Line-frequency Noise Suppression Circuit to Mitigate Audible Noises in Induction Heating Systems

Abstract

Induction heating (IH) systems suffer from various noises during operation. Among these, pulsating noise is generated by the rectified system frequency and is proportional to the amount of variation in the resonant current. Research has been conducted on combining IH systems with a Line-frequency Noise Suppressor (LNS) circuit to reduce pulsating noise. The IH-LNS combined structure reduces pulsating noise by decreasing the variation in the pulsating frequency of the resonant current through partial power transfer. However, introducing an auxiliary circuit changes the input current waveform, failing to meet harmonic standards (e.g., IEC 61000-3-2). Therefore, this research presents a modeling approach for the input current and a design methodology based on this model to meet harmonic standards. The validity of the proposed method is verified through experiments using a 2 kW half-bridge series resonant inverter and an LNS circuit prototype.