scholarly journals Wireless Power Transfer under Wide Distance Variation Using Dual Impedance Frequency

Electronics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 110
Author(s):  
Woochan Lee ◽  
Dukju Ahn
Keyword(s):  
Output Power ◽  
Coupling Coefficient ◽  
Large Distance ◽  
High Efficiency ◽  
Wireless Power Transfer ◽  
The Other ◽  
Wireless Power ◽  
Frequency Selection ◽  
Small Coupling ◽  
Close Distance

A dual-impedance operation, where coil impedance is controlled by operating frequency selection, is proposed to maintain optimum reflected impedance across coupling variation. More specifically, this work focuses on how high coupling between coils presents excessively high reflected resistance to transmitter (Tx) inverters, degrading the efficiency and output power of the inverter. To overcome this problem, the proposed system is equipped with dual-impedance coil and selects high- or low-impedance coil based on the ability to operate both at 200 kHz and 6.78 MHz frequencies. The reactive impedances of 6.78 MHz coils are designed to be higher than that of 200 kHz coils. Since the reflected resistance is proportional to the coil impedances and coupling squared, at close distance with high coupling coefficient, 200 kHz coils with low coil impedances are activated to prevent an excessive rise in reflected resistance. On the other hand, at large distance spacing with low coupling coefficient, 6.78 MHz coils with high coil impedances are activated so that sufficient reflected resistance is obtained even under the small coupling. The proposed system’s advantages are the high efficiency and the elimination of bulky mechanical relay switches. Measured efficiencies are 88.6–50% across 10 coupling variations.

scholarly journals Circuit Model and Analysis of Multi-Load Wireless Power Transfer System Based on Parity-Time Symmetry

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3260 ◽  
Author(s):  
Chengxin Luo ◽  
Dongyuan Qiu ◽  
Manhao Lin ◽  
Bo Zhang
Keyword(s):  
Output Power ◽  
Coupling Coefficient ◽  
Power Distribution ◽  
Wireless Power Transfer ◽  
Circuit Model ◽  
Transfer Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Time Symmetry ◽  
Constant Output

In the multi-load wireless power transfer (WPT) system, the output power and transfer efficiency will drop significantly with the change of distance between transmitter and receiver. Power distribution among multiple loads is also a major challenge. In order to solve these problems, a novel multi-load WPT system based on parity–time symmetry (PT-WPT) is proposed in this paper. Firstly, the multi-load PT-WPT system is modeled based on the circuit model. Then, the transmission characteristics of the multi-load PT-WPT system are analyzed. It is found that constant output power with constant transfer efficiency can be maintained against the variation of coupling coefficient, and the power distribution relationship among loads is only related to the coupling coefficient. Further, power distribution under different coupling situations is analyzed in detail to meet different power demands. Finally, taking a dual-load PT-WPT system as an example, the system parameters are designed and the circuit simulation is carried out. The simulation results are consistent with the theoretical analysis, which shows that PT symmetry can be applied to the multi-load WPT system to achieve constant output power, constant transfer efficiency, and power distribution simultaneously.

Optimal Range of Coupling Coefficient of Loosely Coupled Transformer Considering System Resistance

2021 ◽  
Vol 35 (11) ◽  
pp. 1368-1369
Author(s):  
Jiawei Ge ◽  
Hassan Eldeeb ◽  
Kun Liu ◽  
Jinping Kang ◽  
Haisen Zhao ◽  
...  
Keyword(s):  
Output Power ◽  
Coupling Coefficient ◽  
Wireless Power Transfer ◽  
Transfer System ◽  
Power Transfer ◽  
Wireless Power ◽  
Optimal Range ◽  
Loosely Coupled ◽  
System A ◽  
Wireless Power Transfer System

Accurate system resistance may lead to an obvious error between the simulated and the real efficiency of the system. This paper proposes an optimal range of coupling coefficient for ensuring the efficiency and the sufficient output power of the WPT (wireless power transfer) system. A 3-kW prototype WPT system is manufactured and the effectiveness of the optimal range of coupling coefficient is validated.

scholarly journals Highly Efficient Target Power Control for Two-Receiver Wireless Power Transfer Systems

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2726 ◽  
Author(s):  
Weikun Cai ◽  
Dianguang Ma ◽  
Houjun Tang ◽  
Xiaoyang Lai ◽  
Xin Liu ◽  
...  
Keyword(s):  
Output Power ◽  
High Efficiency ◽  
Impedance Matching ◽  
Wireless Power Transfer ◽  
Mutual Inductance ◽  
Maximum Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Target Power ◽  
Target Output

Multiple-receiver wireless power transfer (MRWPT) systems have revolutionary potential for use in applications that require transmitting power to multiple devices simultaneously. In most MRWPT systems, impedance matching is adopted to provide maximum efficiency. However, for most MRWPT systems, achieving target power levels and maximal efficiency is difficult because the target output power and maximum efficiency conditions are mostly not satisfied. This study establishes a target power control (TPC) strategy to balance providing target transfer powers and operating under high efficiency. This study is divided into the following points: First, this study derives the optimal mutual inductance to verify that it’s difficult for two-receiver wireless power transfer (WPT) system to achieve both maximum efficiency and power distribution simultaneously; Second, this study illustrates that for impedance matching method the mutual inductances play a more important role than equivalent impedances in increasing the system efficiency, and hence system should give priority in improving the mutual inductance as large as possible; Third, this study proposes a simplified system model which helps to derive the analytic solutions of equivalent impedances; Fourth, this study developed a 100-kHz two-receiver WPT system and establishes a TPC strategy for enabling the system to achieve target output power levels with high efficiency; At last, the proposed system is proved to achieve an efficiency level of more than 90 % and satisfies the target output power levels requirements.

