CN104297706A - Magnetic field generation device based on resonance and design method thereof - Google Patents

Abstract

The invention discloses a magnetic field generation device based on resonance and a design method of the device. Compared with a common magnetic field generation device, the magnetic field generation device is mainly characterized in that conversion efficiency from electricity to magnetism is greatly improved, and generation of a low-noise low-harmonic magnetic field is achieved. After the specification of a magnetic field generation coil and the specification of a current-detecting resistor are determined, series impedance ZL of the magnetic field generation coil and the current-detecting resistor at work frequency f is calculated; the maximum value of the resonance-current ratio Iratio is calculated by means of the series impedance ZL; according to an expected resonance-current ratio Iratio and cut-off frequency f1 and f2 of a filter, parameters of the filter are deduced through bandpass ripples; finally, the magnetic field generation device is assembled and debugged.

Description

A kind of field generator for magnetic based on resonance and method for designing thereof

Technical field

The invention belongs to generation technique field, magnetic field, more specifically, relate to a kind of field generator for magnetic based on resonance, more particularly, relate to a kind of efficient field generator for magnetic based on resonance principle, be used for producing high s/n ratio single-frequency magnetic field.

Background technology

Magnetic phenomenon is the earliest by one of physical phenomenon of human cognitive, and the compass of one of ancient Chinese four inventions utilizes needle magnetic field force induced effect in terrestrial magnetic field exactly, thus is taken one's bearings.In modern age, a series of revolutionary character found to make people recognize close contacting between electricity and magnetic, and the rule that utilization has been grasped achieves the mutual conversion between electricity and magnetic.

Magnetic field produce and application in scientific experiment more and more extensive, such as, in the magnetism characteristic measurement of magnetic material, just need to produce a certain size the magnetizing field of magnetic field as material.When particularly needing the physical characteristics accurately measuring these magnetic materials, magnetizing field should have stable, low noise, feature without harmonic wave.

AC magnetic field generation device performance conventional at present depends primarily on the power amplifier properties of device inside.When experiment has more high request to magnetizing field, the performance requirement of power amplifier is harsher, and even harshness is difficult to realize to prior art sometimes.In order to reduce the dependence of device performance to power amplifier, be necessary to design a kind of novel field generator for magnetic.

Summary of the invention

For above defect or the Improvement requirement of prior art, the invention provides a kind of field generator for magnetic based on resonance with its method for designing.Its object is to significantly to improve the conversion efficiency of electricity to magnetic, solve low noise, the having problems of low harmony wave magnetic field thus.

According to one aspect of the present invention, provide a kind of field generator for magnetic based on resonance, described device comprises industrial computer, data collecting card, power amplifier, wave filter, and electromagnetic field generating coil and inspection leakage resistance, wherein:

Two-way communication between described industrial computer and data collecting card, industrial computer is by data collecting card output drive Wave data, and simultaneous data-collecting card is also to industrial computer feedback magnetic field generation coil current information;

The output port of data collecting card is connected to power amplifier, and excitation waveform is by successively acting on wave filter, electromagnetic field generating coil, inspection leakage resistance after power amplification;

Data collecting card obtains electromagnetic field generating coil current information by gathering inspection leakage resistance voltage.

Further, described wave filter comprises resistance R ₁, series capacitance C ₁, resistance in series L ₁mutual series connection, shunt capacitance C ₂, shunt inductance L ₂parallel with one another, wherein:

Resistance R ₁, series capacitance C ₁with resistance in series L ₁mutual series connection;

Shunt capacitance C ₂with shunt inductance L ₂parallel with one another;

The resistance R of series connection ₁, series capacitance C ₁with resistance in series L ₁, then with shunt capacitance C in parallel ₂with shunt inductance L ₂series connection.

