scholarly journals Convex optimization of coil spacing in cascaded multi-coil wireless power transfer

2020 ◽  
Vol 7 (1) ◽  
pp. 42-50
Author(s):  
Connor Badowich ◽  
Jacques Rousseau ◽  
Loïc Markley
Keyword(s):  
Convex Optimization ◽  
Convex Function ◽  
Power Efficiency ◽  
Wireless Power Transfer ◽  
Higher Order ◽  
Optimal Number ◽  
Maximum Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
High Q

AbstractIn this paper, we use convex optimization to maximize power efficiency through cascaded multi-coil wireless power transfer systems and investigate the resulting characteristic spacing. We show that although the efficiency is generally a non-convex function of the coil spacing, it can be approximated by a convex function when the effects of higher-order couplings are small. We present a method to optimize the spacing of cascaded coils for maximum efficiency by perturbing the solution of the convex approximation to account for higher-order interactions. The method relies on two consecutive applications of a local optimization algorithm in order to enable fast convergence to the global optimum. We present the optimal configurations of coil systems containing up to 20 identical coils that transfer power over distances up to 4.0 m. We show that when spacing alone is optimized, there exist an optimal number of coils that maximize transfer efficiency across a given distance. We also demonstrate the use of this method in optimizing the placement of a select number of high-Q coils within a system of low-Q relay coils, with the highest efficiencies occurring when the high-Q coils are placed on either side of the largest gaps within the relay coil chain.

scholarly journals Maximizing Transfer Efficiency with an Adaptive Wireless Power Transfer System for Variable Load Applications

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1417
Author(s):  
Jung-Hoon Cho ◽  
Byoung-Hee Lee ◽  
Young-Joon Kim
Keyword(s):  
Loading Condition ◽  
Wireless Power Transfer ◽  
Input Voltage ◽  
Transfer Efficiency ◽  
Maximum Efficiency ◽  
Variable Load ◽  
Power Transfer ◽  
Wireless Power ◽  
Variable Loading ◽  
Power Transfer Efficiency

Electronic devices usually operate in a variable loading condition and the power transfer efficiency of the accompanying wireless power transfer (WPT) method should be optimizable to a variable load. In this paper, a reconfigurable WPT technique is introduced to maximize power transfer efficiency in a weakly coupled, variable load wireless power transfer application. A series-series two-coil wireless power network with resonators at a frequency of 150 kHz is presented and, under a variable loading condition, a shunt capacitor element is added to compensate for a maximum efficiency state. The series capacitance element of the secondary resonator is tuned to form a resonance at 150 kHz for maximum power transfer. All the capacitive elements for the secondary resonators are equipped with reconfigurability. Regardless of the load resistance, this proposed approach is able to achieve maximum efficiency with constant power delivery and the power present at the load is only dependent on the input voltage at a fixed operating frequency. A comprehensive circuit model, calculation and experiment is presented to show that optimized power transfer efficiency can be met. A 50 W WPT demonstration is established to verify the effectiveness of this proposed approach.

scholarly journals Coherently Driven and Superdirective Antennas

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 845 ◽  
Author(s):  
Alex Krasnok
Keyword(s):  
Dielectric Resonator ◽  
Electromagnetic Waves ◽  
Wireless Power Transfer ◽  
Higher Order ◽  
Power Transfer ◽  
Wireless Power ◽  
Entire Spectrum ◽  
Guided Mode ◽  
Dielectric Antennas ◽  
Antenna Systems

Antennas are crucial elements for wireless technologies, communications and power transfer across the entire spectrum of electromagnetic waves, including radio, microwaves, THz and optics. In this paper, we review our recent achievements in two promising areas: coherently enhanced wireless power transfer (WPT) and superdirective dielectric antennas. We show that the concept of coherently enhanced WPT allows improvement of the antenna receiving efficiency by coherent excitation of the outcoupling waveguide with a backward propagating guided mode with a specific amplitude and phase. Antennas with the superdirectivity effect can increase the WPT system’s performance in another way, through tailoring of radiation diagram via engineering antenna multipoles excitation and interference of their radiation. We demonstrate a way to achieve the superdirectivity effect via higher-order multipoles excitation in a subwavelength high-index spherical dielectric resonator supporting electric and magnetic Mie multipoles. Thus, both types of antenna discussed here possess a coherent nature and can be used in modern intelligent antenna systems.

scholarly journals Differential Evolution in Waveform Design for Wireless Power Transfer

Telecom ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 96-113
Author(s):  
Pavlos Doanis ◽  
Achilles Boursianis ◽  
Julien Huillery ◽  
Arnaud Bréard ◽  
Yvan Duroc ◽  
...  
Keyword(s):  
Power Efficiency ◽  
Optimization Problem ◽  
Nonlinear Behavior ◽  
Wireless Power Transfer ◽  
Waveform Design ◽  
Optimal Solutions ◽  
Power Transfer ◽  
Wireless Power ◽  
Single Input Single Output ◽  
Single Output

The technique of transmitting multi-tone signals in a radiative Wireless Power Transfer (WPT) system can significantly increase its end-to-end power efficiency. The optimization problem in this system is to tune the transmission according to the receiver rectenna’s nonlinear behavior and the Channel State Information (CSI). This is a non-convex problem that has been previously addressed by Sequential Convex Programming (SCP) algorithms. Nonetheless, SCP algorithms do not always attain globally optimal solutions. To this end, in this paper, we evaluate a set of Evolutionary Algorithms (EAs) with several characteristics. The performance of the optimized multi-tone transmission signals in a WPT system is assessed by means of numerical simulations, utilizing a simplified Single Input Single Output (SISO) model. From the model evaluation, we can deduce that EAs can be successfully applied to the waveform design optimization problem. Moreover, from the presented results, we can derive that EAs can obtain the optimal solutions in the tested cases.

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