Wireless Power Transfer System Research Articles

재전송 기반의 무선 정보 전력 동시 전송 시스템

재전송 기반의 무선 정보 전력 동시 전송 시스템

Detuning piezoelectric receivers by resistive load adjustment for electrodynamic wireless power transfer

This article investigates electrical detuning techniques for low-frequency electrodynamic wireless power transfer (EWPT) systems. This study focuses on protecting the receiver from potential damage when quick increases in magnetic fields occur due to transmitter–receiver distance variation or in-rush transmitter coil currents. In the case of such event, to avoid damaging the mechanical receiver, the solution investigated in this article is to adjust the electrical load connected to the receiver. This adjustment enables precise tuning and detuning of the receiver’s resonant frequency and damping characteristics, thereby allowing to reduce its mechanical displacement amplitude and protecting it from damage. Based on well-known models of EWPT systems, we develop an analysis of two key operational modes of the proposed tuning/detuning approach: maximum transmitted power (MTP) mode, where the receiver circuitry’s input impedance is optimized for peak power transfer, and minimum displacement (MD) mode, which involves electrically detuning the receiver’s resonant frequency to limit its mechanical displacement. We establish transition conditions between MD and MTP modes based on the receiver voltage amplitude, enabling automated monitoring and adjustment of the receiver’s detuning. Experimental validation has been conducted with an EWPT experimental setup and a custom piezoelectric receiver. The results, in good agreement with the proposed analytical model predictions, confirm the effectiveness of the proposed detuning algorithm, which successfully reduces the receiver displacement by 60% in response to sudden magnetic field increases.

Coupling coefficient calculation method of circular coil with bilateral finite magnetic shields at horizontal misalignment in wireless power transfer systems

AbstractThe coupling coefficient determines the transfer efficiency of the wireless power transfer (WPT) system. The magnetic leakage can be reduced, and the coupling coefficient of the coil can be enhanced by adding a magnetic shield. Thus, the transfer efficiency of the WPT system can be improved. However, when the receiving coil is added with magnetic shield and occurs horizontally misaligned, the coupling coefficients between the coils with the magnetic shield can only be calculated by finite element simulation, and there is no calculation method for the coupling coefficient of two circular coils with bilateral finite magnetic shield at horizontal misalignment. Therefore, based on Maxwell's equations and Bessel's function, the formula of the coupling coefficient between circular coils at coaxial is derived by the subdomain hierarchical analysis (SHA) method. On this basis, the coupling coefficient calculation formula between circular coils at horizontal misalignment is further derived by using the boundary vector equivalence (BVE) method. The results show that the maximum experimental error is not more than 5.58%, and the longest average time of the algorithm is not more than 1.282 s, which verifies the effectiveness and rapidity of the proposed method.

Resonant coil matrix shielding for dynamic WPT systems

In this article, a magnetic shield for automotive Wireless Power Transfer (WPT) systems is proposed. Its innovative feature consists in the positioning of the shield, that is part of the Ground Assembly (GA) of the WPT system. Passive coils, assembled in an array-like structure to build the shields properly located near the transmitting coils are investigated. Currently, there are a variety of shielding methods, each of them with its peculiar feature. The proposed method is simple and does not increase the transmitting and the receiving coil sizes, a constraint that is often critical from a practical and an economical point of view. The main characteristic of the proposed shielding method is the location of the shielding coils on the same level as the GA. The results here presented are validated by Finite Element (FE) based simulations and are referred to an experimental prototype of wireless charging systems for electric vehicles operating at 85 kHz with a transmitted nominal power of 3.3 kW. The results show that the proposed shield reduces the leakage magnetic flux density in the system up to 37% with a marginal impact on the transmission efficiency, complying the SAE J2954 international standard.

Tri-band antenna with metasurface-based ground plane for Sub-6 GHz 5G and 6G WPT applications

