Inductive Charging System Research Articles

Misalignment analysis of WPT level 3/Z2-class of CirPT with DDPR and CirPR for EVs stationary charging.

Future inductive charging ports must possess the capability to charge any electric vehicle (EV), irrespective of the specific coil architecture it is equipped with. This study examines the misalignment scenarios of the global circular pad at transmitter side (CirPT) with circular receiver pad (CirPR) and a double-D receiver pad (DDPR). The CirPT, CirPR, and DDPR configurations for WPT3 (11.1kW) with ground clearance meeting the Z2-class specifications and above ground surface installation are built by utilizing circuit analysis and 3D-finite element simulations, as outlined by the Society of Automotive Engineering (SAE) J2954 standard. The simulated designs are employed to determine the frequency (f) and the compensating network components (CNCs) required to achieve optimal power transfer efficiency while maintaining nominal power levels. The analysis of misalignment scenarios involves examining various performance factors, including coupling coefficient (k), transmission power (Po), efficiency (η), and leakage electromagnetic fields (EMFs). These factors are assessed under conditions of ideal alignment, as well as various linear and angular misalignments within the inductive charging system. The results demonstrate that both the CirPR and DDPR configurations can successfully interface with the CirPT to provide the required Po to the EV battery with commendable efficiency. In perfect alignment, the efficiencies are 95.10% for the CirPT-CirPR model and 91.60% for the CirPT-DDPR model. In maximum misalignment, the efficiencies are 87.10% for the CirPT-CirPR model and 89.50% for the CirPT-DDPR model, all exceeding the acceptable threshold of 80%.

Highly Efficient Inductive Charging System with Easy-to-use Vehicle Positioning

Highly Efficient Inductive Charging System with Easy-to-use Vehicle Positioning

Mechanistic Analysis of Reflective Cracking Potential in Electrified Pavement with Inductive Charging System.

Electrified pavements with inductive charging systems provide an innovative way of providing continuous wireless power transfer to electric vehicles (EVs). Electrified pavements have unique construction methods, resulting in different mechanical and thermodynamic characteristics from traditional pavements. This study aimed to investigate the mechanistic design of electrified pavements to mitigate thermal-induced reflective cracking due to the inclusion of concrete slabs with inductive charging units (CUs) under an asphalt surface layer. Finite element (FE) models were developed to analyze the temperature profiles, pavement responses, and crack potential in electrified pavements. The fatigue model and Paris' law were utilized to evaluate crack initiation and propagation for different pavement designs. Within the allowable range for sufficient wireless charging efficiency, increasing the surface layer thickness had a noticeable benefit on mitigating crack initiation and propagation. The results indicate that increasing the asphalt surface layer thickness by 20 mm can delay crack initiation and propagation, resulting in a two to threefold increase in the number of cycles needed to reach the same crack length. Reflective cracking can also be retarded by the optimized design of the charging unit. Increasing the concrete slab thickness from 100 mm to 180 mm resulted in an approximately 20% increase in the number of cycles to reach the same crack length. Reducing the slab width and length (shortening joint spacing) could also effectively reduce the reflective cracking potential, with the slab length having a more significant influence. These findings highlight the importance of balancing charging efficiency and structural durability in the design of electrified pavements.

Quasi-Resonant Flyback Converter in an 800 V Inductive Charging System: Abnormal Operation and Control Aspects

Quasi-Resonant Flyback Converter in an 800 V Inductive Charging System: Abnormal Operation and Control Aspects

A New Cross-Overlapped Decoupling Coil Structure for EV Dynamic Inductive Wireless Charging System

A New Cross-Overlapped Decoupling Coil Structure for EV Dynamic Inductive Wireless Charging System

A 5 kW Hull-Compatible Inductive Charging System With 360° Folded Spatial Unipolar Coupler for Autonomous Underwater Vehicles (AUVs)

A 5 kW Hull-Compatible Inductive Charging System With 360° Folded Spatial Unipolar Coupler for Autonomous Underwater Vehicles (AUVs)

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.

