Insights into Dynamic Tuning of Magnetic-Resonant Wireless Power Transfer Receivers Based on Switch-Mode Gyrators

Abstract

Magnetic-resonant wireless power transfer (WPT) has become a reliable contactless source of power for a wide range of applications. WPT spans different power levels ranging from low-power implantable devices up to high-power electric vehicles (EV) battery charging. The transmission range and efficiency of WPT have been reasonably enhanced by resonating the transmitter and receiver coils at a common frequency. Nevertheless, matching between resonance in the transmitter and receiver is quite cumbersome, particularly in single-transmitter multi-receiver systems. The resonance frequency in transmitter and receiver tank circuits has to be perfectly matched, otherwise power transfer capability is greatly degraded. This paper discusses the mistuning effect of parallel-compensated receivers, and thereof a novel dynamic frequency tuning method and related circuit topology and control is proposed and characterized in the system application. The proposed method is based on the concept of switch-mode gyrator emulating variable lossless inductors oriented to enable self-tunability in WPT receivers.

An Improved Autonomous Current-Fed Push-Pull Parallel-Resonant Inverter for Inductive Power Transfer System

“…Bifurcation-free region Bifurcation region In Figure 11, the measured frequency data are marked as data points (red circle for Exp 1 data f Exp1 and blue triangle for Exp 2 data f Exp2 ), the theoretical exact solutions in Equations (11) and (15) are plotted as solid lines (green for the great bifurcation frequency f + , red for the small bifurcation frequency f − , and purple for the middle bifurcation frequency f m ) and the approximate solutions of Equation (16) are presented as dashed lines (blue for the great bifurcation approximate frequency f +app and yellow for the small bifurcation approximate frequency f −app ).…”

“…Various solutions have been proposed in the previous literature. One is dynamic tuning of reactive elements in either the primary or the secondary compensation network through variable inductors [14][15][16], switchable capacitor bank [9], or transistor-controlled variable capacitor [17], Energies 2018, 11, 2653 2 of 16…”

“…Especially when it occurs to the frequency bifurcation region, the power transfer capability and efficiency can deteriorate rapidly at the original resonant frequency [2,13].Various solutions have been proposed in the previous literature. One is dynamic tuning of reactive elements in either the primary or the secondary compensation network through variable inductors [14][15][16], switchable capacitor bank [9], or transistor-controlled variable capacitor [17], Energies 2018, 11, 2653 2 of 16respectively. This method aims to keep the ZVS frequency fixed under coupling variation, although it needs more switching devices, passive components, and even a complicated control unit.…”

High Efficiency and Power Tracking Method for Wireless Charging System Based on Phase-Shift Control

“…The authors usually build their mathematical models based on the equivalent electrical circuit method using linear equations with lumped electrical parameters, but only few of them consider also the parasitic effects (e.g., [12][13][14][15][16]). Another frequently proposed approach is to describe the system behaviour while using electromagnetic field calculated through the finite element analysis [28][29][30][31][32][33][34][35][36][37][38][39][40]. A great effort has been devoted also to the control strategies [41][42][43][44][45][46][47][48].…”

Retuning high Q inductive power transfer systems at MHz frequencies: a switched capacitor design method incorporating COSS

“…FIGURE15 Experimental I 2 p frequency response. I p is divided by its peak value at the corresponding switching state to eliminate the impact of variable AC resistance…”