RU2158428C2 - Fiber-optical device to register shape of pulses of superheavy currents - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: fiber-optical device to register shape of pulses of superheavy currents includes fiber-optical measuring unit, recorder and analog differentiating-integrating unit whose two inputs are connected to outputs of fiber-optical measuring unit correspondingly and whose output is linked to input of recorder that is capable of memorizing shape of signal in digital or analog form. According to one version of implementation of device analog differentiating- integrating unit incorporates differentiator, two multipliers, integrator and adder whose output is output of analog differentiating-integrating unit. In agreement with another version analog differentiating-integrating unit has two differentiators, two multipliers and adder whose output is connected via integrator to output of analog differentiating- integrating unit. EFFECT: diminished frequency band of signals coming to input of recorder, simplified design of device. 2 cl, 4 dwg

Description

The invention relates to the field of electrical engineering and can be used in experiments on thermonuclear fusion to record the shape of a current pulse in Z-pinch electrophysical installations in which there is a need to register current pulses with an amplitude of ~ 10 ⁶ -10 ⁸ A at pulse durations of ~ 1 μs.

 It is well known to use a magneto-optical sensor for measuring electric current in the electric power industry. The magneto-optical sensor is based on the use of the Faraday effect - the property of a magnetic field to rotate the plane of polarization of light passing through a sensitive element made of magneto-optical material. The use of optical fiber as a sensing element of a magneto-optical sensor is also well known.

Known polarizing electric current sensor [1], consisting of an optical radiation source, which through a polarizer is optically connected to the input of the sensing element in the form of an optical fiber wound around a current-conducting conductor with a measured current. The output of the sensor is optically connected to the analyzer input in the form of a Wollaston prism, splitting the beam into two beams with mutually orthogonal linear polarizations. The analyzer outputs are optically connected to the inputs of the photodetector unit, the output of which is connected to the recorder. If the angle between the polarizer and the Wollaston prism is 45 ^o , the photodetector unit generates at its output a signal described by the formula
U _O = k • sin (2V • I ), ( 1)
where k is a constant value determined by the implementation of the photodetector unit, V is the Verdet constant, I is the measured current. Since the region of unambiguity of the sine is π / 2, the maximum measured current strength I _max , by virtue of formula (1), is
I _max = 0.25 π V. (2)
The Verdet constant V in the material of the optical fiber, as a rule, is V ≈ 4.6 • 10 ^-6 Rad / A, in this case the maximum measured current will be I _max = 1.7 • 10 ⁵ A, which is lower than the required.

,
где I - измеряемый ток; U_{out k} - выходной сигнал с k-го магнитооптического датчика. Недостатком данного устройства является то, что для измерения тока 10⁸A необходимо использовать ~ 600 магнитооптических датчиков, что сильно усложняет конструкцию.A device for measuring ultra-large currents [2], containing n magneto-optical sensors with a sensitive element in the form of an extended fiber from a magneto-optical material and a measuring and computing unit. The position of the optical input of the fiber of each of the n magneto-optical sensors coincides with the optical output of the fiber of the neighboring sensor in such a way that the fibers of all the sensors form a closed, simply connected circuit, covering only the current-carrying conductor with the measured current, and the outputs of the n magneto-optical sensors are connected to the corresponding inputs of the measuring and computing unit, the number n is selected from the condition n> 4V • I _max π, where V is the Verde constant of the fiber material, I _max is the maximum measured current, and the measuring and computing unit configured to implement a function

,
where I is the measured current; U _{out k} is the output signal from the k-th magneto-optical sensor. The disadvantage of this device is that for measuring the current 10 ⁸ A it is necessary to use ~ 600 magneto-optical sensors, which greatly complicates the design.

 To register the waveform, analog and digital oscilloscopes are used, for example, a digital recorder SRG8. However, they can remember the shape of the signal converted to voltage. Therefore, when registering the shape of pulses of extra-large currents, it is necessary to convert the current strength to voltage, which is the object of the present invention.

