Wireless Power Transfer Characteristics Research Articles

A Review on Characteristics of Wireless Power Transfer

In this paper we discuss the various types of WPT scheme implementations. we analysis wireless power transfer, we discuss the advantage and disadvantage of wireless transfer system, current trends of WPT system technology and research done by various researchers in the field of WPT system. WPT is the transmission of power from AC source to batteries without wire or connector is called wireless power transfer. Today WPT technology used in many applications smart devices household products and the various field of electronics by the use of technology wireless power transfer we can remove the wired connectors and other mode of transferring power physical link due to this the mobility and use of these devices become convenient for everyone the use of WPT technology in near future increases rapidly research and development work in WPT maybe increase in near future the distance between power transfer wireless link or power receiving source like rechargeable device or battery source or increases the power voltage transfer capacity are the main research and development areas for future development

DEA-based on optimization of inductive coupling for powering implantable biomedical devices

Inductive coupling wireless power transfer (WPT) is one of the best technologies for powering implantable microelectronic devices (IMD). A wireless power transfer system’s important elements (indicators) are power transfer efficiency (PTE) and power delivered to load (PDL). The key characteristics of WPT are the size of the transmitting (Tx) and receiving (Rx) coils, the operating frequency, and the separation distance between the two parts of the system. The main goal of this research is to use the differential evolution algorithm (DEA) to optimize a wireless energy transfer system in order to maximize the PTE and PDL. By comparing the results acquired by the proposed technique to those obtained by other methodologies, we were able to validate the results obtained by the suggested method. With the aim of raising the PTE and PDL. Using this metaheuristic approach, we were able to improve WPT’s critical parameters. For is, a PTE of 95% and 136 mW of power delivered to the load for a 13 cm separation distance.

Sensitivity analysis of wireless power transmission

The compensation networks that realize constant current/constant voltage in the wireless power transfer are high-order resonant networks, and there are multiple resonance frequency points to achieve load-independent constant current/constant voltage output. However, the output characteristics of wireless power transfer based on high-order resonant networks are extremely susceptible to the effects of resonant network parameters. Therefore, the analysis of the resonance point of the wireless power transfer is helpful to select the appropriate resonance frequency point and achieve stable output. This article analyzes the resonance conditions of the double-sided LCC compensation network and then gives a parameter design method to achieve load-independent CC/CV output characteristics under ZPA conditions. The effects of the resonant network’s primary/secondary series compensation capacitor parameters on the resonance point and output characteristics of the wireless power transfer system are analyzed. Finally, the correctness of the parameter design of the resonance network and the accuracy of the theoretical analysis are verified.

Directional Characteristics of Wireless Power Transfer via Coupled Magnetic Resonance

The wireless power transfer (WPT) system via coupled magnetic resonance (CMR) is an efficient and practical power transmission technology that can realize medium- and long-distance power transmission. People’s requirements for the flexibility of charging equipment are becoming increasingly prominent. How to get rid of the “flitch plate type” wireless charging method and enhance the anti-offset performance is the main research direction. Directional characteristics of the system can affect the load receive power and system efficiency in practical applications. In this paper, the power and efficiency of the WPT system via CMR were analyzed according to the principle of near-field strong coupling at first. The expression of the mutual inductance between the transmitting and the receiving coils under angular offset was derived from the perspective of the mathematical model, and the influences of angular deviation were analyzed. Second, simulation models were established under different distance between coils, different coil types, and different coil radius ratios in symmetrical and asymmetrical systems. Afterwards, the directional law was obtained, providing reference for the optimal design of coupling coils. Finally, an experimental system was built, and directional characteristic experiments were carried out under different conditions. Experimental results were consistent with simulation results, which verified the theoretical analysis.

Research on the Characteristics of Wireless Power Transfer in Non-ferromagnetic Metal Pipe

With the development of various electronics, the way of transmitting energy by wire has brought increasingly negative effects on the operability and convenience of products. As wireless power transfer (WPT) technology requires no transmission lines, it has received increasingly wide attention. Most of the previous research on the technology of magnetic resonant coupling WPT mainly focused on the transmission of energy in the air. This paper establishes the wireless power transfer system model under non-ferromagnetic metallic environment and studies the effect of non-ferromagnetic metallic environment on coil self-inductance L, mutual inductance M and coil resistance R of WPT system. On this basis, the study on the relationship between coil diameter and mutual inductance is carried out for aluminium pipe, and the relationship between coil diameter and diameter of metal pipe at the maximum mutual inductance is fitted. Besides, experimental verification is conducted for the change of mutual inductance between the coils of WPT system in the aluminium pipe, presenting that the actual measurement results of mutual inductance in the aluminium pipe are consistent with the theory.