In this paper, a spiral-shaped metamaterial-loaded rhombic slotted microstrip patch antenna is investigated for Sub-6 GHz 5G and 6 GHz tri-band applications. A 1.524 mm thick Rogers RO4003 substrate (ϵr = 3.55, LosTanδ = 0.0027) opts for the antenna design. A partially grounded mechanism is implemented to control the operating frequencies of the antenna. A 5×5 triangular unit cell metasurface is deposited beside the partial ground plane to enhance the impedance bandwidth as well as to improve the impedance matching. A G-shaped metallic structure enclosed within the rhombic slotted antenna helps in creating circular polarization (CP) properties. The presented antenna resonates at 3.28 GHz (Mid-range Sub 6 GHz 5G band), 4.94 GHz (Upper range Sub 6 GHz 5G band), and 6.92 GHz (Sub 6 GHz 6G Band) frequencies. The maximum gain offered by the antenna is 8.81 dBi. Also, the developed antenna offers CP characteristics in all three operating bands with wide axial ratio (AR) bandwidth characteristics above 400 MHz in both the first and third operating bands. The radial characteristics of the proposed antenna show its capability of receiving EM signals from all directions as desired for a WPT system. For validation purposes, a prototype is fabricated and characterized as well.

PERANCANGAN DAN IMPLEMENTASI PROTOTIPE WIRELESS POWER TRANSFER PADA SEPEDA MOTOR LISTRIK

Advances in Wireless Power Transfer (WPT) system technology are increasingly being applied to the process of recharging battery packages for electric motorbikes. The battery package for an electric motorbike, 48 Volt 15 Ah, is used as a reference for the achievement target in this research. The WPT system is designed to be able to transfer or produce power equal to 10% of the battery package capacity. Utilization of Faraday's law which states that the number of turns in the transmitter and receiver coils used in the WPT system affects changes in flux and the amount of energy that can be transferred by the coil. In this paper, we will explain the WPT system experiments to compare system efficiency by changing the variables of coil diameter, number of coil turns, and distance between coils. Experiments show that the larger the coil diameter, the greater the output power on the receiver coil. The more turns the coil has, the greater the output power on the receiver coil, but the greater the distance between the coils, the smaller the output power on the receiver coil.

A stacking machine‐learning based method for accelerating magnetic coupler design with ferrite cores in inductive power transfer applications

AbstractThis paper presents a magnetic coupler design method for WPT systems based on stacking machine‐learning algorithms. A synthetic dataset generated by ANSYS Maxwell is used for training and evaluating machine‐learning models. Stacking technology effectively combines the results from multiple models and make best predictions. The designed model allows us to obtain the optimal values of the coil inner radius and number of turns , when other coil design parameters such as the coil outer radius , the wire diameter , and the coil inductance , are given based on the application environment. The proposed method provides practical solutions meeting design requirements quickly, easily accommodating magnetic couplers with ferrite cores, and showing advantages in designing magnetic couplers with optimal power transfer efficiency.

Analysis of Leakage Current in Dynamic Wireless Power Transfer Systems Based on LCC-S Architecture

This paper investigates the issue of leakage current at the transmitter in the Dynamic Wireless Power Transfer (DWPT) system for electric vehicles and puts forward a novel bilateral resonant compensation topology structure based on the conventional LCC-S architecture. Based on the LCC-S framework, a circuit model was developed for traditional (unilateral)/bilateral resonant compensation topologies. The Fourier series voltage-to-earth expansions for the power supply rail were deduced for both topologies. Subsequently, the voltage-to-earth waveforms for the power supply rail were obtained by utilizing the Fourier series expansions of the voltage-to-earth and the corresponding circuit simulation models. The results demonstrate the efficacy of the bilateral resonant compensation topology in mitigating higher-order harmonics of the voltage to earth on the power supply rail by effectively suppressing the distortion in the leakage current and minimizing its conduction. The effectiveness of the double-ended resonant compensation topology in suppressing leakage current conduction has been verified through experimental tests and waveform comparisons of the voltage to earth and leakage current on the power supply rail under two different topologies. Through experimental testing, during which the unilateral/bilateral resonant compensation topologies were compared, an analysis was conducted on the waveforms of the voltage to earth and leakage current of the power supply rail. The results verified the effectiveness of the bilateral resonant compensation topology in mitigating the conduction of leakage current. This study provides empirical evidence supporting the use of the bilateral resonant compensation topology for suppressing leakage current in power rail applications.

