Protective device for a voltage-controlled semiconductor switch

1. A protective device for a voltage-controlled semiconductor switch having a gate connection, a power emitter connection, an auxiliary emitter connection and a collector connection, wherein the voltage-controlled semiconductor switch can switch a current between the collector connection and the power emitter connection, the protective device comprising:

a voltage-limiting device for limiting a voltage between the gate connection and the power emitter connection; and

a deactivation device connected to said voltage-limiting device and deactivating said voltage-limiting device during a switch-on of the voltage-controlled semiconductor switch, said deactivation device having at least one timing element, wherein a time constant of said timing element at least also determines a duration of a deactivation of said voltage-limiting device after a sudden change in a gate-auxiliary emitter voltage.

2. The protective device according to claim 1 , further comprising a capacitive coupling device which affects a capacitive coupling between the gate connection and the power emitter connection.

3. The protective device according to claim 1 , wherein a gate-auxiliary emitter voltage between the gate connection and the auxiliary emitter connection is applied to an input-side of said deactivation device, said deactivation device deactivating said voltage-limiting device on a basis of the gate-auxiliary emitter voltage.

4. The protective device according to claim 1 , wherein said deactivation device has an output-side connected in series with said voltage-limiting device.

5. The protective device according to claim 1 , wherein said deactivation device is configured such that, in an event of a sudden change in a gate-auxiliary emitter voltage present between the gate connection and the auxiliary emitter connection, said deactivation device deactivates said voltage-limiting device.

6. The protective device according to claim 1 , wherein said timing element is an RC timing element having at least one capacitor and at least one resistor.

7. The protective device according to claim 1 , wherein said deactivation device has a voltage-controlled switch element with a control connection, a control voltage generated using a gate-auxiliary emitter voltage being applied to said control connection of the voltage-controlled switch element.

8. The protective device according to claim 7 , wherein the gate-auxiliary emitter voltage is applied to said control connection of said voltage-controlled switch element via said timing element.

9. A configuration, comprising:

a voltage-controlled semiconductor switch having a gate connection, a power emitter connection, an auxiliary emitter connection and a collector connection;

a protective device having a voltage-limiting device for limiting a voltage between said gate connection and said power emitter connection and a deactivation device connected to said voltage-limiting device and deactivating said voltage-limiting device during a switch-on of said voltage-controlled semiconductor switch, said deactivation device having at least one timing element, wherein a time constant of said timing element at least also determines a duration of a deactivation of said voltage-limiting device after a sudden change in a gate-auxiliary emitter voltage; and

an activation circuit for activating said voltage-controlled semiconductor switch, said activation circuit connected to said gate connection and said auxiliary emitter connection and controls said voltage-controlled semiconductor switch by means of a gate-auxiliary emitter voltage.

10. A method for protecting a voltage-controlled semiconductor switch equipped with a gate connection, a power emitter connection, an auxiliary emitter connection and a collector connection, which comprises the steps of:

limiting a voltage between the gate connection and the power emitter connection via a voltage-limiting device when the voltage-controlled semiconductor switch is fully switched on; and

deactivating the voltage-limiting device via a deactivation device during a switching-on period of the voltage-controlled semiconductor switch, the deactivation device having at least one timing element, wherein a time constant of the timing element at least also determines a duration of a deactivation of the voltage-limiting device after a sudden change in a gate-auxiliary emitter voltage.

11. The method according to claim 10 , which further comprises:

monitoring a voltage between the gate connection and the auxiliary emitter connection for a sudden voltage change; and

deactivating the voltage-limiting device in an event of the sudden voltage change occurring.