Uma análise matemática e experimental de 3 e 4 bobinas acopladas magneticamente em sistemas de transferência de potência sem fio

Abstract

This work demonstrates that, although wireless power transfer (WPT) systems with three coils generally achieve higher efficiency and power delivery to the load than equivalent four-coil systems, the four-coil topology enables unique characteristics not achievable with three coils. In particular, a method is proposed to optimize the power delivered to the load, in which the efficiency becomes independent of the mutual inductance between the communication coils (coils 2 and 3), and remains valid for any load resistance. The necessary conditions for this behavior are derived, supported by circuit analysis and experimental validation. Five identical solenoidal coils (150 mm diameter, 22 turns, 20 AWG wire, ≈138 µH at 552 kHz) were constructed for the experiments. Results show that, in the four-coil configuration, coils three and four can behave as a single unit when closely spaced, enabling power transfer optimization regardless of the load (RL), and confirming the feasibility of controlling transmission efficiency through adjustment of the mutual inductance (M34).