Closest to the claimed is a fiber-optic device for measuring ultra-large pulsed currents, containing a fiber-optic measuring unit and a recorder [3]. The fiber-optic measuring unit contains a light source that is optically connected through the polarizer to the input of the sensing element, made in the form of an optical fiber wound around a current-conducting conductor with a measured current. The output of the sensor is connected to the input of the optical divider, the outputs of which are connected to the first and second prisms of Wollaston, the two outputs of each of which are the outputs of the fiber-optic measuring unit. At the outputs of the fiber-optic measuring unit, signals are generated whose light power is proportional to: 1) 1 + sin 2VI; 2) 1-sin 2VI; 3) 1 + cos 2VI; 4) 1-cos 2VI. In the prototype, the outputs of the first and second prisms of Wollaston are connected respectively to the optical inputs of the first and second, third and fourth photodetectors. The outputs of the first and second photodetectors are connected to the inputs of the first analog electronic unit, and the outputs of the third and fourth photodetectors are connected to the inputs of the second analog electronic unit. The outputs of the first and second analog electronic units are connected to the inputs of the first and second analog-to-digital recorders, the outputs of which are connected to a computer. The angle between the input polarizer and the first Wollaston prism is 45 ^o and a signal is determined from the output of the first analog electronic unit, defined by the formula U _o1 = k • sin (2V • I), (3), where k is the parameter determined by the implementation of the circuit of the analog electronic unit .

The second Wollaston prism is rotated relative to the first by an angle of 45 ^o and a signal is determined from the second analog electronic unit, which is determined by the formula U _out2 = k • cos (2V • I), (4). The recorder captures the signals from the first and second analog electronic units, and the computer can calculate the shape of the measured pulse current I at any values of its amplitude from the measured values of U _o1 and U _oo2 . (In this case, a recorder is used that can memorize the waveform in digital or analog form).

 The disadvantages of this device are the high requirements for the frequency band of the recorders, the need to use two analog-to-digital recorders.

So, the signal front duration t _f 'described by formula (3) or (4) can be estimated using the simplified formula t _f ' = π • t _f / (4V • I _max ), (5), where t _f is the front duration pulse of the measured current; I _max - the amplitude of the measured current. With a current front duration of 1 μs and an amplitude of 10 ⁸ A, it is necessary to register bipolar signals with front durations of 3 ns, which corresponds to the need to increase the frequency bandwidth of analog-to-digital recorders from 350 kHz to 120 MHz.

 The technical results provided by the claimed invention are to reduce the frequency band of the signals received at the input of the recorder, i.e., reduce the requirements for the registrar, and simplify the device by reducing the number of registrars by half.

 The technical result is achieved in that the fiber-optic device for measuring ultra-large pulsed currents, comprising a fiber-optic measuring unit and a recorder, further comprises an analog differential integrating unit, two inputs of which are connected to the corresponding outputs of the fiber-optic measuring unit, and the output to the input of the registrar.

 The technical result in the device is also ensured by the fact that the analog differential integrating unit contains two differentiators, two multipliers, an adder, an integrator, and the first input of the analog differential integrating unit is connected to the first input of the second multiplier and through the first differentiator to the second input of the first multiplier, the second input of the analog differential integrating unit is connected to the first input of the first multiplier and through the second differentiator to the second input of the second multiplier, pr my first output and an inverted output of the second multiplier connected to inputs of an adder whose output is connected via an integrator to the output of the analog differential integrating unit.

 The technical result in the device is also ensured by the fact that the analog differential integrating unit contains a differentiator, two multipliers, an integrator, an adder, the first input of the analog differential integrating unit connected to the first inputs of the first and second multipliers, and the second input of the analog differential integrating unit to the second output of the first multiplier and through the differentiator to the second input of the second multiplier, the direct output of the first multiplier is connected to the first input of the adder, nvertirovanny output of the second multiplier is connected via an integrator to a second input of the adder whose output is the output of the analog differential integrating unit.

 The invention consists in converting two high-frequency signals into a single signal with a frequency band matching the frequency band of the measured current, and linearly dependent on the measured current. This allows you to use one registrar (and in the prototype - two) and, in addition, reduce the requirements for the frequency band of the registrar, which greatly simplifies the proposed device.