Research on the Characteristics of Wireless Power Transfer in Ferromagnetic Metal Pipe

With the development of society, radio energy transmission technology has been paid more and more attention. However, in the actual application environment, the surrounding metal environment has a significant impact on the radio energy transmission performance. Based on the technology of MRR radio energy transmission, this paper establishes a two coil radio energy transmission model, and analyzes the influence of metal environment on the coil self inductance L, mutual inductance m and coil resistance R of the radio energy transmission system by finite element simulation. On this basis, aiming at the ferromagnetic metal environment, the steel pipe is selected as the research object to study the relationship between coil diameter and mutual inductance in the metal pipe, and the relationship between coil diameter and metal pipe diameter when the maximum mutual inductance is obtained through fitting analysis. At the same time, through the experiment, the mutual inductance between the coils of the wireless energy system in the steel tube is verified, and the experimental results are very consistent with the theory.

Load Parameter Joint Identification of Wireless Power Transfer System Based on the DC Input Current and Phase-Shift Angle

This article presents a multiple load parameter joint identification method, adopting only the measured dc input current and inverter phase-shift angle of the wireless power transfer (WPT) system. First, a WPT fundamental-harmonic model is established, considering the effects of the battery and rectifier load. This model can quantitatively describe WPT characteristics and parameter relationships according to the linear superposition of fundamental and harmonic components. Then, the identification method is proposed through the model, which can achieve the joint identification of multiple important load parameters, including battery voltage, equivalent resistance, charging current, and WPT equivalent load impedance. Furthermore, on the basis of the developed WPT prototype, the effectiveness of the proposed fundamental-harmonic model is proved and the parameter sensitivity is discussed. Finally, the proposed identification method is experimentally studied, and the results show that it can achieve high accuracy on the conditions of battery voltage change, phase-shift angle variation, and coil misalignment.

A Comprehensive Study on Composite Resonant Circuit-Based Wireless Power Transfer Systems

In the magnetic resonant wireless power transfer (WPT) technology, system topology is the main factor that determines the WPT characteristics of the system, and recently, various system topologies based on various composite resonant circuits are being applied in WPT applications. This paper groups the composite resonant circuit-based WPT systems into one family and conducts a comprehensive investigation on their topologies and characteristics. First, characteristics of the composite resonant circuits, which are the fundamental circuits of transmitter and receiver of these systems, are investigated; in the process, a calculation method of resonant frequency, current ratio, and quality factor of these circuits are presented and the characteristics of these parameters are clarified. Second, based on that, the composite resonant circuit-based WPT systems are investigated. Possible topologies of these systems are explored and an equivalent system model of these systems is proposed. Based on that, characteristics evaluation expressions of these systems are derived and the optimal design guide of these systems is discussed. Finally, experimental prototypes are constructed and the proposed theory is verified by experiment results.

An investigation on frequency characteristics of wireless power transfer systems with relay resonators

PurposeThis paper aims to analyze the frequency characteristics of wireless power transfer (WPT) systems with relay resonators in terms of the power delivered to the load and system efficiency. Based on the analytical results, system parameters can be optimized to achieve maximum power transfer and higher system efficiency.Design/methodology/approachBased on Kirchhoff’s voltage law equations, WPT systems with relay resonators are described by the coupled linear second-order differential equations. Splitting frequencies are estimated by using the matrix theory. In addition, critical coupling conditions are demonstrated based on discriminant analysis.FindingsIt was found that multi-maximum values exist for the power delivered to the load and total system efficiency owing to multiple eigenfrequencies of the system. Also, frequency conditions of maximum power transfer and system efficiency, as well as their critical coupling conditions, were quantitatively estimated.Research limitations/implicationsDuring our analytical process, we assume that quality factors of resonators in the system are high and the crossing coupling between resonators is negligible.Originality/valueIn previous works, the exact analysis of frequency characteristics is limited to WPT systems with two resonators. The appealing feature of this work lies in its ability to present a simplified analytical method with negligible approximation errors for WPT systems with relay resonators.

Improvement of Transmission Distance by Using Ferrite in Superconductive Wireless Power Transfer

The wireless power transfer (WPT) characteristics between the transmitter and receiver coils according to the existence of ferrite were analyzed in this study to improve the transmission distance of superconductor resonance coils. To set the optimal reflection coefficient, the thickness increased by 1 mm, from 0 to 10 mm. It was found that the transfer efficiency improved with the lowest reflection coefficient at the thickness of 2 mm. The 2-mm-thick ferrite was applied to the transmitter coil, and the reflection coefficient was measured by the distance. As a result, the transfer efficiency with ferrite was highest at the distance of 2500 mm. Also, it was confirmed that the WPT characteristics were improved up to 500 mm by the application of ferrite. It is believed when the superconductive WPT system is organized using such advantageous ferrite, its transmission distance and efficiency improvement can be secured.