According to another aspect of the present invention, additionally provide a kind of method for designing of the above-mentioned field generator for magnetic based on resonance, comprise the steps:

(1) calculating magnetic field generation electromagnetic field generating coil and the series impedance Z of inspection leakage resistance under frequency of operation f _l, wherein Z _l=p+qj, note Z ₂for shunt inductance L ₂with shunt capacitance C ₂parallel impedance under frequency of operation f, is expressed as Z ₂=aj;

(2) function is drawn curve, the coordinate [a finding curve maximum corresponding _opt, I _max];

(3) by low for wave filter cutoff frequency f ₂with parameter a _optbring system of equations into $\left\{\begin{array}{c}{f}_2=\frac{1}{\sqrt{\frac{1}{f^2}-\frac{2\mathrm{\π}{L}_2}{a_{\mathrm{opt}}f}}}\\ f_2=\frac{1}{2\mathrm{\π}\sqrt{L_2{C}_2}}\end{array}\right.,$ Solve shunt inductance L ₂, shunt capacitance C ₂;

(4) by wave filter higher cutoff frequency f ₁with parameter y _optbring system of equations into $\left\{\begin{array}{c}{f}_1=\sqrt{f^2-\frac{y_{\mathrm{opt}}f}{2\mathrm{\π}{L}_1}}\\ f_1=\frac{1}{2\mathrm{\π}\sqrt{L_1{C}_1}}\end{array}\right.,$ Solve series inductance L ₁, series capacitance C ₁, wherein y _optfor the best value of y, y is Z ₁imaginary part, y _opt=-1 × imag (Z ₂|| Z ₃), Z ₁for resistance R ₁, series capacitance C ₁, resistance in series L ₁series impedance;

(5) emulation is at different resistance R ₁under value condition, the amplitude versus frequency characte of wave filter, selects suitable R ₁to meet the requirement of passband ripple.

In general, the above technical scheme conceived by the present invention compared with prior art, has following beneficial effect:

(1) field generator for magnetic designs based on resonance principle, the reactive power that originally need be provided by power amplifier transfers to be provided voluntarily by the passive element in wave filter, under producing identical magnetic field, the applied power of power amplifier significantly reduces, thus significantly improves the conversion efficiency of electricity to magnetic;

(2) wave filter in field generator for magnetic itself has filter function, and the magnetic field therefore produced has low harmonics distortion, the feature of low noise;

(3) by detecting electromagnetic field generating coil electric current in real time, the closed-loop control realizing electric current can make component ageing, the impact of temperature variation on magnetic field significantly reduces, and improves the stability in magnetic field.

Accompanying drawing explanation

Fig. 1 is a kind of conventional field generator for magnetic structural representation;

Fig. 2 is field generator for magnetic structural representation of the present invention;

Fig. 3 is the circuit diagram of field generator for magnetic of the present invention;

Fig. 4 is the simplification to the circuit diagram shown in Fig. 3;

Fig. 5 is the process flow diagram of field generator for magnetic method for designing of the present invention;

Fig. 6 is that resonance current is than the function curve with parameter a change;

Fig. 7 is the circuit diagram of complete design device in the embodiment of the present invention;

Fig. 8 is the curve of output using common field generator for magnetic power amplifier in the embodiment of the present invention;

Fig. 9 is the curve of output using method for designing power amplifier of the present invention in the embodiment of the present invention;

Figure 10 is size time history plot in magnetic field in the embodiment of the present invention.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.In addition, if below in described each embodiment of the present invention involved technical characteristic do not form conflict each other and just can mutually combine.

As shown in Figure 1, be a kind of structural representation of conventional field generator for magnetic.By leading to the most popular method that exchange current is generation alternating magnetic field to electromagnetic field generating coil, industrial computer control data capture card output drive wave form output in FIG, acts directly on electromagnetic field generating coil in order to produce alternating magnetic field after power amplifier.

As shown in Figure 2, be field generator for magnetic structural representation of the present invention, described field generator for magnetic comprises industrial computer, data collecting card, power amplifier, wave filter, electromagnetic field generating coil and inspection leakage resistance.Two-way communication between industrial computer and data collecting card, industrial computer is by data collecting card output drive Wave data, and simultaneous data-collecting card is also to industrial computer feedback magnetic field generation coil current information.The output port of data collecting card is connected to power amplifier, and excitation waveform is by successively acting on wave filter, electromagnetic field generating coil, inspection leakage resistance after power amplification.Data collecting card obtains electromagnetic field generating coil current information by gathering inspection leakage resistance voltage, industrial computer carries out proportional plus integral control by the error of electromagnetic field generating coil current setting value and value of feedback to electromagnetic field generating coil electric current, makes electromagnetic field generating coil current stabilization.

