale, Marx-type pulse modulators are used as a pulse source. The combination of a conventional Marx generator design equipped with solid-state switches with the concept of resonant charging via current-compensated chokes enables the set-up of a Marx generator having only one active semiconductor switch per stage. Thereby, the pulse shape is defined by the passive components of the RLC-pulse circuit. In the course of the design of such a resonant charging circuit, common-mode current components through the current-compensated chokes need to be considered. Moreover, especially for a generator having its ground connection at its centre, induced voltages versus ground need to be addressed. Therefore, an investigation based on circuit simulations has been made. The simulations showed that the common-mode current components decay to zero just after the resonant charging process and cause a voltage transient at the terminal of the power supply, which needs to be floating versus ground. In order to reduce the amplitude of this transient, the effects of adding a damping resistor have been studied. However, adding this resistor may involve an increase in the common-mode current components. Moreover, the common-mode current components of different chokes are influenced by the on-time of the switches. In the paper, based on the simulation results, different operation modes with and without the damping resistor are discussed. Thereby, the on-time of the switches has been varied. Selected simulation results have been verified by means of measurements.

Simultaneous wireless information and power transfer in resonant beam charging

SummaryFSO links have attracted a significant amount of interest in the recent years driven by the paramount importance of their license‐free spectrum and ease of deployment in wireless networks. Besides, the energy harvesting (EH) paradigm allows recharging terminals via ambient and/or external sources and prolongs battery lifetime operation. Thereby, facilitating free space optical (FSO) in EH networks creates potential scenarios for the future sixth‐generation (6G) communication systems. In this study, an EH system performing simultaneous wireless information and power transfer (SWIPT) while adopting FSO and resonant beam charging (RBC), RBC–SWIPT system is thoroughly analyzed. The performance of RBC‐SWIPT system is analyzed through Monte Carlo simulations, where average bit error ratio (ABER) and energy efficiency (EE) are studied and evaluated. In addition, channel capacity is derived along with the mutual information and studied over indoor line of sight (LOS) optical channel. Monte Carlo simulation results corroborate the accuracy of the derived formulas.

Charging a Smartphone Over the Air: The Resonant Beam Charging Method

Wireless charging for mobile Internet of Things (IoT) devices such as smartphones is extremely difficult. To reduce energy dissipation during wireless transmission in mobile scenarios, laser or narrow radio beams with sophisticated tracking control are typically required. However, reaching the necessary tracking accuracy and reliability is really difficult. In this article, inspired by the features of optical resonators and retroreflectors, we develop an experiment on a self-aligned resonant beam charging system for long-distance mobile power transfer. It exploits light resonances inside a double-retroreflector-based spatially separated laser resonator (SSLR), which eliminates the requirement for any kind of tracking control. Focal telecentric cat’s eye retroreflectors are employed here. The SSLR was investigated by both theoretical calculation and experiment. We also well assembled the transmitter and the receiver and demonstrated its application in mobile smartphone charging. The results show that above 5-W optical power (also obtained more than 0.6-W electrical power) transferring with negligible diffraction loss to a few-centimeter-size receiver is realized while the receiver moves arbitrarily within 2-m vertical distance and 6° field of view from the transmitter. The maximum horizontal moving range is up to ±18 cm. This wireless charging system empowers a smartphone in mobile operation with unlimited battery life without the need for a cable.

DOUBLE-CIRCUIT RESONANT ELECTRIC POWER AMPLIFIER FOR MAGNETIC-PULSE PROCESSING OF METALS

The authors propose and substantiate the functionality of a magnetic-pulse installation consisting of two blocks, the first of which is a resonant double-circuit charger of a capacitive energy storage, and the second block is a discharge circuit with an inductor-tool for performing a given production operation. It is shown that the voltage changes in time according to an exponentially growing harmonic law. It was found that the amplitude of the voltage across the capacitor can be regulated by varying the characteristics of the coupling transformer between the circuits and the characteristics of the circuit of the reactive power conversion unit. Numerical assessments of the characteristics of the charging process showed a high efficiency of voltage formation on the capacitive storage due to resonance phenomena (the transformation ratio is equal to the Q-factor of the circuit ~ 20), which is not comparable with the well-known traditional indicators of induction methods. In terms of phase – the length in time to the maximum charge in the adopted circuit of the active electric power amplifier is set by the inequality - That is, after ~ 30 periods of charging current, the excited voltage reaches a maximum (~ 20 times higher than the source voltage), which will correspond to the end of the transient process and the establishment of a steady state of operation. An example of calculating the characteristics of an elementary resonant base illustrates the effective capabilities of a magnetic-pulse installation, consisting of a resonant charger of a capacitive energy storage and a load in the form of an inductor-tool for flat stamping of metal products. It was found that the square of the ratio of operating frequencies in the load unit and the reactive power amplification unit quantitatively determines the fundamental possibility of resonant amplification of the active electrical energy of a harmonic signal. References 12, figures 5.

