CN101242149B - Control method and device for inductive load wide-frequency amplitude-constant AC square wave current - Google Patents

Abstract

The present invention provides a control method and a device for sensitive load broadband constant amplitude alternating rectangular wave current, which are especially suitable for alternating rectangular wave current generated by electromagnetic transmitting loop in frequency domain electromagnetic method and is applied to the geophysical prospecting and the nondestructive examination field. The method of the invention, comprising: regulating the voltage of an output current frequency, a voltage reference and an embedding voltage source (4) to generate cyclic load current waveform with same shape and constant amplitude value, to calculate a reversing slope of the rectangular wave current, reversing time and amplitude value of the current. The device of the invention comprises a DC power supply, an alternating current rectangular wave current generator (2), an alternating current rectangular wave current control circuit, a sensitive load, an energy supplementing circuit (1), a hysteresis loop control circuit(3), an embedding circuit (3) and an embedding voltage source (4). The invention improves gradient of reversing side of the alternating rectangular wave current, accomplishes reversing side linearity, and solves problems of improvement and invariableness of current amplitude value and expansion of frequency range and so on.

Description

The wide-frequency amplitude-constant AC square wave current control method and the device of inductive load

Technical field:

The present invention relates to a kind of wide-frequency amplitude-constant AC square wave current control method and device of inductive load, be used for frequency domain electromagnetic method electromagnetism and send coil generation AC square wave current, be applicable to geophysical exploration, Non-Destructive Testing field.

Background technology:

In some research and industrial application, need to use forward square wave current, negative sense square wave current or AC square wave current.The reference waveform of AC square wave current is characterized in constant amplitude during output current, the current waveform cyclic variation, and positive negative sense waveform symmetry does not have transit time when the current polarity counter-rotating changes.

Produce the device of square wave current, can produce forward, negative sense or bipolar square wave electric current, pulse period, adjustable amplitude value.Produce the circuit of AC square wave current, realized by full-bridge circuit, four brachium pontis adopt all-controlling power electronics device.

Prior art comprises clamped voltage source, AC square wave current control circuit, drive circuit, loop control circuit, reference voltage circuit stagnate, wherein clamped voltage source is a D.C. regulated power supply, and the AC square wave current control circuit produces circuit by frequency adjustment, control timing and drive circuit is formed.And for example license number is ZL200410081518.9 " linear adjustable control method and the device of current impulse trailing edge with rising edge hoisting power ", can realize that the trailing edge linearity is adjustable, but current amplitude constant can not realize that the rising edge linearity can be in harmonious proportion high frequency the time.The problem that prior art exists is: the load of square wave current device is an inductive load, particularly load is under the big inductance quantity loading conditions such as coil, had a strong impact on the shape of square wave current, square wave current is not desirable ac square wave, to bearing or to positive commutation process all being arranged by negative certain time of delay, electric current commutates along poor linearity electric current by just.The AC square wave current device uses as a kind of driving source, it is adjustable commutating period to solve AC square wave current simultaneously, property along the line commutates, problem such as current amplitude is constant when high-frequency emission and frequency change is the difficult point in the power electronic technology, it is elongated that the delay on commutation edge makes electric current reach time of stable state, the size of current amplitude when having influenced the raising of AC square wave current frequency and high frequency.

Summary of the invention:

The object of the present invention is to provide a kind of wide-frequency amplitude-constant AC square wave current control method and device of inductive load, improved the steepness on AC square wave current commutation edge, realize commutation property along the line, solved the lifting of current amplitude and constant, problems such as the expansion of frequency range.

In order to realize the foregoing invention purpose, technical scheme of the present invention is

1, undertaken by following concrete grammar step:

(1), the S that closes a switch, by the frequency adjustment in the AC square wave current control circuit 2, regulate output AC square wave current i _o(t) frequency, the cycle of AC square wave current must be greater than the opening of electronic switch S, turn-off time sum;

(2), regulate clamped voltage source 4 voltage V _C, change the slope on output AC square wave current commutation edge, make the ac square wave output current property along the line that commutates, V _C0 and the electronic switch rated insulation voltage between;

(3), by regulating reference voltage circuit 5, change output AC square wave current amplitude, the maximum current that current amplitude can be born less than full control property electronic switch;

(4), by control AC square wave current generator 2, reference voltage and clamped voltage source 4 voltage V _C, make each output cycle produce the load voltage waveform v that shape is identical and amplitude equates _o(t);

Forward AC square wave current i _o(t) voltage, the electric current between rising, decrement phase:

At t ₀～t ₁During this time: the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, the voltage v that provides to load _o(t ₀)=V _C, load voltage is clamped at V _COn, V _CMuch larger than DC power supply voltage V ₁, AC square wave current rises to I by zero fast linear, and booster tension is realized with clamped voltage source 4;

