scholarly journals A Frequency-Tracking and Impedance-Matching Combined System for Robust Wireless Power Transfer

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Yanting Luo ◽  
Yongmin Yang ◽  
Suiyu Chen ◽  
Xisen Wen
Keyword(s):  
Model Simulation ◽  
Impedance Matching ◽  
Experimental Studies ◽  
Wireless Power Transfer ◽  
Power Transfer ◽  
Wireless Power ◽  
Combined System ◽  
Embedded Devices ◽  
Load Impedance ◽  
Frequency Tracking

One of the greatest challenges to power embedded devices using magnetically coupled resonant wireless power transfer (WPT) system is that the amount of power delivered to the load is very sensitive to load impedance variations. Previous adaptive impedance-matching (IM) technologies have drawbacks because adding IM networks, relay coils, or other compensating components in the receiver-side will significantly increase the receiver size. In this paper, a novel frequency-tracking and impedance-matching combined system is proposed to improve the robustness of wireless power transfer for embedded devices. The characteristics of the improved WPT system are investigated theoretically based on the two-port network model. Simulation and experimental studies are carried out to validate the proposed system. The results suggest that the frequency-tracking and impedance-matching combined WPT system can quickly find the best matching points and maintain high power transmission efficiency and output power when the load impedance changes.

A Solution to Frequency Splitting in Magnetic Resonance Wireless Power Transfer Systems Using Double Sided Symmetric Capacitors

2021 ◽  
Vol 5 (2) ◽  
pp. 6-12
Author(s):  
Thabat Thabet ◽  
John Woods
Keyword(s):  
Magnetic Resonance ◽  
Resonance Frequency ◽  
High Efficiency ◽  
Impedance Matching ◽  
Wireless Power Transfer ◽  
Maximum Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Frequency Tracking ◽  
Tuning Method

The technology of wireless power transfer using magnetic resonance coupling has become a subject of interest for researchers with the proliferation of mobile. The maximum efficiency is achieved at a specific gap between the resonators in the system. However, the resonance frequency splits as the gap declines or gets smaller. Different methods have been studied to improve this such as frequency tracking and impedance matching, including capacitive tuning. However, the system has to maintain the same working frequency to avoid moving out of the license exempt industrial, scientific, and medical (ISM) band; and the efficiency must be as large as possible. In this paper, a symmetric capacitance tuning method is presented to achieve these two conditions and solve the splitting problem. In the proposed method, the maximum efficiency at one of the splitting frequencies is moved to match the original resonance frequency. By comparison to other works, both simulation and experiment show considerable improvements for the proposed method over existing frequency tracking and impedance matching methods. The paper also presents a proposal to apply this method automatically which can achieve wireless charging for electronic applications with high efficiency and through variable distance.

scholarly journals Frequency-Tracking Algorithm Based on SOGI-FLL for Wireless Power Transfer System to Operate ZPA Region

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1303
Author(s):  
Do-Hyun Kim ◽  
Min-Soo Kim ◽  
Hee-Je Kim
Keyword(s):  
Resonant Frequency ◽  
Wireless Power Transfer ◽  
Tracking Algorithm ◽  
Physical Contact ◽  
Switching Frequency ◽  
Power Transfer ◽  
Wireless Power ◽  
Coupling Condition ◽  
Frequency Tracking ◽  
Load Variation

The wireless power transfer (WPT) system has attracted attention for energy transmission without physical contact. However, a WPT system has low coupling condition because of a big air gap between transmitter and receiver coils. The low coupling condition has a high leakage inductance. To overcome this problem, we design a proposed system for WPT using series-series (S-S) topology of one resonant circuit. To obtain the higher efficiency power conversion of the WPT system, it has to operate the resonant frequency in the zero phase angle (ZPA) point even under mutual coefficient and load variation. Therefore, we propose the resonant frequency tracking algorithm to operate ZPA point based on the second order generalized integrator-frequency locked loop (SOGI-FLL) method. This proposed frequency-tracking algorithm can estimate ZPA point by changing switching frequency. We can reduce the switching loss with this proposed algorithm and improve the low conversion efficiency of the WPT system. The performance of the proposed frequency-tracking algorithm is automatically verified through various coupling coefficients and the load variation.

scholarly journals Analysis and Introduction of Effective Permeability with Additional Air-Gaps on Wireless Power Transfer Coils for Electric Vehicle Based on SAE J2954 Recommended Practice

Energies ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4797 ◽  
Author(s):  
Dongwook Kim ◽  
Hongseok Kim ◽  
Anfeng Huang ◽  
Qiusen He ◽  
Hanyu Zhang ◽  
...  
Keyword(s):  
Coupling Coefficient ◽  
Effective Permeability ◽  
Impedance Matching ◽  
Wireless Power Transfer ◽  
The Self ◽  
Power Transfer ◽  
Wireless Power ◽  
Electrical Parameters ◽  
Testing Procedures ◽  
Receiving Coil

The wireless power transfer (WPT) method for electric vehicles (EVs) is becoming more popular, and to ensure the interoperability of WPT systems, the Society of Automotive Engineers (SAE) established the J2954 recommended practice (RP). It includes powering frequency, electrical parameters, specifications, testing procedures, and other contents for EV WPT. Specifically, it describes the ranges of self-inductances of the transmitting coil, the receiving coil, and coupling coefficient (k), as well as the impedance matching values of the WPT system. Following the electrical parameters listed in SAE J2954 RP is crucial to ensure the EV wireless charging system is interoperable. This paper introduces a method for adjusting the effective permeability of the ferrite blocks in the standard model, to tune the self-inductance of the coils as well as the coupling coefficient. To guarantee the given values of the self-inductance of the coil and coupling coefficient matched those in the standard, we slightly modified the air-gap between the ferrite tiles in a specific region. Based on this method, it was possible to successfully tune the self-inductance of the transmitting coil and receiving coil as well as the coupling coefficient. The proposed method was verified by simulation and experimental measurements.

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