A fixed‐frequency second‐order generalized integrator phase‐locked loop‐based phase synchronization control in multisegment wireless power transfer systems

SummaryMultisegment wireless power transfer (MSWPT) technology provides a solution to the challenges of dust‐free environments and automation faced by automated material handling systems (AMHS) in current semiconductor wafer factories. However, variations in track current frequency and phase offset on the transmitting side of the MSWPT technology may lead to significant deficits in energy transmission capability. This paper introduces a method based on the fixed‐frequency second‐order generalized integrator phase‐locked loop (FFSOGI‐PLL) structure for frequency and phase synchronization among multiple transmitters in a MSWPT system. By synchronizing the track currents of multiple transmitters, this method significantly enhances the energy harvesting capacity of the H‐type pickup in the overhead hoist transport (OHT) system, ensuring stable voltage at the receiver (Rx) load. Both theoretical simulations and experiments confirm that the proposed method can effectively capture the phase difference of track current and achieve frequency locking and phase tracking. Building on this theoretical foundation, we constructed three transmitter (Tx) systems and a 1.5 kW Rx equipped with an H‐type pickup. This setup is capable of real‐time monitoring and phase‐synchronization control of track currents with varying phase offsets. The results convincingly demonstrate the strong performance and stability of the proposed method.

A novel bipolar coil structure with high interoperability performance for electric vehicle wireless charging systems

SummaryThe magnetic couplers play an important role in electric vehicle (EV) wireless power transfer (WPT) systems. Conversational coupling structures are mainly based on unipolar, bipolar, and quadrupole coils, and the interoperability among them cannot be achieved. To solve the interoperability problem in the coupling structure, a novel bipolar coil structure is proposed in this paper. Energy transfer with unipolar and bipolar coils is achieved by interconnecting unipolar and bipolar types crosswise in the same plane and combining them with the corresponding topologies. They are connected in series on the dc side. An experimental prototype is built to verify the interoperability performance of the proposed novel bipolar coil structure. The proposed novel bipolar coil structure can be compatible with unipolar, bipolar, and quadrupole coils and achieve a maximum dc‐dc efficiency of more than 85%.

Analysis and design of wireless power transfer system with anti-misalignment constant voltage output characteristics

PurposeThis study aims to solve the problem of high output voltage fluctuation and low efficiency caused by the misalignment of the magnetic coupling structure in the wireless charging system for electric vehicles. To address these issues, this paper proposes a dual LCC-S wireless power transfer (WPT) system based on the double-D double-layer quadrature (DDDQ) coil, which can realize the anti-misalignment constant voltage output of the system.Design/methodology/approachFirst, this paper establishes the equivalent circuit of a WPT system based on dual LCC-S compensation topology and analyzes its constant-voltage output characteristics and the relationship between system transmission efficiency and coupling coefficient. 1. Quadruple D (Ahmad et al., 2019) and double-D quadrature pad (DDQP) (Chen et al., 2019) coils have good anti-misalignment in the transverse and longitudinal directions, but the magnetic induction intensity in the center of the coils is weak, making it difficult for the receiving coil to effectively couple to the magnetic field energy. 2. Based on the double-D quadrature (DDQ) structure coil that can eliminate the mutual inductance between coupling coils and cross-coupling, Gong et al. (2022a) proposed a parameter optimized LCC-LC series-parallel hybrid topology circuit, which ensures that the output current fluctuation is controlled within 5% only when the system is misaligned within the 50% range along the X direction, achieving constant current output with anti-misalignment. The magnetic coupling structure’s finite element simulation model is established to analyze the change in magnetic induction intensity and the system’s anti-misalignment characteristics when the coil offsets along the x and y axes. Finally, an experimental prototype is developed to verify the constant voltage output performance and anti-misalignment performance of the system, and the proposed anti-misalignment system is compared with the systems in existing literature, highlighting the advantages of this design.FindingsThe experimental results show that the system can achieve a constant voltage output of 48V under a time-varying load, and the output voltage fluctuates within ±5% of the set value within the range of ±60 mm lateral misalignment and ±72 mm longitudinal misalignment.Originality/valueBased on the dual LCC-S WPT system, the mutual inductance between the same side coils is reduced by adding decoupling coils, and the anti-misalignment characteristics and output power of the system are improved in a certain range. It is aimed at improving the stability of the system output and transmission efficiency.

Design and Performance Investigation of a Series Compensated Inductive Wireless Power Transfer System for Supplying a Low Power DC Load

In this study, a series compensated WPT system is presented for low power DC load applications. Series LC resonant circuits are applied for both transmitter and receiver sides of WPT system to reduce the impedance at a specified operation frequency, and thus, ensure low power losses. The operation frequency is chosen as 109 kHz for the series compensated WPT system. Then, the series resonant LC filter is designed according to the operation frequency and WPT rating values. In addition, the power electronics systems with their controller and operation principle are demonstrated in depth. To investigate the performance of the proposed system, a 100 W series compensated WPT model is designed and constructed in Matlab/Simulink enviroment. Different simulation results are provided to illustrate the performance of the proposed WPT model. The simulation results show the stable operation of the proposed system under the designed system parameters.

