130kHz, 7.5kW current source inverters using static induction transistors for induction heating applications

This paper describes a control scheme of a high frequency, high power current source inverter using static induction transistors to suppress the surge voltage and to reduce the switching loss during the commutation of current. The inverter is operated at a leading power factor, which requires the phase angle of the output current to be adjusted to each specific load point by the controller. The stable operation is verified by the experiments under the commutation inductance, 1.8µH, i.e., 18% reactance (130kHz, 250V, 30A base). As a result, the switching loss is estimated to be half of the conducting loss and the efficiency of the inverter to be 95%.