scholarly journals Maximum efficiency solution for capacitive wireless power transfer with N receivers

2020 ◽  
Vol 7 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Ben Minnaert ◽  
Mauro Mongiardo ◽  
Alessandra Costanzo ◽  
Franco Mastri
Keyword(s):  
Impedance Matching ◽  
Cross Coupling ◽  
Wireless Power Transfer ◽  
Maximum Efficiency ◽  
System Efficiency ◽  
Single Variable ◽  
Power Transfer ◽  
Wireless Power ◽  
Multiple Devices ◽  
Single Receiver

AbstractTypical wireless power transfer (WPT) systems on the market charge only a single receiver at a time. However, it can be expected that the need will arise to charge multiple devices at once by a single transmitter. Unfortunately, adding extra receivers influences the system efficiency. By impedance matching, the loads of the system can be adjusted to maximize the efficiency, regardless of the number of receivers. In this work, we present the analytical solution for achieving maximum system efficiency with any number of receivers for capacitive WPT. Among others, we determine the optimal loads and the maximum system efficiency. We express the efficiency as a function of a single variable, the system kQ-product and demonstrate that load capacitors can be inserted to compensate for any cross-coupling between the receivers.

scholarly journals Capacitive Wireless Power Transfer with Multiple Transmitters: Efficiency Optimization

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3482
Author(s):  
Ben Minnaert ◽  
Alessandra Costanzo ◽  
Giuseppina Monti ◽  
Mauro Mongiardo
Keyword(s):  
Maximum Output Power ◽  
Cross Coupling ◽  
Wireless Power Transfer ◽  
Maximum Efficiency ◽  
Maximization Problem ◽  
Maximum Output ◽  
System Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
The Cross

Wireless power transfer with multiple transmitters can have several advantages, including more robustness against misalignment and extending the mobility and range of the receiver(s). In this work, the efficiency maximization problem is analytically solved for a capacitive wireless power transfer system with multiple coupled transmitters and a single receiver. It is found that the system efficiency can be increased by adding more transmitters. Moreover, it is proven that the cross-coupling between the transmitters can be eliminated by adding shunt susceptances at the input ports. Optimal values for the input currents and receiver load are determined to achieve maximum efficiency. As well the optimal load, the optimal input currents and the maximum efficiency are independent on the cross-coupling. By impedance-matching the internal conductances of the generators, the maximum-efficiency solution also becomes the one that provides the maximum output power. Finally, by expressing each transmitter–receiver link with its kQ-product, the maximum system efficiency can be calculated. The analytical results are verified by circuital simulation.

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.

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 Design of Asymmetrical Relay Resonators for Maximum Efficiency of Wireless Power Transfer

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Bo-Hee Choi ◽  
Jeong-Hae Lee
Keyword(s):  
Design Method ◽  
Impedance Matching ◽  
Wireless Power Transfer ◽  
Load Resistance ◽  
Maximum Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Optimum Placement ◽  
Power Transfer Efficiency ◽  
Source Resistance

This paper presents a new design method of asymmetrical relay resonators for maximum wireless power transfer. A new design method for relay resonators is demanded because maximum power transfer efficiency (PTE) is not obtained at the resonant frequency of unit resonator. The maximum PTE for relay resonators is obtained at the different resonances of unit resonator. The optimum design of asymmetrical relay is conducted by both the optimum placement and the optimum capacitance of resonators. The optimum placement is found by scanning the positions of the relays and optimum capacitance can be found by using genetic algorithm (GA). The PTEs are enhanced when capacitance is optimally designed by GA according to the position of relays, respectively, and then maximum efficiency is obtained at the optimum placement of relays. The capacitance of the second resonator tonth resonator and the load resistance should be determined for maximum efficiency while the capacitance of the first resonator and the source resistance are obtained for the impedance matching. The simulated and measured results are in good agreement.

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