Design and development of an LC compensated WPT system with multiple constant voltage outputs function

SummaryWith the increasing demand for the constant voltage (CV) charging of multiple loads, this article proposes an LC compensated wireless power transfer (WPT) system with multiple load‐independent CV outputs function. Each transmission channel consists of a compensation capacitor and a compensation inductor forming a resonant loop. By configuring different combinations of compensation inductor and capacitor for each transmission channel, different CV outputs can be achieved without affecting the output voltages of other transmission channels. In addition, the proposed system can achieve near zero phase angle (ZPA) and zero‐voltage switching (ZVS) operations, thereby improving system efficiency. Firstly, a detailed theoretical derivation of the proposed system with multiple load‐independent CV outputs and ZPA operation is performed, and the detailed parameter design process is provided. Secondly, the implementation method of ZVS operation is introduced and verified through simulation. Finally, an experimental prototype of two transmission channels is taken as an example to verify the correctness and rationality of the proposed system.

Development of soft magnetic composites for magnetized pavement to improve the efficiency of electric vehicle's wireless power transfer

Integrating the wireless power transfer (WPT) system into the pavement is an effective way to solve the inconvenience of electric vehicles (EVs)’ charging, accelerating the growth of ownership of EVs to achieve net carbon zero in transportation. However, the existence of a cement paving layer between coils was a negative impact factor. Here, two types of ferrite powders were separately mixed into the cement to prepare soft magnetic composite (SMC) material to enhance the coupling degree of coils. The magnetic and mechanical performance of the composite were tested by a vibrating sample magnetometer and compressive and flexural strength tester. Furthermore, to explore the optimal layout of the magnetized pavement structure, nine pavement layouts were designed based on the distribution of magnetic flux. Finally, the effect of SMC material on improving the charging performance was verified by WPT system test platform. Results showed that the Ni–Zn ferrite powder exhibited superior magnetic permeability due to its stronger magnetic moments and lower magnetic domain wall energy compared to Mn–Zn ferrite powder. The peak relative permeability of SMC materials reached 14.370 with an equal mass ratio of Ni–Zn ferrite powder to cement. Conversely, optimal strength was attained with a Mn–Zn ferrite to cement ratio of 0.2, resulting in a compressive strength of 36.0 MPa and a flexural strength of 4.0 MPa. Strategically placing SMC within the pavement, both in the core's interior and exterior to the coil, enhanced the coupling coefficient of coils, thereby improving the transmission efficiency of the WPT system. The incorporation of Ni–Zn ferrite powder in a 1:1 mass ratio to cement materialized the highest efficiency. Nonetheless, considering the mechanical performance, the SMC material with a 0.6 mass ratio of Mn–Zn ferrite powder to cement was recommended for magnetized pavements. The WPT system test results showed a transmission efficiency of 89.78% when utilizing magnetized pavement, surpassing the efficiency with the whole pavement material by 1.36%, which indicated great value and potential in energy conservation and carbon reduction of employing magnetized pavement in WPT technology.

Design of tile shaped coil structure for wireless power transmission for underwater vehicle

A pair of tile-shaped transmitting and receiving coils, which is suitable for wireless power transfer system of autonomous underwater vehicle (AUV), is proposed in this paper. Both coils are designed as the tile shape to fit the AUV’s outer shell. And the transmitting coil which is located on the dock is a little larger than the receiving coil that is embedded in the UAV. With the HFSS software, the proposed coil shape was optimized. The performance of the coils was analyzed. By adjusting the coil offset distance and angle. the positioning relationship between the two coils was optimized. A serial-serial compensation topology was established, and an appropriate capacitor was selected to construct the WPT system. The experimental results verified the correctness of the theoretical analysis. The output power reached 30 W and the transmission efficiency reached 68.5%.

Wireless Power Transfer Efficiency Optimization Tracking Method Based on Full Current Mode Impedance Matching.

