RU2434237C1 - Short-time test device for items from electrotechnical steel plates - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is designed for measurement of dynamic hysteresis loop and the main magnetisation curve of items from electrotechnical steel plates at frequencies of 1 to 10000 Hz. Short-time test device for items from electrotechnical steel plates includes AC source, differential magnetic bridge applied to the tested specimen and representing H-shaped core from permalloy, to neutral section of which there applied is measuring coil, and to four poles - similar magnetising coils, which are connected in series so that lower and upper coils are connected to each other in alignment, and pair of upper and pair of lower ones are connected in opposite manner, and connected to AC source output. AC source consists of sine voltage generator and AC amplifier the first input of which is connected to output of sine voltage generator and the second one is connected to measuring coil output. Current sensor is connected in series to magnetising coils. Device also includes memory unit with delay of output signal relative to input signal for one fourth of period of output voltage of generator; the first input of memory unit is connected to output of measuring coil, and the second one is connected to the second output of sine voltage generator, recording unit having two inputs; the first one is connected to output of memory unit and the second one is connected to current sensor output.

EFFECT: possibility of measuring magnetic induction and intensity of magnetic field in the tested specimen; increasing test speed and improving measurement accuracy.

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Description

The invention relates to magnetic measurements and is intended to measure the dynamic hysteresis loop and the main magnetization curve of products from sheet electrical steel (ILETS) at frequencies from 1 to 10,000 Hz.

A known installation for measuring the amplitudes of the values of magnetic induction and the magnetic field of the electrical steel bands [see Prince Magnetic properties of electrical steel / VV Druzhinin. - M .: Energia, 1974. - S.207-211], containing a power source, an average voltmeter, a frequency counter, a coil for measuring magnetic quantities, a coil for compensating magnetic flux outside the sample, an apparatus for testing samples made up of strips.

The disadvantage of this device is the need for preparatory operations on the test sample, which reduces the speed of measurements, as well as the inability to use on samples-blanks for the magnetic circuit having a complex shape.

A device for monitoring steel samples [Application RU No. 94022668/25], comprising a power supply unit, an open U-shaped magnetic circuit with magnetizing and measuring coils located on its cores, the power supply unit being connected to a magnetizing coil; a measurement unit containing a microammeter, the inputs of which are connected to a power supply and a measuring coil, the measurement unit being made according to a compensation circuit. A controlled steel sample closes the air gap between the cores of the magnetic circuit. The device uses special protrusions of V-shaped cores with an angle of 90 ° and a cut of a symmetrical two-stage shape with a depth equal to the length of the side of the corner, which allows you to control steel samples having different geometric shapes and sizes.

The disadvantage of the device for monitoring steel samples is the increased error when measuring in fields close to core saturation, and when the test sample is saturated, because the fraction of the scattering flux causing the error increases.

Closest to the technical nature of the claimed device is selected as a prototype device for measuring magnetic susceptibility on a differential magnetic bridge [see Prince Devices for measuring magnetic quantities / E.N. Chechurina. - M .: Energy, 1969. - S. 70-73]. A device for measuring magnetic susceptibility on a differential magnetic bridge contains an AC source, a primary magnetic flux transducer (differential magnetic bridge), a phase-sensitive detector and a recording unit. The differential magnetic bridge is an H-shaped permalloy core. At the poles of the core there are four identical magnetizing coils, powered by an alternating current source. The magnetizing coils are connected in series so that the lower and upper coils are interconnected in concert, and the pair of upper and lower pairs are interconnected. The measuring coil is applied to the neutral cross section of the H-shaped core, its output is connected to the input of the phase-sensitive detector, the output of which is connected to the input of the recording unit. The test sample is applied to the lower or upper ends of the H-shaped core.

The disadvantage of a device for measuring magnetic susceptibility on a differential magnetic bridge is that it only allows magnetic susceptibility to be measured and does not provide the ability to determine the induction and magnetic field strength in the test sample, that is, it does not allow to determine the parameters of the dynamic hysteresis loop and the main magnetization curve.

The objective of the invention is to develop a device for rapid testing of products from sheet electrical steel.

The technical result of the invention is to expand the functionality of the prototype device by providing the ability to measure magnetic induction and magnetic field strength in the test sample, as well as increasing the test speed and measurement accuracy.