At t ₁～t ₂During this time: the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, v _o(t ₁)=V ₁, output forward AC square wave current, i _o(t)=I;

At t ₂～t ₃During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t) by just becoming negative value, v _o(t ₂The V of)=- _C, load voltage is clamped at-V _COn, AC square wave current begins linear decline, at t ₃Moment current i _o(t) decay to zero;

The rising of negative sense AC square wave current, the control voltage of decline process, electric current:

At t ₃～t ₄During this time: the first switching tube J ₁Conducting, second switch pipe J ₂The voltage v that provides to load is provided _o(t ₄The V of)=- _C, load voltage is clamped at-V _COn, V _CMuch larger than DC power supply voltage V ₁, AC square wave current i _o(t) fast linear rises to-I, and booster tension is realized with clamped voltage source 4;

At t ₄～t ₅During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t)=-V ₁, output negative sense AC square wave current, i _o(t)=-I;

At t ₅～t ₆During this time: the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, v _o(t) become on the occasion of, v by negative value _o(t ₅)=V _C, load voltage is clamped at V _COn, negative sense AC square wave current i _o(t) descend by-I is linear, at t ₆Current attenuation constantly is to zero;

Wherein:

t ₀: the zero hour of output forward AC square wave current, t ₁: v _o(t) drop to V ₁The moment,

t ₂: the moment that the forward AC square wave current begins to descend, t ₃: the forward AC square wave current drops to for zero the moment,

t ₄: v _o(t) drop to-V ₁The moment, t ₅: the moment that the negative sense AC square wave current begins to descend,

t ₆: the negative sense AC square wave current drops to zero the moment, V _C: clamped voltage source 4 voltages,

i _o(t): AC square wave current, I: AC square wave current amplitude;

(5), calculate AC square wave current trailing edge slope absolute value K ₁, following " slope " all refers to the absolute value of slope:

i _o(t) by I or-I drops to zero slope:

$K_1=\left|\frac{{\mathrm{di}}_o\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_o\left(t\right)-V_C}{L}\right|---\left(1\right)$

Wherein:

R _L: the load dc resistance;

L: load inductance amount;

V _C: clamped voltage source 4 voltages;

Work as V _C＞＞R _LDuring I,

AC square wave current i _o(t) by I or-the I linearity drops to zero, the descending slope of forward AC square wave current and negative sense AC square wave current equates;

(6), calculate AC square wave current rising edge slope K ₂:

i _o(t) by above freezing be raised to I or-slope of I

$K_2=\left|\frac{{\mathrm{di}}_o\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_o\left(t\right)+V_C}{L}\right|---\left(2\right)$

Wherein:

R _L: the load dc resistance;

L: load inductance amount;

V _C: clamped voltage source 4 voltages;

Work as V _C＞＞R _LDuring I,

Load current i _o(t) by zero line rise to I or-I, the rate of rise of forward AC square wave current and negative sense AC square wave current equates;

(7), calculate output AC square wave current t commutating period _d(unit: μ s):

AC square wave current t fall time _D1: ${\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6---\left(3\right)$

AC square wave current rise time t _D2: ${\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right){\&times;10}^6---\left(4\right)$

AC square wave current is by just to negative t commutating period _d:

$t_d={\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d+{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right){\&times;10}^6---\left(5\right)$

Work as V _C＞＞R _LDuring I, get by (1) Get by (2) formula

${\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d\&ap;\frac{\mathrm{IL}}{V_C},{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d\&ap;\frac{\mathrm{IL}}{V_C}$

$t_d={\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d+{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d\&ap;\frac{2\mathrm{IL}}{V_C}---\left(6\right)$

By changing V _C, scalable AC square wave current t commutating period _dImprove V _C, shortened t _d, V _CBe arranged on 0 between the electronic switch rated insulation voltage;

(8), calculate AC square wave current amplitude I (unit: A):

Work as V _C＞＞R _LDuring I, $I=K_2{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=\frac{V_C}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6---\left(7\right)$

By changing V _C, scalable AC square wave current amplitude; Improve V _C, can improve the amplitude of AC square wave current, the lowest high-current value that I can bear less than electronic switch; I and supply voltage, frequency, load inductance amount have nothing to do;

(9), the commutation of output AC square wave current is along slope K:

Work as V _C＞＞R _LDuring I, get by (1) and (2) formula,

$K=K_1=K_2\&ap;\frac{V_C}{L}---\left(8\right)$

AC square wave current rising and falling edges slope is identical, promptly commutates along slope

Constant, commutation is the constant straight line of a slope along waveform, the current waveform symmetry;

(10), the first constant current inductance L ₁With the second constant current inductance L ₂Determine

Constant current inductance minimum value computing formula:

