WO2019205775A1

WO2019205775A1 - Current sensor

Info

Publication number: WO2019205775A1
Application number: PCT/CN2019/075178
Authority: WO
Inventors: 王建国; 诸敏; 白建民; 于方艳
Original assignee: 宁波希磁电子科技有限公司
Priority date: 2018-04-27
Filing date: 2019-02-15
Publication date: 2019-10-31
Also published as: CN108398588A

Abstract

A current sensor, comprising: at least three magnetic sensor units (10a-10h) which are distributed surrounding the periphery of an area to be detected, the area to be detected being used for being penetrated with a wire to be detected (A); each magnetic sensor unit comprises: a first magnetic resistor (11a); and a second magnetic resistor (12a) which is in series connection with the first magnetic resistor (11a), two in series-connected terminals thereof being respectively connected to two terminals of a power supply, wherein the magnetic sensitive direction of the second magnetic resistor (12a) is opposite to the magnetic sensitive direction of the first magnetic resistor (11a); an output terminal (Vo) of each magnetic sensor unit is disposed between the first magnetic resistor (11a) and the second magnetic resistor (12a); and the output terminal (Vo) of each magnetic sensor unit is connected to the output terminal (Vo) of at least one of other magnetic sensor units. By means of the present current sensor, magnetic resistors in a plurality of magnetic sensor units are actually arranged in parallel connection, such that even if one magnetic sensor unit is broken, the remaining magnetic sensors may still work normally and output measurement results.

Description

Current sensor

Technical field

The present application relates to the field of sensor technologies, and in particular, to a current sensor.

Background technique

Current sensors are widely used in new energy, intelligent transportation, industrial control, smart home appliances and smart grids.

As shown in FIG. 1 , the prior art discloses a current sensor in which a plurality of magnetic sensor units are disposed around a wire to be tested, and each of the magnetic sensor units includes a first magnetoresistance and a second magnetoresistance in opposite directions of magnetic sensitivity. The adjacent magnetoresistors are connected end to end to form a sensor chain arranged in series, and both ends of the sensor chain serve as an output end of the current sensor.

However, in a series of sensor chains, once a magnetoresistive is damaged, the entire current sensor cannot output the measurement result.

Summary of the invention

In view of this, the embodiment of the present application provides a current sensor to solve the problem that one of the existing current sensors is damaged, which may cause the entire current sensor to fail to output the measurement result.

The embodiment of the present application provides a current sensor, comprising: at least three magnetic sensor units arranged around a region to be inspected, wherein the to-be-detected region is used for threading a wire to be tested; each magnetic sensor unit includes: a magnetoresistance; a second magnetoresistance, in series with the first magnetoresistance, two ends of the series connected to the power source respectively; wherein the second magnetoresistance is opposite to the magnetic sensitivity direction of the first magnetoresistance; An output of each magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance; an output of each of the magnetic sensor units is coupled to an output of at least one of the other magnetic sensor units.

Optionally, the outputs of the at least three sensor units are connected.

Optionally, the current sensor further includes: a first operational amplifier, an output end of the at least three magnetic sensor units being connected to be connected to a first input end of the first operational amplifier, the first operational amplifier The second input is connected to the reference voltage.

Optionally, the at least three magnetic sensor units comprise a first magnetic sensor unit and a second magnetic sensor unit, wherein the first magnetic sensor unit and the second magnetic sensor unit are connected to a magnetic source of the same potential source The magnetic sensitive direction of the resistor is opposite; the first magnetic sensor unit and the second magnetic sensor unit are alternately arranged around the area to be detected; the output ends of the first magnetic sensor are connected, The output ends of the second magnetic sensor are connected.

Optionally, the current sensor further includes: a second operational amplifier, wherein an output end of the first magnetic sensor unit is connected and then connected to a first input end of the second operational amplifier, the second operational amplifier The second input terminal is connected between the first magnetoresistance and the second magnetoresistance in each of the second magnetic sensor units.

Optionally, each of the magnetic sensor units further includes: a third magnetoresistance; a fourth magnetoresistor connected in series with the third magnetoresistance, and two ends connected in series are respectively connected to the two ends of the power source; wherein the fourth magnetoresistance and the third magnetism The magnetic sensitive direction of the resistor is opposite; in each magnetic sensor unit, the magnetic resistance of the magnetoresistance connected to the same potential source is opposite; the first output end of the magnetic sensor unit is disposed at the first magnetoresistance and the second Between the magnetoresistors, a second output end is disposed between the third magnetoresistance and the fourth magnetoresistance; a first output end of each magnetic sensor unit is connected, and a second output end is connected.

