Resonant Wireless Power Transmission Research Articles

A Magnetic Dipole Resonator for Magnetic Coupled Resonance Wireless Power Transmission

This paper proposes a magnetic dipole structure Resonator for the magnetic coupled resonance wireless power transmission (WPT). The various characteristics are investigated by using simulations. To investigate the advantage of the proposed structure coil, a same geometric size traditional single-layer spiral coil is used for the power transfer characteristics Comparison. Due to the proposed structure, if the magnetic dipole resonator needs to be resonated at the same frequency with the traditional spiral coil, the larger number of turns is needed. This causes the resistance of loss to dramatically increase, thus decreasing the power transfer efficiency. To solve this problem, the tightly coupled parallel-connected coil structure was used. Depending on the characteristics of the tightly coupled parallel-connected coil structure the proposed magnetic dipole resonator can offer significantly reduced resistance with very little self-inductance loss. Simulation results show that compare to the same resonance frequency traditional single-layer spiral coil, a magnetic dipole resonator contributed by the tightly coupled parallel-connected coil structure can increase the Q factor by approximately 54.3%. Moreover, the simulation evaluation results confirmed that the proposed resonator can also dramatically improves the system power transfer flexibility performance.

Design and Experiment of a Reconfigurable Magnetic Resonance Coupling Wireless Power Transmission System

Magnetic resonance coupling wireless power transmission (WPT) provides a safe and efficient power supply for small household appliances and implanted devices, but the tolerance of the transmission distance is poor. To improve the robustness of the transmission distance of the magnetic resonance WPT system, a method of using a reconfigurable helical coil array is proposed. Compared with the traditional four-coil structure of the same volume, different source and load coils are selected under distinct distance conditions. The coupling coefficient between the coils is changed to increase the stability of transmission efficiency and distance. To avoid the mechanical movement, all source and load coils have been adjusted at fixed position. Moreover, a control method is introduced to achieve coil switching. The experimental results show that the transmission distance of the proposed system is increased to 1.75 times of the coil diameter, while the efficiency remains above 70%.

Influence of coil spacing on performance of resonant wireless power transmission system

Influence of coil spacing on performance of resonant wireless power transmission system

Research on Frequency Tracking of Magnetic Coupled Resonant wireless Power Transmission System

In order to solve the problem that the magnetic coupling resonant WPT system with SS compensation structure causes a decrease in transmission efficiency when it is detuned, the resonant state of the system is tracked by detecting the output voltage of the transmitting coil inverter and the coil current of the receiving coil. Phase difference is converted into dc voltage signal with phase discriminator, ADC module is used to sample dc signal, PID algorithm is used to track resonance frequency of the system, 90° phase difference is taken as expected value of PID algorithm, and 90° phase shift is indirectly realized by digital method. The experiment shows that the resonant frequency tracking method is effective.

Wireless power transmission with a sown auxiliary coil to improve power efficiency for an implantable device

In this study, a magnetic resonance wireless power transmission system with a sown auxiliary coil is described. The system is proposed to deliver power to an “implantable cardioverter defibrillator” (ICD) device from a bed. The auxiliary coil is supposed to be sown in a shirt. With the coil, the poor coupling coefficient and the effective quality factor can be improved. In this study, the power efficiency was investigated on a magnetic resonance wireless power transmission system with a sown auxiliary coil by using a 1/2 scaled model. As a result, when transfer distance was 100 mm (200 mm in the full scaled model) and lord resistance was 20 Ω, the maximum transfer efficiency with an auxiliary coil was measured to be about 70% much higher than without that.

Research on Mutual Inductance Prediction of Resonant Magnetic Coupling Wireless Power Transmission System Based on Recursive Least Square Method

In this paper, based on recursive least square algorithm and resonant magnetic coupling wireless power transmission technology, the magnetic coupling mutual inductance value, which is a significant factor affecting the transmission power and efficiency of wireless transmission system, is predicted. According to the characteristics of the system, a mathematical model of LCC-P-type topology structure is established. Through mathematical deduction and analysis, combined with MATLAB/Simulink simulation results are obtained, and its feasibility is verified by experimental results.

Compensating Resonant Frequency via Adjusting Adjustable Coil Automatically

Background: Detuning is the main problem that affects the efficiency and transmission distance of the resonant coupling Wireless Power Transmission (WPT). The distance of load and the offset of the load position could cause serious detuning. Methods: This paper presents an adjustable coil in which inductance can be adjusted. Then a model of WPT was established that could compensate resonant frequency automatically using the adjustable coil. Next, the relationship between the primary resonant frequency and the transmission efficiency is analyzed from the circuit. The analysis proved that the design of the adjustable coil could improve the transmission efficiency of the WPT system. Finally, a prototype of WPT system was built. Results: The experimental results showed that WPT system with adjustable coil can improve the transmission efficiency which proves the theoretical research. At the same time, it has essential reference value for the future research of WPT. Conclusion: In this paper, aiming at the system detuning caused by some other factors, such as the position shift of the load during the wireless power transmission, an adjustable coil is proposed.