Smart Steps Towards Sustainable Transportation: Profitability of Electric Road System

The global average temperature has increased by about 1°C compared to pre-industrial times and the temperature increase continues. The effects of climate change are already affecting living conditions on Earth. Through the Paris Agreement, the countries of the world have committed to limit global warming to below 2°C compared to pre-industrial times and to make efforts to keep the increase below 1.5°C. The transportation sector accounts for about 15% of Turkey's greenhouse gas emissions, and more than three-quarters come from diesel fuel. Already in ten years, transport emissions must be reduced by 70% according to the national targets. It is about both reducing emissions by 2030 but also ensuring that we are completely emission-free by 2050. The vast majority of emissions in the transport sector come from road traffic. Electric vehicles have emerged as the most promising solution to energy and environmental security concerns. However, a major constraint for electric vehicles has been the limited range and fast charging capacity. Various electric road technologies have great potential to reduce dependence on fossil fuels, reduce greenhouse gas emissions, reduce air pollution, and reduce noise in urban areas. This article proposes to discuss the inductive and conductive charging system and required system configuration in the concept of electric roads for electric buses. The model solution algorithm is designed and it is validated on the E-bus route R40 in Kayseri City, Turkey. It is found that if an electric road system is used instead of a diesel bus for a bus line route of 35.5 km, it will amortize itself in 10 years.

Thermo-viscoelastic analysis of an inductive charging system included in an eRoads. Incit-ev project

This paper presents work carried out in WP4 of the European project INCIT-EV, to develop a thermo-mechanical model, for simulating the performance of electrified roads using an inductive system for the charging of electric vehicles. The system consists of a charging unit, made of a box containing a litz coil, inserted into the road, at low depth under the surface, and sealed using a resin. In previous studies [1], several solutions for the insertion of this system in the road structure were evaluated, using experimental and numerical studies. The purpose of this paper is to highlight the potential of thermo-viscoelastic FEM structural simulations to predict the response of the electric road system (ERS) taking into account daily thermal variations, and heat released by the inductive charging system. Firstly, thermal laboratory tests were performed to evaluate the temperature variations due to the operation of the charging system, and compared with FEM simulations, in order to validate different modelling assumptions (material characteristics, boundary conditions). Then, transient thermo-mechanical simulations were performed, considering different materials for the coil block (polyethylene, or concrete), and for the sealing resin, in order to evaluate different possible designs of the charging elements. The variations of the deformations of the different structures, and of the strain and stress fields, during representative temperature cycles, were studied and compared. Differences in mechanical response obtained with different sealing resins (elastic or viscoelastic) and different coil block materials (polyethylene, and concrete) were analysed and compared.

Pavement integration of an inductive charging system for electric vehicles. Results of the INCIT-EV project

This paper presents first studies carried out in the European project INCIT-EV, to design a solution for integrating a wireless inductive charging system for electric vehicles in a bituminous pavement. In the project, specific tests and simulations were developed to study the mechanical and thermal behaviour of this electric road. In particular, laboratory wheel tracking tests were used to study, at reduced scale, the mechanical behaviour of a charging coil integrated in the pavement. Charging tests were also performed to study the temperature variations produced by the heat dissipation in the inductive coils. Finally, finite element models have been used to simulate the thermal and mechanical response of the system in the pavement structure. The paper presents some main results of this study, which allowed to validate the mechanical behaviour of the proposed pavement structure, but also highlighted risks of overheating when the system is in operation, which will need further investigation.

A critical review on inductive wireless power transfer charging system in electric vehicle

