阅读说明：本技术 实时补偿杂散磁场的装置及方法 (Device and method for compensating stray magnetic field in real time ) 是由 李玉清 宋素雅 马杰 武寄洲 肖连团 贾锁堂 于 2019-09-05 设计创作，主要内容包括：本发明是一种实时补偿杂散磁场的装置及方法,属于消除环境中杂散磁场技术领域。本发明的线性电源、补偿线圈I、补偿线圈Ⅱ、采样电阻和场效应管依次串联,线性电源的正极与补偿线圈组连接,其负极与场效应管的源极连接,磁通门计设置在补偿线圈组的外侧,采样电阻两端电压接入到反馈电路,反馈电路分别与磁通门计、采样电阻和场效应管连接,测量磁通门计x、y方向的输出电压与其z方向杂散磁场的依赖关系,将磁通门计x、y方向的输出电压的平均值乘以一比例因子后的电压信号与采样电阻两端的电压比较,所获得的误差信号经过带有比例、积分的反馈电路处理,输入到场效应管的栅极-源极电压端口,以实现对环境中变化杂散磁场的实时补偿。(The invention discloses a device and a method for compensating stray magnetic fields in real time, and belongs to the technical field of stray magnetic field elimination in the environment. The linear power supply, the compensating coil I, the compensating coil II, the sampling resistor and the field effect transistor are connected in series in sequence, the anode of the linear power supply is connected with the compensating coil group, the negative electrode of the magnetic flux gate meter is connected with the source electrode of the field effect tube, the magnetic flux gate meter is arranged on the outer side of the compensation coil group, voltages at two ends of the sampling resistor are connected to the feedback circuit, the feedback circuit is respectively connected with the magnetic flux gate meter, the sampling resistor and the field effect tube, the dependency relationship between output voltages in the x direction and the y direction of the magnetic flux gate meter and stray magnetic fields in the z direction of the magnetic flux gate meter is measured, voltage signals obtained by multiplying the average value of the output voltages in the x direction and the y direction of the magnetic flux gate meter by a scale factor are compared with the voltages at two ends of the sampling resistor, and obtained error signals are processed by the feedback circuit with proportion and integral and input to a grid electrode-source electrode voltage port of the field effect tube.)

1. An apparatus for compensating for stray magnetic fields in real time, comprising: the device comprises a linear power supply (1), a compensation coil group, a sampling resistor (4), a field effect transistor (5), a fluxgate meter (6) and a feedback circuit (7), wherein the linear power supply (1), the compensation coil group, the sampling resistor (4) and the field effect transistor (5) are sequentially connected in series through a lead to form a current loop, the positive electrode of the linear power supply (1) is connected with the compensation coil group, and the negative electrode of the linear power supply is connected with the source electrode of the field effect transistor (5); the fluxgate meter (6) is arranged at the outer side of the compensation coil group, the z direction of the fluxgate meter (6) is consistent with the axial direction of the compensation coil group, and a target magnetic field along the z direction at the center of the compensation coil group has no influence on magnetic fields in the x direction and the y direction at the fluxgate meter (6); the feedback circuit (7) is connected to two ends of the sampling resistor (4), and the feedback circuit (7) is also connected with the fluxgate meter (6) and the field effect tube (5) respectively.

2. The apparatus of claim 1, wherein the apparatus comprises: the linear power supply (1) operates in a constant voltage mode.

3. The apparatus of claim 1, wherein the apparatus comprises: the compensating coil group comprises a compensating coil I (2) and a compensating coil II (3), the compensating coil I (2) and the compensating coil II (3) are square coils and are provided with currents which are the same in direction and magnitude.

4. The apparatus of claim 3, wherein the apparatus comprises: and the distance between the two coils of the compensation coil I (2) and the compensation coil II is equal to the average side length of the coils.

5. The apparatus of claim 1, wherein the apparatus comprises: measuring the dependency relationship between the output voltage of the fluxgate meter (6) in the x and y directions and the stray magnetic field in the z direction; and comparing a voltage signal obtained by multiplying the average value of the output voltages of the fluxgate meter (6) in the x and y directions by a scaling factor with the voltage at two ends of the sampling resistor (4), processing an obtained error signal by a feedback circuit (7) with proportion and integration, and inputting the error signal into a grid-source voltage port of the field effect tube (5) to realize real-time compensation of the variable stray magnetic field.

