Quasi variable capacitor applied to soft switching inverter for induction heating

In this paper, a quasi-variable capacitor applied to soft switching inverter for induction heating and its novel operation control scheme are presented. The proposed quasi variable capacitor has many advantages, such as wide output power regulation range and outputting at double or triple frequency. Moreover, a stable operation is achieved because all switches are always maintaining a soft switching even if different metal, such as stainless steel, aluminum, ferromagnetic metal and paramagnetic metal are heated respectively. Through the experimental results, the usefulness of the proposed quasi variable capacitor has been proved.