Resonant Wireless Power Transmission Research Articles

Optimal Design of Relay Coil Inductance to Improve Transmission Efficiency of Four-Coil Magnetic Resonance Wireless Power Transmission Systems

Magnetic resonance wireless power transmission consists of a source coil and relay coil (transmission coil (Tx-coil), receiving coil (Rx-coil)). The relay coil is designed with windings and a series capacitor, which are resonant with the input voltage frequency. Magnetic resonant wireless power transmission by a relay coil enables the transmission of power from a few centimeters to several meters. Recently, research has been conducted on the shape and material of each coil to increase the transmission distance. However, limitations remain with respect to increasing the transmission distance. Specifically, the optimization of the electrical characteristics of the relay coil is necessary to increase the transmission distance and improve efficiency. In this study, we configured the inductance of the relay coil to be approximately 95 μH, 270 μH, and 630 μH. Accordingly, we designed the series capacitors to have the same resonant frequency and analyzed the transmission characteristics of each relay coil. We confirmed that as the inductance increased, the transmission efficiency increased by up to 10%. The relay coil was designed to have an inductance of approximately three to six times that of the source coil (load coil). Thus, the optimal design of the relay coil is believed to be the most efficient and economical coil design.

Research on the structure of magnetic coupling resonant wireless power transmission coil

Research on the structure of magnetic coupling resonant wireless power transmission coil

Single-Wire Transmission Methods: Justification of a Single-Wire Resonant Power Transmission System

Electricity supply as well as the provision of other forms of resources is one of the foundations of efficient agriculture. However, due to the reduction in the number of people living in rural settlements, there have been a large number of power lines with considerable lengths supplying small loads, hence resulting in an increase in power supply efficiency. A single-wire power transmission is an option for reducing the capital cost of power line construction by utilizing fewer conductors and fittings and lighter power transmission towers while lowering operational expenses. This paper considers the possible methods for single-wire energy transmission via the analysis of information sources such as Yandex and Google search engines; Scopus and Google Scholar scientific databases; and Cyber Leninka, eLIBRARY.ru, Elsevier, Springer, IEEE Xplore, and IGI Global electronic libraries. The conducted review revealed four alternatives: a single-wire earth return (SWER) system, a single-wire balanced line (B-Line), resonant wireless power transmission (SWPT) system, and a resonant single-wire power transmission system. The latter is of particular interest due to the lack of comprehensive and detailed information describing this technology, although it has distinct characteristics because of the peculiarities of the resonant mode of operation. The paper provides a comprehensive review of all existing published materials on the topic of “resonant systems for the transmission of electrical energy along a single wire”. The study covers the history of development and the structure of this system; describes its features, advantages, and the problems of using it; and the experience and fields of its application.

Spatial Azimuthal Misalignment Characteristics of High-Temperature Superconducting Wireless Power Transmission Systems

Magnetically coupled resonant wireless power transmission technology (WPT) based on high-temperature superconducting (HTS) coils has gained wide popularity due to its low impedance and high-quality factor Q value characteristics. This technology has greatly improved the energy transfer performance of wireless power transmission (WPT) systems. However, practical applications of conventional WPT, such as wireless charging of autonomous underwater vehicles at mooring points, often encounter spatial misalignment issues due to the complex ocean environment and ocean currents. Nonetheless, few studies have investigated the spatial misalignment of HTS WPT systems, particularly the angular misalignment. This paper presents a solution to address this problem by constructing magnetically coupled resonant wireless energy transmission systems based on HTS coils and copper coils. The study analyzes the relationship between the transmission efficiency of the WPT system and the received power of the load with respect to the spatial orientation of the coil. The performance of the superconducting coil and copper coil WPT systems is compared. The experimental results demonstrate that, under the same spatially misaligned conditions, the WPT system using HTS coils can significantly improve the transmission efficiency and load power compared to the conventional copper WPT system. Moreover, simultaneous adjustment of the lateral misalignment distance and different orientation deflection angles can improve the transmission efficiency and smooth load output power of the high-temperature superconducting WPT system.