Voltage transfer ratio analysis for multi‐receiver resonant power transfer systems

The wireless power transfer characteristics of system architectures with single transmitter and multiple receiver coils are investigated. With multiple receivers in a limited space, couplings within receivers occur. Effective resonant frequency is changed due to such couplings, the desired working region should be adjusted accordingly. An equivalent circuit model is developed to describe the system with a single receiver, and extended to describe the system with two receivers. The circuit model yields transfer frequency responses that are in good agreement with experimental measurements over a range of frequencies that span the resonance. In a multi-receiver system, a method for tracking frequency shifts or retuning the lumped capacitance so as to maximise the efficiency is proposed. The simulation and experimental results well agree with the theoretical analysis.

Energy Link Optimization in a Wireless Power Transfer Grid under Energy Autonomy Based on the Improved Genetic Algorithm

In this paper, an optimization method is proposed for the energy link in a wireless power transfer grid, which is a regional smart microgrid comprised of distributed devices equipped with wireless power transfer technology in a certain area. The relevant optimization model of the energy link is established by considering the wireless power transfer characteristics and the grid characteristics brought in by the device repeaters. Then, a concentration adaptive genetic algorithm (CAGA) is proposed to optimize the energy link. The algorithm avoided the unification trend by introducing the concentration mechanism and a new crossover method named forward order crossover, as well as the adaptive parameter mechanism, which are utilized together to keep the diversity of the optimization solution groups. The results show that CAGA is feasible and competitive for the energy link optimization in different situations. This proposed algorithm performs better than its counterparts in the global convergence ability and the algorithm robustness.

초전도 공진 코일의 효율성을 높이기 위한 차폐 재질에 따른 무선전력전송 효율비교 분석

The magnetic resonance method requires high quality factor(Q-factor) of resonators. Superconductor coils were used in this study to increase the Q-factor of wireless power transfer(WPT) systems in the magnetic resonance method. The results showed better transfer efficiency compared to copper coils. However, as superconducting coils should be cooled below critical temperatures, they require cooling containers. In this viewpoint, shielding materials for the cooling containers were applied for the analysis of the WPT characteristics. The shielding materials were applied at both ends of the transmitter and receiver coils. Iron, aluminum, and plastic were used for shielding. The electric field distribution and S-parameters (S11, S21) of superconducting coils were compared and analyzed according to the shield materials. As a result, plastic shielding showed better transfer efficiency, while iron and aluminum had less efficiency. Also, the maximum magnetic field distribution of the coils according to the shielding materials was analyzed. It was found that plastic shielding had 5 times bigger power transfer rate than iron or aluminum. It is suggested that the reliability of superconducting WPT systems can be secured if plastic is used for the cooling containers of superconducting resonance coils.

Partial element equivalent circuit modeling and design for wireless power transfer system via magnetic resonant coupling

To study the characteristics of wireless power transfer (WPT) resonators via magnetic resonant coupling (MRC), distributed parameter models based on partial element equivalent circuit (PEEC) are built for MRC-WPT resonators and cou- pling link between two resonators, which is essential to design a MRC-WPT system. The track of one turn in WPT coil is modeled as a complete ring carrying constant current, and the parasitic parameters and high-frequency losses are considered in this modeling method. The circuit parameters of PEEC network are calculated by numerical integrals and analytical formulas. This modeling method can predict resonant frequency and power transfer capability for MRC-WPT system. Impedance and scattering parameter S21 of circular spiral resonators are also calculated by method of moments (MoM), and the proposed modeling method shows good agreement with the simulated results and has high calculation efficiency. Two types of WPT res- onators are designed in laboratory. Impedance and scattering parameter S21 are measured for each of the cases, and the results show that the PEEC modeling method has a better accuracy and can predict resonant frequency and power transfer capacity for MRC-WPT system.

릴레이 코일을 포함한 자기 공명 방식 무선 전력 전송 시스템의 분석 및 모델링

In this paper, characteristics of wireless power transfer (WPT) systems using magnetically coupled resonance scheme with relay coils are investigated and modeled. Especially, asymmetric frequency splitting characteristics in over-coupled region of WPT with relays are measured and accurately modeled. Transmitter, receiver, and relay coils are modeled with R, L, C equivalent circuits. Using these circuit models and mutual inductances between coils, a WPT system is described with a linear matrix equation. For under-coupled region, a matrix is simplified considering only mutual inductances between adjacent coils. An analytical transfer characteristic of WPT system vs. distance is extracted using an inverse matrix that is acquired by Gauss elimination method for the simplified matrix. For over-coupled region, a matrix considering mutual inductances between non-adjacent coils is used to predict a frequency splitting characteristics accurately. A 6.3MHz WPT system with relay coils is implemented and measured. An accuracy of the model is investigated by comparing the output of the model with the measured results.

Analysis of Wireless Power Transfer Characteristics for Multiple Receivers by Time Sharing Technique

A multiple charging method for a wireless power transfer system (WPTS) in the near-field region is proposed. We analyzed the frequency characteristics of multiple receivers in the near-field region. The results suggested that the time division WPTS can achieve efficient and equal power transmission at multiple receivers. We conclude that this system has an advantage for charging multiple receivers.