As shown in Figure 3, the circuit diagram of described field generator for magnetic comprises AC power supplies, wave filter (shown in dotted line frame) and loaded impedance Z _l.AC power supplies represents power amplifier, the structure of empty wire frame representation wave filter, loaded impedance Z _lrepresent and coil and the series impedance under inspection leakage resistance at the operating frequencies f occur.Structure and the second order bandpass filtering of wave filter are similar, resistance R ₁, series capacitance C ₁, resistance in series L ₁mutual series connection, shunt capacitance C ₂, shunt inductance L ₂parallel with one another.

As shown in Figure 4, be the simplification to circuit diagram shown in Fig. 3.Wherein Z ₁represent R in Fig. 3 ₁, C ₁, L ₁series impedance, Z ₂represent C in Fig. 3 ₂, L ₂parallel impedance, Z _lrepresent the series impedance that electromagnetic field generating coil and inspection leakage resistance f at the operating frequencies occur.I ₁represent and flow through Z ₁branch current, I ₂represent and flow through Z ₂branch current, I _lrepresent load branch electric current.

In the field generator for magnetic reduced graph shown in Fig. 4, load current I _lwith power amplifier output current I ₁the modulus value of ratio and electric current ratio be designated as I _ratiomeet formula (1):

$I_{\mathrm{ratio}}=\left|\frac{I_L}{I_1}\right|=\left|\frac{Z_2}{Z_L+Z_2}\right|---\left(1\right)$

Easily know this ratio only with Z ₂, Z _lrelevant, understand from the angle of circuit theory, now Z ₂with Z _lform parallel resonance, the feature of parallel resonance is that circuit is when being in resonance, electric current on resonant branch is greater than input current, the present invention is just based on this point, make electromagnetic field generating coil and the shunt inductance in inspection leakage resistance and wave filter and electric capacity generation resonance, to make the electric current on electromagnetic field generating coil and inspection leakage resistance be less than power amplifier output current, thus raising efficiency.Wherein, Z _lelectromagnetic field generating coil and the series impedance of inspection leakage resistance under frequency of operation f, after electromagnetic field generating coil and inspection leakage resistance are determined, Z _lvalue is constant, can represent Z _l=p+qj; Z ₂shunt inductance L ₂with shunt capacitance C ₂parallel impedance under frequency of operation f, can be expressed as Z ₂=aj, by Z _l, Z ₂bring in formula (1) and obtain formula (2):

$I_{\mathrm{ratio}}=\left|\frac{\mathrm{aj}}{p+(q+a)j}\right|---\left(2\right)$

Electric current ratio is I _ratiothe function of parameter a, by drawing the curve of function shown in formula (2), the coordinate [a finding curve maximum corresponding _opt, I _max].

The low cutoff frequency f of wave filter ₂with Z ₂relation can be represented by system of equations (3):

$\left\{\begin{array}{c}{Z}_2=\frac{1}{\frac{1}{2\mathrm{\πf}{L}_2}-2\mathrm{\πf}{C}_2}j\\ f_2=\frac{1}{2\mathrm{\π}\sqrt{L_2{C}_2}}\end{array}\right.---\left(3\right)$

System of equations (3) brings Z into ₂=a _optj, and system of equations (4) can be obtained to it with separating distortion:

$\left\{\begin{array}{c}{f}_2=\frac{1}{\sqrt{\frac{1}{f^2}-\frac{2\mathrm{\π}{L}_2}{a_{\mathrm{opt}}f}}}\\ f_2=\frac{1}{2\mathrm{\π}\sqrt{L_2{C}_2}}\end{array}\right.---\left(4\right)$

System of equations (4) has more directly reacted the low cutoff frequency f of wave filter ₂with shunt inductance L ₂, shunt capacitance C ₂relation.

C ₂, L ₂selection principle be loaded impedance (the i.e. Z making power amplifier ₁+ Z ₂|| Z ₃) minimum.Z ₂, Z ₃value Z in parallel ₂|| Z ₃formula (5) can be expressed as:

$Z_2\left|\right|Z_3=\frac{1}{\frac{1}{a_{\mathrm{opt}}}j+\frac{1}{p+\mathrm{qj}}}---\left(5\right)$

Z ₁imaginary part and Z _l|| Z ₃imaginary part and value be zero be Z ₁+ Z ₂|| Z _lget the necessary condition of minimum value.From the angle of circuit theory, now circuit generation series resonance, be characterized in that circuit loop is resistive, whole impedance loop is minimum, electric current I ₁reach maximum.If Z ₁imaginary part is y, as y and Z ₂|| Z ₃circuit generation series resonance when imaginary values and value are zero, the best value y of y _optavailable formula (6) represents:

y _opt＝-1×imag(Z ₂||Z _L) (6)

Wherein imag represents and gets imaginary part function, y _optrepresent Z ₁imaginary part is the best value of y.