Calculation and analysis of optimal design for wireless power transfer

In this paper, a detailed theoretical analysis, derivation and calculation of the working characteristics of the electric vehicle wireless power transmission system is provided. Firstly, the circuit model of the resonant wireless power transmission is established using the reflection impedance theory. Secondly, the dual LCCL (Inductance capacitance capacitance Inductance) resonant compensation topology is analyzed, and the equations of the output power P and the transmission efficiency η are obtained. Then, the relationships of the output power P and the transmission efficiency η in respect to the mutual inductance M and the coupling coefficient k, as well as the formulas of the mutual inductance M and the coupling coefficient k is analyzed. And a method to realize the optimal design of the planar spiral coupling coil is proposed using the evaluation function. Finally, a prototype of a 3.3 KW WPT (wireless power transform) system was built. Experimental results show that this way is the best.

Research on four-coil structure of magnetically coupled resonant wireless power transmission system

Research on four-coil structure of magnetically coupled resonant wireless power transmission system

자기 공진형 무선전력전송 시스템의 효율 향상을 위한 변압기 적용 시스템 모델 분석

자기 공진형 무선전력전송 시스템의 효율 향상을 위한 변압기 적용 시스템 모델 분석

Control method of magnetic resonant WPT maintaining stable transmission power with wide misalignment tolerance

Many applications of wireless power transmission (WPT) require high misalignment tolerance. However, the transmission power of WPT is highly susceptible to the misalignment. To solve this problem, the magnetic resonant WPT control method with high misalignment tolerance is proposed here. First, based on the general mutual model, the complex ratio transformer model is established. This model gives an intuitive physical picture in power transmission process and frequency splitting phenomenon. Second, approximately constant voltage gain at frequency splitting point in a wide range of misalignment is analysed. Considering this frequency splitting characteristics of Magnetic resonant WPT, the maximum peak point tracking control methods for wide misalignment, maintaining constant output power is proposed. Finally, the corresponding simulation and experimental validation is given, demonstrating the feasibility of the control method. When the misalignment reached 40%, the fluctuation of the output voltage will be <4%, the DC–DC transmission efficiency will be enhanced to 80%.

Research on impedance matching method for magnetic resonant coupling wireless power transmission system

Research on impedance matching method for magnetic resonant coupling wireless power transmission system

Wireless power transmission based on the double two-way spiral coil

Magnetically coupled resonant (MCR) wireless power transmission (WPT) has the advantages of high efficiency, large transmission power and so on. It is suitable for medium-distance power supply. However, the traditional MCR WPT system based on the single one-way spiral coil (SOSC) will suffer frequency splitting due to the over-coupling between the transmitting and receiving coils during short-distance transmission. After analyzing the effect of coupling coefficient on the transmission efficiency of such systems, this paper proposed a double two-way spiral coil (DTSC) design method. This method used the structural features of the designed spiral coil to counteract the increased coupling coefficient due to short-distance transmission, thereby weakening the over-coupling between the transmitting coil and the receiving coil, narrowing the over-coupling region of the system, and compensating the effect of frequency splitting on the transmission efficiency during short-distance WPT. This method narrowed the system’s frequency splitting region and improved the system’s short-distance transmission efficiency. This paper analyzed the effect of the inner and the outer radius, the number of turns, and the pitch of the DTSC on the efficiency of the WPT system. This study showed that compared with the WPT system based on the SOSC, the WPT system based on the DTSC could narrow the frequency splitting region and significantly improve the short-distance transmission efficiency of the system. The correctness of the theoretical analysis has been verified by simulations and experiments.

Wireless power supply technology for uniform magnetic field of intelligent greenhouse sensors

Sensors play an important role in the automated management system of the intelligent greenhouse, but sensor node energy consumption and charging issues have always been a bottleneck to constrain the development of intelligent greenhouses. To solve this problem, the paper proposes the “Enclose-Loop” sensor using wireless power supply technology, analyzes the efficiency formula for the magnetic resonance coupling method and the relationship with the energy power, and designs the “Enclose-Loop” magnetic resonance wireless power supply system. The system can form a large uniform magnetic spatial field, and evenly distribute the power in the case of a plurality of secondary coils. In addition, the use of the primary and secondary coils on the same plane balances the relationship between efficiency and distance. Simulation experiments are conducted to simulate the power of the “Enclose-Loop” magnetic resonance wireless power transmission. With the primary and secondary coils of different sizes in the same plane, distance and efficiency wireless power transmission achieves satisfactory results. Finally, an experimental verification platform is built. The experimental results show that the proposed control algorithm can provide 40 W power for the load and effectively solve the power supply problem of the sensor. This paper provides new ideas for the power supply of sensors and promotes the development of intelligent greenhouses to some extent.

