CN113625203A - Device for generating rotating magnetic field - Google Patents
Device for generating rotating magnetic field Download PDFInfo
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- CN113625203A CN113625203A CN202110729138.5A CN202110729138A CN113625203A CN 113625203 A CN113625203 A CN 113625203A CN 202110729138 A CN202110729138 A CN 202110729138A CN 113625203 A CN113625203 A CN 113625203A
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- magnetic field
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/032—Measuring direction or magnitude of magnetic fields or magnetic flux using magneto-optic devices, e.g. Faraday or Cotton-Mouton effect
Abstract
The invention discloses a generating device of a rotating magnetic field, which comprises a rotating magnetic field driving circuit and two groups of Helmholtz coils which are orthogonal to each other; two paths of sinusoidal alternating current signals with the phase difference of 90 degrees, which are generated by a rotating magnetic field driving circuit, are respectively introduced into two groups of Helmholtz coils which are orthogonal to each other, and a corresponding rotating magnetic field is generated in the center of a space surrounded by the coils; the device can accurately control the rotating magnetic field frequency, the magnetic induction intensity, the rotating direction and the space rotating track.
Description
Technical Field
The invention belongs to the technical field of vector atom magnetometers and quantum precision measurement, and particularly relates to a rotating magnetic field generating device.
Background
The rotating magnetic field has wide application prospect and academic value in the fields of metallurgy, biology, medical treatment, magnetic field detection and the like. For example: the rotating magnetic field can be used for controlling the microstructure of the alloy solidification, and the material characteristics of the alloy solidification are researched and improved. In biomedicine, researchers report that the rotating magnetic field has a promoting effect on wheat seed germination and seedling growth and has a certain treatment effect on altitude erythrocytosis. In addition, the rotating magnetic field can also be used for physical phenomenon research related to magnetic field measurement, signal detection and other applications. In the above applications and studies, the characteristics of the rotating magnetic field have an important influence on the depth of the research work and the accuracy of the results.
At present, a rotating magnetic field is mainly to introduce multiple groups of sinusoidal alternating current signals with specific phase differences into helmholtz coils distributed in corresponding spaces, and generate a rotating magnetic field with the same frequency as the sinusoidal signals in a space surrounded by the coils. Uncertain factors such as electronic circuit transmission distance and electronic component characteristics affect sinusoidal signal phase delay and amplitude, so that deviation is generated between the design and the actual state, the rotating magnetic field track is changed into an ellipse, errors are introduced into the system under the condition, and the accuracy of measurement and research results is reduced.
Disclosure of Invention
In view of the above, the present invention provides a device for generating a rotating magnetic field, which is capable of precisely controlling the frequency of the rotating magnetic field, the magnetic induction intensity, the rotating direction and the spatial rotating trajectory.
The technical scheme for realizing the invention is as follows:
a device for generating a rotating magnetic field comprises a rotating magnetic field driving circuit and two groups of Helmholtz coils which are orthogonal to each other; two paths of sinusoidal alternating current signals with the phase difference of 90 degrees, which are generated by a rotating magnetic field driving circuit, are respectively introduced into two groups of Helmholtz coils which are orthogonal to each other, and a corresponding rotating magnetic field is generated in the center of a space surrounded by the coils;
the rotating magnetic field driving circuit comprises a 10MHz active crystal oscillator, a first DDS, an MCU, a second DDS, a first band-pass filter, a second band-pass filter, a first isolation circuit, a second isolation circuit, a first voltage amplification circuit, a second voltage amplification circuit, a first power amplification circuit, a second power amplification circuit, a first current adjustment module and a second current adjustment module;
the 10MHz active crystal oscillator is used as a system clock of the first DDS and the second DDS, a 10MHz system clock signal is transmitted to the first DDS and the second DDS, and the MCU controls the first DDS and the second DDS to output a same-frequency sine alternating current signal with a phase difference of 90 degrees;
the first DDS, the first band-pass filter, the first isolation circuit, the first voltage amplification circuit, the first power amplification circuit and the first current adjustment module are sequentially connected in series;
the second DDS, the second band-pass filter, the second isolation circuit, the second voltage amplification circuit, the second power amplification circuit and the second current regulation module are sequentially connected in series.
Furthermore, the first band-pass filter and the second band-pass filter are both filter circuits formed by resistors and capacitors.
Further, the first isolation circuit and the second isolation circuit are both emitter followers adopting a triode-based design.
Furthermore, the first voltage amplifying circuit and the second voltage amplifying circuit are both inverse proportion amplifying circuits integrated with operational amplifiers, and control the sinusoidal signal voltage.
