RU2390789C1 - Device for measuring characteristics of magnetically soft materials - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device for measuring characteristics of magnetically soft materials has series-connected power supply, a magnetising winding placed on the test specimen and a measuring shunt. The output of the power supply is connected in series to a scaling device, the first input of an integro-summing amplifier and the first input of recording device. The output of the measuring shunt is connected to the input of the amplifier whose output is connected to the second input of the recording device. A differentiator, whose input is connected to the output of the amplifier. A divider, whose first input is connected to the output of the amplifier and the second input to the output of the scaling device. A null device, whose input is connected to the output of the differentiator. An analogue-to-digital converter, whose first input is connected to the output of the divider and the second input to the output of the null device. A register, whose first input is connected to the first output of the analogue-to-digital converter and the second input to the second output of the analogue-to-digital converter. A digital-to-analogue converter whose first input is connected to the output of the register and the second input to the output of the amplifier. The output of the digital-to-analogue converter is connected to the second input of the integro-summing amplifier.

EFFECT: higher accuracy of measuring magnetic characteristics of objects made from magnetically soft materials.

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Description

The invention relates to magnetic measurements and is intended to measure the magnetic characteristics of products from soft magnetic materials (MMM).

A device for determining the magnetic properties of soft materials [Avt.sv. USSR No. 1167552], containing a generator, a power amplifier, a permeameter with two yokes, magnetizing and measuring windings, an ammeter, a voltmeter, a wattmeter, a voltmeter and a voltage meter of a wattmeter are connected to the outputs of the measuring winding of the permeameter, with the first output of the magnetizing power winding, the first output is connected the input of which is connected to a generator, a choke with two yokes and a magnetizing winding, two measuring AC transformers, the first of which contains two, and the second - three windings, two rubber a torus and a switch, and inserts of magnetic material are placed in the gaps of the inductor’s magnetic circuit and in the magnetic circuit of the permeameter, the second output of the magnetizing winding of the permeameter is connected to the first output of the first windings of the measuring transformers connected in series, the first output of the magnetizing windings of the inductor to the first output of the second windings of the measuring transformers , and the second output to the first output of the power amplifier, the second winding of the first measuring transformer it is connected to the first resistor, the second terminals of the first and second windings of the second measuring transformer are connected to the second output of the power amplifier, the ammeter and the current circuit of the wattmeter are connected to the third winding of the second measuring transformer, the first terminal of the second resistor is connected to the first output of the power amplifier, the second terminal to the movable the contact of the switch, the fixed contacts of which are respectively connected to the second terminal of the magnetizing winding of the permeameter and to the first terminal of the magnetizing magnet weave throttle.

The disadvantage of this device is the need to apply a measuring winding to the test sample, which complicates the procedure for measuring the magnetic characteristics of samples from MMM and makes it impossible to measure the magnetic characteristics of finished products (electromagnet, stators of electrical machines, etc.).

The closest in technical essence to the claimed device is the selected device as a prototype for measuring the characteristics of MMM without applying a measuring winding [Testing of magnetic materials and systems. / E.V. Komarov, A.D. Pokrovsky, V.G.Sergeev, A.Ya. Shikhin. - M .: Energoatomizdat, 1984. - P.243-244], which contains a serially connected power source, a magnetizing winding deposited on the test sample, a measuring shunt, a scaling device, a first input of an integrating sum amplifier, a first input are sequentially connected to the output of the power source the recording device, the input of the amplifier is connected to the output of the measuring shunt, the second input of the recording device and the second input of the integrating summing amplifier are connected to its output.

The voltage at the output of the power source is determined by the expression:

where I is the current flowing through the magnetizing winding; R _H is the active component of the resistance of the magnetizing winding; dF - change in the magnetic flux penetrating the magnetizing winding during the time dt; k is the coefficient determined by the number of turns of the magnetizing winding, the length of the magnetic line 1, the cross-sectional area of the test sample.

