Optimizing the Efficiency of Series Resonant Half-Bridge Inverters for Induction Heating Applications

This paper reviews the current state of research on half-bridge (HB) inverters used in induction heating power supplies, emphasizing their topological structures, output power control methods, and switching strategies. The study explores various control techniques to regulate low power levels in a series resonant inverter (SRI) configured with an HB structure for induction heating applications. Pulse frequency modulation (PFM) is commonly employed to regulate standard power levels by adjusting the operating frequency relative to the resonant frequency. As the operating frequency increases beyond resonance, the output power decreases. However, in certain scenarios, achieving low power levels necessitates high frequencies, which introduces significant control challenges. To address these issues, it is crucial to develop alternative approaches that ensure efficient power reduction, without compromising system performance. This work evaluates and compares multiple solutions tailored for a high-frequency induction heating system delivering 18 kW at an operating frequency of approximately 100 kHz. The study places particular emphasis on optimizing key component sizing and analyzing inverter losses to enhance overall system efficiency and reliability.