Optionally, the current sensor further includes: a third operational amplifier, wherein the first output end of each magnetic sensor unit is connected to the first input end of the third operational amplifier, and the first input of each magnetic sensor unit The two outputs are connected to the second input of the third operational amplifier.

Optionally, the at least three magnetic sensor units are evenly arranged around the to-be-detected area according to a predetermined geometric figure, and the predetermined geometric figure comprises a circle, an ellipse or a center-symmetric polygon.

In the current sensor provided by the embodiment of the present application, each magnetic sensor unit is respectively connected to two ends of the power source, and the output end of the magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance, so that the magnetic in the plurality of magnetic sensor units The resistors are actually arranged in parallel. Even if one magnetic sensor unit is damaged, the remaining magnetic sensors can still work normally and output measurement results.

DRAWINGS

The features and advantages of the present application will be more clearly understood from the following description of the appended claims.

Figure 1 shows a schematic diagram of a current sensor in the prior art;

2 shows a schematic diagram of a current sensor in accordance with an embodiment of the present application;

3 shows a schematic diagram of another current sensor in accordance with an embodiment of the present application;

FIG. 4 shows a schematic diagram of a signal processing module according to an embodiment of the present application; FIG.

Figure 5 shows a schematic diagram of the simulation;

Figure 6 shows the results of the simulation performed in the manner shown in Figure 5;

Figure 7 shows another simulation diagram;

Figure 8 shows the results of simulation performed in the manner shown in Figure 7;

FIG. 9 shows a schematic diagram of another current sensor according to an embodiment of the present application;

FIG. 10 shows a schematic diagram of another signal processing module according to an embodiment of the present application;

FIG. 11 shows a schematic diagram of another current sensor according to an embodiment of the present application;

FIG. 12 shows a schematic diagram of another signal processing module in accordance with an embodiment of the present application.

detailed description

The technical solutions in the embodiments of the present application are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present application. It is a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person skilled in the art based on the embodiments of the present application without creative efforts are within the scope of the present application.

In addition, in the current sensor provided by the embodiment of the present application, the magnetic sensor unit is arranged around the area to be detected, and the area to be detected is used to pierce the wire to be tested. According to the "Ampere Loop Theorem of Magnetic Fields": the integral of the magnetic induction B along any closed path is equal to the algebraic sum of the respective currents enclosed by the closed path, multiplied by the permeability", ie ∫B.d1=μI. The current sensor provided by the embodiment measures the magnetic induction intensity at a position around the wire to be tested by a magnetic sensor arranged around the wire to be tested, and obtains a line integral of the magnetic induction along a closed path around the wire to be tested by discretization, thereby The current value of the wire to be tested surrounded by the closed path is obtained, and the measured value of the current sensor is not affected by the position error of the wire to be tested, and is not interfered by the external magnetic field (the measured value is only related to the current value in the closed figure) ).

Embodiment 1

The embodiment of the present application provides a current sensor, as shown in FIG. 2 and FIG. 3, comprising at least three magnetic sensor units arranged around a region to be inspected for piercing a wire to be tested. Each of the magnetic sensor units includes a first magnetoresistance and a second magnetoresistance. The first magnetoresistance is connected in series with the second magnetoresistance. The two ends of the series are respectively connected to the two ends of the power source, and the second magnetoresistance and the magnetism of the first magnetoresistance The opposite direction is sensitive. The output of each magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance. The outputs of these magnetic sensor units are connected.

As shown in FIGS. 2 and 3, the magnetic sensor units 10a-10h are arranged around the wire A to be tested in a closed pattern, which may be a circular, elliptical or centrally symmetrical polygon or the like. The magnetic sensor unit 10a includes a first magnetoresistive resistor 11a and a second magnetoresistive resistor 12a. The resistance of the first magnetoresistive resistor 11a increases as the magnetic induction intensity at the position thereof increases (ie, the positive sensitive direction), and the second magnetoresistance The resistance of 12a decreases as the magnetic induction intensity at the position thereof increases (ie, the negative sensitive direction); or, the resistance of the first magnetoresistive resistor 11a decreases as the magnetic induction intensity at the position thereof increases ( That is, the negative sensitive direction), the resistance of the second magnetoresistive resistor 12a increases as the magnetic induction intensity at the position thereof increases (ie, the positive sensitive direction). The remaining magnetic sensor units 10b-10h are also arranged as such. The output terminals Vo of the magnetic sensors 10a-10h are connected together.

