Di/dt current sensing

• US 8,981,763 B2
• Filed: 09/22/2010
• Issued: 03/17/2015
• Est. Priority Date: 09/22/2010
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Ejury, Jens
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): NGUYEN, HOANG T
• Application Number:
  US12/887,835
• Publication Number:
  US 20120068691A1
• Time in Patent Office: 1,637 Days
• Field of Search: 324/103.R, 324/117.R, 324/117.H, 324/126, 324/127, 32476201-76203, 324260-263
• US Class Current: 324/127
• CPC Class Codes: G01R 15/181 using coils without a magnetic core, e.g. Rogowski coils
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence
• CPC Class Codes: H01F 19/04 Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range resonant circuits H03H
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter

Abstract

A circuit includes a power circuit and a current sensing circuit. The power circuit has a main current loop. The current sensing circuit is spaced apart from and electrically decoupled from the power circuit. The current sensing circuit is operable to generate a voltage proportional to an electromagnetic field generated responsive to a current change in the main current loop of the power circuit and generate a current information signal based on the voltage. The current information signal describes the current in the main current loop.

Claims

1. A circuit, comprising:

a power circuit having a main current loop;

a current sensing circuit spaced apart from and electrically decoupled from the power circuit, the current sensing circuit operable to generate a voltage proportional to an electromagnetic field generated responsive to a current change in the main current loop of the power circuit and generate a current information signal based on the voltage, the current information signal describing the current in the main current loop; and

a controller operable to control a current dependent operation of the power circuit based on the current information signal.

2. The circuit of claim 1, wherein the current sensing circuit comprises:

a conductive loop spaced apart from the power circuit and disposed over at least a portion of the main current loop, the conductive loop electrically decoupled from the power circuit and operable to generate the voltage proportional to the electromagnetic field;

a rectifier coupled to the conductive loop and operable to rectify the voltage generated by the conductive loop; and

a capacitor coupled to the rectifier and operable to accumulate charge responsive to the rectified voltage, wherein a voltage across the capacitor is related to the current in the main current loop.

3. The circuit of claim 2, wherein the rectifier comprises a plurality of silicon rectifier diodes coupled together to form a bridge rectifier, each of the plurality of silicon rectifier diodes having a negative forward voltage temperature coefficient.

4. The circuit of claim 2, wherein the current sensing circuit comprises a switch device coupled to the capacitor and operable to periodically reset the capacitor responsive to a reset signal.

5. The circuit of claim 4, wherein the switch device is operable to permit the capacitor to integrate the rectified voltage over a plurality of sampling periods prior to resetting the capacitor.

6. The circuit of claim 2, wherein the current sensing circuit comprises an analysis circuit operable to compare the voltage across the capacitor to a plurality of thresholds and generate the current information signal based on which of the plurality of thresholds the voltage exceeds.

7. The circuit of claim 6, wherein the analysis circuit comprises at least one of an analog-to-digital converter, an amplifier and a trigger circuit.

8. The circuit of claim 6, wherein the analysis circuit is operable to analyze the voltage across the capacitor over a plurality of sampling periods and smooth the current information signal over the plurality of sampling periods.

9. A method of operating a circuit including a power circuit with a main current loop and a current sensing circuit spaced apart from and electrically decoupled from the power circuit, the method comprising:

generating an electromagnetic field by the power circuit responsive to a current change in the main current loop of the power circuit;

generating a voltage by the current sensing circuit that is proportional to the electromagnetic field;

generating a current information signal by the current sensing circuit based on the voltage, the current information signal describing the current in the main current loop; and

controlling a current dependent operation of the power circuit based on the current information signal.

10. The method of claim 9, comprising:

generating the voltage to the electromagnetic field by a conductive loop of the current sensing circuit that is spaced apart from the power circuit, disposed over at least a portion of the main current loop, and electromagnetically coupled to at least a portion of the power circuit;

rectifying the voltage generated by the conductive loop; and

accumulating charge in a capacitor responsive to the rectified voltage, wherein a voltage across the capacitor is a function of the change in current in the main current loop.

11. The method of claim 10, comprising periodically resetting the capacitor responsive to a reset signal.

12. The method of claim 11, comprising permitting the capacitor to integrate the rectified voltage over a plurality of sampling periods prior to resetting the capacitor.

13. The method of claim 10, comprising:

comparing the voltage across the capacitor to a plurality of thresholds; and

generating the current information signal based on which of the plurality of thresholds the voltage exceeds.

14. A circuit, comprising:

a power circuit having a main current loop; and

a current sensing circuit spaced apart from and electrically decoupled from the power circuit, the current sensing circuit operable to generate a voltage proportional to an electromagnetic field generated responsive to a current change in the main current loop of the power circuit and generate a current information signal based on the voltage, the current information signal describing the current in the main current loop, the current sensing circuit comprising;

a conductive loop spaced apart from the power circuit and disposed over at least a portion of the main current loop, the conductive loop electrically decoupled from the power circuit and operable to generate the voltage proportional to the electromagnetic field;

a rectifier coupled to the conductive loop and operable to rectify the voltage generated by the conductive loop;

a capacitor coupled to the rectifier and operable to accumulate charge responsive to the rectified voltage, wherein a voltage across the capacitor is related to the current in the main current loop; and

a switch device coupled to the capacitor and operable to periodically reset the capacitor responsive to a reset signal and permit the capacitor to integrate the rectified voltage over a plurality of sampling periods prior to resetting the capacitor.

15. A circuit, comprising:

a power circuit having a main current loop; and

a current sensing circuit spaced apart from and electrically decoupled from the power circuit, the current sensing circuit operable to generate a voltage proportional to an electromagnetic field generated responsive to a current change in the main current loop of the power circuit and generate a current information signal based on the voltage, the current information signal describing the current in the main current loop, the current sensing circuit comprising;

a conductive loop spaced apart from the power circuit and disposed over at least a portion of the main current loop, the conductive loop electrically decoupled from the power circuit and operable to generate the voltage proportional to the electromagnetic field;

a rectifier coupled to the conductive loop and operable to rectify the voltage generated by the conductive loop;

a capacitor coupled to the rectifier and operable to accumulate charge responsive to the rectified voltage, wherein a voltage across the capacitor is related to the current in the main current loop; and

an analysis circuit operable to compare the voltage across the capacitor to a plurality of thresholds and generate the current information signal based on which of the plurality of thresholds the voltage exceeds.

16. The circuit of claim 15, wherein the analysis circuit comprises at least one of an analog-to-digital converter, an amplifier and a trigger circuit.

17. The circuit of claim 15, wherein the analysis circuit is operable to analyze the voltage across the capacitor over a plurality of sampling periods and smooth the current information signal over the plurality of sampling periods.