Accurate Calculation of the Power Transfer and Efficiency in Resonator Arrays for Inductive Power Transfer

Abstract

This paper studies the power transfer characteristics of a resonator array for inductive power transfer by means of the accurate analytical solution of its circuit model. Through the mathematical inversion of a tridiagonal matrix, it is possible to obtain closed-form expressions for the current in each resonator and consequently expressions for the power transfer and efficiency of the system. The method can be applied to a resonator array powering a load at the end of the array or a receiver facing the array at any position. With the expressions obtained, it is possible not only to achieve a better understanding of the power transfer characteristics in resonator arrays but also to obtain the conditions for maximum power transfer or maximum efficiency, for several conditions and parameters of the system. A prototype of a stranded-wire resonator array powered by a resonant inverter, capable of delivering power to a load from 65 W to 90 W with efficiency values between 63% and 88%, was built in order not only to validate the expressions obtained but also to show their practical applicability and demonstrate that these arrays can be used for higher power transfer applications.

Multiple Input Multiple Output Resonant Inductive WPT Link: Optimal Terminations for Efficiency Maximization

“…In the given hypotheses, the maximum power gain, and the corresponding currents (up to an arbitrary factor) can be determined by solving (12) with the constraint…”

“…It can be observed that by (12) it is also possible to determine the maximum power gain when the role of the ports is interchanged, that is when the power supply is provided at ports b 1 , . .…”

“…This configuration has been widely investigated in the literature and the design equations for maximizing the possible figures of merit of interest have been derived [5][6][7][8][9]. In the SISO configuration, a possible strategy for improving the performance in terms of either transfer distance or efficiency consists in using additional resonators interposed between the transmitter and the receiver [10][11][12].…”

Repeater coil‐based wireless power transfer system powering multiple gate drivers of series‐connected IGBTs

“…However, in most of the existing WPT systems, usually, only one load is powered via the magnetic or electric field [6][7][8][9]. Recently, more and more publications investigated the WPT system with multiple loads [10][11][12][13][14][15][16][17][18]. In [10], a WPT system with two receivers (Rxs) was designed, where the two receiving coils are decoupled by adjusting the winding direction of turns.…”

“…Considering that the gate drivers are placed near these IGBTs, the WPT system should have the capability to transfer power over a long distance. The repeater coil structure [14, 15] could be a good solution because the coils can not only increase the power transfer distance but also be connected to multiple loads. In [16], the repeater coils were adopted to power multiple loads.…”