Estimation of the Maximum Efficiency and the Load Power in the Periodic WPT Systems Using Numerical and Circuit Models

Abstract

The article presents an analysis of the maximum efficiency and maximum load power, which are available to obtain in periodic wireless power transfer (WPT) systems. The numerical computations of the proposed WPT structures are performed using the finite element method and branch current method. Two theoretical models are discussed, i.e., a numerical model with simplified structure and boundary conditions as well as an equivalent circuit model is proposed to solve WPT systems with many magnetically coupled planar coils. A multivariate analysis is performed, which takes into account the variability of the number of turns, distance between a transmitting and receiving coil, and the frequency of an energy source. The outputs, such as overall efficiency, power of the source and power transferred to a load are discussed. The formulas for the load impedance required to maximize the efficiency or load power, which are taking into account the electrical parameters of the system resulting from its geometry, are presented. The results obtained from proposed models are consistent, which confirm the correctness of the adopted circuit model, which is less complex and faster to compute than numerical one. It is also possible to perform a quick assessment of electrical parameters of the analyzed WPT structure, using presented analytical formulas and numerical model or experimental data. The results allow for a detailed discussion of the dependence of the efficiency and power of the WPT system with respect to geometry of spiral coils.

Accurate Theoretical Models for Frequency Diverse Array Based Wireless Power Transmission

“…e j2π∆ f n,m t × e −jπ(n(cos θ sin ϕ−sin ϕ t )+m(sin θ−sin θ t )) 2 ( 11) Comparing (11) with ( 5), it can be seen that each summation term of FDA-WPT system has a time-dependent complex weighting factor 'exp(j2π∆ f n,m t)' and the complex weighting factor is equal to 1, if and only if t = 0. When t = 0, the FDA-WPT system can be considered as a PA-WPT system.…”

“…Although near-field WPT systems based on inductive/resonant coupling have been developed with some degree of success, far-field WPT system faces significant challenges in practical implementation [1][2][3]. Some recent works, with novel concepts and structures, on near-field WPT systems can be found in [9][10][11]. The application of far-field WPT system is often limited by its long transmission range, high cost and low efficiency [1,3].…”

“…The transmitting antenna is designed to focus the radiated power towards the receiving end with high efficiency, whereas the rectenna is used to collect the power. The flexible charging mode makes WPT systems attractive to numerous commercial and industrial applications, such as smart phones, RFID tags, unmanned aerial vehicles, hybrid electric vehicles, and others [1][2][3][4][5][6][7][8][9][10][11]. In general, the beam collection efficiency (BCE) significantly decreases with the increase in the transmission range [3].…”

Extension and Correction of Budeanu Power Theory Based on Currents’ Physical Components (CPC) Theory for Single-Phase Systems

“…The change in the description of the Budeanu theory was and is intended to improve the value of the power factor [5,11,12,14,15]. Additionally, single-phase systems are currently used to supply wireless power transmission (WPT) 2 of 18 devices [16][17][18][19][20]. The WPT system, built of appropriately selected reactance elements, is also exposed to losses resulting from the nonsinusoidal supply and nonlinearity resulting from the control system.…”

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

“…Several review works [6][7][8] described the WPT theory and its applications. Still, developments in the resonant coupled system [9][10][11][12], in the influence of couplings and frequency on efficiency and in human exhibition aspects [13,14] have not been widely considered.…”