The technical result is achieved using a device for the rapid testing of products from sheet electrical steel containing an alternating current source, a differential magnetic bridge applied to the test sample and representing an H-shaped core made of permalloy, on the neutral cross section of which a measuring coil is applied, and on four poles - the same magnetizing coils, connected in series so that the lower and upper coils are interconnected, and the pair of upper and pair the lower ones are opposite, and connected to the output of the alternating current source, consisting of a sinusoidal voltage generator and an alternating voltage amplifier, the first input of which is connected to the output of the sinusoidal voltage generator, and the second - to the output of the measuring coil, a current sensor is connected in series with the magnetizing coils, the device also contains a storage device with a delay in the output signal relative to the input for a quarter period of the output voltage of the generator, the first input is stored his devices connected to the output of the measuring coil and the other - to the second output of the sinusoidal voltage generator, the recording unit having two inputs, one connected to the output of the memory device, and the second - to the output current sensor.

The search among the means of the same purpose as the claimed did not reveal identical technical solutions in relation to the totality of the essential features of the invention. This allows us to conclude that it meets the criterion of "novelty."

An analysis of the prior art allowed us to establish that the distinguishing features inherent in the present invention, such as a current sensor, a memory device with a delay of the output signal relative to the generator input voltage output by a quarter of the period, registering a block having two inputs, when they are introduced in this connection with the rest of the circuit elements in the inventive device for measuring the characteristics of IELETs, the above blocks show new properties, which leads to the expansion of the functionality of the device otipa, i.e. it provides a measurement of the magnetic induction and magnetic field intensity in the test sample. This allows you to make a positive conclusion about the conformity of the technical solution to the criterion of "inventive step".

Figure 1 presents a block diagram of a device for express testing ILETS. Figure 2 presents a diagram of a sinusoidal voltage generator, figure 3 is a diagram of a storage device with a delay of the output signal relative to the input for a quarter period of the output voltage of the generator.

The device for rapid testing of products from sheet electrical steel contains an alternating current source (not indicated), consisting of a sinusoidal voltage generator 1 and an alternating voltage amplifier 2, the first input of which is connected to the output of a sinusoidal voltage generator 1, a differential magnetic bridge 3 applied to the subject sample 4 and which is an H-shaped core made of permalloy, on the neutral cross section of which a measuring coil 5 is applied, and the same poles are applied to the four poles stitching coils 6-9, connected in series so that the upper 6, 7 and lower 8.9 magnetizing coils are connected together in a consistent manner, and a pair of upper 6, 7 and a pair of lower 8.9 are interconnected, and connected to the output of an alternating amplifier voltage 2, a current sensor 10 is connected in series with magnetizing coils 10, the device also contains a storage device 11, the first input of which is connected to the output of the measuring coil 5, and the second to the second output of the sinusoidal voltage generator 1, the recording unit 12, two inputs, the first is connected to the output of the storage device 11, and the second to the output of the current sensor 10, in addition, the second input of the AC voltage amplifier 2 is connected to the output of the measuring coil 5.

The circuit of the sinusoidal voltage generator 1 is shown in figure 2 and contains a pulse generator 13 with start and stop by external signals, the output of which is connected to the input of the N-bit pulse counter 14 and to the second input of the storage device 11, the output of the N-bit pulse counter 14 is connected to N address inputs of the read-only memory 15, a (N-2) low-order bits from the output of the N-bit pulse counter 14 are connected to the second input of the read-only device 11, the output of the read-only memory 15 is connected to the digits analog converter 16, the output of the digital to analog converter 16 is connected to the first input of the AC voltage amplifier 2.

The memory circuit 11 is shown in FIG. 3 and contains a read / write random access memory 17, a read permission pulse shaper 18, the input of which is connected to the output of the pulse generator 13, and the output - to the read permission input of the random access memory 17, a pulse shaper write permissions 19, the input of which is connected to the output of the pulse generator 13, and the output to the input of the write permission of the random access memory 17, an analog-to-digital converter 20, the input of which connected to the output of the measuring coil 5, and the output to the information input of random access memory 17, and a digital-to-analog converter 21, the input of which is connected to the information output of random access memory 17, and the output to the first input of the recording unit 12, address inputs of random access memory 17 connected to (N-2) lower output bits of the N-bit pulse counter 14.

The device operates as follows.

