Verfahren und Vorrichtung zum Überstrom- und Kurzschlussstromschutz eines Halbleiter-Leistungsschalters

摘要

The invention relates to a method and a device (1) for overload and short-circuit current protection of a semiconductor power switch (2) using the desaturation properties of the power switch (2). The time progression of the voltage (U_CE) applied on the power switch is monitored and an overload or short-circuit current is detected if the voltage (U_CE) exceeds a pre-determined voltage level (U_1). In order to further improve overload or short-circuit monitoring of the power switch (2) so that overload or short-circuit currents can be detected safer, more reliably and faster, an additional predetermined voltage level (U_2) higher than the first voltage level (U_1) is defined and overload or short-circuit current is detected if the voltage (U_CE) does not fall below the second voltage level (U_2) within a given time limit (t_2) after the power switch (2) has been connected. Depending on the moment when the overload or short-circuit current has appeared, the power switch (2) to be protected is disconnected immediately or in a delayed manner within a defined time period (t-v).