Comparative Analysis of Wireless Power Transfer Efficiency in Resonant vs. Non-Resonant Systems

Thesis Abstract

Wireless power transfer (WPT) technology has gained significant attention due to its potential to revolutionize energy delivery systems, especially in applications such as electric vehicle charging, biomedical devices, and consumer electronics. Despite widespread interest, there remains a notable gap in comprehensive comparative evaluations of the efficiency performance between resonant and non-resonant WPT systems under varying operational conditions. This study aims to systematically analyze and compare the transfer efficiency of resonant and non-resonant wireless power transfer configurations, with a focus on identifying the fundamental factors influencing performance disparities. The specific objectives include quantifying efficiency variations across a range of transfer distances, frequencies, and load conditions; evaluating the influence of coil design parameters; and developing predictive models for efficiency optimization. The research adopts a quantitative, cross-sectional comparative research design that facilitates empirical analysis of the two WPT systems. The population comprises twenty-four prototypes—twelve resonant and twelve non-resonant—constructed using standardized coil dimensions and core materials, to ensure consistency in experimental conditions. A purposive sampling technique was employed to select system configurations that reflect typical design standards in the industry. Data collection involved systematic measurements of transfer efficiency across diverse transfer distances—ranging from 0.1 to 2 meters—at frequencies of 100 kHz to 1 MHz, using high-precision power analyzers. Additional data were obtained through parameters such as coil coupling coefficients and resonant frequencies, captured via vector network analyzers. Validity and reliability of the measurement instruments were established through calibration procedures aligned with industry standards, and repeated measurements ensured data consistency. Data analysis involved descriptive statistics to summarize efficiency trends, followed by inferential statistical procedures, notably analysis of variance (ANOVA), to examine differences between systems across conditions. Regression analysis was employed to develop multivariate models predicting efficiency based on transfer distance, frequency, and coil parameters. Theoretical underpinnings were grounded in the coupled-mode theory and resonant inductive coupling principles, providing a framework to interpret the observed performance variations. The study further incorporates the energy transfer efficiency theory, especially focusing on resonant energy exchange dynamics. Expected findings indicate that resonant systems demonstrate significantly higher transfer efficiency—averaging 85% at optimal conditions—compared to non-resonant configurations, which average around 60%. However, efficiency in resonant systems exhibits a notable decline beyond a 1-meter transfer distance, whereas non-resonant systems show relatively steady, albeit lower, efficiency across the range. The results are anticipated to reveal that coil design parameters, especially the quality factor (Q-factor), substantially influence transfer efficiency, with resonant systems benefiting more from optimized coil configurations. This research contributes to the existing body of knowledge by providing a rigorous, data-driven comparison of resonant and non-resonant WPT systems under real-world conditions, filling a critical gap in empirical performance analysis. The findings offer valuable insights into the design and deployment of more efficient wireless transfer systems and inform future standards and optimization strategies. Based on the results, it is recommended that system designers prioritize resonant coupling for applications demanding high efficiency over shorter distances, while non-resonant systems could be suited for low-power, long-range scenarios. Future studies are suggested to explore the impact of advanced coil materials and adaptive tuning techniques on transfer efficiency, as well as examining system performance under dynamic load conditions.