A starting inverter for a voltage-source series inverter with a transformer-coupled high-Q induction heating load (type A inverter)

The voltage-source series inverter with a transformer-coupled high-Q induction heating load is found to have latching and commutation problems at starting due to insufficient output current. This is because a high-Q load requires a number of cycles before sufficient energy, and therefore current is built up in the series load. A novel starting inverter is presented which establishes sufficient current in the load at starting. The operation of the inverter is described, and the modes of operation are identified. The behavior of the inverter in each mode is analyzed, and an optimum mode is selected which results in the minimum rating of the starting inverter. The selection and the rating of the components to design the starting inverter are presented. A prototype inverter system has been built and all theoretical results have been verified experimentally