Dynamic Wireless Power Transfer System Research Articles

Magnetic Design for Three-Phase Dynamic Wireless Power Transfer With Constant Output Power

This paper details the design of a three-phase transmitter-receiver topology for use in a dynamic wireless power transfer (DWPT) system for heavy-duty electric vehicles. The proposed approach eliminates the power oscillation and voltage/current sharing problems that plague planar three-phase DWPT systems. Multi-objective optimization is employed to maximize magnetic coupling and minimize undesired positive–negative sequence coupling. Selected designs are simulated for a 200-kW/m DWPT system, verifying the elimination of power oscillation and phase imbalance with minimal impact on magnetic performance. A prototype DWPT system is designed, and low-ripple power output is demonstrated at 52-kW operation.

An Economical DWPT System With Mutual Compensation of Segmented Power Supply Rails Based on LCL Topology

For high-power, long-mileage dynamic wireless power transfer (DWPT) system, its economy and adaptability to complex working conditions are the main factors limiting its popularization and application. In this paper, the compensation and power supply of segmented rails are studied, and a DWPT system with mutual compensation of segmented power supply rails based on LCL topology is constructed. By multiplexing components, the number, cost and volume of devices are reduced, and the economy of the system is improved. The power supply topology is optimized to achieve constant-current characteristics over a wide load range to generate a stable high-frequency magnetic field in space and avoid short-circuit current induced by mutual coupling of adjacent rail. The resonant control conditions of the system are derived, and a phase shift control method based on the three-leg inverter is proposed to realize the full range regulation of transmitter current and output power, and improve the adaptability of the system. The characteristics of the proposed DWPT system have been verified by an experimental prototype.

An Easily Scalable Dynamic Wireless Power Transfer System for Electric Vehicles

This article deals with a LCC-LCC compensated dynamic wireless power transfer system for electric vehicle charging applications. The presented prototype system allows for a power transfer of about 10 kW at 20 cm coil copper to copper distance. With just one circular pickup coil and a very straightforward control scheme, a new coil arrangement enables a seamless power transfer. Furthermore, the system’s design power level is easily adjustable by the size of the the pickup coil. The hardware architecture as well as the software functionality are described in detail. A 20 m test track was built up according to the outlined principle. By measuring the transmitted power, the efficiency and the interference between the primary segments and its effect on the inverter currents are examined. The results show an effective DC to DC efficiency in the range of 91 to 92% and a power fluctuation of approximately 25%.

Composite Control to Suppress Output Fluctuation for Receiver Side of Dynamic Wireless Power Transfer System

Mobile device charging is made possible by the dynamic wireless power transfer technology and it's developing towards higher power levels. The output power fluctuates significantly with the movement of the device due to the discontinuous coil switching and the peculiarities of the dynamic magnetic coupler, which has an impact on charging effectiveness and battery life. In this paper, a three-level Buck (Buck TL) is used as a DC-DC converter at the receiver side and a composite control aiming to suppress output power fluctuations is proposed. The minimum effective suppression range for the frequency of the coupling fluctuation and the control performance in the transient state are analyzed theoretically. Compared with PI control, the simulation is built, and the 2.6 kW experiment results showed that the composite control could reduce the system output voltage ripple from 13% to 4.4% with resistive load and the output charging current ripple from 22% to 9% with battery load without impacting the efficiency of the Buck TL system, which verified the effectiveness of the proposed composite control strategy.

Electromagnetic Interference in Cardiac Implantable Electronic Devices Due to Dynamic Wireless Power Systems for Electric Vehicles