Enhancing the field of view of a distributed-cavity laser incorporating cat-eye optics by compensating the field-curvature

The influence of field curvature (FC) on a distributed-cavity laser incorporating cat-eye optics was theoretically and experimentally investigated. We found that the FC can defocus the cat-eye and seriously limit its field of view (FoV), since the cavity stability region becomes very narrow at long working distances of several meters. Three improved cat-eye designs are demonstrated, in which the FC-induced defocusing was compensated by choosing off-the-shelf components with appropriate parameters or by using a customized aspheric lens. With these new designs, a distributed-cavity diode-end-pumped Nd:YVO4 laser was capable of operating efficiently within a large receiver FoV of ±20°, which was an order of magnitude larger than that achieved prior to optimization (using a traditional cat-eye design), at a long working distance of 5 m. The effectiveness and robustness of these new designs pave the way for alignment-free lasers with long-distributed-cavities, which are essential for resonant laser charging applications.

Transient Analysis for Resonant Beam Charging and Communication

High communication speed and sufficient energy supply are the directions of technological development. Energy and information available anywhere and anytime has always been people's good wishes. On this basis, resonant beam system (RBS) has demonstrated its unique superiority in meeting the needs for energy and communication. The previous work has mostly focused on the analysis of charging performance of RBS and its steady-state characteristics. In order to analyze the communication performance of RBS more thoroughly, we propose a resonant beam charging and communication (RBCC) system and use the equivalent circuit analysis method to conduct transient analysis on it. The equivalent circuit reveals the dynamic establishment process of the resonant beam from scratch, which facilitates the analysis of the relaxation oscillation process and a deeper understanding of the energy transmission and communication performance. In addition, we explore the energy transmission and communication performance of the RBCC under different energy allocation strategies.

Research on the Bipolar Microsecond Pulse Generator Using the Multistage Resonant Charging

In this article, a bipolar pulse generator based on multistage resonant charging has been proposed, which can deliver microsecond-range pulses for medical and industrial applications. The main circuit consists of two sets of identical Marx generators connected back to back with the load between them. It can flexibly output bipolar pulses with adjustable amplitude, pulse width, and frequency. In this research, six eight-stage Marx generators have been employed to verify the performance of the proposed bipolar pulse generator. From the experimental results, the proposed generator can deliver pulses with the amplitude of ±10 kV to no-load and a resistive load of 50 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{k}\Omega $ </tex-math></inline-formula> . The repetitive frequency can be adjusted from 1 Hz to 1 kHz, and pulse width can be adjusted from 0.2 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$400~\mu \text{s}$ </tex-math></inline-formula> with 50 ns rising and falling time. The relaxation time between the positive and negative pulses can be determined from 0.2 to 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> . In the high-voltage field, the proposed Marx generator can deliver higher output voltage pulses and has smaller voltage differences between stages than the traditional solid-state Marx generator.

A new switched-capacitor multilevel inverter with soft start and quasi resonant charging capabilities

Switched-capacitor multilevel inverters (SCMLIs) are gaining widespread attention in recent decades due to their simple design, voltage boosting capability, and inherent capacitor voltage balancing feature. However, the advantages offered by SCMLIs come at the cost of employing a higher number of active and passive components and capacitor voltage balancing issues with an inrush current profile. This paper introduces a novel configuration of SCMLIs with a lower number of power components with inherent voltage boost. The basic 5-level topology consists of a single capacitor, an inductor, a diode, and seven active switching elements. To improve the transient response and the inrush current profile of the converter, a soft start and quasi-resonant charging capability has been explored and implemented. Considering the inherent capacitor voltage balancing of the proposed SCMLI, a new finite control set-model predictive control (FCS-MPC) method with a single objective and a less computational burden is also developed, which contributes to injecting a fully controlled current for the grid-connected applications. The proposed topology is compared with other existing five-level inverter topologies to show its superior capabilities/advantages. And finally, the performance of the proposed topology and its associated FCS-MPC mechanism are validated by the measurement results.

