Driver circuit and method for controlling a semiconductor switch

Patent metadata

Field	Value
Publication number	US-12348222-B2
Application number	US-202118546349-A
Country	US
Kind code	B2
Filing date	Nov 24, 2021
Priority date	Feb 16, 2021
Publication date	Jul 1, 2025
Grant date	Jul 1, 2025

Abstract

Some circuits for controlling a semiconductor switch include: a contact for connection to a control terminal of the semiconductor switch; and a device to carry out a measurement of a value dependent on the level of the current flowing through the semiconductor switch, in the course of a switch-off process of the semiconductor switch. The value is either the level of the gate current at a point in time or in a time window after the start of the switch-off process or a timespan from the start of the switch-off process until a definable threshold value of the voltage drop across the semiconductor switch is reached. Depending on the size of the value, the device activates a control measure to reduce the change over time in the current flowing through the semiconductor switch.

First claim

What is claimed is:

1. A driver circuit for controlling a semiconductor switch, the circuit comprising:
a contact for connection to a control terminal of the semiconductor switch; and
a device to carry out a measurement of a value dependent on the level of the current flowing through the semiconductor switch, in the course of a switch-off process of the semiconductor switch;
wherein the value is either the level of the gate current at a point in time or in a time window after the start of the switch-off process or a timespan from the start of the switch-off process until a definable threshold value of the voltage drop across the semiconductor switch is reached; and
depending on the size of the value, the device activates a control measure to reduce the change over time in the current flowing through the semiconductor switch.

2. The driver circuit as claimed in claim 1 , wherein the control measure includes temporarily switching the semiconductor back on.

3. The driver circuit as claimed in claim 1 , wherein the control measure includes changing the gate voltage as a control measure.

4. The driver circuit as claimed in claim 1 , wherein the control measure includes switching to a higher gate resistance.

5. The driver circuit as claimed in claim 1 , wherein the device transmits a signal to a higher-level controller based on the magnitude of the value.

6. The driver circuit as claimed in claim 1 , wherein the device:
stores the measured value during a first switch-off process;
determines a difference between the value measured in the subsequent switch-off process and the stored value during a subsequent switch-off process; and
controls the control measure based on the difference.

7. The driver circuit as claimed in claim 1 , wherein the device determines:
a result value from the measured value using a stored value table; and
controls the control measure based on the result value.

8. The driver circuit as claimed in claim 1 , wherein the device uses at most 10% of the nominal voltage of the semiconductor switch as a threshold value of the collector-emitter voltage.

9. The driver circuit as claimed in claim 1 , wherein the device defines a start of a switch-off process using a threshold value for the gate voltage.

10. The driver circuit as claimed in claim 1 , wherein the device defines a start of a switch-off process using a control command from the higher-level controller.

11. The driver circuit as claimed in claim 1 , wherein:
the device determines a start of a switch-off process based on the value of a control voltage; and
the control voltage is a voltage value between an output stage of the driver circuit and a gate resistor.

12. The driver circuit as claimed in claim 1 , wherein the device defines a time in which it is possible to carry out the control measure by means of a delay circuit.

13. The driver circuit as claimed in claim 1 , wherein the device sets a time in which the implementation of the control measure is possible, determined using a voltage measurement at a Z-diode connected to the collector-emitter voltage by a voltage divider.

14. A system comprising:
a semiconductor switch;
a contact for connection to a control terminal of the semiconductor switch; and
a device to carry out a measurement of a value dependent on the level of the current flowing through the semiconductor switch, in the course of a switch-off process of the semiconductor switch;
wherein the value is either the level of the gate current at a point in time or in a time window after the start of the switch-off process or a timespan from the start of the switch-off process until a definable threshold value of the voltage drop across the semiconductor switch is reached; and
depending on the size of the value, the device activates a control measure to reduce the change over time in the current flowing through the semiconductor switch.

15. A method for controlling a semiconductor switch, the method comprising:
measuring a value dependent on the level of the current flowing through the switch is carried out during the course of a switch-off process of the semiconductor switch;
wherein the value is either the level of the gate current at a point in time after starting the switch-off process or a timespan from the start of the switch-off process until a definable threshold value of the voltage drop across the switch is reached and depending on the size of the value, a control measure is taken to reduce the change over time in the current flowing through the semiconductor switch.

Assignees

• Siemens Ag

Inventors

• Neumeister Matthias
• Pfeifer Markus

Classifications

• H03K17/163 Primary

  Soft switching · CPC title

• H03K17/168 Primary

  in composite switches · CPC title

• H03K17/166

  Soft switching · CPC title