Current detection device and method for sensing an electrical current

Patent metadata

Field	Value
Publication number	US-10013008-B2
Application number	US-201415117513-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Feb 13, 2014
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

The invention relates to the evaluation of a variable of an electric current in a power path by evaluating another electric current in a measuring path. To avoid excessively large electric currents in the measuring path, the current in said path is limited to a predetermined maximum limit value.

First claim

The invention claimed is:

1. A current detection device ( 10 ) for sensing an electric current (I sense ) in a measuring path, which conducts an electric current that corresponds to an electric current (I E ) in a power path, the current detection device comprising:
a current measuring device ( 11 ), which is disposed in the measuring path and is designed to provide an output signal that corresponds to an electric current flowing through said current measuring device ( 11 ); and
a current limiting device ( 12 ) configured to limit the electric current through the current measuring device ( 11 ) to a predetermined maximum limit value,
wherein, when the electric current (I E ) in the power path exceeds a predefined value, the electric current (I Sense ) in the measuring path is limited to the predetermined maximum limit value.

2. The current detection device ( 10 ) according to claim 1 , wherein the current measuring device ( 11 ) is configured to provide a voltage signal which is proportional to the electric current that flows through said current measuring device ( 11 ), and when the electric current (I Sense ) in the measuring path is limited to the predetermined maximum limit value, the electric current (I E ) through the power path is not limited.

3. A current detection device ( 10 ) for sensing an electric current (I sense ) in a measuring path, which conducts an electric current that corresponds to an electric current (I E ) in a power path, the current detection device comprising:
a current measuring device ( 11 ) disposed in the measuring path and configured to provide an output signal that corresponds to an electric current flowing through said current measuring device ( 11 ), the current measuring device including an analog/digital converter configured to convert the output signal dependent on the electric current flowing through the current measuring device ( 11 ) into a digital signal; and
a current limiting device ( 12 ), which is configured to limit the electric current through the current measuring device ( 11 ) to a predetermined maximum limit value.

4. The current detection device ( 10 ) according to claim 1 , wherein the current limiting device ( 12 ) comprises a reference voltage source (U Ref ) which is designed to provide a predetermined reference voltage; and the current limiting device ( 12 ) is designed to compare a further voltage signal to the reference voltage provided by the reference voltage source (U Ref ) and to adjust the electric current through the current measuring device ( 11 ) on the basis of the comparison.

5. The current detection device ( 10 ) according to claim 4 , wherein the current limiting device ( 12 ) comprises a transistor (T 5 ) having a control connection and said current limiting device ( 12 ) is designed to provide, at the control connection of the transistor (T 5 ), a control signal based on the comparison between provided reference voltage and the further voltage signal.

6. A circuit arrangement ( 1 ) for providing an electric current (I E ), the circuit arrangement comprising:
a current control device ( 20 ) which is designed to provide an electric current (I E ) in a power path and to provide an electric measuring current (I Sense ) in a measuring path which corresponds to the electric current (I E ) provided in the power path; and
the current detection device ( 10 ) according to claim 1 .

7. The circuit arrangement ( 1 ) according to claim 6 , wherein the current control device ( 20 ) comprises one bipolar transistor having an insulated gate, the one bipolar transistor providing the electric measuring current (I Sense ) to the measuring path and the electric current (I E ) to the power path.

8. A method for sensing an electric current (I Sense ) in a measuring path, which conducts an electric current that corresponds to an electric current (I E ) in a power path, comprising the following steps:
providing a current measuring device ( 11 ) for the electric current (I Sense ) in the measuring path;
sensing the electric current (I Sense ) through the current measuring device ( 11 )-provided in the measuring path;
emitting an output signal from the current measuring device ( 11 ) as a function of the sensed electric current (I Sense ) in the measuring path;
limiting the electric current (I Sense ) through the current measuring device ( 11 ) in the measuring path to a predetermined maximum limit value; and
not limiting the electric current (I E ) through the power path when the electric current (I Sense ) in the measuring path is limited to the predetermined maximum limit value.

9. The method according to claim 8 , further comprising the steps:
providing a predetermined reference voltage; and
comparing the emitted output signal to the predetermined reference voltage;
wherein the step for limiting the electric current adjusts the current in accordance with the comparison of the predetermined reference voltage to a voltage value.

10. The method according to claim 8 , including providing a current control device ( 20 ) including one bipolar transistor that outputs both the electric current (I Sense ) in the measuring path and the electric current (I E ) in the power path,
wherein the one bipolar transistor includes an insulated gate.

11. The method according to claim 10 , wherein the current measuring device ( 11 ) is a resistor, and
the limiting of the electric current through the current measuring device ( 11 ) is provided by a transistor (T 5 ) having a control connection.

12. The method according to claim 10 , wherein the current measuring device includes an analog/digital converter configured to convert the output signal of the current measuring device ( 11 ) into a digital signal.

13. The circuit arrangement according to claim 7 , the circuit arrangement further comprising a compensation circuit ( 30 ) that receives the electric current (I E ) from the power path.

14. The circuit arrangement according to claim 13 , the compensation circuit ( 30 ) including two voltage sources, a current source (I O ), and transistors (T 1 -T 4 ).

Assignees

• Bosch Gmbh Robert

Inventors

• Sievert Holger
• Butzmann Stefan

Classifications

• G01R15/146

  Measuring arrangements for current not covered by other subgroups of G01R15/14, e.g. using current dividers, shunts, or measuring a voltage drop (if no voltage isolation is involved G01R1/203 or G01R19/0092) · CPC title

• G05F1/573 Primary

  with overcurrent detector · CPC title

• G01R19/0092

  Measuring current only · CPC title