AbstractConsidering a prospect where a driverless electric vehicle (EV) requires an automatic charging system that does not need a person to do anything. In this case, there is a need for a fully automated, fast, safe, cost‐effective, and reliable charging infrastructure that can be used for EVs and other EVs. This infrastructure must also be profitable and allow for quick adoption in electric transportation systems. Wireless charging methods may allow you to understand these characteristics. Wireless power transfer (WPT) is a future technology that offers flexibility, convenience, safety, and the capacity to be automated. Due to its high efficiency and ease of maintenance, resonant inductive wireless charging should get more attention in WPT techniques than other WPT methods. This literature provides an overview of the status of Resonant Inductive Wireless Power Transfer Charging technology, as well as a look at the current and prospects of the wireless EV industry. First, the article provides a brief history of wireless charging technologies, outlining the benefits and drawbacks. Then, the research assists in a comparative analysis of various types of WPT methodologies, control strategies, and compensation networks that have been done so far. The static and dynamic charging procedures, as well as their features, are shown. To increase charging power, a novel approach to the usage of superconducting materials in coil designs is examined, and their potential influence on wireless charging is highlighted. The detailed role and importance of power electronics, as well as the many types of converters utilized in diverse applications, are highlighted. The batteries and their management systems, as well as numerous WPT difficulties, are also discussed. Different trades are investigated, including cyber security economic consequences, health and safety, foreign object identification, and the effect and influence on the distribution grid. This article also highlights the opportunities and challenges associated with wireless charging systems. We anticipate that our effort will contribute to the advancement of WPT system research and development.

A Dual-Receiver Inductive Charging System for Automated Guided Vehicles

As an intelligent collection of power electronics, automated guided vehicles (AGVs) tend to involve more and more devices. Thus, it is necessary to develop a versatile charger with different double outputs for AGVs. This article investigates a dual-receiver inductive charging system. Through a well-organized magnetic coupling structure, relatively load-independent outputs can be realized simultaneously by these two receivers. Specifically, the first receiver ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm {X}}$ </tex-math></inline-formula> #1) can realize constant current (CC) output, whereas the second one ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\mathrm {X}}$ </tex-math></inline-formula> #2) can achieve constant voltage (CV) output. By utilizing such a passive coupling structure, complex control methods and additional decoupling circuits can be avoided, facilitating a compact and light on-board part. Moreover, this system can realize zero phase angle (ZPA) to lower the volt-ampere rating and improve the overall efficiency. Overall, a scaled-down experimental prototype with 2 A charging current and 12 V charging voltage is constructed to validate the feasibility of such a system. Experimental results demonstrate that the voltage and current deviation, compared to the reference, is as small as 3.33% and 4%, respectively, when the load at the first receiver side ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{L1}$ </tex-math></inline-formula> ) varies from 5 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\Omega $ </tex-math></inline-formula> . Moreover, the voltage and current deviation is as small as 3.33% and 1.5%, respectively, when the load at the second receiver side ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{L2}$ </tex-math></inline-formula> ) varies from 10 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20~\Omega $ </tex-math></inline-formula> .

Using Zone Impedance Matching Technique to Improve the Power Transfer Capability of an Inductive Charging System over a Long Distance

In many outdoor inductive charging applications, the objects can move quickly, and the environment can change unpredictably. It is therefore difficult to design a fast controller that tracks the change in mutual coupling between the transmitter and receiver. The diminished power delivery to the objects either leads to incomplete charging or prolongs the charging time. In this paper, the concept of a zone impedance matching technique is proposed. This technique pre-matches the transmitter coil to the desired coupling coefficients. Thus, the power transfer capability of the inductive charger can be maintained at a reasonably high level over a long transmission distance and under a wide receiver misalignment. Based on a three-coil inductive power transfer (IPT) system, the proposed concept is practically implemented with a simple control scheme. The proposed IPT system equips a multi-tap transmitter coil to provide flexibility in selecting different numbers of turns in the transmitter coil. The controller senses the currents of the transmitter coil and the repeater coil to determine the zone of impedance to adapt to the change in mutual coupling of the coils. A mathematical analysis is conducted to formulate the design procedures for the proposed system. Under a wide range of distance and misalignment conditions, practical measurement results verified that the proposed system achieves higher power delivery than an ordinary design.

Wireless charging structure and efficiency analysis based on wind–solar hybrid power supply system

The industry of electric vehicle is developing rapidly. But because of the limit of the driving distance, the electric vehicle has not been effectively promoted. Therefore, the analysis of the wireless inductive charging system of EV is particularly important. In this paper, the wireless charging system which based on Wind/PV system is studied, including the coil topology, the circuit structure and the control mode. Ansoft and Matlab/Simulink is used to simulate and analyze the system. The research provides a theoretical basis for the development and application of wireless charging systems.

