Optimization of Capacitive Wireless Power Transfer System for Maximum Efficiency

Abstract

Optimal inductance and capacitance values of a receiver (Rx) LC matching network are proposed in order to maximize the efficiency of capacitive wireless power transfer (CWPT). To maximize the overall Tx-to-load efficiency, a general polynomial equation is proposed that gives an optimum Rx inductance and capacitance value under the given constraints of inductor losses, load impedance, and coupling capacitance. It is found that the efficiency is maximized when the Rx input resistance is approximately equal to the impedance of the coupling capacitance. It is also shown that Tx inductance and capacitance values should be chosen based on the trade-off between efficiency and Tx amplifier operation. The proposed method is applied to wireless charging of an Unmanned Aerial Vehicle (UAV) because the small Rx plate of CWPT can easily be mounted on a UAV. The fabricated system delivers 45 W with overall efficiency of 78.2% across wide lateral misalignments even with a small Rx plate at 6.78 MHz.

Capacitive Wireless Power Transfer with Multiple Transmitters: Efficiency Optimization

“…The optimal terminating load admittance corresponds to the value found in scientific literature for a CPT system with a single transmitter (N = 1) coupled to a single receiver [30][31][32].…”

Near‐field wireless power transfer used in biomedical implants: A comprehensive review

“…The thin configuration of the metal plates results in a compact coupling interface that is simple to establish with the devices. For optimal power transfer, the small capacitance between the two parallel plates gives the reactance compensation an essential role in coupling [59]. Figure 5 shows the main components of the CC-WPT system, which involves converting DC voltage to high-frequency AC voltage to supply two primary metal plates using a high-frequency inverter [60].…”

A Comprehensive Review on Wireless Capacitive Power Transfer Technology: Fundamentals and Applications

“…Both inductive and capacitive power transfer technologies are investigated in drone charging applications [252]. Considering CPT applications, the receiver side of the system is minimized to ensure compatibility [253,254], and to obtain the maximum efficiency [255]. A capacitive coupler design is proposed to decrease parasitic capacitances with a rotational misalignment capability [113,256].…”

“…• Reduced cross-coupling capacitance [113] • High efficiency [113,255] • Reduced size [253] • High tolerance to misalignments [256] • Increased flight range [254] • High occupied space [113,256] • Relatively low efficiency [253] • High computation burden [255] • Require extra circuitry [254] Underwater • High efficiency [262,264] • High tolerance to misalignments [263] • Increased transfer distance [258,263] • Design complexity [262][263][264] • No insulation layer on the plate [262] • Increased cost [258,263] • Compact structure [265] • No sensitive to speed [265,266,268] • High efficiency [267] • Control complexity [59,267,268] • Requires extra circuitry [59,268] • More influence of parasitic components [59,[265][266][267][268] Three-phase…”