Control circuit for controlling an electronic circuit and method for this

• US 7,459,954 B2
• Filed: 02/07/2005
• Issued: 12/02/2008
• Est. Priority Date: 03/19/2004
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Kuehner, Jochen, Mueller, Stefan, Ruf, Armin, Rees, Stephan, Plikat, Robert
• Primary Examiner(s): Wells; Kenneth B.
• Application Number:
  US10/593,516
• Publication Number:
  US 20080001586A1
• Time in Patent Office: 1,394 Days
• Field of Search: 327/374, 363/51, 361/91.1
• US Class Current: 327/374
• CPC Class Codes: H03K 17/04123 in field-effect transistor switches
• CPC Class Codes: H03K 17/0822 in field-effect transistor switches
• CPC Class Codes: H03K 17/166 Soft switching
• CPC Class Codes: H03K 4/02 having stepped portions, e.g. staircase waveform

Abstract

A control circuit for controlling an electronic circuit, which has a current path through a semiconductor switch and a line; when the semiconductor switch is switched, the inductance of the line and/or of a component in the current path producing an excess voltage between a first and a second current-carrying terminal of the semiconductor switch; the control circuit having a controllable current source for charging or discharging a charge-controlled gate of the semiconductor switch with the aid of a control current, as well as a control unit; the control unit controlling the current source in such a manner, that in the case of a switching operation, the terminal voltage across the current-carrying terminals of the semiconductor switch does not exceed a predefined setpoint terminal voltage.

Claims

1. A control circuit for controlling an electronic circuit, comprising:

a semiconductor switch;

a current path through the semiconductor switch and a line, wherein when the semiconductor switch is switched, an inductance of at least one of the line and a component in the current path produces an excess voltage between a first current-carrying terminal and a second current-carrying terminal of the semiconductor switch;

a controllable current source for one of charging and discharging a charge-controlled gate of the semiconductor switch with the aid of a control current; and

a control unit controlling the current source in such a manner, that in the case of a switching operation, a terminal voltage across the first current-carrying terminal and the second current-carrying terminal does not exceed a predefined setpoint terminal voltage;

wherein in a circuit-closing operation, the control unit initially adjusts the setpoint terminal voltage to a first setpoint value, and then to a second setpoint value after expiration of a period of time, the second setpoint value being less than or equal to a low operating potential in the case of a self-blocking semiconductor switch, or greater than or equal to a high operating potential in the case of a self-conducting semiconductor switch.

2. The control circuit as recited in claim 1, wherein the setpoint terminal voltage is a function of a maximum permissible terminal voltage between the first current-carrying terminal and the second current-carrying terminal.

3. The control circuit as recited in claim 1, further comprising:

a comparator circuit for comparing the terminal voltage to the setpoint terminal voltage and controlling the current source as a function of a comparison result.

4. The control circuit as recited in claim 3, wherein the control unit includes a P controller for controlling the current source in such a manner, that a change in the control current is proportional to a difference between the terminal voltage and the setpoint terminal voltage.

5. The control circuit as recited in claim 1, wherein in one of a circuit-breaking operation and a circuit-closing operation, the terminal voltage is greater than an operating voltage applied to the current path.

6. The control circuit as recited in claim 5, wherein a control input of the semiconductor switch is chargeable via the current source to a potential that is lower than a lowest potential of the current path.

7. The control circuit as recited in claim 1, wherein the first setpoint value is selected so that the semiconductor switch operates in an active operating range.

8. The control circuit as recited in claim 7, further comprising:

a delay element in order to fix a period of time starting with a circuit-closing operation, the period of time at least corresponding to a time after which the circuit-closing operation is definitely ended.

9. The control circuit as recited in claim 8, further comprising:

a timing unit for selling the setpoint terminal voltage as a function of at least one of a current characteristic and a voltage characteristic in the current path.

10. The control circuit as recited in claim 9, wherein the semiconductor switch includes a field-effect transistor, the terminal voltage representing a drain-source voltage between a drain terminal and a source terminal, and a control input representing the gate terminal.

11. The control circuit as recited in claim 10, wherein the period of time is determined by the start of a commutation and a maximum commutation period after a start of the circuit-closing operation, the start of commutation being determined in that the increase in the gate-source voltage between the gate terminal and source terminal is 0 for the first time after the start of the circuit-closing operation.

12. The control circuit as recited in claim 10, wherein the period of time is determined by the start of a commutation and a maximum commutation period after the start of the circuit-closing operation, the start of commutation being determined in that the drain-source voltage falls below a threshold potential, the threshold potential being between a maximum operating potential and the first setpoint voltage.

13. The control circuit as recited in claim 10, wherein the period of time is determined by the start of a commutation and a maximum commutation period after the start of the circuit-closing operation, the start of commutation being determined in that the control current falls below a threshold value for the first time after the start of the circuit-closing operation, the threshold value being between 0 V and a control-current setpoint value.

14. The control circuit as recited in claim 1, wherein the semiconductor switch includes an IGBT component.

15. A method for controlling an electronic circuit, which has a current path through a semiconductor switch and a line, comprising:

switching the semiconductor switch, an inductance of the line producing an excess voltage between a first and a second current-carrying terminal of the semiconductor switch; and

one of charging and discharging a gate of the semiconductor switch with the aid of a control current, the control current being controlled in such a manner that, in the case of a switching operation, the terminal voltage of the semiconductor switch does not exceed a predefined setpoint terminal voltage;

wherein in a circuit-closing operation, a control unit initially adjusts the setpoint terminal voltage to a first setpoint value and then to a second setpoint value after expiration of a period of time, the second setpoint value being less than or equal to a low operating potential in the case of a self-blocking semiconductor switch, or greater than or equal to a high operating potential in the case of a self-conducting semiconductor switch.