Comparative Analysis of Wireless Power Transfer Efficiency in Topologies

Thesis Abstract

Wireless power transfer (WPT) systems have emerged as a pivotal solution for untethered charging in consumer electronics, electric vehicles, and industrial automation, yet comparative efficiencies across dominant topologies remain insufficiently characterized under realistic operating conditions. The study addresses the gap by investigating how inductive, resonant inductive, and capacitive WPT topologies perform in terms of energy transfer efficiency, sensitivity to misalignment, and load regulation, with implications for design optimization and standardization. The objective is to quantify efficiency across topologies under varying coupling coefficients (k = 0.05 to 0.45), air-gap distances (5–40 mm for inductive, 20–150 mm for resonant inductive), and load profiles (5 ?, 10 ?, 20 ?) using standardized test conditions that replicate consumer charging scenarios and medium-range industrial power transfer. Specific objectives include (a) deriving comparative efficiency curves as a function of distance and misalignment, (b) identifying optimal operating points for each topology, (c) evaluating the impact of parasitic elements and Q-factors on overall performance, and (d) developing a predictive model to guide topology selection for given application constraints. A mixed-methods methodology is employed. The population comprises commercially available WPT transceiver modules representing each topology, with a sample of 30 units per topology sourced from three leading manufacturers to ensure representativeness. An experimental, cross-sectional design measures steady-state transfer efficiency, input power, output power, and temperature rise using high-precision source meters (Keithley 2450) and thermal imaging (FLIR X6580). Data collection instruments include a calibrated vector network analyzer (Agilent E5071C) for impedance characterization, a precision power analyzer (Keysight N6705) for efficiency calculation, and a positioner system to impose controlled misalignment. Data will be analyzed using analysis of variance (ANOVA) to test efficiency differences across topologies, distances, and misalignment levels, followed by multiple regression to model efficiency as a function of coupling, load, and parasitic parameters. Complementary finite-element simulations (Ansys HFSS) will validate experimental results and provide insight into field distributions and resonant modes. The study will also employ sensitivity analyses to determine robustness to component tolerances and temperature effects. Expected findings indicate that resonant inductive topology will exhibit superior efficiency over conventional inductive at moderate distances (above 10 mm) and modest misalignment, due to enhanced load self-resonance, while inductive topology will outperform in near-contact configurations with tight alignment. Capacitive-based WPT is anticipated to display lower efficiency at practical distance ranges but may offer advantages in specific alignment scenarios or compact form factors. Across all topologies, efficiency is expected to deteriorate with increasing misalignment and temperature rise, with varying degrees of susceptibility depending on Q-factor and parasitic coupling. The predictive model is anticipated to achieve R-squared values exceeding 0.85 in explaining efficiency variance across scenarios. The study contributes to knowledge by providing a rigorous, side-by-side empirical comparison of WPT topologies under standardized conditions, clarifying trade-offs between distance, alignment tolerance, and efficiency, and delivering practical guidelines for topology selection in consumer and industrial charging applications. It offers a validated analytical framework and a simulation-empirical pipeline that researchers and engineers can reuse for future topology assessments, and it informs design strategies for thermal management and electromagnetic compatibility. The main conclusion is that topology choice should be context-driven resonant inductive is generally preferred for mid-range distances with tolerable misalignment, while traditional inductive remains advantageous for near-field, high-throughput scenarios; capacitive approaches may suit niche applications requiring compactness or planar integration. Recommendations include prioritizing precise alignment mechanisms and active feedback control in resonant systems, implementing adaptive impedance matching to sustain high efficiency across load variations, and developing standardized benchmarking protocols to facilitate cross-study comparability.