Fluxgate Magnetic Field Detection Method and Circuit

Patent metadata

Field	Value
Publication number	US-2016334473-A1
Application number	US-201514975777-A
Country	US
Kind code	A1
Filing date	Dec 19, 2015
Priority date	May 12, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

A circuit and method for magnetic field detection is disclosed. A fluxgate sensor comprises a fluxgate having a first core and a second core. A sense coil has a first winding around the first fluxgate core and a second winding around the second fluxgate core. A fluxgate detection circuit is coupled to the sense coil and outputs a signal proportional to an external magnetic field applied to the fluxgate. A detection circuit is coupled to the first winding and outputs a signal that indicates whether voltage pulses have been detected on the first winding.

First claim

What is claimed is:

1 . A circuit for detecting magnetic fields, comprising:
a magnetic core having an excitation winding and a sense winding; a signal generator configured to provide excitation signals to the excitation winding; and a detection circuit configured to detect signals on the sense winding and to provide an output signal that indicates whether an external magnetic field is affecting the magnetic core, wherein the presence of the external magnetic field is detected when excitation winding signals are being generated but no sense winding signals are present.

2 . The circuit of claim 1 , wherein the magnetic core is part of a two-core fluxgate sensor, and wherein the excitation winding is wrapped around both cores and the sense winding is wrapped around a portion of a single core.

3 . The circuit of claim 2 , wherein the two cores of the fluxgate sensor are joined together at one or both ends.

4 . The circuit of claim 1 , wherein the magnetic core is part of a ring-core fluxgate sensor, and wherein the excitation winding is wrapped around substantially all of the ring cores and the sense winding is wrapped around a portion of the ring core.

5 . The circuit of claim 1 , wherein the detection circuit is configured to:
demodulate the signals on the sense winding to a sense signal; integrate the sense signal to a final value; and compare the final value to a fixed reference value.

6 . The circuit of claim 1 , wherein the excitation signals comprise current pulses, and wherein the detection circuit synchronizes the signals on the sense winding to the current pulses.

7 . The circuit of claim 1 , wherein the detection circuit further comprises:
a voltage-to-current converter having an input coupled to the sense coil; a demodulator switch receiving an output from the voltage-to-current converter and generating current signal; a capacitor coupled to the output of the demodulator switch; and a comparator coupled to the capacitor and to a reference voltage, the comparator outputting a signal indicating detection of voltage pulses on the core rod.

8 . A fluxgate sensor, comprising:
a fluxgate having a first core section and a second core section; a sense coil having a first winding around the first core section; and a detection circuit coupled to the first winding and configured to detect signals on the first winding and to provide an output signal that indicates whether the fluxgate is being effected by an external magnetic field.

9 . The sensor of claim 8 , wherein the presence of an external magnetic field is indicated when excitation signals are generated on the fluxgate and no corresponding first winding signals are detected by the detection circuit.

10 . The sensor of claim 9 , further comprising:
a signal generator configured to provide excitation signals to an excitation winding on the fluxgate.

11 . The sensor of claim 8 , wherein the first core section and the second core section are segments of a single magnetic core.

12 . The sensor of claim 8 , wherein the first core section and the second core section are separate magnetic cores in a two-core fluxgate sensor.

13 . The sensor of claim 12 , wherein the two cores of the fluxgate sensor are joined together at one or both ends.

14 . The sensor of claim 8 , wherein the first core section and the second core section are segments of a ring-core fluxgate sensor.

15 . The sensor of claim 8 , wherein the detection circuit is configured to:
demodulate the signals on the first winding to a sense signal; integrate the sense signal to a final value; and compare the final value to a fixed reference value.

16 . A method for detecting saturation in a fluxgate sensor, comprising:
demodulating signals detected on a sense winding of a magnetic core to a sense signal; integrating the sense signal to a final value; and comparing the final value to a fixed reference value.

17 . The method of claim 16 , further comprising:
providing an output signal that indicates whether the magnetic core is saturated, wherein saturation is detected when excitation signals are applied to the magnetic core but no significant sense winding signals are present.

18 . The method of claim 17 , wherein the excitation signals comprise current pulses applied by a signal generator to an excitation coil on the magnetic core, and wherein the sense signal is synchronized to the current pulses.

19 . The method of claim 16 , wherein the magnetic core is part of a two-core fluxgate sensor.

20 . The method of claim 16 , wherein the magnetic core is part of a ring-core fluxgate sensor.

Assignees

• Texas Instruments Deutschland

Inventors

• Snoeij Martijn F
• Schäffer Viola

Classifications

• G01R33/04

  using the flux-gate principle · CPC title

• G01R33/0041 Primary

  using feed-back or modulation techniques · CPC title