A test sample 4 is applied to the upper or lower side of the differential magnetic bridge 3. Preparatory operations on the test sample, such as applying measuring or magnetizing coils, are not required, which increases the measurement speed. At the initial moment of time, an external signal starts the pulse generator 13. It generates pulses of constant frequency, which are fed to the counting input of the N-bit pulse counter 14. Codes corresponding to one period of the sinusoidal waveform are pre-recorded in the cells of the permanent storage device 15. A digital code at the output of the N-bit pulse counter 14 sets the address of the memory cell of the read-only memory 15, in which a code is written corresponding to the required voltage value at the output of the sinusoidal voltage generator 1. From the output of the read-only memory 15, the code is supplied to the inputs of the digital-to-analog converter 16. The voltage from the output of the digital-to-analog converter 16 (output of the sinusoidal voltage generator 1), it is supplied to the first input of the alternating voltage amplifier 2. Magnetizing the ears 6-9 applied to the differential magnetic bridge 3 are connected in series and are supplied with voltage from the output of the alternating voltage amplifier 2. The current flowing in the magnetizing coils 6-9 creates magnetic fluxes in the upper and lower parts of the differential magnetic bridge 3 directed oppositely to each other to a friend in the neutral cross section of the core of the differential magnetic bridge 3. The magnetic flux f _top created in the upper part of the core of the differential magnetic bridge 3, with the sample attached to it, is determined by by rage:

F _top = f _o + f _races ,

where Ф _о is the magnetic flux passing through the test sample 4, Ф _ra is the magnetic dispersion flux passing in the upper part of the core of the differential magnetic bridge 3, outside of the sample 4, through the air.

The magnetic flux f _bottom created in the lower part of the core of the differential magnetic bridge 3 without a sample is determined by the expression:

F _bottom = f _races ,

where f _ra - the magnetic flux of the dispersion passing in the upper part of the core of the differential magnetic bridge 3, outside the sample 4, through air equal to the diffusion flux in the upper part of the core of the differential magnetic bridge 3.

The difference in the magnetic flux values in the upper F _upper and lower F _lower parts of the core of the differential magnetic bridge 3 is due only to the presence of the test sample 4. The difference in magnetic fluxes in the neutral cross section of the core of the differential magnetic bridge 3 is equal to the magnetic flux in sample 4. Measurement of magnetic flux through the neutral cross section of the core differential magnetic bridge 3 eliminates the influence of magnetic flux scattering on the measurement result, which increases the accuracy of the measurements.

The magnetic flux in the neutral section of the core of the differential magnetic bridge 3 induces an EMF in the measuring coil 5, proportional to the rate of change of the magnetic flux in the neutral section of the core of the differential magnetic bridge 3, the rate of change of the magnetic flux and magnetic induction in sample 4:

,

,

where e is the EMF induced in the measuring coil 5, Ф _n is the magnetic flux in the neutral cross section of the core of the differential magnetic bridge 3, k is the number of turns of the measuring coil 5, S is the cross-sectional area of the test sample 4, B _o is the magnetic induction in the test sample four.

The signal from the output of the measuring coil 5 is fed to the second input of the AC voltage amplifier 2. The output signal of the AC voltage amplifier 2, proportional to the difference between the signal of the sinusoidal voltage generator 1 and the EMF taken from the measuring coil 5, provides a sinusoidal change in the magnetic induction in sample 4:

,

,

Substitute (2) in (1):

,

,

.where f is the frequency of the output sinusoidal voltage of the generator 1, T is the period of change of the sinusoidal voltage at the output of the generator of the sinusoidal voltage 1,

.