Electric vehicles (EV) are now considered the present and future of road transportation to reduce the emission of CO2 into the environment and thus progressively reduce global warming and climate change. However, EVs currently have some weaknesses such as the available range of battery-powered EVs and the recharging time of the batteries. To overcome these problems, some electrification projects have been proposed for road transportation such as the dynamic wireless power transfer (DWPT), where an EV charges as it moves along an electrified lane using magneto-resonant coupling between short tracks mounted on the road pavement and the vehicle’s onboard pickup coils. While the results are encouraging from an electrical point of view, there is concern regarding the magnetic field in the environment produced by the DWPT coils, which can produce adverse health effects in humans and electromagnetic interference (EMI) in electronic devices. The latter also includes implantable medical devices (IMDs) and in particular cardiac implantable electronic devices (CIEDs), which may be present among vehicle passengers and pedestrians in areas surrounding the vehicle. The aim of this study is the numerical analysis of the EMI produced by a DWPT system in CIEDs with leads such as pacemakers, implantable cardioverter defibrillators (ICDs), etc. EMI is mainly produced by the incident magnetic field and the induced voltage at the input port of a CIED; therefore, in this work the magnetic field levels produced by a DWPT system operating at 85 kHz are calculated first, then the voltage at the input port of a pacemaker is evaluated as that produced by the magnetic field incident on the loop surface formed by a lead implanted in the venous system. According to ISO 14117 standard, it is assumed that the lead loop is planar, semicircular in shape and with an area equal to 225 cm2. Since the lead can be placed anywhere where a human can be and with any orientation, an innovative and sophisticated roto-translation algorithm is proposed to find the maximum value of the peak-to-peak induced loop voltage in the most critical regions inside the vehicle cabin and beside the vehicle near the DWPT coils. The preliminary results obtained show that there is no EMI risk inside the vehicle for the passengers with CIEDs, while some concern for pedestrians is due to the induced voltage at the input port of a CIED with unipolar leads which can exceed the ISO 14117 limit in the region next to the vehicle.

Analysis and Design of Rotary Wireless Power Transfer System With Dual-Coupled XLC/S Compensation Topology

This paper presents a dynamic wireless power transfer (DWPT) system for rotary equipment. Two concentric coils on the primary side are used to keep the mutual inductance between the primary and secondary constant during the rotation. The dual-coupled XLC/S compensation topology is proposed to enhance the radial misalignment tolerance performance and improve the flexibility in the design of loosely coupled transformers (LCT). The design flow of LCT and optimization process of component parameters are proposed to achieve radial misalignment tolerance. The characteristics of constant current output (CCO) and zero voltage switch (ZVS) are realized. The power flow is analyzed. A 200-W prototype is designed and implemented to validate the proposed design method. The experimental results show that the proposed LCT structure with dual-coupled XLC/S compensation topology can achieve high tangential and radial misalignment tolerance. Therefore, the system proposed in this article is suitable for powering the device that rotates around an axis wirelessly.

A Detuning-Repeater-Based Dynamic Wireless Charging System With Quasi-Constant Output Power and Reduced Inverter Count

High-density coil installation to achieve a smooth power transfer inevitably increases construction costs, reducing the acceptance of dynamic wireless power transfer (DWPT). In this article, a detuning-repeater-based DWPT system is proposed to provide a relatively constant power at a reduced count of inverters. Half of the inverter-connected transmitter coils in conventional DWPT systems are served as passive repeater coils. The repeater relays the power from the transmitters on both sides to take the role of the main power transfer channel when the receiver is moving towards it. A detuning method is proposed to suppress the standby currents inside the idle repeater coils by utilizing the variation of receiver reflecting impedance during the receiver moving towards/away. An optimization method to achieve less power fluctuation is designed based on the detuning rate. The tradeoff between the power fluctuation and current suppression is analyzed. The system performance against parameter variations is also performed. A 100 W down-sized prototype is developed, and the experimental results show that the proposed DWPT system can achieve a quasi-constant output power with a power fluctuation of 8.5% and a system efficiency of around 82% during the entire dynamic process.

Modeling and Control of Dynamic Wireless Power Transfer System for Electric Vehicle charger application

This paper proposes a nonlinear state-space model for a dynamic wireless power transfer system (DWPT). The DWPT system comprises emitter coils supplied by DC/AC converters, with a phase angle control to achieve maximum power transfer. The power receiver coil is connected to a full bridge diode rectifier followed by an equivalent load resistance. To emulate the dynamic movement property of WPT, the coupling factors between the emitter and receiver coils are set to be variable and depend on the movement of the power receiver alongside the power emitter coils. The control has been successfully demonstrated under variable coupling coefficients to achieve maximum power transfer. Such improvement maintains the power and voltage across the load during transient states.

Dynamic Wireless Power Transfer System with Twin Perpendicular Receiver Coils (Invited Paper)

Dynamic Wireless Power Transfer System with Twin Perpendicular Receiver Coils (Invited Paper)

Efficient management of industrial electric vehicles by means of static and dynamic wireless power transfer systems