When the output ends of the current sensors provided in the embodiments of the present application are connected, the errors of the position of the wires to be tested or the external uniform magnetic field can be well suppressed. The reasons are as follows:

Taking the magnetic sensor unit as the center of the area to be detected and arranging a circular array around the wire to be tested, assume that the resistance of the first magnetoresistance is R ₁ =R ₀ +k·B _i , where R ₀ is the first The resistance of a magnetoresistance when the magnetic induction is zero, B _i is the magnetic induction intensity where the first magnetoresistive is located, k is the rate of change of the first magnetoresistance; and the resistance of the second magnetoresistive resistor is R ₂ =R ₀ - k·B _j , where R ₀ is the resistance of the second magnetoresistance when the magnetic induction intensity is zero (when the magnetic induction intensity is zero, the resistance values of the first magnetoresistance and the second magnetoresistance are equal), and B _j is the second magnetic field The magnetic induction intensity at which the resistance is located, and k is the rate of change of the second magnetoresistance. Then the signals output by the output ends of all the magnetic sensor units are

Wherein Vcc is the power supply voltage (ie, VCC in the drawing of the present application), and n is the number of magnetic sensor units.

If the wires to be tested are located at the center of the circular array without offset, the magnetic induction at each magnetic sensor unit is equal, assuming B ₀ , the output can be simplified to

If the wire to be tested deviates from the center of the circle or is affected by an external uniform magnetic field, then

Where δB _i is the amount of change in magnetic induction intensity when the i-th magnetic sensor unit is not offset from the wire to be tested. Since R _{0 is} much larger than the resistance change amount k·B, the first order approximation to equation (3) is

among them,

It is the average value of the amount of change in the magnetic induction intensity at the position where the n magnetic sensor units are located. Here,

So you can get

That is, the output ends of the current sensors provided by the embodiments of the present application can better suppress the error caused by the positional deviation of the wires to be tested or the external uniform magnetic field.

In addition, in the experimental data, according to the above formula (1), the magnetic sensor unit is arranged in a circular shape with a radius of 25 cm, and the position of the wire to be tested is deviated from a certain position of the center of the circle (as shown in FIG. 5), and the positional deviation can be obtained. The relationship between the amount and the measurement error of the current sensor is shown in Fig. 6. It can be seen from FIG. 6 that the output ends of the magnetic sensor units are connected such that the parallel connection of the plurality of magnetoresistors can better suppress the error caused by the positional deviation of the wires to be tested, and the more the number of magnetic sensor units, the more the effect of suppressing the error is. it is good.

In addition, according to the above formula (1), there is a wire with the same current beside the wire to be tested, and the two wires are simulated at a distance of 50 mm (as shown in Fig. 7), and the error generated by the external wire is as shown in Fig. 8. It can be seen from 8 that the output ends of the magnetic sensor units are connected such that the parallel connection of the plurality of magnetoresistors can better suppress the error caused by the magnetic field generated by the external current, and the more the number of the magnetic sensor units, the better the effect of suppressing the error.

It should be noted that the output terminals Vo of the magnetic sensors 10a-10h can be directly used as the output terminals after being connected. Alternatively, as an optional implementation manner of this embodiment, as shown in FIG. 4, the output terminal Vo is connected to the first input end of the first operational amplifier, and the second input end of the first operational amplifier is connected to the reference voltage. Vref. Amplifying the output signal Vo by an operational amplifier can make its value easier to acquire.

Embodiment 2

The embodiment of the present application provides a current sensor, as shown in FIG. 9, including at least three magnetic sensor units, which are arranged around the area to be detected, and the area to be detected is used to pierce the wire to be tested. Each of the magnetic sensor units includes a first magnetoresistance and a second magnetoresistance. The first magnetoresistance is connected in series with the second magnetoresistance. The two ends of the series are respectively connected to the two ends of the power source, and the second magnetoresistance and the magnetism of the first magnetoresistance The opposite direction is sensitive. The output of each magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance.