From the output of the measuring coil 5, the EMF is supplied to the first input of the storage device 11, which provides a delay of a quarter of the voltage period at the output of the sinusoidal voltage generator 1. To determine the required delay value, a control signal from the second output of the sinusoidal voltage generator 1 is received at the second input of the storage device 11, these are signals from the output of the pulse generator 13 and (N-2) low-order bits of the N-bit pulse counter 14. At the same time, the read permission 18 and a write enable pulse shaper 19 receives a signal from a pulse generator 13. A read enable pulse shaper 18 is a standby multivibrator operating along the front of the input pulse. The recording resolution pulse generator 19 is a standby multivibrator that is triggered by a drop in the input pulse. Random access memory 17 has (N-2) address inputs, and when using one N-bit counter 14 as a working address generator, for read-only memory 15 and for random access memory 17, the information capacity of random access memory 17 should be four times less information capacity of the permanent storage device 15 and, accordingly, store information about a quarter of the voltage period at the output of the sinusoidal voltage generator 1 and, therefore, voltage at the output of the measuring coil 5. The first to the input of the random access memory 17 is a pulse from the output of the read permission pulse former 18 and the information about the contents of the random access memory block 17 is output at the address determined by the (N-2) low-order bits of the N-bit pulse counter 14, to the digital-to-analog converter 21. From the output of the digital-to-analog converter 21, the voltage is supplied to the first input of the recording unit 12. Then, without changing the signal at the output of the N-bit counter pulses 14, a pulse is generated at the output of the write enable pulse shaper 19, which allows recording to the memory unit 17. The signal from the output of the analog-to-digital converter 20 is recorded in the random access memory unit 17 at the address determined by the (N-2) low-order bits of the output signal N-bit pulse counter 14. Then, in the first period of time equal to a quarter of the voltage period at the output of the sinusoidal voltage generator 1, the output of the random access memory unit 17 will be an undefined signal stored in random access memory 17 until any information is recorded in it, and subsequently, its output will contain a signal shifted relative to the signal from the output of the measuring coil 5 by a quarter of the voltage period at the output of the sinusoidal voltage generator 1 and, proceeding from formulas (2) and (3), proportional to the magnetic induction in the test sample 4.

The use of a storage device 11 with a quarter-period shift, coupled with providing sinusoidal induction in the test sample 4, eliminates the need to connect an integrating device to convert the EMF signal to the induction signal to the output of the measuring coil 5, which eliminates the integration error and improves the measurement accuracy.

The output signal from the storage device 11 with a quarter-period shift proportional to the magnetic induction in the test sample 4 is supplied to the first input of the recording unit 12. From the output of the current sensor 10, connected in series to the magnetizing coil circuit 6-9, a current signal proportional to the magnetic field in the sample, is fed to the second input of the recording unit 12. The device operates cyclically.

The blocks included in the device for testing products from ferromagnetic materials can be made, for example:

- AC voltage amplifier 2 - any differential amplifier with a gain of at least 20;

- the core of the differential magnetic bridge 3 - the core is H-shaped from permalloy;

- measuring coil 5 is applied with a copper wire with a diameter of not more than 0.1 mm, the number of turns from 50 to 200;

- magnetizing coils 6-9 are applied with a copper wire with a diameter of 1-1.5 mm, the number of turns from 150 to 200;

- current sensor 10 - measuring shunt;

- recording unit 12 - any two-coordinate recorder.

The blocks included in the composition of the sinusoidal voltage generator 1 can be performed, for example:

- pulse generator 13 on the chip KA7500;

- pulse counter 14 - composite on the chip K155IE7;

- read-only memory 15 on the chip LH2164-15;

- digital-to-analog converter 16 on the AD569AD chip.

The blocks that are part of the storage device 11 with a delay of the output signal relative to the input for a quarter period of the output voltage of the sinusoidal voltage generator 1 can be performed, for example:

- random access memory with the ability to write / read 17 on the MCM 100484-20;

- analog-to-digital Converter 20 on the chip AD7552KN;

- pulse shapers permission read 18 and write permission 19 on the chips K155AG1;

- D / A converter 21 on the AD569AD chip. Experimental studies of the layout of the inventive device for express testing of products from sheet electrical steel on samples with known magnetic characteristics showed that the inventive device provides a measurement error of not more than 5%.

Claims (1)

A device for rapid testing of products from sheet electrical steel containing an alternating current source, a recording unit, a differential magnetic bridge, which is an H-shaped core, on the neutral cross section of which a measuring coil is applied, and on the four poles - the same magnetizing coils connected in series so that the lower and upper coils are interconnected, and the pair of upper and lower pairs are interconnected, and connected to the output of the source of alternating Oka, characterized in that the alternating current source consists of a sinusoidal voltage generator and an alternating voltage amplifier, the first input of which is connected to the output of the sinusoidal voltage generator, and the second to the output of the measuring coil, a current sensor, a storage device, a first input are connected in series with the magnetizing coils which is connected to the output of the measuring coil, and the second to the second output of the sinusoidal voltage generator, and the recording unit has two inputs, the first chen to the output memory, and the second - to the output of the current sensor.

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