Phase-shifted third harmonic modulation technique for induction heating applications to improve soft switching capability

Induction heating (IH) systems have been attracting more attention due to their direct heating capability. Moreover, IH systems have the advantages of fast heating performance, high efficiency, cleanliness, and safety. However, they also have the disadvantage of limited pot material, size, and misalignment. In general, IH systems cannot properly heat non-ferromagnetic pots because of their low resistance, which induces a large switch current. Third harmonic modulation (THM) is proposed to mitigate this issue. The conventional THM can heat low-impedance pots; however, it has drawbacks in high possibility of hard switching due to the high first harmonic current in the resonant tank. In this paper, a phase-shifted THM is proposed to improve soft switching and the maximum heating capabilities compared with the conventional THM by reducing the first harmonic component of the resonant current.