$L_{\min }=\frac{R_L}{f_{\max }\ln \frac{R_{L}I-V_1}{R_{L}I+R_L\mathrm{\&Delta;I}-V_1}}-L---\left(9\right)$

Choose L ₁=L ₂〉=L _Min

Wherein:

Δ I: the undulating value of AC square wave current amplitude;

f _Max: the 3rd switching tube J ₃The highest switching frequency;

V ₁: DC power supply voltage;

(11), the raising of frequency

Work as V _C＞＞R _LDuring I, by formula (6)

Learn:

Improve V _C, t commutating period of shortening AC square wave current _d, reduce t commutating period _dShared ratio in one-period has increased the ratio that AC square wave current is in the flat region, improves the frequency of AC square wave current.

2, a kind of wide-frequency amplitude-constant AC square wave current device of inductive load, it is characterized in that this device comprises DC power supply, clamped voltage source 4, clamped circuit 3, loop control circuit 5, AC square wave current control circuit, energy supplementary circuit 1 and AC square wave current generator 2 stagnate, AC square wave current generator 2 is a full-bridge circuit, and the last brachium pontis of full-bridge circuit is the first constant current inductance L ₁With the second constant current inductance L ₂, two following brachium pontis are two all-controlling power electronics devices; DC power supply is connected with switch S, and switch S is connected with energy supplementary circuit 1 input, and the output of AC square wave current generator 2 connects inductive load; AC square wave current control circuit 2 is made of frequency adjustment, control timing generation circuit, drive circuit, and the AC square wave current control circuit is connected to AC square wave current generator 2; Two inputs of energy supplementary circuit 1 are connected with dc power anode, clamped voltage source 4 positive poles respectively, the output of energy supplementary circuit 1 is connected with the input of AC square wave current generator 2, and the output of the loop control circuit 5 that stagnates is connected with energy supplementary circuit 1; The negative pole of clamped voltage source 4 is connected with power cathode, and the input of clamped circuit 3 is connected with inductive load, and the output of clamped circuit 3 is connected with the positive pole of clamped voltage source 4.

3, according to the wide-frequency amplitude-constant AC square wave current device of specification 2 described inductive loads, the last brachium pontis that it is characterized in that AC square wave current generator 2 circuit is the first constant current inductance L ₁With the second constant current inductance L ₂, the first constant current inductance L ₁With the second constant current inductance L ₂An end be connected with the two ends of load inductance respectively.

4,, it is characterized in that energy supplementary circuit 1 comprises the 5th diode D according to the wide-frequency amplitude-constant AC square wave current device of specification 2 described inductive loads ₅, the 6th diode D ₆With the 3rd switching tube J ₃, the 5th diode D ₅Positive pole connect mains switch, the 3rd switching tube J ₃With the 6th diode D ₆Parallel connection, the 6th diode D ₆Positive pole meet the negative pole of the 5th diode D5 and the input of AC square wave current generator 2, the 6th diode D ₆Negative pole meet the clamped voltage source 4 and the first diode D ₁, the second diode D ₂Negative pole.

5,, it is characterized in that clamped circuit 3 comprises the first diode D according to the wide-frequency amplitude-constant AC square wave current device of specification 2 described inductive loads ₁With the second diode D ₂, the first diode D ₁The negative pole and the second diode D ₂Negative pole connect the first diode D ₁Positive pole and an end and the first constant current inductance L of inductive load ₁An end connect the second diode D ₂Positive pole and the other end and the second constant current inductance L of inductive load ₂An end connect.

The present invention compared with prior art, its technique effect is:

1, during AC square wave current commutation, load voltage is clamped on the voltage of clamped voltage source 4, has realized that commutate property along the line, commutating period of AC square wave current is short.

2, regulate the voltage of clamped voltage source 4, realized that AC square wave current is adjustable commutating period.

3, improve the voltage V of clamped voltage source 4 _C, make V _C＞V ₁, realized the lifting of high-frequency ac square wave current amplitude.

4, adopt constant current inductance and energy supplementary circuit, realized the constant of load current amplitude, the variation with supply voltage, frequency, load does not change.

5, improve the voltage V of clamped voltage source 4 _C, make V _C＞＞V ₁, shortened commutating period, improved the frequency of AC square wave current.

6, measured data of the present invention: emission current 12A, V ₁=12V, coil resistance 0.3 Ω, winding inductance quantity 500 μ H, the voltage of clamped voltage source 4 is 800V, electronic switch adopts the MOSFET module of 1200V, 31A, the electric current 15 μ s that commutate.

