Efficiency maximization of resonant wireless power transfer using an advanced dynamic frequency tracking approach: Experimental and simulation analysis

Abstract

Maintaining resonance is essential for maximizing the efficiency of resonant wireless power transfer (RWPT) systems, especially under varying load and coil alignment conditions. Frequency tracking plays a crucial role in this context, allowing the system to dynamically adjust to resonance shifts and sustain optimal energy transmission. However, many existing studies either remain theoretical or do not implement real-time, experimentally validated control strategies. To bridge this gap, this work presents a practical and adaptable solution based on frequency tracking combined with pulse-width modulation (PWM), validated through both experimentation and simulation. The investigation begins with the design and implementation of an experimental setup, which includes a voltage inverter controlled using a triangular-sinusoidal pulse width modulation (TS-PWM) technique. A fixed ratio of 39 is maintained between the reference signal and the carrier signal, as defined by the DMAH860 inverter, whose implementation in this context represents a novel application for real-time control of resonant converters. The transfer system employs pancake-shaped coils, carefully aligned and modularly spaced using custom mechanical supports. A series-series (SS) compensation topology is utilized, with electrical parameters selected to operate efficiently in the frequency range of 10 kHz to 100 kHz. Although many RWPT systems have been studied experimentally, the practical integration of frequency tracking with PWM remains relatively underexplored, particularly in terms of real-time dynamic adaptation under varying operating conditions. Experimental measurements of inverter output voltage and resonant current were digitized and analyzed using Fourier Transform methods. These results were compared with simulations conducted in the Simulink-MATLAB environment, demonstrating strong agreement between practical and theoretical outcomes. Harmonic distortion rates were also calculated for both experimental and simulated cases to validate system performance. To fill this gap, this work proposes a novel, experimentally validated control approach that combines PWM and real-time frequency tracking to maximize active power transfer in resonant inductive systems. A significant contribution of this study is the development of a robust and adaptive frequency-tracking algorithm, which dynamically adjusts the carrier signal while preserving a fixed ratio with the reference signal. Implemented in Simulink-MATLAB, the model uses a single-phase full-bridge inverter to drive the resonant circuit. Active power, derived from the instantaneous voltage and current of the resonant load, is compared with delayed power values to fine-tune the operating frequency. The delay parameter ensures system stability, while the exponential step size enhances convergence toward optimal resonance. The algorithm demonstrates excellent tracking performance maintaining efficient operation across different load and alignment scenarios. A parametric study further quantifies the impact of coupling coefficient, system efficiency, and load resistance versus coil spacing, emphasizing the system’s practical flexibility. This comprehensive approach introduces a control technique that improves WPT performance while being suitable for real-world deployment. Full details of the algorithm design, tuning, and extended case studies will be provided in the enlarged version of this paper.