Temperature Rise in Thyristors during Turn-on†

The temperature rise in rectangular thyristors during the gate-triggered. turn-on process is analysed by means of Laplace transforms and residue calculus: Two models for the heat generation in the thyristor material are considered: uniform heat generation throughout the tumed-on volume of the thyristor and heat generated only in the turned-on region of the central p-n junction. Conditions for excessive temperature in the thyristor during turn-on are considered. Critical factors (besides the current and voltage of the thyristor), giving a large temperature rise, are shown to be the current rise time, the spreading velocity of the current-carrying region and the geometry of the thyristor. The most critical factor, however, is found to be the distribution of the heat generation in the thyristor. The temperature rise under pulsed load conditions is also treated. Numerical examples are given. The mathematical model given in the paper may be used to calculate the excess temperature for thyristors of arbitrary geometry.