Industrial companies are moving toward the electrification of equipment and processes, in line with the broader energy transition taking place across the economy. Particularly, the energy efficiency and, consequently, the reduction of environmental pollution of intralogistics activities have become a competitive element and are now an actual research and development objective. A wireless power transfer is a contactless electrical energy transmission technology based on the magnetic coupling between coils installable under the ground level and a coil mounted under the vehicle floor, and it represents an excellent solution to decrease the demand for batteries by reducing vehicle downtimes during the recharge. This work aims to define a methodology to determine the optimal positioning of wireless charging units across the warehouse, both for static and dynamic recharging. To this aim, firstly, a mathematical model of the warehouse is proposed to describe transfers and storage/retrieval operations executed by the forklifts. Then, an integer linear programming problem is applied to find the best possible layout of the charging infrastructures. The optimal solution respects the energetic requirements given by the customer and minimizes the overall system cost. The proposed approach was applied to optimize the installation in a real-size warehouse of a tire manufacturing company. Several scenarios were computer generated through discrete event simulation in order to test the optimizer in different warehouse conditions. The obtained results show that integrated dynamic and static WPT systems ensure a constant state of charge of the electric vehicles during their operations.

Parameter Identification Method With Dynamic Impedance Modulation for the DWPT System

A novel parameter identification method with dynamic impedance regulation is proposed to maintain constant output voltage of dynamic wireless power transfer (DWPT) system under varied loads and mutual inductance conditions. The resonant capacitor in the receiver side is replaced with a switched-controlled capacitor (SCC) structure, which enables the system to work under two operation modes. And then a comprehensive mathematical model is established according to these two modes to achieve the parameter identification. To avoid the deterioration of identification accuracy caused by the capacitors’ parameter drift, a dynamic impedance regulation method is introduced. The SCC is under dynamic closed-loop modulation to realize precious control of the equivalent capacitance of resonant capacitor in the receiver side. An experimental prototype is built in the laboratory, and the experimental results clearly demonstrate the accuracy of the proposed parameter identification.

Analysis and improvement of output power drop of dynamic wireless power transfer systems with transmitting coil switching for inspection robots

Analysis and improvement of output power drop of dynamic wireless power transfer systems with transmitting coil switching for inspection robots

Novel dynamic wireless power transfer system using in‐tire and in‐wheel repeater coil for battery electric vehicles

AbstractIn order to improve the mileage per charge of battery electric vehicles (BEV), dynamic wireless power transfer systems are being developed. There are some problems such as is the wide gap between coils when mounted under the floor of a vehicle, and the effect of foreign objects between coils on power transmission. In‐wheel coils, in which the coils are placed inside the wheel, have been proposed as a solution to these problems. However, they a plastic wheel such as CFRP and cannot reduce the gap between coils. In this paper, we propose a coil configuration in which the coils are placed inside the tire and the wheel. This configuration has the advantage of using a conventional aluminum to reduce the gap between coils. The effectiveness of this method is demonstrated via simulations and experiments.

A Five Leg Converter with Multi-Transmitter for an In-Motion Charging System

A dynamic wireless power transfer (DWPT) extends the driving range of an Electric Vehicle (EV). The dependency of the bulk volume energy storage device can be reduced by electrified highways. The effective concern on the design of charging pads will improve the power transferring profile and the constant charging. The life cycle of the batteries will be increased by DWPT technology. There are several issues related to the coil design in the DWPT system including sensitive misalignment tolerance, volume to weight ratio of the couplers, and electromagnetic exposure limits. The SAE J2954 guides the designer by their developed standards on the DWPT charging system. The power transfer capability of the charging pads maintained maximum level during misalignment conditions by compensation network. The charging couplers positioned on the roadside has driven by an expandable multiple leg converter. The five-leg converter is proposed in this paper to energize the four charging couplers and the single receiver is used to charge the battery.

The Design and Optimization of Ground-Side Coils for Dynamic Wireless Power Transfer Considering Coupling Variations

Dynamic wireless power transfer (DWPT) has attracted widespread attention for its charging flexibility; short-segmented DWPT systems are more suitable for EV charging scenarios because of their higher charging efficiency and lower electromagnetic radiation, compared to long-track DWPT systems. For short-segmented DWPT systems, the structural design of the ground-side coil affects the coupling characteristics of the system, while simultaneously the electric vehicle driving speed and coil arrangement also cause coupling variations, and this will inevitably have an impact on the system’s performance. Therefore, this paper demonstrates the coupler design of a short-segmented system for electric vehicles, focusing on the optimization of ground-side coil. The coupling variations causing by driving speed of EV and coil arrangement are taken into account. Considering the tradeoffs and restrictions, a multi-objective optimization process of coils in DWPT systems is proposed based on the Pareto optimizing method, with three objectives: transfer power, high efficiency and low cost. A reasonable optimal solution is selected from the Pareto front to verify the optimizing method through a constructed prototype.