Nonlinear Modeling and Transmission Efficiency Optimization of MCR-WPT System Based on Monte Carlo-Interior Point Method

With the optimization goal of improving the transmission efficiency of the magnetically coupled resonant wireless power transmission (MCR-WPT) system, the influencing factors and suppression methods of frequency splitting phenomenon (FSP) are analyzed from the perspective of input impedance based on the mutual inductance model. Then we propose the Monte Carlo-Interior Point method (MC-IPM) for nonlinear modeling to determine the optimal system parameters while ensuring that the system does not suffer from FSP. Finally, the simulation results show that the proposed method can obtain the optimal parameters faster and achieve higher transmission efficiency. The optimized system can meet the practical requirements and provides a reference value for improving the transmission performance of MCR-WPT.

Investigation on Induced Energy Extraction from High-Voltage Transmission Lines Based on Three-Coil WPT Systems

In order to realize an online power supply, this article develops an explicit design of induction power extraction technology combined with wireless power transmission (WPT) technology. Unlike the power supply mode of traditional batteries of online monitoring devices of high-voltage transmission lines, this technology solves the short battery life cycle problems. First, the principle of induction power extraction is analyzed. Based on the equivalent circuit of the mutual inductance model, expressions of induction power extraction without and with core saturation are derived, respectively. According to the current transformer (CT) magnetic coupling diagram, the open-circuit voltage of the secondary side of the CT is deduced. Therefore, the CT material and size could be selected. The CT coupling model is used to equivalent the current transformer to the ideal voltage source. Then, the four basic topological spaces of the magnetic coupling resonant WPT system are analyzed and calculated, and the efficiency of the SS topology WPT system is analyzed. Furthermore, aiming at long-distance power transmission, this article described the building of a three-coil WPT system and the analysis of the corresponding transmission efficiency and output power expression. With the aid of Maxwell, the technology proposed is simulated based on a 110 kV high-voltage transmission line with 1.2 m as the transmission distance of the system. Finally, the influence of a coupling coefficient and load resistance on the transmission characteristics of the multicoil system is obtained. Consequently, the simulation results with a system output power of 14.4 W verify the effectiveness of the technology.

Research on Output Power of Series–Series Resonance Wireless Power Transmission System

The popularization of smart mobile devices has led to the research on wireless power transfer (WPT) technology. Previous research shows that increasing the excitation coil or the energy transfer coil can increase the energy transmission distance of the WPT system. But the mutual inductance calculation of coils is not accurate enough when the distance is close. This paper presents an improved formula to calculate the mutual inductance between two round inductance coils. Contrasts with the previous calculation methods, computer simulation and experimental results are done to validate the accuracy of the formula, especially when the two inductance coils are close together. On the basis of this formula, the maximum output power (MOP) and the maximum output power distance (MOPD) of the two-, three- and four-coil series–series resonance WPT systems based on circuit models are studied and compared. The simulation and experimental results show a high consistency with the theoretical calculation results. We can find that the farther the MOPD of the system is, the smaller the MOP is. Moreover, when the operating frequency increases, the MOPD of the two-coil conformation increases, while the four-coil conformation is just opposite.

Analysis of the Electromagnetic Coupling Characteristics of Dual-Load Wireless Power Transmission Channels

This paper studies the characteristics of four dual-load systems, coaxial different sides, coaxial same side, different axis same side, and coplanar coaxial, based on the principle of near-field resonance wireless power transmission. Firstly, a dual-load cooperative coupling equivalent circuit model is established, the mathematical expression of system energy efficiency is derived, and the influence of the cross-coupling of the receiving coils in the system on the performance of the system is compared and analyzed in four coupling situations. Secondly, the magnetic field distribution characteristics and the influence of transmission distance and load impedance on the transmission characteristics are studied by electromagnetic field simulation software. Finally, the experimental results show that the maximum efficiency of the dual-load wireless power transmission system is only 0.43 in the case of coaxial and coplanar coupling, which is not suitable for power transmission. In the case of coaxial coupling on the same side, the received power of dual loads has a large difference, which is suitable for electrical equipment with different power requirements. When the coupling distance between the transmitting and receiving coils changes synchronously in the case of coaxial opposite-side and different axis same-side coupling, the efficiency of the former persisting declination and the efficiency of the latter rise first and then drop.