Compact all-solid-state high frequency LC-Marx generator based on magnetic switch

An all-solid-state LC-Marx generator based on magnetic switch has been proposed and analyzed by theory, simulation and experiment. This system is controlled by 1 MOSFET and magnetic switches that are made by 1 magnetic core. It has dimensions of 130 mm (diameter) and 60 mm (height), which almost not change with the stage increase. The capacitors could be charged to 1.82 times source voltage according to the principle of resonant charging. Five-stage LC-Marx generator could obtain a peak output voltage of −10.9 kV with rise time of 80 ns when the source voltage of 950 V is applied, and the energy efficiency is 30.43% on 500 Ω. The generator has been tested under 30 kHz that could work steadily. It could output higher voltage when used for atmospheric discharge.

Safety Analysis of Long-Range and High-Power Wireless Power Transfer Using Resonant Beam

Resonant Beam Charging (RBC) is a promising Wireless Power Transfer (WPT) technology to realize long-range and high-power charging for electronic devices. However, the safety mechanism of the RBC system has not been investigated so far. In this paper, we propose an analytical model based on electromagnetic field analysis for evaluating the performance of the RBC system with external object invasion, such as the benchmark for the WPT safety, irradiance on the invading object. For the RBC system with $\text{5}\;$ m transmission distance and $\text{1}\;$ W output electric power, the safety numerical analysis of radiation illustrates that the maximum irradiance on the invading object is $\text{0.81}\;\text{W/cm}^2$ , which is approximately $1/10$ compared with $ \text{8.22}\;\text{W/cm}^2$ for the comparable laser charging system. Particularly, the peak irradiance on the invading object of the RBC system satisfies the Maximum Permissible Exposure (MPE) requirement for human skin, which is $\text{1}\;\text{W/cm}^2$ in the standard “Safety of Laser Products IEC $60825-1$ ”. Hence, the RBC system can realize skin-safe WPT with Watt-level power over meter-level distance.

$C_{\text{oss}}$ Loss Tangent of Field-Effect Transistors: Generalizing High-Frequency Soft-Switching Losses

The dissipated energy ( $E_{\text{diss}}$ ) related to the resonant charging–discharging of a transistor output capacitance becomes a dominant loss factor for power converters operating in the MHz range. A recent letter has introduced a small-signal measurement method to quantify $E_{\text{diss}}$ with a frequency-dependent small-signal resistance, $R_{\text{s}}$ , and an effective small-signal output capacitance, $C_{\text{oss}}^{\text{eff}}$ . This letter provides further insights on the effect of $R_{\text{s}}$ and $C_{\text{oss}}$ upon the device losses in a broader sense. In particular, the $C_{\text{oss}}$ loss tangent, tan ( $\delta$ ), is introduced as a normalized $E_{\text{diss}}$ to combine the roles of $R_{\text{s}}$ and $C_{\text{oss}}$ together with the operating frequency into a single loss parameter. By evaluating commercial device families, it is demonstrated that tan ( $\delta$ ) is constant for a given family, independent of device on -state resistance, $R_{\text{DS(on)}}$ . It is shown that a minimum $E_{\text{diss}}$ is achieved by having the lowest tan ( $\delta$ ) for a given stored energy ( $E_{\text{oss}}$ ) in $C_{\text{oss}}$ . With accompanying guidelines, this letter identifies tan ( $\delta$ ) as a powerful figure of merit to classify field-effect transistors (FETs) for soft-switching applications, regardless of $R_{\text{DS(on)}}$ variations in devices within a family. The proposed concept provides a comprehensive method to characterize and benchmark field-effect transistors for efficient operation in high and very-high-frequency (VHF) applications.

Fractional-order time-sharing-control-based wireless power supply for multiple appliances in intelligent building

The wired power transmission is usually adopted to supply power for the devices in the traditional buildings. With the development of intelligent buildings, the way of wired power supply would greatly increase the complexity and consumption of laying the lines. To improve the flexibility of power supply and reduce the cost of wiring, wireless power transfer technology has been used in smart buildings. However, it remains a fundamental challenge to create a simple wireless power transfer system in which power can be wirelessly transferred to multiple appliances. Therefore, this paper proposes a wireless power transfer scheme based on fractional-order time-sharing control for a variety of household appliances in intelligent building. In the proposed scheme, only one fractional-order capacitor in the transmitter is needed to realize the time-sharing resonant charging. In contrast, the traditional multiple-receiver systems require complicated control scheme, for example, controlling a plurality of sets of series-parallel capacitors through a series of relay switches. To demonstrate the method, a 150 W LED TV with 300 kHz and a 5 W mobile phone charger with 127 kHz serve as the actual loads. The experimental results show that the proposed system can supply power to the TV and the mobile phone by a time-sharing way wirelessly.