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This research paper presents a dynamic feedback control algorithm designed to continuously track and maintain the resonant frequency in induction heating systems. The research paper begins by introducing a theoretical framework for the dynamic algorithm that enables real-time measurement of the resonant frequency. The proposed method removes the necessity for frequency sweeps or time delays commonly used in tracking and synchronization. The dynamics of achieving resonant frequency synchronization are examined as variations in induction load characteristics—such as changes in temperature and material properties—alter the system, thereby causing corresponding shifts in the resonant frequency. The proposed system for tracking and synchronizing with resonant frequency consists of a combination of hardware and software components. The hardware consists of a full-bridge resonant inverter connected to an RLC tank circuit, along with a microcontroller-based feedback system designed to monitor, measure, and synchronize the resonant frequency. The proposed feed-back control algorithm, implemented as a software component in the microcontroller, determines the instantaneous half-cycle duration of each individual resonant frequency voltage signal and regulates the resonant inverter's switching frequency to match this duration. Comprehensive simulation and laboratory tests were carried out to evaluate the proposed induction heating system. These tests included trials under both no-load and various load conditions to assess the system’s performance, response accuracy, and robustness. Additionally, the efficiency of the induction heating system was determined experimentally. Satisfactory results of the experiments validated the effectiveness of the proposed frequency tracking system.
Shami et al. (Thu,) studied this question.