Description of drawings:

Fig. 1 is load current waveform figure and the load voltage waveform figure of the present invention in one-period;

Fig. 2 is the composition frame chart of apparatus of the present invention;

Fig. 3 is the circuit topology figure of apparatus of the present invention composition frame chart;

Fig. 4 is for surveying emission current by just commutating along oscillogram to negative;

Fig. 5 is for surveying emission current by bearing to just commutating along oscillogram;

Fig. 6 is actual measurement v _o(t) oscillogram.

In Fig. 1:

t ₀: the forward AC square wave current begins to rise constantly, v ₀(t)=V _C,

t ₁: the forward AC square wave current rises to I constantly, v _o(t) by V _CDrop to V ₁,

t ₂: the forward AC square wave current begins to descend constantly, v _o(t) by V ₁Drop to-V _C,

t ₃: the forward AC square wave current drops to zero constantly, v ₀(t)=-V _C

t ₄: the negative sense AC square wave current rises to-the I moment, v ₀(t) by-V _CRise to-V ₁,

t ₅: the negative sense AC square wave current begins to descend constantly, v _o(t) by-V ₁Rise to V _C,

t ₆: the negative sense AC square wave current drops to 0 constantly, v _o(t)=V _C,

V ₁: DC power supply voltage, V _C: clamped voltage source 4 voltages,

v _o(t): load voltage waveform, i _o(t): load AC square wave current waveform,

t _d: AC square wave current commutating period.

In Fig. 2:

i _o(t), I, v _o(t), V _CImplication and Fig. 1 in i _o(t), I, v _o(t), V _CIdentical.

In Fig. 2, Fig. 3:

The 1-energy supplementary circuit,

2-AC square wave current control circuit,

The clamped circuit of 3-,

The clamped voltage source of 4-,

The 5-loop control circuit that stagnates.

Embodiment:

Concrete control method of the present invention is:

1, the S that closes a switch regulates AC square wave current control circuit 2, and making output AC square wave current frequency is 10kHz;

2, regulate the voltage V of dc power supply ₁=12v, output AC square wave current amplitude is I=12A, the maximum current that the full-control type electronic switch of selecting for use can bear is 31A;

3, the periodic load voltage waveform v of output _o(t) be:

t ₀: v _o(t)=V _C, be V among the figure _o=800V;

t ₁: v _o(t) reduce to V by 800V ₁

t ₂: v _o(t) by V ₁Rise to-800V;

t ₃：v _o(t)＝-800V；

t ₄: v _o(t) drop to-V by-800V ₁

t ₅: v _o(t) by-V ₁Rise to 800V;

t ₆：v _o(t)＝800V；

Control voltage, AC square wave current between the rising of forward AC square wave current, decrement phase:

At t ₀～t ₁During this time, the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, v _o(t ₀)=V _C=800V, the constant current inductance is connected with load inductance, and the diode current flow in the clamped circuit 3 is with the V of load inductance voltage clamping at clamped voltage source 4 _COn, i _o(t) rise to I by zero line, current value is promoted;

At t ₁～t ₂During this time: the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, v _o(t)=V ₁, by the power supply power supply, supply power voltage is low, and load current slowly descends, and works as i _o(t) drop to

Wherein Δ I is the undulate quantity of output current amplitude, and energy supplementary circuit 1 work is changeed by clamped voltage source 4 power supplies, because of V _CVoltage is very high, the Constant Electric Current inductance energy is replenished at short notice, therefore, has kept load current amplitude constant in the AC square wave current flat region;

At t ₂～t ₃During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t) by just becoming negative value, v _o(t ₂The V of)=- _C=-800V, AC square wave current drops to zero by the I linearity, at t ₃Load current decays to zero constantly;

The rising of negative sense AC square wave current, the control voltage of decline process, electric current:

At t ₃～t ₄During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t ₃The V of)=- _C=-800V, the constant current inductance is connected with load inductance, the diode current flow in the clamped circuit 3, with the load inductance voltage clamping at clamped voltage source 4-V _COn, i _o(t) by zero line rising-I, current value is promoted;

At t ₄～t ₅During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t ₄The V of)=- ₁, by the power supply power supply, supply power voltage is low, and load current slowly descends, and works as i _o(t) drop to

Energy supplementary circuit 1 work is changeed by clamped voltage source 4 power supplies, because of V _CVoltage is very high, the Constant Electric Current inductance energy is replenished at short notice, therefore, has kept load current amplitude constant in the AC square wave current flat region;

At t ₅～t ₆During this time: the first switch J ₁Turn-off second switch pipe J ₂Conducting, v _o(t ₅)=V _C=800V, AC square wave current drops to zero by-I linearity, at t ₆Load current decays to zero constantly;

5, calculate AC square wave current trailing edge slope K ₁, following " slope " all refers to the absolute value of slope:

i _o(t) by I or-I drops to zero slope:

${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_1=\left|\frac{{\mathrm{di}}_0\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_0\left(t\right)-V_C}{L}\right|$