Review of research progress and application of magnetic resonant WPT technology

Compared with traditional contact charging, wireless power transfer technology (WPT) has the advantages of convenience and flexibility, strong environmental adaptability, safety and reliability, and has attracted the research interest of a large number of researchers. Among them, the resonant wireless power transmission technology has good application value because of its long transmission distance and high-efficiency energy transmission characteristics, and is one of the important development directions in the field of wireless power transmission. This paper mainly introduces the concept and classification of wireless power transmission technology, reviews the development history of resonant WPT technology, and summarizes the basic structure and working principle of resonant WPT technology, hot technical issues, and product development and practical application status. It is pointed out that the resonant network including the non-contact transformer is the key to restrict the whole resonant WPT system.

Structure Design of Quadrilateral Overlapped Wireless Power Transmission Coupling Coil

The application of wireless power transmission technology is becoming more and more extensive. However, in practical applications, the problem of reducing the energy transmission efficiency caused by the offset of the coupling coil needs to be solved urgently. Changing the coil structure is a widely adopted method to deal with this problem. Based on the characteristics of the existing magnetic coupling resonant wireless power transmission system and the principle of the anti-offset coil, this paper innovatively designs a new type of quadrilateral overlapping wireless power transfer coupling coil, which has a strong anti-offset capability. The new type of coil model was built in the simulation and experiment, and the relevant parameters were measured. Experimental results verify that the proposed coil structure has an excellent anti-offset capability.

Optimization of Electric Vehicle Wireless Power Transmission Efficiency Based on Ant Lion Optimizer

<div class="section abstract"><div class="htmlview paragraph">Magnetically coupled resonance wireless power transmission technology (MCR-WPT), as a technological innovation in the electric vehicle industry, is of great significance to promote the development of the electric vehicle industry chain. The current wireless charging technology is affected by the design of the vehicle itself, the distance between the vehicle-mounted part of the wireless charging and the ground is not fixed. And the changeable parking attitude will cause the projection of the transmitting coil and the receiving coil to deviate. Therefore, reasonable matching of transmission frequency, matching impedance and other parameters is of great significance for optimizing power transmission efficiency. This paper establishes a mathematical model of transmission frequency, matching impedance, distance between two coils and wireless power transmission efficiency. Based on the preliminary analysis of 10 experimental data of wireless charging in the laboratory under different coil spacings, the relationship between various parameters and wireless charging efficiency is obtained. In view of the problem of coil offset under actual charging conditions, a nonlinear optimization model for maximizing the efficiency of the MCR-WPT system is proposed. The selected optimization parameters are parameters such as transmission frequency and matching impedance. The goal is to ensure the maximum value of automotive coil offset under high transmission efficiency. In this paper, the optimization model is solved based on the Ant lion optimizer, and the optimal parameter values under the specified working conditions are obtained, and the relative error is less than 3%. When the coil spacing is 10mm, the maximum offset of the coil with a transmission efficiency higher than 80% is 0.3423m, and the RMSE between theoretical and experimental results is less than 0.015. Algorithm optimizes the power transmission efficiency and improved the fault tolerance rate of wireless charging system during parking.</div></div>

A study on the influence of efficiency by way of changing the inductance ratio between resonant tank and transmission coil of the series connected resonant tank wireless power transmission system

A study on the influence of efficiency by way of changing the inductance ratio between resonant tank and transmission coil of the series connected resonant tank wireless power transmission system

Modeling and optimization of pavement scale-model for magnetically coupled resonant in wireless power transmission systems

Electric vehicles (EVs) can achieve energy conservation and sustainable development. However, the development has been limited by mileage and battery size. The application of magnetically coupling resonant (MCR) wireless power transmission (WPT) can be used to solve the drawbacks of the EVs. In this study, the parameters of the primary coils and the secondary coils were selected and optimized by using COMSOL Multiphysics finite element software. The influence of the primary coils on the mutual inductance of the secondary coils were conducted to adopt the modes of non-superposition, 1/3 superposition and 1/2 superposition, respectively. The mutual inductance formulas of coils were derived in different superposition modes, the calculation results were in well coincided with the simulation. The pavement scale-model based on MCR wireless power transmission was established by simulation and calculation results to determine the coil parameters and the optimum superposition mode. The influence of the secondary coil on the wireless charging efficiency was explored in static and different moving speeds. The results showed that speed of 40–60 cm/s and spacing of 28 mm were deemed as the optimal charging efficiency when considering the requirements of movement state of the EV and coil embedment.