6. A method of compensating for stray magnetic fields in real time as claimed in any of claims 1 to 5, characterized by: the method comprises the following steps:

(1) adjusting the distance between the compensation coil I (2) and the compensation coil II (3) to enable the compensation coil group to meet the requirements of Helmholtz coils, so that uniform magnetic fields with the same size are generated in a smaller space range;

(2) placing a compensation coil I (2) and a compensation coil II (3) at spatial positions to enable the center of a compensation coil group to coincide with a required target magnetic field position;

(3) the linear power supply (1) works in a constant voltage mode, and the compensation coil I (2) and the compensation coil II (3) are supplied with currents with the same direction and the same magnitude;

(4) the sampling resistor (4) is used for measuring the current in the compensation coil group, when the current flows through the sampling resistor (4), two ends of the sampling resistor can generate a voltage signal, and the voltage signal and a compensation magnetic field generated by the compensation coil group have a determined proportional relation;

(5) the field effect transistor (5) can change the resistance of a drain electrode-source electrode by controlling the voltage of the gate electrode-source electrode thereof, the signal output by the feedback circuit (7) is input to the gate electrode-source electrode, and the current of the compensation coil group is changed by adjusting the effective resistance of the drain electrode-source electrode of the field effect transistor (5), so that the compensation coil group generates a uniform magnetic field at the center to compensate the stray magnetic field in the environment;

(6) the fluxgate meter (6) is placed on the outer side of the compensation coil, the z direction of the fluxgate meter (6) is along the axial direction of the compensation coil group, and a target magnetic field along the z direction at the center of the compensation coil has no influence on magnetic fields in the x direction and the y direction at the fluxgate meter (6); because the distribution of the spatial magnetic field meets the requirement that the divergence of Maxwell equation is zero, the magnetic fields of the fluxgate meter (6) in the x and y directions are in direct proportion to the stray magnetic field along the axial direction at the center of the compensation coil and can change along with the change of the stray magnetic field;

(7) the dependence of the output voltage of the fluxgate meter (6) in the x and y directions and the stray magnetic field in the z direction can be obtained through measurement; and comparing a voltage signal obtained by multiplying the average value of the output voltages of the fluxgate meter (6) in the x and y directions by a scaling factor with the voltage at two ends of the sampling resistor (4), processing an obtained error signal by a feedback circuit (7) with proportion and integral, and inputting the error signal into a grid-source voltage port of the field effect tube (5) to realize real-time compensation of the variable stray magnetic field.

Technical Field

The invention discloses a device and a method for compensating stray magnetic fields in real time, and belongs to the technical field of stray magnetic field elimination in the environment.

Background

A homogeneous magnetic field can be generated over a local spatial range using a set of energized helmholtz coils. The precision and stability of the spatial magnetic field are very important for many scientific research and engineering applications, such as precision measurement, atomic interferometers, new product calibration, and the like. The current in the coil can be accurately controlled by adopting a feedback circuit with a Hall sensor and a field effect tube, and the accuracy and the stability of a magnetic field at the symmetrical center of the coil are improved. However, the magnetic field in the space is affected by the stray magnetic field in the environment, so that the precision and stability of the magnetic field are deteriorated. The stray magnetic field in the environment mainly comprises a geomagnetic field, non-demagnetized materials, a power supply and a weak magnetic field generated by other electrified instruments, and in addition, an elevator and a subway close to an electrified coil can generate a stray magnetic field with amplitude changing along with time at the center of the coil. Therefore, how to eliminate the influence of stray magnetic fields in the environment, especially the magnetic field that changes irregularly with time, becomes the key to improve the precision and stability of the spatial magnetic field.

Disclosure of Invention

The invention aims to eliminate the influence of stray magnetic fields in the environment on the precision and the stability of a space magnetic field, and provides a device and a method for compensating the stray magnetic fields in real time aiming at the stray magnetic fields which change irregularly along with time in practice.