Work as V _C＞＞R _LDuring I, ${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_1\&ap;\frac{V_C}{L}=\frac{800}{500\&times;{10}^{-6}}={1.6\&times;10}^6$

Wherein: L=500 μ H, V _C=800V

6, calculate AC square wave current rising edge slope K ₂:

i _o(t) by above freezing be raised to I or-slope of I

${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_1=\left|\frac{{\mathrm{di}}_0\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_0\left(t\right)+V_C}{L}\right|$

Work as V _C＞＞R _LDuring I, ${\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\&ap;\frac{V_C}{L}=\frac{800}{500\&times;{10}^{-6}}={1.6\&times;10}^6$

Wherein: L=500 μ H, V _C=800V

7, calculate output AC square wave current t commutating period _d(unit: μ s):

AC square wave current t fall time _D1: ${\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6$

AC square wave current rise time t _D2: ${\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right){\&times;10}^6$

AC square wave current is by just to negative t commutating period _d:

$t_d={\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d+{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right){\&times;10}^6=15\mathrm{\&mu;s}$

8, calculate current amplitude I (unit: A):

Work as V _C＞＞R _LDuring I, electric current rate of rise K ₂

${\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\&ap;\frac{V_C}{L}=\frac{800}{500\&times;{10}^{-6}}={1.6\&times;10}^6$

Current rise time t _D2:

${\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right)\&times;{10}^6=-\frac{500\&times;{10}^{-6}}{0.3}\ln \frac{800}{800+12\&times;0.3}\&times;{10}^6\&ap;7.5\mathrm{\&mu;s}$

AC square wave current amplitude I:

$I={\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=\frac{V_C}{R_L}\left(\ln \frac{V_C}{V_c+{\mathrm{IR}}_L}\right)\&times;{10}^6=11.795A$

9, the commutation of output current is along slope K:

AC square wave current trailing edge slope $K_{}$ ${}_1=\left|\frac{{\mathrm{di}}_0\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_0\left(t\right)-V_C}{L}\right|$

AC square wave current rising edge slope $K_{}$ ${}_2=\left|\frac{{\mathrm{di}}_0\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_0\left(t\right)+V_C}{L}\right|$

Work as V _C＞＞R _LDuring I, $K={\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_1={\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">K</figure-callout>}}_2\&ap;\frac{V_C}{L}=\frac{800}{500\&times;{10}^{-6}}=1.6\&times;{10}^6,$ The commutation edge is that slope is

K=1.6 * 10 ⁶Straight line, the current waveform symmetry;

10, determining of constant current inductance value

At V ₁=12V, I=12A, R _L=0.3 Ω, L=500 μ H, Δ I=0.4A, switching tube J ₃Maximum operation frequency f _MaxUnder=10kHz the situation, constant current inductance value is:

$L_{\min }=\frac{R_L}{f_{\max }\&CenterDot;\ln \frac{R_{L}I-V_1}{R_{L}I+R_L\mathrm{\&Delta;I}-V_1}}-L=1.58\mathrm{mH}$

Wherein:

Δ I: the undulating value of AC square wave current amplitude;

f _Max: the 3rd switching tube J ₃The highest switching frequency;

Consider the 3rd switching tube J ₃Operating frequency is low more, and the Constant Electric Current sensibility reciprocal that needs is big more, chooses L ₁=L ₂〉=L _Min, get 2mH at this;

11, the raising of frequency

Improve V _C, the commutating period of shortening AC square wave current, improve frequency;

If V _C=1000V, L=100 μ H works as V _C＞＞R _LDuring I,

$t_d=t_d={\mathrm{<figure-callout\; id="1"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d+{\mathrm{<figure-callout\; id="2"\; label="t\; d"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">t</figure-callout>}}_d=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right)\&times;{10}^6-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right)\&times;{10}^6=2.4\mathrm{\&mu;s}$

Electric current t commutating period then _d=2.4 μ s, and frequency is 100kHz, the cycle is 10 μ s, and the AC square wave current flat region time is 3.8 μ s, and promptly in such cases, the frequency of output current can reach 100kHz;

12, current amplitude is constant

Actual the 3rd switching tube J ₃Maximum switching frequency is 100kHz, L ₁=L ₂=2mH, V ₁=12V, I=12A, R _L=0.3 Ω, L=500uH, the undulating value Δ I of AC square wave current amplitude:

$\mathrm{\&Delta;I}=\frac{V_1}{R_L}-I+(I-\frac{V_1}{R_L})e^{\frac{R_L}{({\mathrm{<figure-callout\; id="1"\; label="L"\; filenames="S2008100692721E00011.png,S2008100692721E00021.png"\; state="\{\{state\}\}">L</figure-callout>}}_1+L)f_{\max }}}=0.034A$

This shows that load current is in the AC square wave current flat region, the current fluctuation rate

Realize current constant.