True Nulls-Free Magnetoinductive Waveguides Using Alternate Coupling Polarities for Batteryless Dynamic Wireless Power Transfer Applications

A dynamic wireless power transfer (DWPT) system using the conventional magnetoinductive (MI) waveguide suffers from periodic power nulls resulting from standing waves. Although numerous methods have been developed to mitigate the nulls, additional active circuitry was required, increasing the complexity. In this article, the MI waveguide with alternate magnetic coupling polarities between successive resonator cells is proposed for a true nulls-free DWPT system with no use of active components. Two configurations of the alternately coupled MI (ACMI) waveguide are developed—one with the incorporation of a quadrature-phase termination for a linear waveguide, and the other with the adoption of a circular waveguide. Extensive analysis of the generalized ACMI waveguide is provided, and the developed configurations are theoretically verified to maintain power transfer efficiency, independent of the free-positioned load. Practical implementation of DWPT systems using the linear and circular ACMI configurations with seven resonator cells at 13.56-MHz operation are experimentally demonstrated to exhibit no power transfer nulls and achieve up to fivefold reduction in efficiency variation, as compared to their MI counterparts. Comparisons with theoretical calculation are given for verification of the analysis integrity. An experimental model of a batteryless DWPT system is also demonstrated using the circular waveguide as accompanied by a video.

A Comprehensive Review of the On-Road Wireless Charging System for E-Mobility Applications

The recent progress in the dynamic wireless power transfer (DWPT) system brings feasibility to increase the driving range of an electric vehicle (EV). The on-road wireless charging system reduces the volume of the EV’s battery and charging the vehicle while driving. So, the powered roadways can potentially decrease the dependency on heavy-sized batteries for EV applications. The capability of transferring maximum power from the ground surface to the vehicle requires the critical design of the entire DWPT system. The various factors such as wireless charging pads, power electronic converters, compensators, and controllers influence the power transfer rate of the system. An appropriate impedance matching network assists the system during power transfer. Moreover, the design of coils in DWPT needs to consider the sensitive misalignment tolerance, safety issues, complex design, and cost factors. In this article, the basic topologies, history, and fundamentals of the DWPT charging system are discussed. In addition, the impact on the power grid due to the DWPT system and factors involved in microgrid integration are discussed. However, the current scenario of different compensators, converters, and design topologies proposed in the dynamic charging system is included. This article presents a comprehensive overview and challenges involved in a DWPT system such as the design of a power converter, charging couplers, compensation network, foreign object detection system, economic factors, and microgrid-integrated DWPT system. An economic analysis, electromagnetic compatibility, and interference of the charging system are also analyzed vastly. The human exposure level with its allowable limits developed for the wireless power transfer system is discussed.

A Cost-Effective Segmented Dynamic Wireless Charging System With Stable Efficiency and Output Power

This article presents a cost-effective dynamic wireless power transfer (DWPT) system for efficient and stable output power charging of autonomous moving equipment. The proposed system is realized based on a low-cost segmented configuration and a flexible operating strategy. Specifically, the configuration is a combination of a dynamic <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> -series/series topology and extended transmitter (Tx) coils. The topology eliminates the cross-coupling impact of adjacent Tx coils and tunes the dynamic circuits at resonance. It makes the switching circuits equivalent to a unified analytical model for simplified control, which reduces the cost of inverter, decoupling, compensation, and position detection in the DWPT. The extended Tx coil with a simplified structure, which is obtained from winding coupling characteristics and a finite-element analysis based algorithm, is proposed to improve the moving misalignment tolerance, thereby reducing the number of Tx segments. An operating principle with three modes behind the proposed strategy is designed to fully utilize the efficient coupling area of individual Tx segment and improve the efficiency in the transition region from one segment to the other one. The operating parameters including the transition and compensation are obtained based on the topology and its operating principles. Position detection and power regulation methods are developed and embedded in the system control to configure/coordinate the segmented coils as the strategy and mitigate power fluctuation in the transition region. The performance and effectiveness of the proposed cost-effective DWPT system are evaluated based on experimental results on a scaled-down prototype.

Comparison and Verification of Control and Filter Methods for Efficiency and Current Harmonic Components of a Dynamic Wireless Power Transfer System

Comparison and Verification of Control and Filter Methods for Efficiency and Current Harmonic Components of a Dynamic Wireless Power Transfer System

Novel Dynamic Wireless Power Transfer System Using In-Tire and In-Wheel Repeater Coil for Battery Electric Vehicles

Novel Dynamic Wireless Power Transfer System Using In-Tire and In-Wheel Repeater Coil for Battery Electric Vehicles