The invention is realized by adopting the following technical scheme: a device for compensating stray magnetic fields in real time comprises a linear power supply, a compensation coil group, a sampling resistor, a field effect transistor, a fluxgate meter and a feedback circuit, wherein the linear power supply, the compensation coil group, the sampling resistor and the field effect transistor are sequentially connected in series through a lead to form a current loop, the positive pole of the linear power supply is connected with the compensation coil group, and the negative pole of the linear power supply is connected with the source electrode of the field effect transistor; the fluxgate meter is arranged on the outer side of the compensation coil group, the z direction of the fluxgate meter is consistent with the axial direction of the compensation coil group, and a target magnetic field along the z direction at the center of the compensation coil group has no influence on magnetic fields in the x and y directions at the fluxgate meter; the feedback circuit is connected to two ends of the sampling resistor and is also connected with the fluxgate meter and the field effect tube respectively.

Further, the linear power supply operates in a constant voltage mode.

Furthermore, the compensation coil group comprises a compensation coil I and a compensation coil II, the compensation coil I and the compensation coil II are square coils, and currents with the same direction and the same size pass through the square coils.

Further, the distance between the two coils of the compensation coil I and the compensation coil II is equal to the average side length of the coils.

Further, the dependence of the output voltage of the fluxgate meter in the x and y directions on the stray magnetic field in the z direction is measured. And comparing a voltage signal obtained by multiplying the average value of the output voltages of the fluxgate meter in the x and y directions by a scaling factor with the voltage at two ends of the sampling resistor, processing an obtained error signal by a feedback circuit with proportion and integral, and inputting the error signal into a grid-source voltage port of the field effect tube so as to realize real-time compensation of the variable stray magnetic field.

The invention also provides a method for compensating stray magnetic fields in real time, which is carried out according to the device and comprises the following steps:

(1) adjusting the distance between the compensation coil I and the compensation coil II to enable the compensation coil group to meet the requirements of Helmholtz coils and generate uniform magnetic fields with equal sizes in a smaller space range;

(2) placing the compensation coil I and the compensation coil II at spatial positions to enable the center of the compensation coil group to be superposed with the required target magnetic field position;

(3) the linear power supply works in a constant voltage mode, and the compensation coil I and the compensation coil II are supplied with currents with the same direction and the same magnitude;

(4) the sampling resistor is used for measuring the current in the compensation coil group, when the current flows through the sampling resistor, a voltage signal is generated at two ends of the sampling resistor, and the voltage signal and a compensation magnetic field generated by the compensation coil group have a determined proportional relation;

(5) the field effect transistor can change the resistance of a drain electrode-source electrode by controlling the voltage of the gate electrode-source electrode of the field effect transistor, inputs a signal output by the feedback circuit on the gate electrode-source electrode, and changes the current of the compensation coil group by adjusting the effective resistance of the drain electrode-source electrode of the field effect transistor, so that the compensation coil group generates a uniform magnetic field at the center to compensate the stray magnetic field in the environment;

(6) the fluxgate meter is placed on the outer side of the compensation coil, so that the z direction of the fluxgate meter is along the axial direction of the compensation coil group, and a target magnetic field along the z direction at the center of the compensation coil has no influence on magnetic fields in the x and y directions at the fluxgate meter; because the distribution of the spatial magnetic field meets the requirement that the divergence of Maxwell equation is zero, the magnetic fields of the fluxgate meter in the x and y directions are in direct proportion to the stray magnetic field along the axial direction at the center of the compensation coil and can change along with the change of the stray magnetic field;

(7) the dependence relationship between the output voltage of the fluxgate meter in the x and y directions and the stray magnetic field in the z direction can be obtained through measurement; and comparing a voltage signal obtained by multiplying the average value of the output voltages of the fluxgate meter in the x and y directions by a scaling factor with the voltage at two ends of the sampling resistor, processing an obtained error signal by a feedback circuit with proportion and integral, and inputting the error signal into a grid-source voltage port of the field effect tube so as to realize real-time compensation of the variable stray magnetic field.

The invention has the beneficial effects that: the method can eliminate the influence of the change of the stray magnetic field along with time on the target magnetic field in the environment, is simple, and effectively improves the precision and the stability of the space magnetic field.

Drawings

Fig. 1 is a schematic diagram of embodiment 1.

Fig. 2 is a circuit diagram of a feedback circuit in embodiment 1.

In the figure: 1. a linear power supply; 2. a compensation coil I; 3. a compensation coil II; 4. sampling a resistor; 5. a field effect transistor; 6. a fluxgate meter; 7. a feedback circuit.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and more obvious, the following will further describe the apparatus and method for compensating stray magnetic fields in real time according to the present invention with reference to the accompanying drawings and specific examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.