As shown in Figure 2, the inventive system comprises DC power supply, clamped voltage source 4, clamped circuit 3, energy supplementary circuit 1, stagnant loop control circuit 5, AC square wave current control circuit and AC square wave current generator 2, wherein AC square wave current generator 2 is a full-bridge circuit, and the last brachium pontis of full-bridge circuit is the first constant current inductance L ₁With the second constant current inductance L ₂, two following brachium pontis adopt all-controlling power electronics device; DC power supply is connected with switch S, and switch S is connected with the input of energy supplementary circuit 1, and the output of AC square wave current generator 2 connects inductive load; The AC square wave current control circuit is made of frequency adjustment, control timing generation circuit, drive circuit, and the AC square wave current control circuit is connected to AC square wave current generator 2; Two inputs of energy supplementary circuit 1 are connected with the positive pole of dc power anode, clamped voltage source 4 respectively, the output of energy supplementary circuit 1 is connected with the input of AC square wave current generator 2, and loop control circuit 5 outputs that stagnate are connected with energy supplementary circuit 1; The negative pole of clamped voltage source 4 is connected with power cathode, and the input of clamped circuit 3 is connected with inductive load, and the output of clamped circuit 3 is connected with the positive pole of clamped voltage source 4.

As shown in Figure 3, energy supplementary circuit 1 comprises the 5th diode D ₅, diode D ₆With the 3rd switching tube J ₃, the 5th diode D ₅Positive pole connect mains switch, the 3rd switching tube J ₃With the 6th diode D ₆Parallel connection, the 6th diode D ₆Positive pole meet the 5th diode D ₅Negative pole and the input of AC square wave current generator 2, the 6th diode D ₆Negative pole meet clamped voltage source 4, the first diode D ₁The negative pole and the second diode D ₂Negative pole; Clamped circuit 1 comprises the first diode D ₁With the second diode D ₂, the first diode D ₁Negative pole and diode D ₂Negative pole connect the first diode D ₁The positive pole and the second diode D ₂Positive pole be connected the first diode D respectively with the two ends of inductive load ₁Positive pole and an end and the first constant current inductance L of inductive load ₁An end connect the second diode D ₂Positive pole and the other end and the second constant current inductance L of inductive load ₂An end connect; The loop control circuit 5 that stagnates comprises first resistance R ₁, second resistance R ₂With the 3rd resistance R ₃, comparator A ₁, drive circuit, reference voltage circuit and stagnant loop control circuit 5 control Constant Electric Current inducing currents are constant; Comparator A ₁Inverting input meet R ₀, R ₀As current sampling, be used to detect the amplitude of output AC square wave current; Comparator A ₁Output signal through the 3rd resistance R ₃Receive drive circuit.

As output current i _o(t) less than

The time, comparator output signal is by drive circuit control electronic switch J ₃Conducting, clamped voltage source 4 provides energy for energy supplementary circuit 1, and the electric current of constant current inductance is risen to

Work as i _o(t) greater than

The time, comparator output signal is controlled the 3rd switching tube J ₃Ending, is steady state value thereby keep the Constant Electric Current inducing current, and the constant current inductance has played the effect of constant-current source.

By regulating reference voltage circuit, realization I's is adjustable.

By regulating the magnitude of voltage of clamped voltage source 4, realize that AC square wave current commutation slope and commutating period are adjustable.

As shown in Figure 4 and Figure 5: actual measurement emission current 12A, V ₁=12V, coil resistance 0.3 Ω, winding inductance quantity 500 μ H, the voltage of clamped voltage source 4 is 800V, electronic switch adopts the MOSFET module of 1200V, 31A, electric current μ s commutating periods 15.

The present invention has improved the steepness on AC square wave current commutation edge, has realized commutation property along the line, has solved the lifting of current amplitude and constant, the scaling problem of frequency range.

Claims (5)

1. the wide-frequency amplitude-constant AC square wave current device of an inductive load, it is characterized in that this device comprises DC power supply, clamped voltage source (4), clamped circuit (3), loop control circuit (5), AC square wave current control circuit, energy supplementary circuit (1) and AC square wave current generator (2) stagnate, AC square wave current generator (2) is a full-bridge circuit, and the last brachium pontis of full-bridge circuit is the first constant current inductance L ₁With the second constant current inductance L ₂, two following brachium pontis are two all-controlling power electronics devices; DC power supply is connected with switch S, and switch S is connected with energy supplementary circuit (1) input, and the output of AC square wave current generator (2) connects inductive load; The AC square wave current control circuit is made of frequency adjustment, control timing generation circuit, drive circuit, and the AC square wave current control circuit is connected to AC square wave current generator (2); Two inputs of energy supplementary circuit (1) are connected with dc power anode, clamped voltage source (4) positive pole respectively, the output of energy supplementary circuit (1) is connected with the input of AC square wave current generator (2), and the output of the loop control circuit (5) that stagnates is connected with energy supplementary circuit (1); The negative pole of clamped voltage source (4) is connected with power cathode, and the input of clamped circuit (3) is connected with inductive load, and the output of clamped circuit (3) is connected with the positive pole of clamped voltage source (4).