Furthermore, the first current adjusting module and the second current adjusting module respectively comprise a high-capacitance electrolytic capacitor, an adjustable-resistance power resistor, a current-limiting power resistor, an inner coil assembly and a coil inductor which are sequentially connected in series.
Has the advantages that:
(1) the rotating magnetic field driving circuit can be theoretically extended to multi-path DDS phase precision control, has the advantages of constant phase difference, high phase control precision and the like, and has important application significance in the fields of high-precision electronic systems, radars and the like.
(2) The rotating magnetic field generating device can accurately control the frequency, the rotating direction, the space track and the magnetic induction intensity of the rotating magnetic field.
Drawings
Fig. 1 shows a rotating magnetic field generating device.
Fig. 2a current regulation module.
Wherein, 1-10MHz active crystal oscillator; 2-a first DDS; 3-MCU; 4-a second DDS; 5-a first band-pass filter; 6-a second band-pass filter; 7-a first isolation circuit; 8-a second isolation circuit; 9-a first voltage amplification circuit; 10-a second voltage amplification circuit; 11-a first power amplification circuit; 12-a second power amplification circuit; 13-a first current adjustment module; 14-a second current regulation module; 15-rotating magnetic field drive circuit; 16-helmholtz coil; 17-high capacitance electrolytic capacitor; 18-adjustable resistance power resistor; 19-current limiting power resistor; 20-inner set of coils; 21-coil inductance.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
The invention provides a device for generating a rotating magnetic field, which can accurately control the frequency, the magnetic induction intensity, the rotating direction and the space rotating track of the rotating magnetic field. The rotating magnetic field is generated by passing two sinusoidal alternating current signals with a phase difference of 90 degrees into two sets of mutually orthogonal Helmholtz coils, and generating a corresponding rotating magnetic field in the center of a space surrounded by the coils, wherein the rotating magnetic field comprises a rotating magnetic field driving circuit 15 and two sets of mutually orthogonal Helmholtz coils 16.
As shown in fig. 1, the rotating magnetic field driving circuit 15 is configured to generate two sinusoidal ac electrical signals with a phase difference of 90 °, and includes modules, such as a 10MHz active crystal oscillator 1, a first DDS2, an MCU3, a second DDS4, a first band-pass filter 5, a second band-pass filter 6, a first isolation circuit 7, a second isolation circuit 8, a first voltage amplification circuit 9, a second voltage amplification circuit 10, a first power amplification circuit 11, a second power amplification circuit 12, a first current adjustment module 13, and a second current adjustment module 14;
the 10MHz active crystal oscillator 1 is used as a system clock of a first DDS2 and a second DDS4, and the distance from a 10MHz system clock signal to the first DDS2 and the second DDS4 is ensured to be the same during PCB design, so that the phase difference is the minimum when the 10MHz system clock signal reaches the two DDSs;
the MCU3 adopts parallel port mode programming to the first DDS2 and the second DDS4, and a frequency control word and a phase control word are written in sequence, wherein the frequency control word controls the frequency of the DDS output signals, and the phase control word controls the phase difference between the sinusoidal signals output by the first DDS2 and the second DDS 4. The DDS adopts an external UPDATE command UPDATE CLK, and the rising edge of the external UPDATE command UPDATE CLK simultaneously occurs in the first DDS2 and the second DDS 4;
the first band-pass filter 5 and the second band-pass filter 6 adopt filter circuits consisting of resistors and capacitors;
the first isolation circuit 7 and the second isolation circuit 8 adopt emitter followers based on triode design;
the first voltage amplifying circuit 9 and the second voltage amplifying circuit 10 adopt an inverse proportion amplifying circuit integrated with operational amplifier to control sinusoidal signal voltage;
the first power amplifying circuit 11 and the second power amplifying circuit 12 amplify the output power of the sinusoidal signal by adopting power amplifiers, so that the load capacity of the driving circuit is improved, and the coil generates a required rotating magnetic field;
the circuit form in the first current adjusting module 13 and the second current adjusting module 14 can be regarded as a series resonant circuit consisting of a capacitor, a resistor and an inductor, wherein the capacitor is an electrolytic capacitor with a high capacitance value, and the electrolytic capacitor and the coil inductor form the series resonant circuit. The resistors in the circuit are a fixed resistance power resistor and an adjustable resistance power resistor and are used for controlling the working current of the coil.
