Sensor interface circuits

Patent metadata

Field	Value
Publication number	US-9726705-B2
Application number	US-201414457954-A
Country	US
Kind code	B2
Filing date	Aug 12, 2014
Priority date	Aug 12, 2014
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

An interface circuit for a bridge sensor has a switch that connects to a resistive bridge circuit. The resistive bridge circuit includes a first input terminal, a second input terminal, and a pair of resistive branches that connect between the first and second input terminals. Both of the resistive branches include an output terminal. The switch is connected to the first input terminal and is in series with both resistive branches for connecting and disconnecting a voltage source from the resistive branch output terminals.

First claim

What is claimed is:

1. A sensor interface circuit, comprising:
first and second input terminals;
a resistive bridge circuit including a pair of parallel resistive branches connected between the first and second input terminals, both resistive branches including an output terminal disposed between serially arranged resistors of the resistive branches;
a first switch connected to the first input terminal and in series with the resistive branches for connecting a first voltage source to both resistive branch output terminals;
a second switch connected to the second input terminal and in series with the resistive branches for connecting a second voltage source to both resistive branch output terminals;
a first voltage source connected to the first input terminal through the first switch;
a second voltage source connected to the second input terminal through the first switch; and
a voltage differential measurement module connected to the resistive branch output terminals
wherein the sensor interface circuit has a first configuration and a second configuration, the first switch being closed and the second switch being open in the first configuration, the first switch being open and the second switch being closed in the second configuration,
wherein the differential measurement module is compare a differential voltage measurement acquired in the first configuration with a differential measurement acquired in the second configuration to determine at least one of magnitude and leakage in the circuit.

2. A circuit as recited in claim 1 , further including an output lead connected between an output of the first resistive branch and the voltage differential measurement module.

3. A circuit as recited in claim 2 , further including an input lead connecting the switch to the voltage differential measurement module through the output lead.

4. A method of detecting current leakage within a sensor interface circuit, comprising:
connecting a first voltage source to a first input terminal of a bridge sensor;
determining voltage at a first output terminal of a first output lead connected to a first resistive branch of the bridge sensor;
determining voltage at a second output terminal of a second output lead connected to a second resistive branch of the bridge sensor;
calculating a first differential between the determined voltages;
disconnecting the first voltage source from the first input terminal of the bridge sensor;
connecting a second voltage source to a second input terminal of the bridge sensor;
determining voltage at the first output terminal of the first lead connected to the first resistive branch of the bridge sensor;
determining voltage at the second output terminal of the second lead connected to the second resistive branch of the bridge sensor;
calculating a second differential between the determined voltages;
comparing the second differential with the first differential;
determining at least one of magnitude and location of a leakage resistor using comparison the second differential and first differential.

5. A method as recited in claim 4 , further including quantifying leakage current flow from one of the first and second output leads using the calculated first differential or second differential.

6. A method as recited in claim 4 , further including determining a location of the leakage current flow from one of the first and second output leads using the first differential.

7. A method as recited in claim 4 , wherein connecting the first voltage source to the first input terminal includes closing a first switch connected between the first voltage source and the first input terminal of the bridge sensor.

8. A method as recited in claim 4 , wherein connecting the second voltage source to the second input terminal includes closing a second switch connected between the second voltage source and the second input terminal of the bridge sensor.

9. A method as recited in claim 8 , further including:
disconnecting the first voltage source; and
quantifying leakage current from an input lead connected between the first switch and the first input terminal.

Assignees

• Hamilton Sundstrand Corp
• Simmonds Precision Products

Inventors

• Poisson Richard A
• Durkee Scott R
• Hess Gary L
• Abbott Michael

Classifications

• G01R17/12

  using comparison of currents, e.g. bridges with differential current output · CPC title

• G01R31/025 Primary

  Physics · mapped topic

• G01R31/52 Primary

  Testing for short-circuits, leakage current or ground faults · CPC title