RU2564383C1 - Variable magnetic field sensor - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: sensor includes a magnetosensitive sensor, the control conductor of which is connected with its ends to an external conductor so that a closed circuit is formed. The closed circuit formed with the control conductor and the external conductor connected to it is earthed on the middle of length of the external conductor. In the magnetosensitive sensor, the magnetosensitive element and the control conductor are separated with an insulating layer. The magnetosensitive sensor is arranged inside a cover from magnetically soft material with insulation by a dielectric layer from it. Inside the closed circuit there can be arranged a ferromagnetic concentrator with a multiturn coil wound on it, which is connected with its ends to the realigned capacitor.

EFFECT: providing stable measurement of a magnetic field at movement of the sensor itself in low-frequency and constant magnetic fields of the Earth, surrounding magnetised objects and electromagnetic instruments, improvement of interference immunity of the sensor, including against electrical pulse interference.

7 cl, 2 dwg

Description

The invention relates to the field of instrumentation, in particular to sensors and converters of physical quantities, and can be used in instruments for monitoring and measuring an alternating magnetic field.

A known design of the sensor, containing at least one circuit (loop) of a superconducting material and adjacent magnetoresistive element (US patent No. 8405390, G01R 33/05, G01R 33/02, publ. 03/26/2013). The device also contains a heating element.

Obtaining the desired technical result is hindered by the need to perform a circuit of their superconducting material and the use of a heating element.

A device for measuring a magnetic field is known according to the application of US No. 20060226827, G01R 15/18, publ. 10/12/2006, The specified device is the closest to the claimed invention. The following features coincide with the essential features of the claimed invention: the presence of at least one magnetosensitive sensor, the control conductor of which is connected at its ends to an external conductor with the formation of a closed loop, and in the magnetosensitive sensor, the magnetosensitive element and the control conductor are separated by an insulating layer.

Obtaining the required technical result is hindered by limiting the area of the closed loop, which determines the sensitivity of the device; reduced noise immunity of the device to electrical interference; limited functionality for taking measurements while moving the device, as changes in induction lead to distortion of the received signal due to multiplicative transformations in the magnetically sensitive sensor.

The objective of the invention is to provide a magnetoresistive sensor for measuring an alternating magnetic field.

The technical result is to ensure:

- the stability of the measurement of an alternating magnetic field when moving the sensor itself in the constant and low-frequency magnetic fields of the Earth, surrounding magnetized objects and electromagnetic sources;

- increase the noise immunity of the sensor from electrical noise (for example, high-level electric potentials);

- increase the sensitivity of the sensor;

- the possibility of tuning the frequency of the received narrowband alternating magnetic signal.

To achieve the above technical result, the variable magnetic field sensor contains at least one magnetically sensitive sensor, in which the magnetically sensitive element is separated from the control conductor by an insulating layer, and the control conductor is connected at its ends to an external conductor with the formation of a closed loop that is grounded, the magnetosensitive sensor is placed inside the shell of soft magnetic material with insulation from it with a dielectric layer.

In particular cases of the invention, a closed loop formed by the control conductor of a magnetically sensitive sensor connected at its ends to an external conductor is grounded at a point located half its length.

In particular cases of the invention, the outer conductor is made narrowing at the points of connection of the magnetically sensitive sensor to the control conductor.

In particular cases of the invention, the thickness of the insulating layer between the control conductor and the magnetically sensitive element is more than two times less than the thickness of the dielectric layer between the control conductor and the sheath.

In particular cases of the invention, a magnetic field concentrator is placed inside a closed loop with a multi-turn coil placed on it, connected to a variable capacitor.

In particular cases of the invention, the magnetic field concentrator is made in the form of a ferrite rod.

In particular cases of the invention, the magnetic field concentrator is made of film.

In particular cases of the invention, the magnetic field concentrator is made with a constriction located at a location in a closed loop.

The present invention differs from the closest analogue by the following features: grounding of the circuit formed by the external and connected to it by the control conductor, and the placement of the magnetosensitive sensor inside the shell of magnetically soft material with insulation from it with a dielectric material.

Between the totality of essential features and the achieved technical result, there is a causal relationship.

The electrical “grounding” of the closed loop shorts the stray currents excited by the induced electric potentials, which excludes their flow through the closed loop section, the control conductor of the magnetically sensitive sensor, and thereby excludes the registration of an interference signal.

Placing the magnetosensitive sensor inside the shell of magnetically soft material with insulation from it with a dielectric layer shields the sensor from registering directly the magnetically sensitive element of external constant and variable fields. The magnetic field is recorded only from the current flowing through the control conductor. To eliminate galvanic short circuits in the control conductor and the magnetically sensitive element by the conductive material of the soft magnetic shell, insulating layers of dielectric material are located between it and the magnetically sensitive sensor.

The electrical "grounding" of the closed loop, in essence, is a galvanic connection of a selected portion of the closed loop with the magnetic shell of the magnetically sensitive sensor and one of its terminals having zero potential.

Placing a ferromagnetic concentrator inside a closed loop results in an increase (concentration) of the alternating magnetic flux passing through the closed loop. The flow is even more concentrated in the narrowing of the hub, which leads to an increased level of excitation of alternating current in a closed loop. Placing a multi-turn coil connected to a variable capacitor (resonant circuit) on the hub allows you to tune to the frequency of the received signal of an alternating magnetic field.