The innovation points of the invention are as follows: the precise control of the phase difference of two paths of sine alternating current signals in the coil driving circuit, the power of the sine alternating current signals, the working current in the coil and other parameters is realized, and the precise control of the rotating magnetic field magnetic induction intensity, the rotating direction and the rotating track is realized. The precise control of the phase difference of the two paths of sinusoidal alternating current signals is realized by setting different phase control words to precisely adjust the phase difference on the basis of realizing the phase synchronization of the two paths of DDSs; the power control of the sine alternating current signal is realized by the comprehensive adjustment of a voltage amplifying circuit and a power amplifying circuit; the current in the coil is set as a current working point through the series resonance characteristic of the capacitor, the fixed resistance power resistor and the coil inductor, and the adjustable resistance power resistor realizes the precise adjustment of the current.
Example (b):
a. in the examples a rotating magnetic field with a frequency of 20Hz and a strength of 500nT is generated in the X-Y plane. The Helmholtz coil is a square coil, the side length is 34cm, the coil interval is 18cm, and the uniformity of a central magnetic field of a space surrounded by the coil can be ensured.
b. The driving circuit leads sinusoidal alternating current signals with the frequency of 20Hz and the phase difference of 90 degrees to two groups of X-axis coils and Y-axis coils with mutually vertical axes, the coils generate a rotating magnetic field with the same frequency as the sinusoidal alternating current signals in the surrounding space, and the synthesized magnetic field is shown as an expression (1):
c. the two sinusoidal alternating current signals with the frequency of 20Hz and the phase difference of 90 degrees are designed to comprise an active crystal oscillator 1 of 10MHz, a MCU3 of a singlechip MSP430, and a first DDS2 and a second DDS4 of two paths of AD9852 of AD companies. In the design of a circuit PCB, a 10MHz active crystal oscillator is used as a system clock signal of MSP430 and two AD9852, the distance between the 10MHz active crystal oscillator and the two AD9852 is ensured to be the same, and the phase difference of the 10MHz system clock signal transmitted to the two DDSs is close to zero as much as possible; the MSP430 adopts parallel mode programming for the two AD9852, and corresponding frequency control words and phase control words are written in sequence, wherein the frequency control words set the output signal frequency of the DDS, and the frequency is 20 Hz. The phase control word sets the phase difference between the two paths of AD9852 output sinusoidal signals, and the phase difference is 90 degrees; the DDS adopts an external UPDATE command UPDATE CLK, the MSP430 sets a pin as an UPDATE CLK signal, and the rising edge of the UPDATE CLK triggers the two AD9852 circuits at the same time, so that the two AD9852 circuits UPDATE and output at the same time;
d. the first band-pass filter 5 and the second band-pass filter 6 respectively form two filter circuits of low pass and high pass by adopting a resistor and a capacitor, and filter out direct-current components and frequency components higher than 20Hz in sinusoidal signals;
e. the first isolation circuit 7 and the second isolation circuit 8 adopt an NPN triode 2N2222A to design emitter followers;
the first voltage amplifying circuit 9 and the second voltage amplifying circuit 10 adopt OP27 integrated operational amplifier to form an inverse proportion amplifying circuit to control the voltage of the sinusoidal signal, and the multiple of the amplifying circuit is continuously adjustable within 0-10. The sinusoidal signal voltage peak of the output of the AD9852 is 500 mV. After passing through the band-pass filter, the peak value of a signal transmitted to the input end of the integrated operational amplifier is 80 mV. The voltage of an output signal of the integrated operational amplifier is continuously adjustable within the range of 0-800 mV through an inverse proportion amplifying circuit;
f. the first power amplifying circuit 11 and the second power amplifying circuit 12 amplify the sinusoidal signal power by using power amplifiers. The power amplification circuit adopts a power amplification chip TDA2030A, belongs to an AB class amplifier, has input bias current in the mu A magnitude and has low signal distortion characteristic. The circuit adopts a single power supply form in a technical manual, when the peak value of an input sinusoidal signal is 100mV, the peak value of the output sinusoidal signal of the power amplifying circuit is 2.42V, and the amplification factor of the circuit is 24.2 times;