Wave filter higher cutoff frequency f ₁with Z ₁the relation of imaginary part y can be represented by system of equations (7):

$\left\{\begin{array}{c}y=2\mathrm{\πf}{L}_1-\frac{1}{2\mathrm{\πf}{C}_1}\\ f_1=\frac{1}{2\mathrm{\π}\sqrt{L_1{C}_1}}\end{array}\right.---\left(7\right)$

System of equations (5) brings y=y into _opt, and system of equations (8) can be obtained to it with separating distortion:

$\left\{\begin{array}{c}{f}_1=\sqrt{f^2-\frac{y_{\mathrm{opt}}f}{2\mathrm{\π}{L}_1}}\\ f_1=\frac{1}{2\mathrm{\π}\sqrt{L_1{C}_1}}\end{array}\right.---\left(8\right)$

System of equations (8) has more directly reacted wave filter higher cutoff frequency f ₁with series inductance L ₁, series capacitance C ₁relation.

Resistance R ₁the ripple of major effect wave filter in passband, when selected value is too small, in passband, ripple rises and falls large, when selected value is excessive, will lot of energy, reduce work efficiency.The R be applicable to ₁value makes passband ripple little and consuming little energy.

As shown in Figure 5, the invention provides a kind of method for designing of the field generator for magnetic based on resonance, comprise the steps:

(1) calculating magnetic field generation electromagnetic field generating coil and the series impedance Z of inspection leakage resistance under frequency of operation f _l.

In a concrete instance, frequency of operation f=1kHz, electromagnetic field generating coil DC impedance is 0.18 Ω, inductance value 0.35mH, and inspection leakage resistance size is 0.125 Ω, can calculate Z _l=0.305+2.199j.

(2) function is drawn curve, the coordinate [a finding curve maximum corresponding _opt, I _max].

Wherein, p=0.305, q=2.199, as shown in Figure 6, the coordinate that curve maximum is corresponding is the function curve of drafting [-2.243,7.26].Therefore, a _opt=-2.24, I _max=7.28.

(3) by low for filter characteristic cutoff frequency f ₂with parameter a _optbring system of equations into $\left\{\begin{array}{c}{f}_2=\frac{1}{\sqrt{\frac{1}{f^2}-\frac{2\mathrm{\π}{L}_2}{a_{\mathrm{opt}}f}}}\\ f_2=\frac{1}{2\mathrm{\π}\sqrt{L_2{C}_2}}\end{array}\right.,$ Solve shunt inductance L ₂, shunt capacitance C ₂.

Get f ₂=650Hz, a _opt=-2.243 bring system of equations into, solve L ₂=485uH, C ₂=124uF.

(4) wave filter higher cutoff frequency f ₁with parameter y _optbring system of equations into $\left\{\begin{array}{c}{f}_1=\sqrt{f^2-\frac{y_{\mathrm{opt}}f}{2\mathrm{\π}{L}_1}}\\ f_1=\frac{1}{2\mathrm{\π}\sqrt{L_1{C}_1}}\end{array}\right.,$ Solve series inductance L ₁, series capacitance C ₁.

$Z_2\left|\right|Z_L=\frac{1}{\frac{1}{-2.24j}+\frac{1}{0.305+2.199j}}=16.16+0.09j---\left(9\right)$

Z ₂|| Z _limaginary part be 0.09, therefore get y _opt=-0.09, f ₁=1350Hz brings system of equations into, solves L ₁=17.3uH, C ₁=803uF.

(5) under the filter parameter that (1) ~ (4) step provides above, emulate at different R ₁under value condition, the amplitude versus frequency characte of wave filter.Simulation result shows, works as R ₁during=0.6 Ω, filter transmission band ripple is less than 0.3dB, and wave filter has good bandpass flatness.

(6) assembling of field generator for magnetic and debugging: the theoretical parameter of what above (1) ~ (5) step provided is design of filter, in reality, the parameter of element has certain specification limits, such as series inductance C ₁value is 803uF, and the electric capacity of this large capacitance is difficult to buy in practice, therefore needs to be optimized component parameters.Device circuit schematic diagram after component parameters optimization as shown in Figure 7.Finally to device assembly and adjustment.

