scholarly journals Optimal Position of the Intermediate Coils in a Magnetic Coupled Resonant Wireless Power Transfer System

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3991 ◽  
Author(s):  
Dongsheng Yang ◽  
Jiangwei Tian ◽  
Sokhui Won ◽  
Bowen Zhou ◽  
Zixin Cheng ◽  
...  
Keyword(s):  
Mathematical Expression ◽  
Wireless Power Transfer ◽  
Network Analyzer ◽  
Power Transfer ◽  
Wireless Power ◽  
Distance Ratio ◽  
Optimal Position ◽  
Experimental Platform ◽  
Load Power ◽  
Transmission Distance

Coaxial coil topology is used as the transfer medium in traditional MCR-WPT (Magnetic Coupled Resonant Wireless Power Transfer) systems to improve the transfer characteristics. The intermediate coils are added to extend the transmission distance, whose positions are critical. This paper focuses on the optimal intermediate coil positions for an MCR-WPT system with four coaxial planar circular spiral coils. By modeling the MCR-WPT system, the mathematical expression of the self-inductance and the mutual inductance are used to calculate the load power of the MCR-WPT system, which is composed of four planar circular spiral coaxial coils, and using MATLAB. The optimal distance ratio between the adjacent coils for maximizing the power of load is proposed. Furthermore, the experiments are implemented from the network analyzer and the experimental platform. In the platform, the load power is measured at the different intermediate coil positions, and the optimal position at which the load power is maximized is found. Both experimental results obtained by the network analyzer and the experimental platform have validated the theoretical and simulation results and provided the correctness of the suggested ratios.

scholarly journals Comparison of the Efficiency and Load Power in Periodic Wireless Power Transfer Systems with Circular and Square Planar Coils

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4975
Author(s):  
Jacek Maciej Stankiewicz ◽  
Agnieszka Choroszucho
Keyword(s):  
Power Transmission ◽  
Wireless Power Transfer ◽  
Load Resistance ◽  
Numerical Approach ◽  
Maximum Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Load Power ◽  
Coil Geometry ◽  
Square Planar

In the article, a wireless charging system with the use of periodically arranged planar coils is presented. The efficiency of two wireless power transfer (WPT) systems with different types of inductors, i.e., circular and square planar coils is compared, and two models are proposed: analytical and numerical. With the appropriate selection of a load resistance, it is possible to obtain either the maximum efficiency or the maximum power of a receiver. Therefore, the system is analyzed at two optimum modes of operation: with the maximum possible efficiency and with the highest power transmitted to the load. The analysis of many variants of the proposed wireless power transfer solution was performed. The aim was to check the influence of the geometry of the coils and their type (circular or square) on the efficiency of the system. Changes in the number of turns, the distance between the coils (transmit and receive) as well as frequency are also taken into account. The results obtained from analytical and numerical analysis were consistent; thus, the correctness of the adopted circuit and numerical model (with periodic boundary conditions) was confirmed. The proposed circuit model and the presented numerical approach allow for a quick estimate of the electrical parameters of the wireless power transmission system. The proposed system can be used to charge many receivers, e.g., electrical cars on a parking or several electronic devices. Based on the results, it was found that the square coils provide lower load power and efficiency than compared to circular coils in the entire frequency range and regardless of the analyzed geometry variants. The results and discussion of the multivariate analysis allow for a better understanding of the influence of the coil geometry on the charging effectiveness. They can also be valuable knowledge when designing this type of system.

scholarly journals Central Bulge Ferrite Core for Efficient Wireless Power Transfer

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5111
Author(s):  
Huabo Xu ◽  
Huihui Song ◽  
Rui Hou
Keyword(s):  
Magnetic Coupling ◽  
Wireless Power Transfer ◽  
Expansion Method ◽  
System Size ◽  
Mutual Inductance ◽  
Power Transfer ◽  
Wireless Power ◽  
Ferrite Core ◽  
Transmission Distance ◽  
Central Bulge

To improve the efficiency of the wireless power transfer (WPT) system without increasing the system size, a central bulge ferrite core with a novel configuration is proposed. The mutual inductance between magnetic coupling structures is able to increase obviously, which is approved by eigenfunction expansion method. In this paper, the mathematical models of the planar core and the central bulge core are established, respectively, as two types of the mutual inductance are calculated in same condition. The structure parameters of the central bulge ferrite core are further optimized by Maxwell magnetic field simulation. Experiments are conducted to compare the WPT efficiency of two types of ferrite cores in improving the efficiency of WPT system, in which the influence of transmission distance, lateral misalignment, and load variation are taken into account. The results show that central bulge ferrite core has better performance in WPT efficiency than the planar one, even in the case of long power transfer distance and lateral misalignment.