g. the circuits in the first current adjusting module 13 and the second current adjusting module 14 can be regarded as a series resonant circuit composed of a capacitor, a resistor and an inductor, wherein the capacitor is a high-capacitance electrolytic capacitor, the resistor is a fixed resistance power resistor and an adjustable resistance power resistor, and the circuit form is shown in fig. 2, and the high-capacitance electrolytic capacitor 17, the adjustable resistance power resistor 18, the current-limiting power resistor 19, the coil inner group 20 and the coil inductor 21. Measuring the internal resistance and the inductance of the coil based on a transformer tester (Model 13350) of Chroma company, wherein the internal resistance of the coil on the X axis is 0.8525 omega, the inductance is 116.46 mu H, the internal resistance of the coil on the Y axis is 0.8808 omega, and the inductance is 141.05 mu H when the test frequency point is 20 Hz; the electrolytic capacitance 17 is 470 mu; the current-limiting power resistor 19 is 2 Ω; the resistance adjusting range of the power resistor 18 with the adjustable resistance is 0-10 omega. Based on the series resonance characteristics of the capacitor, the fixed resistance power resistor and the coil inductor, the working current of the coil is set to 47 mA. On the basis, a power resistor with an adjustable resistance value is arranged to precisely adjust the working current of the coil, and the adjustment range is 37 mA-47 mA. The control of the magnetic induction intensity of the X-axis coil and the Y-axis coil is realized through current adjustment, so that the precise adjustment of the rotating track of the rotating magnetic field is realized.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A device for generating a rotating magnetic field is characterized by comprising a rotating magnetic field driving circuit and two groups of Helmholtz coils which are orthogonal to each other; two paths of sinusoidal alternating current signals with the phase difference of 90 degrees, which are generated by a rotating magnetic field driving circuit, are respectively introduced into two groups of Helmholtz coils which are orthogonal to each other, and a corresponding rotating magnetic field is generated in the center of a space surrounded by the coils;
the rotating magnetic field driving circuit comprises a 10MHz active crystal oscillator, a first DDS, an MCU, a second DDS, a first band-pass filter, a second band-pass filter, a first isolation circuit, a second isolation circuit, a first voltage amplification circuit, a second voltage amplification circuit, a first power amplification circuit, a second power amplification circuit, a first current adjustment module and a second current adjustment module;
the 10MHz active crystal oscillator is used as a system clock of the first DDS and the second DDS, a 10MHz system clock signal is transmitted to the first DDS and the second DDS, and the MCU controls the first DDS and the second DDS to output a same-frequency sine alternating current signal with a phase difference of 90 degrees;
the first DDS, the first band-pass filter, the first isolation circuit, the first voltage amplification circuit, the first power amplification circuit and the first current adjustment module are sequentially connected in series;
the second DDS, the second band-pass filter, the second isolation circuit, the second voltage amplification circuit, the second power amplification circuit and the second current regulation module are sequentially connected in series.
2. A device for generating a rotating magnetic field according to claim 1, wherein the first band-pass filter and the second band-pass filter are each a filter circuit including a resistor and a capacitor.
3. The apparatus for generating a rotating magnetic field according to claim 1, wherein the first isolation circuit and the second isolation circuit are emitter followers based on a triode design.
4. The apparatus for generating a rotating magnetic field according to claim 1, wherein the first voltage amplifier circuit and the second voltage amplifier circuit are both inverse proportional amplifier circuits integrated with operational amplifiers, and control the sinusoidal signal voltage.
5. The apparatus for generating a rotating magnetic field according to claim 1, wherein the first current adjustment module and the second current adjustment module each comprise a high-capacitance electrolytic capacitor, a power resistor with adjustable resistance, a current-limiting power resistor, an inner coil assembly, and a coil inductor connected in series.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110729138.5A CN113625203A (en) | 2021-06-29 | 2021-06-29 | Device for generating rotating magnetic field |
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| CN202110729138.5A CN113625203A (en) | 2021-06-29 | 2021-06-29 | Device for generating rotating magnetic field |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LU70695A1 (en) * | 1974-03-27 | 1974-12-10 | ||
| CN101262198A (en) * | 2008-04-14 | 2008-09-10 | 大连理工大学 | Method for driving and controlling universal rotary magnetic field of the medical treatment miniature robot in the body |
| CN102867612A (en) * | 2012-09-06 | 2013-01-09 | 中国科学院电工研究所 | Rotating magnetic field generating device and implementation method thereof |
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2021
- 2021-06-29 CN CN202110729138.5A patent/CN113625203A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LU70695A1 (en) * | 1974-03-27 | 1974-12-10 | ||
| CN101262198A (en) * | 2008-04-14 | 2008-09-10 | 大连理工大学 | Method for driving and controlling universal rotary magnetic field of the medical treatment miniature robot in the body |
| CN102867612A (en) * | 2012-09-06 | 2013-01-09 | 中国科学院电工研究所 | Rotating magnetic field generating device and implementation method thereof |
Non-Patent Citations (2)
| Title |
|---|
| 张 钊 等: "基于DDS 技术的胶囊微机器人外旋转 磁场驱动方法", 自动化技术与应用, vol. 28, no. 03, pages 64 - 67 * |
| 谭超 等: "用于旋转磁场标准装置的低频双路交流恒流", 电子器件, vol. 42, no. 02, pages 319 - 323 * |
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