Method for protecting a controllable semiconductor switch from overload and short-circuiting in a load circuit

Patent metadata

Field	Value
Publication number	US-2016197602-A1
Application number	US-201414912438-A
Country	US
Kind code	A1
Filing date	Jul 31, 2014
Priority date	Aug 20, 2013
Publication date	Jul 7, 2016
Grant date	—

Abstract

A method for protecting a controllable semiconductor switch from overload and short-circuiting in a load circuit, the method—including detecting an output voltage of the semiconductor switch;—comparing a detected output voltage with a predicted switching progress; and—deactivating the semiconductor switch if the detected output voltage is lower than the predicted switching progress.

First claim

1 . A method for the protection of a controllable semiconductor switch against overload and short-circuiting in a load circuit, wherein the method comprises:
detecting an output voltage of the semiconductor switch; comparing a detected output voltage with a predicted switching progress; deactivating the semiconductor switch if the detected output voltage is smaller than the predicted switching progress.

2 . The method as claimed in claim 1 , wherein the steps of detecting an output voltage of the semiconductor switch and comparing the detected output voltage with the predicted switching progress are carried out at least once before the semiconductor switch is fully switched on.

3 . The method as claimed in claim 1 , wherein the detecting an output voltage and comparing the detected output voltage with the predicted switching progress are repeated at least once.

4 . The method as claimed in claim 3 , wherein the detecting the output voltage and comparing the detected output voltage with the predicted switching progress are repeated at cascaded moments in time.

5 . The method as claimed in claim 1 , wherein the predicted switching progress is freely programmable.

6 . The method as claimed in claim 1 , wherein the method further comprises:
measuring a current in the load circuit and/or a voltage drop at the semiconductor switch, as soon as the semiconductor switch is fully switched on; comparing the measured current and/or the measured voltage drop with a specified limit value; and deactivating the semiconductor switch if the measured current and/or the measured voltage drop is larger than the specified limit value.

7 . A protective circuit for a controllable semiconductor switch against overload and short-circuiting in a load circuit, the protective circuit comprising:
a monitoring circuit for detecting an output voltage of the semiconductor switch, at least one comparator for comparing the detected output voltage with a predicted switching progress, and evaluation logic for deactivating the semiconductor switch if the detected output voltage is smaller than the predicted switching progress.

8 . The protective circuit as claimed in claim 7 , wherein the evaluation logic is a digital circuit.

9 . The protective circuit as claimed in claim 7 , wherein the protective circuit further comprises a microcontroller with a data interface for programming a predicted switching progress.

10 . The protective circuit as claimed in claim 7 , wherein the semiconductor switch is a power MOSFET.

11 . A half-bridge circuit for driving a DC motor, comprising a protective circuit as claimed in claim 7 .

12 . The method as claimed in claim 2 , wherein the detecting an output voltage and comparing the detected output voltage with the predicted switching progress are repeated at least once.

13 . The protective circuit as claimed in claim 8 , wherein the protective circuit further comprises a microcontroller with a data interface for programming a predicted switching progress.

Assignees

• Conti Temic Microelectronic

Inventors

• Joos Uli
• Pölzer Alexander
• Speckner Martin
• Stuhler Norbert

Classifications

• H03K17/18

  Modifications for indicating state of switch · CPC title

• H03K17/0822 Primary

  in field-effect transistor switches · CPC title

• H02H7/0811

  for DC motors (H02H7/0833 takes precedence) · CPC title

• H02H3/202

  for DC systems · CPC title