scholarly journals A Loosely Coupled Planar Wireless Power Transfer System Supporting Multiple Receivers

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Zhen Ning Low ◽  
Joaquin Jesus Casanova ◽  
Jenshan Lin
Keyword(s):  
High Efficiency ◽  
Wireless Power Transfer ◽  
Power Delivery ◽  
The Other ◽  
External Control ◽  
Transfer System ◽  
Power Transfer ◽  
Wireless Power ◽  
Wide Range ◽  
Wireless Power Transfer System

A high-efficiency wireless power transfer system which is capable of supporting more than one receiver using class E operation for transmitter via inductive coupling has been designed and fabricated. The design approach of the system is also presented in this paper. The system requires no complex external control system but relies on its natural impedance response to achieve the desired power delivery profile across a wide range of load resistances while maintaining high efficiency to prevent any heating issues. A switch circuit is used to decouple the fully charged receiver from the system so that power delivery to the other receiver can be improved. The fabricated system at 12 V supply voltage is compact and capable of approximately 2.5 W of power delivery to each of the two receivers in a dual receiver setup and 5 W to a single receiver alone or when the other receiver is decoupled by the receiver switch. During high-power delivery state, the system efficiency is between 67.5% and 77.5%.

scholarly journals Simulation-Assisted Design Process of a 22 kW Wireless Power Transfer System Using Three-Phase Coil Coupling for EVs

2021 ◽  
Vol 13 (21) ◽  
pp. 12257
Author(s):  
Chia-Hsuan Wu ◽  
Ching-Ming Lai ◽  
Tomokazu Mishima ◽  
Zheng-Bo Liang
Keyword(s):  
High Power ◽  
Coupling Coefficient ◽  
High Efficiency ◽  
Design Procedure ◽  
Wireless Power Transfer ◽  
Power Converter ◽  
Air Gap ◽  
Power Transfer ◽  
Wireless Power ◽  
Three Phase

The objective of this paper is to study a 22 kW high-power wireless power transfer (WPT) system for battery charging in electric vehicles (EVs). The proposed WPT system consists of a three-phase half-bridge LC–LC (i.e., primary LC/secondary LC) resonant power converter and a three-phase sandwich wound coil set (transmitter, Tx; receiver, Rx). To transfer power effectively with a 250 mm air gap, the WPT system uses three-phase, sandwich-wound Tx/Rx coils to minimize the magnetic flux leakage effect and increase the power transfer efficiency (PTE). Furthermore, the relationship of the coupling coefficient between the Tx/Rx coils is complicated, as the coupling coefficient is not only dominated by the coupling strength of the primary and secondary sides but also relates to the primary or secondary three-phase magnetic coupling effects. In order to analyze the proposed three-phase WPT system, a detailed equivalent circuit model is derived for a better understanding. To give a design reference, a novel coil design method that can achieve high conversion efficiency for a high-power WPT system was developed based on a simulation-assisted design procedure. A pair of magnetically coupled Tx and Rx coils and the circuit parameters of the three-phase half-bridge LC–LC resonant converter for a 22 kW WPT system are adjusted through PSIM and CST STUDIO SUITE™ simulation to execute the derivation of the design formulas. Finally, the system achieved a PTE of 93.47% at an 85 kHz operating frequency with a 170 mm air gap between the coils. The results verify the feasibility of a simulation-assisted design in which the developed coils can comply with a high-power and high-efficiency WPT system in addition to a size reduction.

scholarly journals Optimization of CC-Coil Design for Wireless Power Transfer System with Series-Series Magnetic Resonance Compensation Technique

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Muhammad Muhaimin Mohd Taib ◽  
◽  
Asmarashid Ponniran ◽  
Keyword(s):  
Magnetic Resonance ◽  
Output Power ◽  
Coupling Coefficient ◽  
Wireless Power Transfer ◽  
Power Transfer ◽  
Coil Design ◽  
Wireless Power ◽  
Transfer Distance ◽  
Power Transfer Efficiency ◽  
Compensation Technique

This study aims to increase the coupling coefficient of the coils and power transfer efficiency (PTE) of the wireless power transfer (WPT) system. WPT system has a severe issue with the PTE as the transfer distance between the transmitter and receiver increases. Therefore, the transmitter and receiver of the single-circular coil (CC-coil) need to be optimized in geometry to maintain high coupling at an optimum distance. Ferrite and aluminum shielding are also crucial on CC-coil optimization. Implementing the series-series (S-S) magnetic resonance compensation technique can increase the PTE of the WPT system. Therefore, the CC-coil is optimized using Ansys Electronics Desktop and co-simulated with the magnetic resonance circuit using Ansys Twin Builder. The results show that the CC-coils' coupling coefficient increased by 21.38% with the shielding implementation. The maximum optimum transfer distance of 37 mm for horizontal misalignment and 30 mm for vertical misalignment. Implementing the S-S magnetic resonance compensation technique can improve the PTE and output power of the WPT system. The power transmitted also varied with the transfer distance, which caused the system's variation of input impedance. Hence, it is essential to consider the coil design and compensation circuit to achieve high PTE and output power at a higher transfer distance.

Scaling Law of Coupling Coefficient and Coil Size in Wireless Power Transfer Design via Magnetic Coupling

2017 ◽  
Vol 137 (4) ◽  
pp. 326-333
Author(s):  
Chiaki Nagai ◽  
Kenji Inukai ◽  
Masato Kobayashi ◽  
Tatsuya Tanaka ◽  
Kensho Abumi ◽  
...  
Keyword(s):  
Coupling Coefficient ◽  
Scaling Law ◽  
Magnetic Coupling ◽  
Wireless Power Transfer ◽  
Power Transfer ◽  
Wireless Power ◽  
Coil Size
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