Multi-load parity-time symmetry wireless power transmission system with active directional energy transmission

Wireless Power Transfer Based on Magnetic Coupling

There exist some issues in wireless transmission like low efficiency, short transmission distance and so on. The transmission distance of traditional inductive wireless transmission system is in mm level. For electromagnetic radiant wireless transmission system is transmitted through radiation, the transmission efficiency is very low. The majority of research on wireless power transmission system is based on the traditional coupled magnetic model, which ignores the characteristics of resonance coils under different working frequency. Thus, the resonance frequency obtained isn't able to make the system working with high efficiency. Based on the transmission characteristics of wireless power transmission, this paper establishes the magnetic coupling resonance model, then analyzes and calculates the optimal transmission frequency of wireless transmission system based on coupled-mode theory and resonance theory, namely the work frequency of strong coupling resonance in the system. By using the finite element analysis method, the paper makes experimental verification on the calculated resonant frequency through the CST electromagnetic simulation software, analyzes the transfer characteristics of the system under different load conditions, and the experimental results show that the calculated resonant frequency can make the system work in a high-efficient and strong coupling transmission state. In the last part, the essay conducts certain analysis on the reasons leading to inaccuracy and proposed some methods to reduce residuals. The experiment set up the hardware system of magnetic coupling resonant wireless power transmission, which light the 4 watts LED lamp in the distance of 12cm, and made the wireless transmission of power realized.

In order to solve the problem that electromagnetic induction widely used now is just suited to short distance transmission, and study on the transmission characteristics of wireless power transmission system based on magnetic resonant coupling, a novel method that the two separate-coupling coils achieve wireless power and information synchronous transmission is proposed. The basic theory of wireless power transmission and information system is introduced. The condition that resonant frequency splitting phenomenon is produced of a contact-less power transmission system has been deduced, and it depend on the length of distance between the two coils. The principle prototype of transmission system is designed, and transmission characteristics of the system are analyzed by simulation and experiment. Based on circuit formulation, maximum efficiency is found to exist. The results show that the method of wireless power and information synchronous transmission system is in agreement with theoretical analysis.

The inductive wireless power transmission system is actually applied to the principle of magnetic feld coupling, combined with the flexibility of the electrical equipment to achieve flexible and safe power supply. In the realization process of wireless power transmission, the key point lies in the transmission effciency and power transmission capability. However, wireless transmission still has some disadvantages in these two aspects. In this case, there is an air gap between the transmitting winding and the receiving winding. If it is too large and the coupling coeffcient is too low, in view of this situation, it is necessary to carry out research from aspects such as raising the coupling coeffcient and controlling the air gap. The article frstly describes the development ofwireless power transmission technology and transmission principles, etc. Secondly, it analyzes the output control of wireless power transmission systems. Third, it conducts simulation analysis using loosely coupling transformers and proposes an optimized solution.The simulation design and inspection process were proposed. The main purpose of this paper is to analyze the current wireless energy transmission system and clarify the direction in which it should be strengthened. The signifcance of this study is to provide a feasible direction for the further optimization of the wireless energy transmission system.

This paper presents high-Q factor 3-D stacked MEMS inductors on polyimide substrate for wireless power transmission systems. The 3-D double layer stacked structure was designed, fabricated, and characterized, and self-planarization of polyimide was realized. The 3-D inductor achieves an inductance of 7.189 μH with a high-Q factor of 26.1 at 4.3 MHz. An inductively coupled wireless power transmission system was set up using the 3-D inductor in combination with a solenoid transmitting coil. At the resonant frequency of 1.6 MHz, the peak-to-peak output open circuit voltage could reach 5.2 V with a maximum power transmission efficiency of 11.74% and an output power of 35.5 mW. Effects of the load impedance and transmission distance on the output power were also investigated. Using this wireless transmission system, the driving of an implanted 3-D microelectrode array for neural prosthesis was demonstrated successfully, indicating that this 3-D stacked MEMS inductor design shows promise for applications in supplying power for implanted medical devices.

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.

The variable gap simultaneous of wireless information and power transmission (SWIPT) is a hotspot of wireless power transmission system. Based on the single coil and dual band resonant structure, an energy transmission method is proposed by using the nonlinear gain saturation mechanism of voltage amplifier with variable transmission gap. The accurate analytical solutions of system transmission efficiency and harmonic frequency are deduced by analyzing the circuit model of the system, and the correctness of the theoretical model is verified by using a simulation method.

