Analysis of a Novel Near-Field Plate applied in Wireless Power Transmission System

Abstract

There are many disadvantages in traditional power transmission mode, such as the wire is neither safe nor convenient, the installation of electric equipment is limited by the length of the wire, and the wire aging prone to leakage problems which will harm people's health. In order to overcome these shortcomings, the wireless power transmission mode is adopted in many aspects. The basic structure of the wireless power transmission system is divided into four parts: power source, transmitting coil, receiver coil and load. The power is transmitted through the transmitter coil in the form of electromagnetic waves, and the power is captured by the receiver coil and then transmitted to the load. During the electromagnetic wave propagates from the transmitter coil to the receiver coil, however, the electromagnetic wave produces a large amount of radiation to the surrounding environment, and the loss increases with the increased distance. This not only affects the surrounding other electrical equipment and cause serious harm to the human body. In view of the above problems, this paper presents a novel near-field plate to apply in the wireless power transmission system which not only reduce the power loss and improve the transmission efficiency of the system, but also gather the scattered electromagnetic waves around to reduce the radiation of the system to the surrounding environment. In order to see farther and smaller things, humans have invented telescopes, microscopes, and other tools. The principle of these tools is the use of a lens to interfere with the light waves, allowing one can see a clearer image of the object. The researchers found that the specific interference of light wave can reduce the loss of light wave in the transmission process and enhance the brightness of light. In other words, when the lens has multiple seams, and the distance between the seams and the seams is even times of half light wavelengths, the peak of the light passing through the lens is superimposed to make the brightness of the light stronger. According to the principle that interference of light wave by lens can enhance the brightness of light, a near-field plate is proposed and designed to improve the performance of wireless power transmission system. The near-field plate is constructed by the copper strip which is placed on the surface of a plate to design a special pattern. This special pattern of copper strip has a beneficial interference of electromagnetic wave, so that electromagnetic waves come together through the near-field plate to reduce the loss of electromagnetic wave. When the near-field plate is applied to the wireless power transmission system, the transmitter coil, the receiver coil and the near-field plate must achieve resonance, so as to enhance the electric field intensity at the receiver coil and to improve the transmission efficiency of the system. Through designing and simulation, the near-field plate has the better aggregation effect on the electromagnetic wave when it is designed with a small hole near its center, thus the receiver coil can receive more power. In this paper, a near-field plate is proposed as shown in Fig. 1. There is a small hole in the middle of the near-field plate, and its radius is about 2mm. The dark part near the hole and the outermost dark part are both copper coils. The light color part between the two copper coils is a slit. In addition, in order to guarantee the near-field plate have same resonant frequency with the transmitter coil and the receiver coil, a capacitance is connected to each of the copper coils in the near-field plate. The near-field plate is placed between the transmitter coil and the receiver coil. The wireless power transmission system with near-field plate is simulated. The current induced in the receiver coil is shown in Fig. 2. It can be seen that the current will be increased about 17%. The parameters of the near-field plate can still be optimized and the detail results will be given in full paper.