The at least three magnetic sensor units include a first magnetic sensor unit and a second magnetic sensor unit, wherein magnetic resistances of the magnetoresistors connected to the same potential source of the first magnetic sensor unit and the second magnetic sensor unit are opposite in direction. The first magnetic sensor unit and the second magnetic sensor unit are arranged alternately around each other around the area to be inspected. The output ends of the first magnetic sensor are connected, and the output ends of the second magnetic sensor are connected.

As shown in FIG. 9, 11x in 10x is the first magnetoresistance, and 12x is the second magnetoresistance, where x is any one of a-h. Among the magnetic sensor units 10a-10h, 10a, 10c, 10e, 10g are first magnetic sensor units whose first magnetoresistance is in a positive magnetic sensitive direction, and are both connected to VCC (ie, the first potential source), and the second magnetoresistance It is a negative magnetic sensitive direction and is connected to GND (ie, a second potential source); 10b, 10d, 10f, 10h are second magnetic sensor units whose first magnetoresistance is in a negative magnetic sensitive direction and are both connected to VCC ( That is, the first potential source), the second magnetoresistance is in the positive magnetic sensitive direction, and both are connected to GND (ie, the second potential source), as opposed to the first magnetic sensor unit.

It should be noted that, after the output ends of the first magnetic sensor unit in the current sensor provided in the embodiment of the present application are connected, and the output ends of the second magnetic sensor unit are connected, the digital signal processor and the embedded processor may be connected. The module, or connected to the operational amplifier, processes the first magnetic sensor output signal and the second magnetic sensor output signal to obtain a difference signal as an output value of the current sensor.

When connected to the operational amplifier, as shown in FIG. 10, the output of the first magnetic sensor unit is connected (Vo1 in FIG. 9) to the first input terminal of the second operational amplifier, and the output of the second magnetic sensor unit After the terminals are connected (Vo2 in FIG. 9), the second input terminal of the second operational amplifier is connected, and the operational amplifier is configured as a differential amplifier, which can amplify and output the difference between the signals of the first input terminal and the second input terminal. .

The output ends of the current sensors provided in the embodiments of the present application are connected to each other, which can better suppress the positional deviation of the wires to be tested or the errors caused by the external uniform magnetic field. For details, refer to the first embodiment. The difference is that the output voltage of the current sensor provided by the embodiment of the present application is Vo2-Vo1=2*(Vo-Vcc/2).

Embodiment 3

The embodiment of the present application provides a current sensor, as shown in FIG. 11, including at least three magnetic sensor units, which are arranged around the area to be detected, and the area to be detected is used to penetrate the wire to be tested. Each of the magnetic sensor units includes a first magnetoresistance and a second magnetoresistance. The first magnetoresistance is connected in series with the second magnetoresistance. The two ends of the series are respectively connected to the two ends of the power source, and the second magnetoresistance and the magnetism of the first magnetoresistance The opposite direction is sensitive. The output of each magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance.

Each of the magnetic sensor units further includes a third magnetoresistance and a fourth magnetoresistance, and the third magnetoresistance and the fourth magnetoresistor are connected in series, and the two ends of the series are respectively connected to the two ends of the power source. Wherein, the magnetic resistance of the fourth magnetoresistance and the third magnetoresistance are opposite. In each of the magnetic sensor units, the magnetic resistance of the magnetoresistances connected to the same potential source is opposite. The first output end of the magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance, and the second output end is disposed between the third magnetoresistance and the fourth magnetoresistance. The first output end of each magnetic sensor unit is connected, and the second output end is connected.

As shown in FIG. 11, the magnetic sensor units 20a-20d are arranged around the area to be detected, for the magnetic sensor unit 20y (where y may be a, b, c or d), which includes the first magnetoresistance 21y, The second magnetoresistive resistor 22y, the third magnetoresistance 23y, and the fourth magnetoresistive resistor 24y. The first magnetoresistance 21y and the fourth magnetoresistive resistor 24y are both positive magnetic sensitive directions, and the second magnetoresistance 22y and the third magnetoresistance 23y are both negative magnetic sensitive directions. The first magnetoresistive resistor 21y and the third magnetoresistive resistor 23y are connected to the same potential source (VCC), and the second magnetoresistive resistor 22y and the fourth magnetoresistive resistor 24y are connected to the same potential source (GND). The first output end is disposed between the first magnetoresistive resistor 21y and the second magnetoresistive resistor 22y, and the second output terminal is disposed between the third magnetoresistive resistor 23y and the fourth magnetoresistive resistor 24y. The first output of each magnetic sensor unit is connected (V+ in Fig. 11), and the second output of each magnetic sensor unit is connected (V- in Fig. 11).