Wireless power transmission system is a special type of power transmission process. Wireless power transmission system is used to transmit power from one place to another without any physical contact between the two coils or devices. Wireless Power Transmitter device consists of a transmitter, which takes electric power as input from a power source (either supply or battery), and generates a time-varying electromagnetic field (electromagnetic waves) that carries energy in the form of electric and magnetic waves, and transmits power through free space to a receiver, which extracts power from the field and supplies it to an electrical load. E.g. in the system of charging a phone wirelessly, a transmitter takes in power and generates an electromagnetic field and transmits it which is then received by the receiver and then transformed back into electricity which is used to charge the phone. Transmitter is a set of equipment which is used to generate and transmit electromagnetic waves. The basic working principle of wireless power transfer is: 1. Faraday’s law of Electromagnetic theory and 2. Two objects having similar resonant frequency and in magnetic resonance at powerfully coupled tends to exchange the energy in the form of oscillating electromagnetic field. This method of transmitting power is very useful and reliable. The results of various experiments suggest the standardized application method of wireless transmission in utilization of wireless power for implantable sensors.

Wireless power transmission (WPT) technology has been widely applied in various fields, such as electric vehicles and wireless sensor networks. Magnetic coupling resonance technology is one of the most important technologies in wireless power transmission. A large number of experimental studies have shown that wireless power transmission systems have good power transmission performances when they work at the natural frequencies. Nevertheless, many relevant parameters‘ differences in design, such as the choice of coupling coil structures and parameters, the coupling coefficient between transmitting coil and receiving coil and the quality factor of each coil, will lead to changes in terms of transmission performances. To reduce these adverse effects and make the wireless power transmission system maintain better transmission efficiency, a resonant magnetic coupling four-coil model with Series-Series-Series-Series (SSSS) structure is established based on the equivalent circuit theory. An optimization factor α is proposed to evaluate the transmission performances of the wireless power transmission system. Parameters characteristics of the optimization factor α between the excitation coil and the transmitter coil in the established symmetric structural system model are analyzed in detail. By means of the simulation analysis software MATLAB, the influences of the distance between the excitation coil and the transmitter coil and their respective radius on the optimization factor α are analyzed. And the variation tendency of α with regard to the parameters of the excitation coil and the transmission coil is clarified. Also, the influence of the optimization factor α on the transmission efficiency of the wireless power transmission system is analyzed and the variation trend is cleared up. By studying the optimization factor, the selection specification of system parameters is analyzed and provides a theoretical basis for system design. A resonant magnetic coupling four-coil wireless power transmission experimental system was built through optimization design. Theoretical models and experimental measures are in good agreement in terms of the influence of system transmission distance on transmission efficiency. After optimization, the transmission efficiency is increased by 3.1% compared with the system before optimization

Wireless power transmission has been investigated to realize more efficient and more convenient noncontact power transmission systems for electric tramways, electric vehicles, portable telephones, and so on. Since the magnetic resonance type wireless power transmission system is often used in frequency regions of megahertz, there are some problems, such as the increase of wire resistance due to skin effect and a switching loss in converter. Therefore, it is expected to realize high-power wireless power transmission in low-frequency regions of kilohertz. In a wireless power transmission system using copper coils, however, the transmission efficiency decreases with the decrease of resonance frequency because quality factor decreases with the decrease of the resonance frequency. Therefore, we fabricated a model system using high-temperature superconducting (HTS) double-pancake coils composed of REBCO tape and investigated the transmission efficiency characteristics to evaluate the possibility of application of the HTS coil to a high-efficiency wireless power transmission system operated in the low-frequency region of kilohertz. In the copper coil system, the transmission efficiency increases with the resonance frequency. In the HTS coil system, however, a high-efficiency transmission was obtained, even at a low-resonance frequency, due to a large quality factor at low frequency. Moreover, in the wireless power transmission system using HTS coils, the transmission efficiency was high not only at the resonance frequency but also around the resonance frequency. From these results, we believe that HTS coil can realize the high-efficiency wireless power transmission in a low-frequency region of kilohertz.

The traditional microwave power transmission system is mostly point-to-point static target power transmission, while the microwave wireless power transmission system based on time reversal has good space-time focusing characteristics, which can be used for the development of microwave wireless power transmission to moving targets and multi-target wireless power transmission. However, limited transmission efficiency and large size limit its usage scenarios. Aiming at the application requirements of wireless power transmission in the field of consumer Internet of things, this paper designs a set of wireless power transmission system with high focusing effect in multipath environment. The size of the control circuit is greatly reduced by using RF chip and micro assembly process to replace the NC phase shifter and amplification module required for the original time reversal. On this basis, the design of microstrip array transmitting antenna is completed, and the single target time reversal power transfer simulation is carried out in free space and multipath environment. Compared with the single target power transfer simulation results of traditional phased focusing array based on geometric optics method, it is verified that the microwave wireless power transfer system based on time reversal has better focusing effect in multipath environment.