Effects of Electro-Magnetic Properties of Obstacles in Magnetic Resonant Wireless Power Transfer

Magnetic resonant wireless power transmission (MRWPT) is a method of transmitting power over a long distance at a specific frequency. Because this system uses an alternating magnetic field, if an object with electrical/magnetic properties is placed between the transmit and receive coils, this will have a significant impact on the power transfer. In this paper, the effect of an obstacle located between two coils on the resonance frequency and transmission power is analyzed. A wireless power transmission system with a resonant frequency of 20 kHz was designed, and ferrite, aluminum, and carbon steel were selected as obstacles with permeability or conductivity. After simulating the system with finite element analysis (FEA) with these obstacles, the results were verified through actual experiments. The results show that the permeability of the obstacle decreases the resonant frequency, and the conductivity increases the resonant frequency and greatly reduces the output power. In addition, part of reduced output could be recovered by adjusting the frequency.

Transmission Distance Improvement of a Two-Coil Magnetic Resonance Wireless Power Transmission System Using Transformers

In this paper, a two-coil magnetic resonance wireless transmission system is studied to improve the transmission distance using transformers. A conventional two-coil and four-coil wireless power transmission (WPT) system as well as a two-coil WPT system with transformers are analyzed comparatively via circuit simulations and experiments. Circuit analysis was used to predict the transmission distance with the highest efficiency. To verify the improvement in the transmission distance of the proposed system, transformers with inductance values of 80, 100, and 140 μH were fabricated and analyzed through experiments and simulations. A maximum <i>S</i><sub>21</sub> parameter of 0.76 was noted when the inductance was 80 μH and the transmitting distance was 4 cm. The experimental results almost matched the simulation results. From the experiments, it was shown that the transmitting distance of a WPT system can be adjusted by using transformers. Additionally, it was found that the transmitting distance is inversely proportional to the transformer inductance, and the efficiency of the WPT system decreases with the transmitting distance.

Research on Three-Coils Magnetic Coupling Resonant Wireless Power Transmission with Power Amplifier

The power of a three-coils magnetic coupling resonant Wireless Power Transmission (WPT) system driven by the signal generator is generally too small to be used directly. Adding a power amplifier before the transmitting coil of the three-coils magnetic coupling resonant WPT system is a promising solution to enhance the received power on the load, namely, the load power. The theoretical analysis of the three-coils magnetic coupling resonant WPT system is carried out, while the functional expressions of the load power and transmission efficiency are deduced. The position of the relay coil with maximum load power or transmission efficiency is analyzed for three different situations. The power amplifier parameters are designed by using the Advanced Design System (ADS) radio frequency simulation platform and then the prototype of the three-coils magnetic coupling resonant WPT system with a power amplifier is built and verified. The final results show that the load power can significantly increase from mill watt level to watt level by adding a power amplifier.

Parameter design and analysis of class E inverter for magnetically coupled resonant wireless power transmission system

Parameter design and analysis of class E inverter for magnetically coupled resonant wireless power transmission system

Research on efficiency optimization control strategy of WPT system based on optimal load matching

Aiming at the problem that the transmission efficiency of SS-compensated MCR-WPT (Magnetic resonance wireless power transmission) is affected by load changes, this paper uses mutual inductance theory to analyze the equivalent circuit model, obtains the relationship between load and transmission efficiency, and proposes a controllable rectifier bridge for load matching, the front-end cascaded buck converter makes the output voltage regulation control scheme. Finally, modeling and simulation are used to verify the correctness of the load matching theory and control strategy.

Research on Tradeoff between Power and Efficiency of Wireless Power Transfer via Magnetic Resonance Coupling

Focusing on the tradeoff problem between the output power and transmission efficiency of magnetic coupling resonance wireless power transmission (MCRWPT) system, this paper firstly analyzes the series–series topology system by using the mutual inductance theory of concentrated parameters, and proposes the concept of power-efficiency composite function by using the method of normalization of output power and then the WPT system is assigned a weight factor. Based on that, the calculation expression of the optimal resonant frequency is obtained. The correctness of theoretical analysis is verified by simulation and experimental platform, which provides a useful reference for further improvement of power-efficiency synchronization and energy saving.

Influence of primary side detuning parameters on three-coil magnetic resonance wireless power transmission system

Influence of primary side detuning parameters on three-coil magnetic resonance wireless power transmission system