Maximizing efficiency through impedance matching from a circuit-centric model of non-radiative resonant wireless power transfer

Wireless powering by magnetic resonant coupling: Recent trends in wireless power transfer system and its applications

“…However, the complexity and inconveniency of CMT make the WPT circuit design questionable. As a solution, a different circuit analysis for coupled coils using reflected load was proposed in [7][8][9] where the experimental results match with the results obtained by EM and circuit simulations. The comparative study of these two analytical theories is described in Section 3.4.2.…”

“…This efficiency versus coupling distance tradeoff is the main weakness of the 2-coil arrangement for mid-range WPT applications and was first explained in [5] using CMT. Also the circuit based RLT presented in [7][8][9] results in the same formulation of transmission efficiency as CMT in steady-state, and either method can effectively utilize to measure system's key performances for both weak and strong coupling conditions.…”

“…They are the power level, coil geometry, including size and weight, the Q-factor, the coupling parameters and the operating frequency. The detail analysis of the resonant coupled WPT has been explained by coupled-mode theory (CMT) [5,6] and reflected load theory (RLT) [7][8][9]. The operating frequency range that is used for inductive coupling is often neglected here, but the overall system efficiency and cost of the resonant coupled WPT system are affected by the operating frequency.…”

A Wireless Charging System Applying Phase-Shift and Amplitude Control to Maximize Efficiency and Extractable Power

“…This work focuses on a circuit based model, but it is worth noting that there exist different other possibilities to model WPT systems [13], [25], [26]. A block diagram of the examined system is shown in Fig.…”

“…1. This method only considers the fundamental component of the input voltage [15], [25], [27] and replaces the active rectifier as well as the DC-DC converter by an equivalent first harmonic impedance Z L = R L + jX L . The applied simplification is sufficiently accurate for high quality factor resonant circuits that operate near resonance frequency.…”