A single-stage type highly efficient ZVS-SEPP high frequency inverter for induction heating applications

This paper presents an improved single-stage type single-ended push pull (SEPP) high frequency inverter for induction heating applications. It unifies a boost-type PFC power converter and a ZVS-SEPP high frequency inverter operating at a fixed frequency. On the other hand, conventional dual stage half-bridge high frequency inverters have PFC converters at the preceding stage followed by SEPP high frequency inverters at the final stage. Our improved circuit constitution brings out that its total conversion efficiency of the proposed inverter reaches more than 96 %. It comes from the fact that the output power is regulated using an asymmetrical PWM control technique at a fixed frequency of 20 kHz. It enables soft switching operation of all switching devices. In addition, total input power factor reaches almost unity by the aid of PFC converter function. This paper explains behavior of the proposed inverter circuit and its steady state operation, with the aid of simulation analysis. Finally, the simulation result is compared with experimental one obtained from a breadboard.