Integrable current sensors

• US 5,041,780 A
• Filed: 09/13/1988
• Issued: 08/20/1991
• Est. Priority Date: 09/13/1988
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Rippel, Wally E.
• Primary Examiner(s): Wieder, Kenneth
• Assistant Examiner(s): BURNS, WILLIAM
• Application Number:
  US07/243,808
• Time in Patent Office: 1,071 Days
• Field of Search: 324/251, 324/254, 324/117 R, 324/117 H, 324/127, 338/32 H, 336/84 R, 336/84 C, 336/84 M
• US Class Current: 324/117.00H
• CPC Class Codes: G01R 15/207 Constructional details independent of the type of device used

Abstract

A current conductor is provided with opposing notches to produce a restricted section and with magnetic flux sensors on opposite sides of the restricted current section. The flux sensors are connected to differential amplification circuitry. The restricted section increases the concentration of magnetic flux sensed, and the differential amplification circuitry eliminates the sensing of currents in external conductive paths. An electrostatic shield is provided between the shaped conductor and the magnetic flux sensors to elminate electrostatic effects on the output signal. The flux sensors and differential amplification circuitry is fabricated in an integrated circuit chip. For small currents, the shaped conductor may be deposited on the chip; otherwise a shaped conductor is formed and a mounting substrate of insulating material, such as ceramic, is used to support the integrated circuit chip on the shaped conductor with each of the two sensors centered respectively within the two opposite notches.

Claims

1. A coreless and coilless current sensor comprising

a shaped conductor having a single planar region of reduced cross section of the conductor through which total current must pass, and

at least one coreless and coilless magnetic flux sensing element positioned in close proximity to said single planar region of reduced cross section of said conductor.

2. A coreless and coilless current sensor comprising

a shaped conductor having a single planar region of reduced cross section of the conductor through which total current must pass,

two coreless and coilless magnetic flux sensing elements positioned in close proximity to said single planar region of reduced cross section of said conductor on opposite sides thereof, said current sensors being disposed in a single plane, said single plane being parallel to said single planar region of said conductor, and

differential amplifying means connected to said coilless magnetic flux sensors to produce an output voltage signal proportional to the difference in instantaneous magnetic flux vectors sensed by said sensor elements.

3. A current sensor comprising

a shaped conductor having a restricted section comprising a constriction in one region to reduce the cross section of the conductor through which total current must pass,

two magnetic flux sensing elements positioned in close proximity to said restricted section of said conductor on opposite sides thereof, and

differential amplifying means connected to said magnetic flux sensors to produce an output voltage signal proportional to the difference in instantaneous magnetic flux vectors sensed by said sensor elements,

wherein said two magnetic flux sensing elements and said differential amplifying means are produced on an integrated circuit chip with spacing between sensor elements for positioning said restrictive region of said shaped conductor between said sensor elements and in close proximity therewith, and an insulating substrate positioned between said semiconductor chip and said conductor.

4. A current sensor as defined in claim 3 wherein said shaped conductor is in the form of a flat bus and said constriction in said one region is formed with notches cut out on opposite edges, and said substrate is a flat piece of insulating material to which said shaped conductor is secured on one side and to which said chip is secured on the other side.

5. A current sensor as defined in claim 4 wherein said notches are rectangular and of even depth and width from each edge of said shaped conductor.

6. A current sensor as defined in claim 4 wherein said notches are V-shaped and of even depth with a flat portion at the point of furthest depth of each notch to leave a restricted section for conduction of current with parallel edges.

7. A current sensor as defined in claim 4 including an electrostatic shield between said current sensors and said shaped conductor.

8. A current sensor comprising

a shaped conductor having a restricted section comprising a constriction in one region to reduce the cross section of the conductor through which total current must pass,

two magnetic flux sensing elements positioned in close proximity to said restricted section of said conductor on opposite sides thereof, and

differential amplifying means connected to said magnetic flux sensors to produce an output voltage signal proportional to the difference in instantaneous magnetic flux vectors sensed by said sensor elements,

wherein said two magnetic flux sensing elements and said differential amplifying means are produced in an integrated circuit chip with spacing between said sensor elements for positioning said restricted section of said shaped conductor between said sensor elements and in close proximity therewith, and with said shaped conductor deposited on said integrated circuit chip with a thin insulating layer between said integrated circuit chip and said shaped conductor.

9. A current sensor as defined in claim 8 wherein said restricted section in said shaped conductor is formed with rectangular notches of even depth and width from each edge of said shaped conductor.

10. A current sensor as defined in claim 8 wherein said restricted section in said shaped conductor is formed with V-shaped notches of even depth with a flat portion at the point of furthest depth of each notch to leave a restricted section for conduction of current with parallel edges.

11. A current sensor as defined in claim 8 including a thin film of metal between said sensor elements in said integrated circuit chip and said shaped conductor with insulating material between said thin film of metal and said sensor element, and insulating material between said shaped conductor and said thin film of metal to provide an electrostatic shield between said sensor elements and said shaped conductor.