Field Wireless Power Transfer System Research Articles

Comparison Techniques for Optimization Switching Frequency In Energy Encryption Of Wireless Power Transfer System

This paper reviews the techniques for optimization switching frequency used in Wireless power transfer (WPT). WPT is one of the most useful ways to transfer power. Based on distances power transfer, the WPT system can be divided into three categories, namely, near, medium, and far fields. Inductive coupling and capacitive coupling contactless techniques are used in the near-field WPT. Magnetic resonant coupling technique is used in the medium-field WPT. Electromagnetic radiation is used in the far-field WPT. From the comparison in this paper, a model and design algorithm to optimize switching frequency for energy encryption of medium field wireless power transfer system are purposed. The maximum value of the performance are suitable to compute the optimal circuit parameter by algorithm itself.

Practical Model for Metamaterials in Wireless Power Transfer Systems

Metamaterials (MTMs) with extraordinary electromagnetic properties are recently applied to wireless power transfer (WPT) systems to improve power transmission efficiency. Although theoretical progress has been made on MTMs in low frequency near field, in the operation frequency of most WPT systems (usually MHz), the design of MTMs still utilizes the model used in high-frequency applications. Therefore, a practical model of MTMs in low MHz band is proposed in this work. The resonance frequency and quality factor are used to describe the characteristics of an MTM slab. The near field WPT systems with MTMs are then modeled as electric circuits, the system efficiency is explicitly deduced, and optimization algorithms are employed to optimize the MTM resonance frequency and maximize the system efficiency. The proposed practical model is validated via a prototype wireless power transfer system operating at 6.78 MHz. Experiments show that the proposed MTM model has good accuracy for low MHz WPT systems compared with the high-frequency model. The proposed practical model of MTMs provides an accurate way to analyze the performance of MTM at low MHz frequencies and greatly benefits the future exploitation of MTM-based low-frequency near field applications.

Optimization of the Alignment Method for an Electric Vehicle Magnetic Field Wireless Power Transfer System Using a Low-Frequency Ferrite Rod Antenna

The establishment of international and regional standards for electric vehicle (EV) magnetic field wireless power transfer (MF-WPT) systems started in 2010 by the Society of Automotive Engineers (SAE). In the meantime, the EV MF-WPT standardization has been focused on primary device and secondary device topology. Recently, the International Organization for Standardization (ISO), the International Electrotechnical Commission (IEC), and SAE have begun describing the communication and alignment techniques for EV MF-WPT. In this paper, we present a fine positioning method using a low-frequency (LF) signal, as mentioned in IEC 61980 and SAE J2954. Through modeling and simulation, we optimized a LF ferrite rod antenna (FRA) for EV MF-WPT fine positioning. We also found the optimal arrangement of LF-FRAs on primary device and secondary device Finally, we used a test bench to experiment and check the results of our proposal.

Numerical analysis on near field wireless power transfer system using reconfigurable transmitting/receiving antenna

Numerical analysis on near field wireless power transfer system using reconfigurable transmitting/receiving antenna

Modifications to Improve the Time-Domain Performance of the Van Veen Loop

The Van Veen loop is intrinsically well adapted to time-domain measurements of net magnetic dipole moment. That is, the system comes very close to preserving the shape of the time-domain waveform of the net or residual magnetic dipole moment produced by the device under test. This property makes the Van Veen Loop very useful in the characterization of magnetic field wireless power transfer systems in which short-time-scale features such as ringing in inverter and rectifier circuits are present in the extraneous magnetic field. We present a unified derivation of the frequency response of the internal coaxial structure of the Van Veen loop showing explicitly why the system intrinsically provides nearly flat frequency response and hence distortionless time response. Additionally, we present two simple modifications to the internal circuitry, which further improve the time- and frequency-domain performance of the system to the extent that it approaches having a distortionless transfer function. A physical explanation for the mechanism by which the time-domain performance is improved is provided. This argument is based on the source termination in a time-domain transmission line analysis. Finally, an alternative frequency-domain analysis based on the high-pass Kuroda transform is given, which provides significant insight into the operation of the distortionless system.

Near field wireless power transfer using curved relay resonators for extended transfer distance

This paper investigates the performance of a near field wireless power transfer system that uses curved relay resonator to extend transfer distance. Near field wireless power transfer operates based on the near-field electromagnetic coupling of coils. Such a system can transfer energy over a relatively short distance which is of the same order of dimensions of the coupled coils. The energy transfer distance can be increased using flat relay resonators. Recent developments in printing electronics and e-textiles have seen increasing demand of embedding electronics into fabrics. Near field wireless power transfer is one of the most promising methods to power electronics on fabrics. The concept can be applied to body-worn textiles by, for example, integrating a transmitter coil into upholstery, and a flexible receiver coil into garments. Flexible textile coils take on the shape of the supporting materials such as garments, and therefore curved resonator and receiver coils are investigated in this work. Experimental results showed that using curved relay resonator can effectively extend the wireless power transfer distance. However, as the curvature of the coil increases, the performance of the wireless power transfer, especially the maximum received power, deteriorates.