Wireless power transfer (WPT) technology is a contactless wireless energy transfer method with wide-ranging applications in fields such as smart homes, the Internet of Things (IoT), and electric vehicles. Achieving optimal efficiency in wireless power transfer systems has been a key research focus. In this paper, we propose a tracking method based on full current mode impedance matching for optimizing wireless power transfer efficiency. This method enables efficiency tracking in WPT systems and seamless switching between continuous conduction mode and discontinuous mode, expanding the detection capabilities of the wireless power transfer system. MATLAB was used to simulate the proposed method and validate its feasibility and effectiveness. Based on the simulation results, the proposed method ensures optimal efficiency tracking in wireless power transfer systems while extending detection capabilities, offering practical value and potential for widespread applications.

An efficient wireless power transfer system planar turn based for implantable medical devices applications

A wireless power transfer system based on inductive coupling for powering implantable medical devices of diverse application is proposed. The system is composed of two resonators based with circular spiral printed on a dielectric substrate. With operation corresponding to the frequency range of medical applications in implants of 403 MHz, and an RF power transfer efficiency (PTE) greater than 50.0 % is obtained with a total reach of 8.0 mm into living tissue. Numerical studies and analyses are carried out in order to investigate the influence of tissues on the frequency response and efficiency of the presented resonators. Through simulations it is possible to establish the maximum input power limit of 120.0 mW of the model to comply with the safety limits of the specific absorption rate (SAR) below 2.0 W/kg. In general, the simulated and measured results demonstrate a good level of agreement. Comparative analyses and conclusions are presented and discussed.

High-Efficiency WPT Systems for Potable Electronics Based on DC-Bias-Voltage- Controlled Variable Capacitor

The power density of wireless power transfer (WPT) systems employed in portable electronics can be enhanced by increasing the operating frequency, but at the expense of lower efficiency due to increased switching and parasitic losses. This paper proposes a method, based on the DC-bias-voltage-controlled variable capacitor (VC) and variable frequency (VF) regulation, to improve the overall efficiency of the WPT system for portable electronics. The method uses VC on the primary side to detune the resonant tank and dynamically regulate the output power, while VF is employed to improve the system efficiency using a look-up table based on a power loss model. A DC bias voltage control module with self-supply ability is employed to control the equivalent capacitance of the VC. A control strategy is proposed to regulate both VC and VF. Experimental results of a 150W prototype are presented to demonstrate that constant output voltage can be maintained despite a wide load range, with an overall efficiency range of 82.1% (@25W) and 92.2% (@150W).

Analysis and Design of Configurable Rectifier With Compensated Near-Zero Impedance Angle for Megahertz Wireless Power Transfer

Adapting to wide load range variations is always one of the main goals pursued by megahertz (MHz) wireless power transfer (WPT) systems. For this, the nonlinear phenomenon of the rectifier has become a problem that must be solved. Compared with the method of optimizing the efficiency around the maximum power point in the traditional design, this paper proposes a global load optimization method. Meanwhile, a novel configurable compensated near-zero impedance angle rectifier (NIAR) is proposed to take full advantage of the global optimization method. The NIAR not only realizes the compression of a wide range of impedance angles, but also solves the classic problems of Class E rectifiers such as large stress, voltage asymmetry, and low real part of input impedance. The configurable design allows the system to adjust the rectifier unit according to the output index, thereby fully improving the coil efficiency, and providing a solution for the application of high-voltage and high-power MHz WPT systems in the future. To verify the effectiveness of the proposed NIAR and design method, a 60 W prototype was built, and a traditional full-wave rectifier was used for comparison. The results show that the proposed NIAR system exhibits better characteristics in terms of system efficiency, voltage stress, and symmetry.

Evaluation of Additive Manufacturing for Wireless Power Transfer Applications

Additive Manufacturing (AM) has emerged as an economical and feasible technology for creating industrial components. This paper evaluates the use of AM for inductive Wireless Power Transfer (WPT) systems. In particular, the innovative use of metal 3D printing is proposed as a manufacturing process for the coils. For this reason, the recent improvement of metal AM is proposed as a suitable solution to increase design opportunities, reduce costs and production time while improving transmission efficiency. In fact, the WPT coil current distribution can be preliminarily studied through Finite Element Analysis (FEA) to optimize its cross-section and geometry. In this work, a general design procedure for WPT coils using metal AM is presented and this technology is compared with traditional solutions (i.e. hollow and litz wire) through extensive experimental measurements. The analysis shows that AM allows to reduce the parasitic resistance, costs and weight while increasing the transmission efficiency. Thus, the obtained results confirm the potential of AM for producing WPT coils, nominating this technology as a flexible, sustainable, and rapid solution for custom WPT coils production.