"TANDEM-H bridge" a new approach towards low switching loss at high switching frequencies

High frequency induction heating applications especially pipe/tube welding requires output power in the range of 100´s of KW at frequencies ranging from 200 KHz to approx 1 MHz. The power frequency product poses a great challenge for designers in terms of semiconductor device selection and cost. Though power MOSFETs are the most popular choice, their lower current capacity and higher costs divert the attraction towards lower cost IGBT usage in modern day power electronic equipment, IGBT´s being economical and having high current capacity, their use is limited by lower switching frequency. This paper presents a new topology that can enable designers to use IGBT´s at higher frequencies while keeping the switching loss low.