Analysis of the Resonance Characteristics by a Variation of Coil Distance in Magnetic Resonant Wireless Power Transmission

Magnetic resonant wireless power transmission is a method that enables high-efficiency power transmission at a longer distance than the conventional magnetic inductive type. However, when the power transmission distance is smaller than a specific value, there is a problem that the frequency division phenomenon occurs and the output and efficiency decrease. In this paper, the equation of output power was formulated with transmission distance as variables and verified through simulation and experiments. After that, the resonance characteristics according to the transmission distance and the magnetic phenomenon in the frequency divided state were analyzed through the circle diagram and the finite-element analysis. From these results, it is possible to design the optimal system for the target transmission distance, and it is possible to calculate the split frequency representing the maximum power in short-range transmission, so that high output and efficiency can be obtained stably.

The Effect of Fractional Orders on the Transmission Power and Efficiency of Fractional-Order Wireless Power Transmission System

To avoid the problems of integer-order magnetic resonant wireless power transmission (WPT) systems, such as low output power and transmission efficiency, high resonant frequency, frequency splitting, and parameter coupling, a novel WPT system based on the fractional-order calculus theory is proposed; the resonant frequency and coupling coefficient can be regulated by the fractional order, so that this system has completely different transmission characteristics from the integer-order WPT system. Therefore, in this paper, the circuit model based on the phasor method of fractional-order WPT system is established, and the output power and transmission efficiency of the system are analyzed. In addition, the comparative analysis of output power and transmission efficiency under different fractional orders are performed to estimate the optimal combination of fractional orders, which is beneficial to produce better characteristics of output power and transmission efficiency and provides a theoretical basis for the design and implementation of an experimental system.

Research on the wireless power transmission technology based on maximum energy efficiency tracking under dynamic distance

Focusing on the maximum efficiency of magnetic resonant coupling wireless power transmission, this paper analyzes circuits by use of lumped parameter models, deduces the relationship between the maximum energy efficiency and the duty cycle of the inverter at the transmitting terminal, and proposes a self-adaptive control technique to ensure that the wireless power transmission system maintains the maximum energy efficiency when the transmission distance changes; the effectiveness and feasibility of this method is verified with a hardware platform.

Study on electromagnetic characteristics of the magnetic coupling resonant coil for the wireless power transmission system.

The resonant coil design is taken as the core technology in the magnetic coupling resonant wireless power transmission system, which achieves energy transmission by the coupling of the resonant coil. This paper studies the effect of the resonant coil on energy transmission and the efficiency of the system. Combining a two-coil with a three-coil system, the optimum design method for the resonant coil is given to propose a novel coil structure. First, the co-simulation methods of Pspice and Maxwell are used. When the coupling coefficient of the resonant coil is different, the relationship between system transmission efficiency, output power, and frequency is analyzed. When the self-inductance of the resonant coil is different, the relationship between the performance and frequency of the system transmission is analyzed. Then, two-coil and three-coil structure models are built, and the parameters of the magnetic field of the coils are calculated and analyzed using the finite element method. In the end, a dual E-type simulation circuit model is used to optimize the design of the novel resonance coil. The co-simulation results show that the coupling coefficients of the two-coil, three-coil, and novel coil systems are 0.017, 0.17 and 0.0126, respectively. The power loss of the novel coil is 16.4 mW. There is an obvious improvement in the three-coil system, which shows that the magnetic leakage of the field and the energy coupling are relatively small. The new structure coil has better performance, and the load loss is lower; it can improve the system output power and transmission efficiency.

Characteristics of 3D magnetic field of magnetic coupling resonant wireless power transmission system

PurposeThe purpose of the paper is to analyze the impact of coupling on the distribution of the magnetic field and study the characteristics of the magnetic flux density in the transmission process of the magnetic coupling resonant wireless power transmission (MCR-WPT) system, which provides guidance on the design of the WPT system.Design/methodology/approachIn this study, a finite element simulation analysis was conducted and a three-dimensional (3D) electromagnetic field measurement platform was used.FindingsIt is shown that the distribution of the magnetic field, as well as the position of maximum magnetic flux density, will change when the coils are coupled. The simulation results of the magnetic field distribution, as well as the transmission performance, are different from those in practice. It cannot describe the actual performance of WPT system.Originality/valueA 3D electromagnetic field measurement system and the host computer software are designed to help optimize the simulation and carry out more accurate and efficient research. The 3D electromagnetic field measurement system can be used to study the distribution of the spatial electromagnetic field, influencing factor, exposure and interoperability between different coils.

Impedance matching network for ground eliminated open‐ended resonant coil structure in distributed wireless power transmission systems

This study reports a novel technique utilising a standing-wave node as a virtual ground to implement an impedance matching network and power level tuning in a ground eliminated (GE) open-ended resonant coil structure. This technique with GE open-ended coils can potentially be used in wireless power transmission (WPT) systems, where an unknown metallic, ungrounded, arbitrary environment is used as a signal propagation medium to deliver electric power to several distributed nodes. To satisfy WPT standards the proposed resonant WPT system with the matching network is implemented and tested at 13.56 MHz. A comprehensive study of the GE open-ended resonant coil structure demonstrates ground-plane effects and the necessity of an impedance matching network in no-ground signal situations. The experimental results confirm the theoretical analysis presenting 9% improvements in mismatch efficiency, and 13.1 times in power transmission efficiency at 13.56 MHz when the matching network is deployed.