Patent ID: 11942926
Assignee: SIEMENS AKTIENGESELLSCHAFT
Field: Basic communication processes (Electrical engineering)
Classification: CPC H | IPC H

Claim 2:
3. A protection circuit for a semiconductor switch, the semiconductor switch having a gate which is controllable by a gate driver, the protection circuit comprising:
an integrator connected to the gate and detecting a gate charge of the gate based on an integrator output voltage of the integrator,
a comparator unit for switching off the semiconductor switch when the gate charge falls below a reference charge, the comparator unit comprising a comparator operational amplifier having a positive input, a negative input and an output, and a comparator diode, and
a reference charge circuit comprising a reference charge capacitor, a reference charge resistor, a first reference charge diode and a second reference charge diode, wherein the reference charge circuit is configured to increase the reference charge during a rise time from zero to a final value, after the semiconductor switch is switched-on,
wherein the positive input of the comparator operational amplifier is connected to an output of the integrator, the negative input of the comparator operational amplifier is connected to a first terminal of the reference charge resistor, to a first electrode of the reference charge capacitor and to an anode of the first reference chare diode, and
wherein the output of the comparator operational amplifier is connected to a cathode of the comparator diode a cathode of the first reference charge diode is connected to a cathode of the second reference chare diode, and an anode of the second reference charge diode is connected to an input of the integrator.