It should be noted that, in the current sensor provided by the embodiment of the present application, after the first output end of the magnetic sensor unit is connected and the second output end is connected, the module may be connected to a digital signal processor, an embedded processor, or the like, or Connected to the operational amplifier, the signal of the first output of the magnetic sensor unit and the second output of the magnetic sensor unit is processed to obtain a difference signal as an output value of the current sensor.

When connected to the operational amplifier, as shown in FIG. 12, the first output end of the magnetic sensor unit is connected (V+ in FIG. 11) is connected to the first input end of the third operational amplifier, and the second output end of the magnetic sensor unit is connected. Connected (V- in Figure 11) to the second input of the third operational amplifier, the operational amplifier is configured as a differential amplifier that amplifies and outputs the difference between the first input and the second input .

The output ends of the current sensors provided in the embodiments of the present application are connected to each other, which can better suppress the positional deviation of the wires to be tested or the errors caused by the external uniform magnetic field. For details, refer to the first embodiment. The difference is that the output voltage of the current sensor provided by the embodiment of the present application is V+-V-=2*(Vo-Vcc/2).

While the embodiments of the present invention have been described with reference to the drawings, various modifications and changes can be made by those skilled in the art without departing from the spirit and scope of the invention. Within the limits defined.

Claims

A current sensor, comprising:

At least three magnetic sensor units are arranged around the area to be inspected, and the area to be detected is used for threading the wires to be tested; each magnetic sensor unit comprises:

First magnetoresistance;

a second magnetoresistance, in series with the first magnetoresistance, two ends of the series connected to the power source respectively; wherein the second magnetoresistance is opposite to the magnetic sensitivity direction of the first magnetoresistance;

An output end of each magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance;

An output of each magnetic sensor unit is coupled to an output of at least one of the other magnetic sensor units.
The current sensor of claim 1 wherein the outputs of said at least three sensor units are coupled.
The current sensor of claim 2, wherein the current sensor further comprises:

And a first operational amplifier, the output ends of the at least three magnetic sensor units are connected to be connected to a first input end of the first operational amplifier, and the second input end of the first operational amplifier is connected to a reference voltage.
The current sensor according to claim 1, wherein said at least three magnetic sensor units comprise a first magnetic sensor unit and a second magnetic sensor unit, wherein said first magnetic sensor unit and said second magnetic The magnetic resistance of the magnetoresistance connected to the same potential source in the sensor unit is opposite in direction;

The first magnetic sensor unit and the second magnetic sensor unit are alternately arranged around the area to be detected;

The output ends of the first magnetic sensors are connected, and the output ends of the second magnetic sensors are connected.
The current sensor of claim 4, wherein the current sensor further comprises:

a second operational amplifier, the output of the first magnetic sensor unit is connected to be connected to a first input end of the second operational amplifier, and the second input of the second operational amplifier is connected to each second Between the first magnetoresistance and the second magnetoresistance in the magnetic sensor unit.
The current sensor of claim 1 wherein each of the magnetic sensor units further comprises:

Third magnetoresistance;

The fourth magnetoresistance is connected in series with the third magnetoresistance, and the two ends of the series are respectively connected to the two ends of the power source; wherein the magnetic resistance of the fourth magnetoresistance and the third magnetoresistance are opposite;

In each magnetic sensor unit, the magnetic resistance of the magnetoresistance connected to the same potential source is opposite;

a first output end of the magnetic sensor unit is disposed between the first magnetoresistance and the second magnetoresistance, and a second output end is disposed between the third magnetoresistance and the fourth magnetoresistance;

The first output end of each magnetic sensor unit is connected, and the second output end is connected.
The current sensor according to claim 6, wherein the current sensor further comprises:

a third operational amplifier, the first output end of each magnetic sensor unit is connected to the first input end of the third operational amplifier, and the second output end of each magnetic sensor unit is connected to the third operation The second input of the amplifier.
The current sensor according to any one of claims 1 to 7, wherein said at least three magnetic sensor units are evenly arranged around said area to be detected in accordance with a predetermined geometric figure, said predetermined geometric figure comprising a circle, An ellipse or a center-symmetric polygon.