PROTECTIVE DEVICE FOR SEMICONDUCTOR ELEMENT

摘要

PURPOSE:To miniaturize a saturable reactor and to control a forward current decrement factor at the turn-off of a semiconductor element within a predetermined value by connecting in series the saturable reactor providing a gap in a magnetic path to a semiconductor element. CONSTITUTION:A gap 3 with suitable length is formed at the iron core of a saturable reactor 1. The saturable reactor 1 is connected in series to a semiconductor element 5 such as a thyristor or the like. The forward current decrement factor at the turn-off of a semiconductor element is controlled by using the saturable reactor 1 and the current is kept within a predetermined value by reducing the peak value of reverse recovery current and by adjusting the length of the gap. Inductance value is reduced by providing the gap and the reverse recovery current of the thyristor 5 is increased and the time for flowing the reverse recovery current will be shortened.