Actual test data analysis:

1., in concrete instance, electromagnetic field generating coil parameter is that 10Gs/A and electromagnetic field generating coil often can produce 10Gs magnetic field by 1A electric current.Two kinds of devices shown in Fig. 1, Fig. 2 are used to produce 30Gs magnetic field, the output parameter of recording power amplifier and magnetic field size respectively, as shown in Figure 8,9, 10.

Fig. 8 is when using Fig. 1 shown device to produce 30Gs magnetic field, the curve of output of power amplifier in one-period.Power amplifier output current amplitude 3A, voltage magnitude 6.1V, can calculate applied power 12.9W.

Fig. 9 is when using Fig. 2 shown device to produce 30Gs magnetic field, the curve of output of power amplifier in one-period.Power amplifier output current amplitude 0.46A, voltage magnitude 7.2V, can calculate applied power 2.34W.

Figure 10 be two kinds of devices shown in Fig. 1, Fig. 2 produce the situation of change of magnetic field in 500s, designed by obvious the present invention device produce magnetic field more stable.

Those skilled in the art will readily understand; the foregoing is only preferred embodiment of the present invention; not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (3)

1. based on a field generator for magnetic for resonance, it is characterized in that, described device comprises industrial computer, data collecting card, power amplifier, wave filter, and electromagnetic field generating coil and inspection leakage resistance, wherein:

Two-way communication between described industrial computer and data collecting card, industrial computer is by data collecting card output drive Wave data, and simultaneous data-collecting card is also to industrial computer feedback magnetic field generation coil current information;

The output port of data collecting card is connected to power amplifier, and excitation waveform is by successively acting on wave filter, electromagnetic field generating coil, inspection leakage resistance after power amplification;

Data collecting card obtains electromagnetic field generating coil current information by gathering inspection leakage resistance voltage.

2. field generator for magnetic as claimed in claim 1, it is characterized in that, described wave filter comprises resistance R ₁, series capacitance C ₁, resistance in series L ₁mutual series connection, shunt capacitance C ₂, shunt inductance L ₂parallel with one another, wherein:

Resistance R ₁, series capacitance C ₁with resistance in series L ₁mutual series connection;

Shunt capacitance C ₂with shunt inductance L ₂parallel with one another;

The resistance R of series connection ₁, series capacitance C ₁with resistance in series L ₁, then with shunt capacitance C in parallel ₂with shunt inductance L ₂series connection.

3. a method for designing for field generator for magnetic as claimed in claim 1 or 2, is characterized in that, described method comprises the steps:

(1) calculating magnetic field generation coil and the series impedance Z of inspection leakage resistance under frequency of operation f _l, wherein Z _l=p+qj, note Z ₂for shunt inductance L ₂with shunt capacitance C ₂parallel impedance under frequency of operation f, is expressed as Z ₂=aj;

(2) function is drawn curve, the coordinate [a finding curve maximum corresponding _opt, I _max];

(3) by low for wave filter cutoff frequency f ₂with parameter a _optbring system of equations into $\left\{\begin{array}{c}{f}_2=\frac{1}{\sqrt{\frac{1}{f^2}-\frac{2\mathrm{\π}{L}_2}{a_{\mathrm{opt}}f}}}\\ f_2=\frac{1}{2\mathrm{\π}\sqrt{L_2{C}_2}}\end{array}\right.,$ Solve shunt inductance L ₂, shunt capacitance C ₂;

(4) by wave filter higher cutoff frequency f ₁with parameter y _optbring system of equations into $\left\{\begin{array}{c}{f}_1=\sqrt{f^2-\frac{y_{\mathrm{opt}}f}{{2\mathrm{\πL}}_1}}\\ f_1=\frac{1}{2\mathrm{\π}\sqrt{L_1{C}_1}}\end{array}\right.,$ Solve series inductance L ₁, series capacitance C ₁, wherein y _optfor the best value of y, y is Z ₁imaginary part, y _opt=-1 × imag (Z ₂|| Z ₃), Z ₁for resistance R ₁, series capacitance C ₁, resistance in series L ₁series impedance;

(5) emulation is at different resistance R ₁under value condition, the amplitude versus frequency characte of wave filter, selects suitable R ₁to meet the requirement of passband ripple.