2. the wide-frequency amplitude-constant AC square wave current device of inductive load according to claim 1 is characterized in that the last brachium pontis of AC square wave current generator (2) circuit is the first equivalent constant current inductance L ₁With the second constant current inductance L ₂, the first constant current inductance L ₁With the second constant current inductance L ₂An end be connected with the two ends of inductive load respectively.

3. the wide-frequency amplitude-constant AC square wave current device of inductive load according to claim 1 is characterized in that energy supplementary circuit (1) comprises the 5th diode D ₅, the 6th diode D ₆With the 3rd switching tube J ₃, the 5th diode D ₅Positive pole connect switch S, the 3rd switching tube J ₃With the 6th diode D ₆Parallel connection, the 6th diode D ₆Positive pole meet the negative pole of the 5th diode D5 and the input of AC square wave current generator (2), the 6th diode D ₆Negative pole connect clamped voltage source (4).

4. the wide-frequency amplitude-constant AC square wave current device of inductive load according to claim 1 is characterized in that clamped circuit (3) comprises the first diode D ₁With the second diode D ₂, the first diode D ₁The negative pole and the second diode D ₂Negative pole connect the first diode D ₁Positive pole and an end and the first constant current inductance L of inductive load ₁An end connect the second diode D ₂Positive pole and the other end and the second constant current inductance L of inductive load ₂An end connect.

One kind according to claim 1 the device control method, it is characterized in that the step of this method is as follows:

(1), the S that closes a switch, by the frequency adjustment in the AC square wave current control circuit, regulate output AC square wave current i _o(t) frequency, the cycle of AC square wave current must be greater than the opening of electronic switch, turn-off time sum;

(2), regulate clamped voltage source (4) voltage V _C, change the slope on output AC square wave current commutation edge, make the output AC square wave current property along the line that commutates, V _C0 and the electronic switch rated insulation voltage between;

(3), by regulating reference voltage circuit, change output AC square wave current amplitude, the maximum current that current amplitude can be born less than full control property electronic switch;

(4), by control AC square wave current generator (2), reference voltage and clamped voltage source (4) voltage V _C, make each output cycle produce the load voltage waveform v that shape is identical and amplitude equates _o(t);

Forward AC square wave current i _o(t) voltage, the electric current between rising, decrement phase:

At t ₀～t ₁During this time: with the first constant current inductance L ₁Be connected the first switching tube J on the same brachium pontis ₁Turn-off, with the second constant current inductance L ₂Be connected the second switch pipe J on the same brachium pontis ₂Conducting, the voltage v that provides to load _o(t ₀)=V _C, load voltage is clamped at V _COn, V _CMuch larger than DC power supply voltage V ₁, AC square wave current rises to I by zero fast linear, and booster tension is realized with clamped voltage source (4);

At t ₁～t ₂During this time: the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, v _o(t ₁)=V ₁, output forward AC square wave current, i _o(t)=I;

At t ₂～t ₃During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t) by just becoming negative value, v _o(t ₂The V of)=- _C, load voltage is clamped at-V _COn, AC square wave current begins linear decline, at t ₃Moment current i _o(t) decay to zero;

The rising of negative sense AC square wave current, the control voltage of decline process, electric current:

At t ₃～t ₄During this time: the first switching tube J ₁Conducting, second switch pipe J ₂The voltage v that provides to load is provided _o(t ₄The V of)=- _C, load voltage is clamped at-V _COn, V _CMuch larger than DC power supply voltage V ₁, AC square wave current i _o(t) fast linear rises to-I, and booster tension is realized with clamped voltage source (4);

At t ₄～t ₅During this time: the first switching tube J ₁Conducting, second switch pipe J ₂Turn-off v _o(t)=-V ₁, output negative sense AC square wave current, i _o(t)=-I;

At t ₅～t ₆During this time: the first switching tube J ₁Turn-off second switch pipe J ₂Conducting, v _o(t) become on the occasion of, v by negative value _o(t ₅)=V _C, load voltage is clamped at V _COn, negative sense AC square wave current i _o(t) descend by-I is linear, at t ₆Current attenuation constantly is to zero;

