Method and device for short-circuit detection by saturation detection in power semiconductor switches

A device (10) for short-circuit detection by saturation detection in power semiconductor switches, comprising:

• at least one decoupling diode (11), which is designed to be electrically connected to a drain terminal (21) or a collector terminal of a power semiconductor switch (20), wherein a voltage drop (UΔ) across an anode of the at least one decoupling diode (11) corresponds to a voltage drop (UΔ) across a load path of the power semiconductor switch (20);
• a current source (12), which is electrically connected to the at least one decoupling diode (11) and is designed to feed an auxiliary current into a load path of the power semiconductor switch (20) when the at least one decoupling diode (11) is electrically connected to the drain terminal or the collector terminal of the power semiconductor switch (20);
• a reference voltage source (13), which is designed to be electrically connected to a supply current source for the power semiconductor switch (20) and to provide a reference voltage (Uref) depending on a supply voltage (UVDD) of the supply current source, with the result that the reference voltage (Uref) follows changes in the supply voltage (UVDD);
• a comparator circuit (14), which is electrically connected to the at least one decoupling diode (11) and the reference voltage source (13) and is designed to generate a differential voltage (Udiff), which corresponds to a difference between the voltage drop (UΔ) across the load path of the power semiconductor switch (20) and the provided reference voltage (Uref);
• and
• evaluation electronics (15), which are designed to compare the generated differential voltage (Udiff) with a predetermined limit voltage (Ulim), wherein a short-circuit current is detected in the load path of the power semiconductor switch (20) when the differential voltage (Udiff) exceeds the limit voltage (Ulim), and to open the power semiconductor switch (20) when a short-circuit current has been detected in the load path of the power semiconductor switch (20).