Inductance Estimator-Based Resonance Frequency Tracking for Induction Heating Applications

Abstract

Induction heating of ferromagnetic materials introduces problematic issues for resonance control. Ferromagnetic materials are highly affected by their current temperature, which affects the equivalent inductance of the Induction Heating (IH) system. Each ferromagnetic material has a Curie temperature, which indicates the phase transition from ferromagnetism to paramagnetism. In this paper, an estimator is proposed to estimate the equivalent inductance of the system and generate the required operating frequency to ensure operating under the resonance condition. The proposed estimator mainly depends on the measured output current magnitude and the phase shift between the inverter output voltage and current. The design, analysis and control method are presented and discussed. The proposed estimator is tested and validated using Matlab/Simulink software simulation package.