Quasi-Resonant Flyback Converter as Auxiliary Power-Supply of an 800 V Inductive-Charging System for Electric Vehicles

This paper presents evaluation of quasi-resonant flyback (QRF) dc-dc converter 57 W with valley-switching in an emerging application. The QRF was supplied from an 800 V variable dc-link and was used as the auxiliary power-supply of a wireless inductive-charging system (ICS). Comparison of state-of-the-art QRF control ICs is presented and suggestions for their improvements are given. Notes on the power-supply architecture, design items specific for the ICS application, over-power protection, and key-component choice are provided. During experiments several original and novel results are generated. The efficiency graphs in ICS power transfer, ICS stand-by, and constant-load operation are analyzed. The maximum efficiency of 87.1 % was reached at 620 V and rated load. Moreover, the unique analysis of QRF losses at no-load, showed their quadratic dependency vs. input-voltage. The measured “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">switching frequency vs. load</i> ” graph is presented. It was changeable with load and input-voltage as expected. From Bode plots the bandwidth, phase-margin, and gain-margin are extracted and plotted versus input-power—for the first time. They were changeable with input-voltage and load as expected. Comparison of simulated and measured Bode plots showed that, even when they were not matched, one can design a Type-2 compensator that ensures stable operation. Evaluation of cross-regulation, when output with 24.1 % of total power was regulated, showed that such approach—contrary to the more common of regulating the biggest one—is feasible too. It is discovered that, for a QRF with variable switching frequency, choice of compensator or the regulated output has influence on its efficiency. The power-thresholds to ensure valley-switching operation represented as “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">input power vs. input voltage</i> ” are shown for the first time. Comparison of bandwidth, phase margin, and gain margin vs. input power, between an ACF and the QRF, were discussed. Conclusion is that QRF, for the same specification, cannot have the same compensator as an ACF. The difference must be at least in a placement of a zero.

Active-Clamp Flyback Converter as Auxiliary Power-Supply of an 800 V Inductive-Charging System for Electric Vehicles

Investigation of active-clamped flyback (ACF) dc-dc converter 57W used as the auxiliary power-supply (APS) of an inductive-charging system (ICS) is presented. The ACF was supplied from variable-dc-link 800V which was challenge for its design. Anyway, some findings are applicable to any ACF. An overview of ACF control ICs is presented revealing that only two vendors have appropriate devices for ICS. The key-parts’ choice and suggestion of new features targeting ACF in this emerging-application are given. Striving for high switching-frequency in ICS is not needed due to large safety-distances of transformer. Measured “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">maximum-efficiency vs. magnetizing-inductance</i> ” graph showed that extremes are reached for 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{H}$ </tex-math></inline-formula> . It was based on four transformers with manually-optimized resonant-tanks. Measurements of “ <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">circulating-power losses vs. input-voltage</i> ” are compared for several transformers. Those losses are in the range of few watts and increase with input-voltage. Measurements of “bandwidth, phase-margin and gain-margin vs. input-power”, for different input-voltages, are discussed. Those quantities were changeable with load and input-voltage as expected. The short-circuit behavior is analyzed showing that usage of the hybrid-clamp with multi-mode control-ICs is mandatory. Finally, comparison with conventional flyback and quasi-resonant flyback converters showed that both are ≈23% cheaper, occupy ≈11% less board-space, and have similar or higher efficiencies. The reason for such efficiency is that ACF circulating-power losses were high as well as dc-voltage-conversion-ratio. Although this is a drawback, for an APS the efficiency is not the key-parameter as long as there are no thermal problems. Moreover, as ACF converter is known for having less EMI-problems that could be the key-advantage for this application. But problem is not-enough electronic components on the market that are suitable for ICS.