 Figure 1 shows a functional diagram of a fiber optic device for measuring ultra-large pulsed currents. Figure 2 and 3 shows the functional diagrams of the implementation of the analog differential integrating unit. In FIG. Figure 4 shows the plots of the signals of the measured current from the outputs of the fiber-optic measuring unit and the output of the analog differential integrating unit.

 A fiber optic device for measuring ultra-large pulsed currents consists of a fiber optic measuring unit 1, an analog differential integrating unit 2 and a recorder 3.

 Analog differential integrating unit 2 can be performed according to the circuit shown in figure 2. In this case, it consists of differentiators 4, 5, multipliers 6, 7, adder 8, integrator 9. The first input of the analog differential integrating unit 2 is connected to the input of the differentiator 4 and to one of the inputs of the multiplier 7. The second input of the analog differential integrating unit 2 is connected to the input of the differentiator 5 and to one of the inputs of the multiplier 6. The outputs of the differentiators 4,5 are connected to the other inputs of the multipliers 7,6, respectively. The outputs of the multipliers are connected to the direct and inverting inputs of the adder 8, the output of which through the integrator 9 is connected to the output of the analog differential integrating unit 2.

 Analog differential integrating unit 2 can be performed according to the circuit shown in figure 3. In this case, it consists of a differentiator 10, multipliers 11, 12, an integrator 13, and a subtraction unit 14. The first input of the analog differential integrating unit 2 is connected to the first input of the multiplier 11 and the second input of the multiplier 12. The second input of the analog differential integrating unit 2 is connected to the second input of the multiplier 11 and through the differentiator 10 to the first input of the multiplier 12. The output of the multiplier 11 is connected to the direct input of the adder 14, the output of the multiplier 12 is connected through the integrator 13. The output of the adder 14 is I Analog output differential integrator unit 2.

 As the fiber optic unit 1 can be taken, for example, the fiber optic current sensor described in the prototype. An analog differential integrating unit can be constructed from the elements described in [4].

 Any digital or storage analog oscilloscope with a bandwidth of more than 1 MHz can be taken as a recorder, for example, a SRG8 digital oscilloscope manufactured by the Scientific Research Institute of Pulse Technology.

 The work of the proposed device is as follows.

When exposed to the measured current I with the pulse shape shown in FIG. 4a, signals U ₁ and U ₂ , described by formulas (3), (4) and depicted in FIGS. 4b and c, are formed on the fiber-optic measuring unit at its outputs. These signals are fed to the first and second inputs of an analog differential integrating block 2, the output of which is formed by a signal U, defined by the formula U = A • I + B, (6), where A, B are the parameters determined by the implementation of the differential integrating circuit block 2. The received signal U, the form of which is shown in Fig.4g, is stored by the recorder 3.

.The operation of the differential integrating unit 2, made according to the circuit shown in figure 2, is described as follows. The signal U ₁ supplied to the first input of the differential integrating unit is differentiated on the differentiator 4 and as a result the signal U ₁ 'is obtained:

.

.Similarly, the signal U ₂ differentiates on the differentiator 5 and the result is a signal U ₂ ':

.

.The multiplier 6 multiplies the signals U ₁ 'and U ₂ , while at its output a signal U _x1 is generated, which is described by the formula

.

.The multiplier 7 multiplies the signals U ₂ 'and U ₁ , while at its output a signal U _x2 is generated, which is described by the formula

.

.The adder 8 is a summation of the signal U _x1 and the inverted signal U _x2 and at its output a signal is defined by the formula

.

On the integrator 9, the signal U _{Σ is} integrated, as a result of which a signal U is generated at its output, which is described by the formula U = 2V • (I (t) -I ₀ ), where I ₀ is the current value at the initial time, which is considered known.

.The operation of the differential integrating unit 2, made according to the circuit shown in figure 3, is described as follows. The first and second inputs of the differential integrating unit 2 receive the corresponding signals U ₁ , U ₂ determined by formulas (3), (4). The signals U ₁ and U _{2 are} multiplied by the multiplier 11 and the signal U _{x1 is} formed at its output, described by the formula

.