Coupling coil is considered as the core link of the wireless power transmission system, and the optimal design of coupling coil the has a direct impact on the transmission efficiency and power of the whole wireless power transmission system. In this paper, we utilized ADS software to build a typical wireless power circuit based on the equivalent circuit model of the prototype system to simulate the energy transfer process and analyze the system transmission efficiency and power output which reduced the computational complexity and simplified the coil design process. In order to implement the optimized coupling coil of the wireless transmission system, coupling coil parameters are calculated to the determine the optimal resonant capacitance compensation, coupling coefficient, and radius of coil by the establishment of simulation model of circuit. The equivalent circuit model of the system has the wide applicability. The simulation results show that the design method can improve the transmission performance optimization of the magnetically coupled resonant wireless power transmission system.

CT power supply is a commonly used power supply method for high voltage line monitoring equipment. Because the high voltage monitoring equipment needs to be installed on the tower, a long connection line will lead to more difficult installation, so wireless transmission is considered. This paper explores a new type of CT power collection mode combined with wireless power transmission, which adopts a new type of three coil magnetic coupling resonance wireless power transmission system. It can stably collect power from CT and supply power wirelessly at the same time, which is convenient for the installation of monitoring device and power collection device. Aiming at the important parameters of transmission efficiency of wireless power transmission system: transmission distance, frequency, load, this paper uses chaotic particle swarm optimization algorithm to optimize the system, and explores the optimal parameters corresponding to the highest transmission efficiency.

The electro-hydraulic composite intelligent completion technology is one of the most effective ways to solve the efficient development of oil and gas. The development of an electro-hydraulic composite wet joint tool that is compatible with the electro-hydraulic composite intelligent completion system can achieve intelligent control between the upper and lower pipe columns of deepwater oil and gas wells and the pluggable transmission of monitoring signals. This article proposes a new type of electromagnetic coupling electro-hydraulic composite wet joint designed to address the defects of friction damage and poor contact in current wet joint direct contact power transmission. The joint uses claw docking and wireless energy transmission to achieve the composite transmission of hydraulic and electric power. Firstly, we independently designed a DC power supply inverter circuit, rectification circuit, and wireless power transmission coil assembly to form a wireless power transmission system. We also conducted testing and analysis on the wireless power transmission efficiency, which exceeded 60%. When the input voltage was above 80 V, the output power was greater than 60 W, meeting the design requirements. Secondly, the mechanical structure of the new electro-hydraulic signal wet joint tool was optimized and its strength was verified. The simulation results showed that the maximum stress was 891.8 MPa, and the maximum deformation of the wet joint docking overall structure was 0.123 mm. The strength and deformation met the design requirements. The hydraulic and electrical connectivity indoor tests were conducted on the electromagnetic coupling wet joint, and all aspects of transmission were normal, thus forming a design scheme for the underground electromagnetic coupling electro-hydraulic signal wet joint. The wireless transmission type electro-hydraulic signal wet joint designed in this article is of great significance for accelerating the promotion and application process of deepwater intelligent completion systems.

In order to prolong continuous working time of the mobile robot to inspect on transmission lines, a robotic power management system is introduced in this paper based on the wireless power transmission technology. Magnetic resonance coupled WPT (wireless power transmission) unit is applied and its performance is analyzed in form of electrical circuit mode method. By modeling the output power of WPT unit, the relationship between coupled coefficient, angular frequency and amount of output power is given, and furthermore the energy consumption of each unit in power management system is quantified. Experiment results verified the validity of the circuit model of WPT and showed that the system could work conveniently in wireless way to provide power for the inspection robot. Keywords-wireless power transfer, coupled coefficient, Q-factor technologies recently due to its capability to transfers energy across large air gap with high efficiency. Although the coupled resonance based WPT need much more attention to design and test the drive circuit as its working frequency is usually up to several mega Hz, it's effective working distance which is up to several meters (decides by the material and the size of the resonance coil in application) is still really attractive for medium distance wireless power transmission applications. In this paper, the fundamental characteristics of a special magnetic resonance system for transmission line inspection robot have been examined. Equivalent circuit is given in order to give numerical analysis of the resonance system. In order to test the output power of the WPT unit, current in load coil is calculated, and the relationship between coupled coefficient, angular frequency and output power is given. Power transmission ratio is also given in chart which shows that amount of power loss of WPT accounts for few part of the total loss of the power management system and the ratio is acceptable. Equivalent circuit are also verified by experiment which shows that the proposed method is suitable for charging the inspection robot and the coupled resonance wireless power transmission system could also be applied in many other fields to avoid the trouble or obstacle of using electric cord. A wireless power transmission technique based robotic power management system is introduced: Section2 shows the general function charts of the power management system, and especially the wireless power transmission unit of the system. Section 3 details the circuit model of WPT for calculating the output power of this unit; Section 4 introduces the experiments results and proves that the WPT based power management system can efficiently transmit power wirelessly and the design in this paper has the function of prolonging continuous working period of the inspection robot.