A Review of Methods and Challenges for Improvement in Efficiency and Distance for Wireless Power Transfer Applications

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sokol Kuka ◽  
Kai Ni ◽  
Mohammed Alkahtani
Keyword(s):  
Electric Vehicles ◽  
Power Efficiency ◽  
Near Field ◽  
Electronic Devices ◽  
Wireless Power Transfer ◽  
Power Transfer ◽  
Wireless Power ◽  
Inductive Power Transfer ◽  
The Past ◽  
Transmission Distance

AbstractOver the past few years, interest and research in wireless power transfer (WPT) have been rapidly incrementing, and as an effect, this is a remarkable technology in many electronic devices, electric vehicles and medical devices. However, most of the applications have been limited to very close distances because of efficiency concerns. Even though the inductive power transfer technique is becoming relatively mature, it has not shown near-field results more than a few metres away transmission. This review is focused on two fundamental aspects: the power efficiency and the transmission distance in WPT systems. Introducing the principles and the boundaries, scientific articles will be reviewed and discussed in terms of their methods and respective challenges. This paper also shows more important results in efficiency and distance obtained, clearly explaining the theory behind and obstacles to overcome. Furthermore, an overlook in other aspects and the latest research studies for this technology will be given. Moreover, new issues have been raised including safety and security.

scholarly journals Simultaneous Power Feedback and Maximum Efficiency Point Tracking for Miniaturized RF Wireless Power Transfer Systems

Sensors ◽  
2021 ◽  
Vol 21 (6) ◽  
pp. 2023
Author(s):  
Sebastian Stoecklin ◽  
Adnan Yousaf ◽  
Gunnar Gidion ◽  
Leonhard Reindl ◽  
Stefan J. Rupitsch
Keyword(s):  
Power Consumption ◽  
Output Voltage ◽  
Impedance Matching ◽  
Wireless Power Transfer ◽  
Sensor Systems ◽  
Power Transfer ◽  
Wireless Power ◽  
Inductive Link ◽  
Load Power ◽  
Voltage Controller

Near-field interfaces with miniaturized coil systems and low output power levels, such as applied in biomedical sensor systems, can suffer from severe efficiency degradation due to dynamic impedance mismatches, reducing battery life of the power transmitter unit and requiring to increase the level of electromagnetic emission. Moreover, the stability of weakly-coupled power transfer systems is generally limited by transient changes in coil alignment and load power consumption. Hence, a central research question in the domain of wireless power transfer is how to realize an adaptive impedance matching system under the constraints of a simultaneous power feedback to increase the system’s efficiency and stability, while maintaining circuit characteristics such as small size, low power consumption and fast reaction times. This paper presents a novel approach based on a two-stage control loop implemented in the primary-side reader unit, which uses a digital PI controller to maintain the rectifier output voltage for power feedback and an on-top perturb-and-observe controller configuring the setpoint of the voltage controller to maximize efficiency. The paper mathematically analyzes the AC and DC transfer characteristics of a resonant inductive link to design the reactive AC matching network, the digital voltage controller and ultimately the DC-domain impedance matching algorithm. It was found that static reactive L networks result in suitable efficiency levels for coils with sufficiently high quality factor even without adaptive tuning of operational frequency or reactive components. Furthermore, the regulated output voltage of the rectifier is a direct measure of the DC load impedance when using a regular DC/DC converter to supply the load circuits, so that this quantity can be tuned to maximize efficiency. A prototype implementation demonstrates the algorithms in a 40.68 MHz inductive link with load power levels from 10 to 100 mW and tuning time constants of 300 ms, while allowing for a simplified receiver with a footprint smaller than 200 mm2 and a self-consumption below 1 mW. Hence, the presented concepts enable adaptive impedance matching with favorable characteristics for low-energy sensor systems, i.e., minimized footprint, power level and reaction time.

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