После перемножения сигналов U₂' и U₁ на умножителе 12 на его выходе образуется сигнал U_x2 описываемый формулой

На интеграторе 13 производится интегрирование сигнала U_x2 и усиление проинтегрированного сигнала в два раза, в результате чего на ее выходе образуется сигнал U_i:

Сигналы U_x1 и U_i поступают на прямой и инвертирующий входы сумматора 14, где осуществляется вычитание из U_x1 U_i и на его выходе образуется выходной сигнал U, описываемый формулой

Использование аналогового дифференциально-интегрирующего блока 2 позволяет преобразовать два высокочастотных сигнала с волоконно-оптического блока в один сигнал с частотной полосой, совпадающей с частотной полосой измеряемого тока, так как с выхода этого блока идет сигнал, линейно зависящий от измеряемого тока.The signal U _{2 is} differentiated on the differentiator 10 and the result is a signal U ₂ ':

After multiplying the signals U ₂ 'and U ₁ on the multiplier 12 at its output, a signal U _x2 is generated described by the formula

On the integrator 13, the signal U _{x2 is} integrated and the integrated signal is amplified twice, as a result of which the signal U _i is generated at its output:

The signals U _x1 and U _i are fed to the direct and inverting inputs of the adder 14, where subtraction from U _x1 U _{i is} carried out and an output signal U is generated at its output, which is described by the formula

Using an analog differential integrating unit 2 allows you to convert two high-frequency signals from a fiber-optic unit into a single signal with a frequency band that coincides with the frequency band of the measured current, since the output of this block is a signal that linearly depends on the measured current.

 Thus, the proposed device in comparison with the prototype is much simpler, because thanks to the introduced unit, the conditions for using one recorder with reduced requirements for the frequency band are provided in it. The prototype used two registrars with increased requirements for the frequency band.

Literature
1. Busurin V.I., Nosov Yu.R. Fiber optic sensors: physical fundamentals, calculation and application issues. - M .: Energoatomizdat, 1990, p. 85.

 2. Device for measuring ultra-large currents. Application for invention N 97110903 from 06/26/97. The decision to grant a patent on 25.2.98.

 3. Lassing H.S., Oomens A.A.M. and Woltjer R. Rev. Sci. Instrum. 57, p. 851 (1986) (prototype).

 4. Kaufman M., Sidman A. A practical guide to the calculation of circuits in electronics. Handbook, t. 1. - M .: Energoatomizdat, 1991, p. 249-255.

Claims (3)

 1. Fiber-optic device for recording the shape of pulses of extra-large currents, containing a fiber optic measuring unit and a registrar, characterized in that the device further comprises an analog differential integrating unit, two inputs of which are connected to the outputs of the fiber-optic measuring unit, respectively, and the output - to the input of the recorder, capable of remembering the waveform in digital or analog form.  2. The fiber optic device according to claim 1, characterized in that the analog differential integrating unit contains two differentiators, two multipliers, an adder, an integrator, and the first input of the analog differential integrating unit is connected to the first input of the second multiplier and through the first differentiator to the second input of the first multiplier, the second input of the analog differential integrating unit is connected to the first input of the first multiplier and through the second differentiator to the second input of the second multiplier, direct to The output of the first and the inverted output of the second multiplier are connected to the inputs of the adder, the output of which is connected through the integrator to the output of the analog differential integrating unit.  3. The fiber optic device according to claim 1, characterized in that the analog differential integrating unit contains a differentiator, two multipliers, an integrator, an adder, and the first input of the analog differential integrating unit is connected to the first inputs of the first and second multipliers, and the second input analog differential integrating unit is connected to the second output of the first multiplier and through the differentiator to the second input of the second multiplier, the direct output of the first multiplier is connected to the first input of the adder, in ertirovanny output of the second multiplier through the integrator - to the second input of the adder whose output is the output of the analog differential integrating unit.

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