High resolution current sensing apparatus

• US 6,466,005 B2
• Filed: 09/18/2001
• Issued: 10/15/2002
• Est. Priority Date: 09/28/1999
• Status: Expired due to Term

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Sullivan, Gerard J., Anderson, Robert J., Yao, Jun Jason
• Primary Examiner(s): Nguyen, Vinh P.
• Application Number:
  US09/955,494
• Publication Number:
  US 20020021122A1
• Time in Patent Office: 392 Days
• Field of Search: 324/99.R, 324/106, 324/244, 324/259, 324/260, 324/658, 324/684, 324/117.R, 324/661, 324/98, 324/99.D, 340/664, 340/686.1, 177/210.C
• US Class Current: 324/117.00R
• CPC Class Codes: G01R 15/185 with compensation or feedback windings or interacting coils, e.g. 0-flux sensors using galvano-magnetic field sensors G01R15/20; conversion of DC into AC using transductors G01R19/20
• CPC Class Codes: G01R 17/08 in which a force or torque representing the measured value is balanced by a force or torque representing the reference value
• CPC Class Codes: G01R 19/20 using transductors , i.e. a magnetic core transducer the saturation of which is cyclically reversed by an AC source on the secondary side
• CPC Class Codes: G01R 33/0286 comprising microelectromechanical systems [MEMS] MEMS devices in general B81B

Abstract

A current sensor includes a deflectable member disposed in a magnetic field. Nulling or compensating members may be mechanically coupled to the deflectable member. Feedback or readout devices coupled to the structure provide signals indicative of deflection of the deflectable member under the influence of applied current and the magnetic field. Nulling current applied to the nulling members tends to oppose deflection of the deflectable member. The nulling current may be modulated to drive the feedback signal to a desired level and is used as a basis for calculating the current to be measured. The current may be measured directly upon calibration of feedback devices coupled to the deflectable member or to the nulling members. Arrays of sensors may be coupled to common busses for applying measured and nulling currents to sensors of the arrays and for detecting feedback signals.

Claims

1. A current sensor comprising:

a plurality of current sensing modules, each module including a deflectable sensing structure and a readout element coupled to the sensing structure for generating an output signal as a function of deflection of the sensing structure;

an input bus coupled to the sensing structures for applying a current to be measured;

an output bus coupled to the sensing structures for receiving the current to be measured; and

a readout bus coupled to the readout elements to detect the output signals.

2. The current sensor of claim 1, wherein the sensing modules are formed on a single substrate.

3. The current sensor of claim 1, wherein the sensing modules include a magnetic field source for producing a magnetic field, the sensing structures being deflectable under combined influence of the magnetic field and the current to be measured.

4. The current sensor of claim 3, wherein the magnetic field source is common to all of the current sensing modules.

5. The current sensor of claim 1, wherein the deflectable sensing structures each include a deflectable sensing beam configured to receive the current to be measured, and a deflectable nulling beam coupled to the sensing beam for receiving a nulling current to resist deflection of the sensing beam.

6. The current sensor of claim 1, wherein the readout elements include capacitors linked to the sensing structures, and wherein the readout bus includes conductive paths coupled to electrodes of the capacitors.