Wherein:

t ₀: the zero hour of output forward AC square wave current, t ₁: v _o(t) drop to V ₁The moment,

t ₂: the moment that the forward AC square wave current begins to descend, t ₃: the forward AC square wave current drops to for zero the moment,

t ₄: v _o(t) drop to-V ₁The moment, t ₅: the moment that the negative sense AC square wave current begins to descend,

t ₆: the negative sense AC square wave current drops to zero the moment, V _C: clamped voltage source (4) voltage,

i _o(t): AC square wave current, I: AC square wave current amplitude;

(5), calculate AC square wave current trailing edge slope absolute value K ₁, following " slope " all refers to the absolute value of slope:

i _o(t) by I or-I drops to zero slope:

$K_1=\left|\frac{{\mathrm{di}}_o\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_o\left(t\right)-V_C}{L}\right|---\left(1\right)$

Wherein:

R _L: the load dc resistance;

L: load inductance amount;

V _C: clamped voltage source (4) voltage;

Work as V _C＞＞R _LDuring I,

AC square wave current i _o(t) by I or-the I linearity drops to zero, the descending slope of forward AC square wave current and negative sense AC square wave current equates;

(6), calculate AC square wave current rising edge slope K ₂:

i _o(t) by above freezing be raised to I or-slope of I

$K_2=\left|\frac{{\mathrm{di}}_o\left(t\right)}{\mathrm{dt}}\right|=\left|\frac{R_L{i}_o\left(t\right)+V_C}{L}\right|---\left(2\right)$

Wherein:

R _L: the load dc resistance;

L: load inductance amount;

V _C: clamped voltage source (4) voltage;

Work as V _C＞＞R _LDuring I,

Load current i _o(t) by zero line rise to I or-I, the rate of rise of forward AC square wave current and negative sense AC square wave current equates;

(7), calculate output AC square wave current t commutating period _d, wherein unit is μ s:

AC square wave current t fall time _D1: $t_{d1}=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6---\left(3\right)$

AC square wave current rise time t _D2: $t_{d2}=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right){\&times;10}^6---\left(4\right)$

AC square wave current is by just to negative t commutating period _d:

$t_d=t_{d1}+t_{d2}=-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6-\frac{L}{R_L}\left(\ln \frac{V_C}{V_C-{\mathrm{IR}}_L}\right){\&times;10}^6---\left(5\right)$

Work as V _C＞＞R _LDuring I, get by (1)

Get by (2) formula

$t_{d1}\&ap;\frac{\mathrm{IL}}{V_C},t_{d2}\&ap;\frac{\mathrm{IL}}{V_C}$

$t_d=t_{d1}+t_{d2}\&ap;\frac{2\mathrm{IL}}{V_C}---\left(6\right)$

By changing V _C, scalable AC square wave current t commutating period _dImprove V _C, shortened t _d, V _CBe arranged on 0 between the electronic switch rated insulation voltage;

(8), calculate AC square wave current amplitude I, wherein unit is A:

Work as V _C＞＞R _LDuring I, $I=K_2{t}_{d2}=\frac{V_C}{R_L}\left(\ln \frac{V_C}{V_C+{\mathrm{IR}}_L}\right){\&times;10}^6---\left(7\right)$

By changing V _C, scalable AC square wave current amplitude; Improve V _C, can improve the amplitude of AC square wave current, the lowest high-current value that I can bear less than electronic switch; I and supply voltage, frequency, load inductance amount have nothing to do;

(9), the commutation of output AC square wave current is along slope K:

Work as V _C＞＞R _LDuring I, get by (1) and (2) formula,

$K=K_1=K_2\&ap;\frac{V_C}{L}---\left(8\right)$

AC square wave current rising and falling edges slope is identical, promptly commutates along slope

Constant, commutation is the constant straight line of a slope along waveform, the current waveform symmetry;

(10), the first constant current inductance L ₁With the second constant current inductance L ₂Determine

Constant current inductance minimum value computing formula:

$L_{\min }=\frac{R_L}{f_{\max }\ln \frac{R_{L}I-V_1}{R_{L}I+R_L\mathrm{\&Delta;I}-V_1}}-L---\left(9\right)$

Choose L ₁=L ₂〉=L _Min

Wherein:

Δ I: the undulating value of AC square wave current amplitude;

f _Max: the 3rd switching tube J ₃The highest switching frequency; The 3rd switching tube J wherein ₃Be included in the energy supplementary circuit (1) the 3rd switching tube J ₃An end connect the first constant current inductance L ₁With the second constant current inductance L ₂Tie point, the other end connects clamped voltage source (4);

V ₁: DC power supply voltage;

(11), the raising of frequency

Work as V _C＞＞R _LDuring I, by formula (6) Learn:

Improve V _C, t commutating period of shortening AC square wave current _d, reduce t commutating period _dShared ratio in one-period has increased the ratio that AC square wave current is in the flat region, improves the frequency of AC square wave current.

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