Design of High-Efficiency Inductive Charging System With Load-Independent Output Voltage and Current Tolerant of Varying Coupling Condition

Maintaining constant-current (CC) and constant-voltage (CV) outputs for meeting the charging profile of lithium-ion batteries while realizing zero-voltage-switching on the primary bridge over wide ranges of load and coupling variations are rather challenging due to the presence of leakage and magnetizing inductances of a loosely coupled transformer. Although the challenges can be greatly relaxed by properly designing a compensation network with load-independent output characteristics, the desirable characteristics rendered by fixed compensation networks will be lost and cannot be fully restored by existing control methods once the designed compensation is deviated from the nominal coupling condition. In this article, a dynamic series/series-parallel compensation network, which originally aims to deliver constant output voltage only, is further investigated as a feasible topology for CC-CV battery charger adaptive to different sizes of air gap/misalignment of the coils. As benefited from the extra controllability offered by the parallel compensation capacitance as compared to the series/series compensation counterpart, this article provides alternative design criterion for the effective parallel compensation capacitance for designing and maintaining desirable charging currents in the CC stage while maximizing the efficiency in the CV stage under varying coupling condition. An experimental prototype with the air gap ranging from 10 to 16 cm is built to verify the idea.

A Closely Coupled and Scalable High-Power Modular Inductive Charging System for Vehicles

For a high-power inductive charging solution that can be used on all types of vehicles, careful consideration must be made in all steps of the design process, including system architecture, coil geometry, and communications. Extensive studies on the effects of human exposure to electromagnetic fields (EMF) have identified recommended guidelines for electromagnetic limits in regions where humans or other living objects may frequent. Commercial wireless low power chargers today operating at 85 kHz and up to 11 kW are capable of meeting international EMF standards such as IEEE C95.1-2019. In this article, we address high-power wireless chargers designed for electrified light and heavy-duty vehicles such as buses and trucks that accept charging in hundreds of kilowatts. Laboratory studies of a modular 50–75-kW coupler confirm that leakage fields from one such module will meet U.S. and International EMF limits at the vehicle perimeter and beyond. In particular, a cluster of four such couplers operating at 65 kW each will not exceed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$27~\mu \text{T}$ </tex-math></inline-formula> adjacent to the vehicle, decaying at 1/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{r}^{3}$ </tex-math></inline-formula> or faster. The experimental results confirm simulation and show that fringing fields meet published standards in the vehicle cabin and beyond its perimeter when operating at 260 kW.

Design and optimization of 3‐kW inductive power transfer charging system with compact asymmetric loosely coupled transformer for special applications

SummaryInductive power transfer (IPT) technology has become popular in wireless charging applications. Compared with the traditional 3‐kW wireless charging application, the diameter for the primary coil and the secondary coil in this special design are required to be smaller than 260 and 110 mm, respectively. In order to achieve this target, an approach to design and optimize the loosely coupled transformer (LCT) is proposed to match the strict geometry limitation, while achieving the high conversion efficiency. Different from the traditional design method, the low resonant current and voltage stress are considered as the input of the design flowchart, especially the LCT. Thus, the overall conversion efficiency can be improved. Based on series–series (S–S) compensation topology, the parameter range of the LCT is determined by analyzing transformer‐based equivalent model. To achieve the desired coil size, an asymmetric LCT with single‐layer primary coil and three‐layer secondary coil is designed and optimized by the proposed approach. Furthermore, the closed‐loop controller with narrow frequency variation range is design to realize constant current (CC) charge and constant voltage (CV) charge. A 3‐kW IPT charging prototype is built to demonstrate the validity of the proposed method. Experimental results show that the peak efficiency from input to battery load is 95.69% at 3‐kW output power in the transition point from CC mode to CV mode.

Direct AC–AC Active-Clamped Half-Bridge Converter for Inductive Charging Applications

In this article, a new direct ac-ac active-clamped half-bridge converter feeding a series-series compensated inductive charging system is proposed. The proposed converter eliminates the rectification stage and bulky life-limited electrolytic dc-link capacitors, resulting in an actual single-stage (ac-to-ac) conversion with low component. The operation principles, steady-state analysis, and design considerations of the proposed converter are presented in detail. Moreover, a new predictive dead-beat technique for input current control and a linear average charging current controller are developed for the proposed converter, which enables the unity power factor and charging current regulation. The performance of the proposed battery charger is validated through experimental results on a 1-kW field programmable gate array (FPGA)-controlled silicon carbide based laboratory prototype.