The invention is illustrated in the drawing, where

in FIG. 1 is a diagram of a variable magnetic field sensor;

in FIG. 2 shows a diagram (section) of the arrangement of a magnetically sensitive element with a control conductor inside the shell.

The variable magnetic field sensor contains at least one magnetically sensitive sensor 1, the control conductor 2 of which is connected at its ends to the external conductor 3 to form a closed loop 4. The closed circuit 4 formed by the control conductor 2 and connected to it by an external conductor 3 has grounding "at point 5. In the magnetosensitive sensor 1 (Fig. 2), the magnetosensitive element 6 and the control conductor 2 are separated by an insulating layer 7. The magnetosensitive sensor 1 is placed inside the shell of magnesium soft material 8 with isolation from it by a dielectric layer 9.

The thickness of the insulating layer 7 between the control conductor and the magnetically sensitive element is more than two times less than the thickness of the dielectric layer 9 between the control conductor and the sheath.

The closed loop formed by the control conductor of the magnetosensitive sensor 2, connected at its ends to the external conductor 3, has an “earth” 5, which is a galvanic connection using, for example, a conductor, a section on the external conductor 3, a sheath of soft magnetic material 8, and an electrical output of the magnetically sensitive element of the sensor 1 having zero electric potential.

Inside the closed loop, a magnetic field concentrator 10 can be placed, which has a narrowing 11 in the region of the outer conductor 3. The multi-turn coil 12 is placed on the hub 10, connected to a variable capacitor 13.

The magnetic field concentrator 10 may be made in the form of a ferrite rod or film.

The external conductor 3 can be made narrowing at the points of connection to the control conductor 2 of the magnetically sensitive sensor 1.

The device operates as follows.

When the magnetic flux penetrating the circuit formed by the control conductor of the magnetosensitive sensor 2 connected at its ends to the external conductor 3 changes in time, an electric ring current arises in the circuit. An alternating magnetic field generates a vortex electric field. If a closed conductor is located in an alternating magnetic field, then the vortex electric field drives the charged particles of this conductor - this is how the induction current arises. The induction current is excited in a closed loop according to the Lenz rule and is always directed so that the magnetic field created by it prevents the magnetic flux causing the induction current from changing. Grounding under these conditions does not affect the operation of the sensor. When using a concentrator in the sensor, the signal from the alternating magnetic field is concentrated (amplified), firstly, in the magnetic field concentrator 10 and, secondly, in its narrowed section 11. By means of an oscillating circuit consisting of a coil 12 and a tunable capacitor 13, resonant tuning to the oscillation frequency of an alternating magnetic signal. As a result, an alternating current is excited in this oscillatory circuit, which, thanks to the hub 10, is transformed into an external conductor 3 and a control conductor 2. This current, due to the ratio of the turns of the coil 12 and the external conductor 3, as well as the narrowing 11, is amplified and registered, due to the arising around control conductor 2 to the magnetic field. Moreover, the specified magnetic field passes without loss through the insulating layer 7.

When exposed to alternating electric fields in the sensor in the absence of alternating magnetic fields in the circuit formed by the control conductor of the magnetically sensitive sensor 2, connected at its ends to an external conductor 3, there is no ring current. In this case, the circuit can be considered as a conductor placed in an alternating electric field in which electrostatic induction occurs, which causes a redistribution of charge on the surface of the outer conductor 3. In this case, the presence of grounding located at half the length of the outer conductor 3 leads to the fact that electric charges move towards the ground along the lines of the external circuit 3 from the junction of the control conductor 2 with the external circuit 3 to the ground point 5, similar to the flow of charges into the lightning s. Thus, grounding prevents the flow of currents through the control conductor 2 of the magnetoresistive sensor 1 and their registration.

When the sensor is exposed to both alternating magnetic and alternating electric fields, induction currents pass through the control conductor 2, and the currents arising from electrostatic induction do not affect the currents flowing in the control conductor. Currents arising in the control conductor 2 are recorded by a magnetically sensitive element.

The sensor can be manufactured using planar technology on standard equipment.

Claims (7)

1. The variable magnetic field sensor containing at least one magnetically sensitive sensor, in which the magnetically sensitive element is separated from the control conductor by an insulating layer, and the control conductor is connected at its ends to an external conductor with the formation of a closed loop, characterized in that the magnetosensitive sensor is located inside shells of soft magnetic material with insulation from it with a dielectric layer, and a closed loop formed by the control conductor of the magnetically sensitive sensor ka, connected at its ends to an external conductor, is grounded, and the grounding is located at half the length of the external conductor. 2. The sensor according to claim 1, characterized in that the external conductor is made narrowing at the points of connection of the magnetosensitive sensor to the control conductor. 3. The sensor according to claim 1, characterized in that the thickness of the insulating layer between the control conductor and the magnetically sensitive element is more than two times less than the thickness of the dielectric layer between the control conductor and the sheath. 4. The sensor according to claim 1, characterized in that a magnetic field concentrator with a multi-turn coil located on it connected to a variable capacitor is placed inside the closed loop. 5. The sensor according to claim 4, characterized in that the magnetic field concentrator is made in the form of a ferrite rod. 6. The sensor according to claim 4, characterized in that the magnetic field concentrator is made of film. 7. The sensor according to claim 4, characterized in that the magnetic field concentrator is made with a constriction located at a location in a closed loop.

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