CIRCUIT FOR PROTECTING POWER SEMICONDUCTOR SWITCHES THAT MAY BE SWITCHED ON AND OFF AGAINST SWITCHING OVERVOLTAGES

摘要

A circuit (28) protects power semiconductor switches (T1, T2) which may be switched on and off through their control input (G) and which form a pair of arms (2) in a current rectifier (4), against switching overvoltages. The circuit (28) has a comparator connected upstream of an analog amplifier with a limiting characteristic curve electroconductively connected at its output with a control input (G) of the power semiconductor switch (T1, T2) to be protected. A real voltage (UCE) and a predeterminable reference voltage (U*CE) of the main connection (C) of said power semiconductor switch (T1, T2) are applied to the comparator. A circuit (28) which protects against overvoltages is thus obtained, so that a capacitor-diode series connection network for the power semiconductor switch may be dispensed with, since even the smallest voltage deviations are immediately recognized and the power semiconductor circuit breaker is switched off in a controlled manner.