Moving IR _H to the left side of the equation and integrating over both parts of the equation over time, we obtain the formula by which the integrator of the device in question calculates the magnetic flux:

Expression (2) is implemented subject to the conditions:

where R ₁ is the resistance of the resistor that determines the transmission coefficient at the first input of the integrosumator; R ₂ is the resistance of the resistor, which determines the transmission coefficient at the second input of the integro-adder; k _mu is the transfer coefficient of the scaling device; k _y is the gain of the amplifier; R _W - the resistance of the shunt.

The active component R _{n of the} resistance of the magnetizing winding is previously determined and then used in calculating the magnetic flux.

The disadvantage of the device taken as a prototype is that during the measurement, due to the current flowing through the magnetizing winding, it is heated, and an increase in the temperature of the magnetizing winding causes an increase in the active component R _{n of} its resistance, which leads to a violation of condition (3). Thus, expression (2), by which the magnetic flux is calculated in the device, is not implemented correctly, which introduces a significant error in the measurement result. To eliminate this error, it is necessary to ensure compliance with condition (3) in the measurement process, subject to changes in R _n .

An object of the invention is to develop a device for measuring the characteristics of soft magnetic materials, which does not require the application of a measuring winding and takes into account the change in the active component of the resistance of the magnetizing winding.

The technical result of the invention is to improve the accuracy of measuring the magnetic characteristics of products from MMM.

The specified technical result is achieved using a device for measuring the characteristics of the MMM, containing a serially connected power source, a magnetizing winding deposited on the test sample, a measuring shunt, a scaling device, the first input of the integrating sum amplifier, the first input of the recording device, are sequentially connected to the output of the recording device, to the output the measuring shunt is connected to the input of the amplifier, the output of which is connected to the second input of the recording device, differential a transmitter, the input of which is connected to the output of the amplifier, a divider, the first input of which is connected to the output of the amplifier, and the second to the output of the scaling device, a zero-organ, the input of which is connected to the output of the differentiator, an analog-to-digital converter, the first input of which is connected to the output of the divider and the second - with the output of the zero-organ, a register, the first input of which is connected to the first output of the analog-to-digital converter, and the second - with the second output of the analog-to-digital converter, digital-to-analog converter, the first input One of which is connected to the output of the register, and the second to the output of the amplifier, the output of the digital-to-analog converter is connected to the second input of the integrosumming amplifier.

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 its criterion of "novelty."

The analysis of the prior art made it possible to establish that the distinguishing features inherent in the present invention, such as a differentiator, divider, zero-organ, analog-to-digital converter, register and digital-to-analog converter, when they are introduced in this connection with other circuit elements in the inventive device for measuring soft magnetic characteristics of materials, the above blocks exhibit new properties, which leads to an increase in the accuracy of measuring the magnetic characteristics of MMM by reducing the error caused by the change HAND active component of the field winding resistance. 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 measuring the characteristics of MMM, figure 2 is a timing diagram of the operation of the device, figure 3 is an example implementation of a power source.

The device for measuring the characteristics of the MMM contains a serially connected power source 1 (PI), a magnetizing winding 2 deposited on the test sample 3, a measuring shunt 4 (IS), a scaling device 5 (MU) is connected in series to the output of the power source 1 (PI), the first input integrosumming amplifier 6 (IU), the first input of the recording device 7 (RU). The output of the measuring shunt 4 (IS) is connected to the input of the amplifier 8 (U), the output of which is connected to the second input of the recording device 7 (RU), the differentiator 9 (DF), the input of which is connected to the output of the amplifier 8 (Y), the divider 10 (DL ), the first input of which is connected to the output of the amplifier 8 (U), and the second to the output of the scaling device 5 (MU), the zero-organ 11 (BUT), the input of which is connected to the output of the differentiator 9 (DF), an analog-to-digital converter 12 (ADC), the first input of which is connected to the output of the divider 10 (DL), and the second to the output of the zero-organ 11 (BUT), p register 13 (P), the first input of which is connected to the first output of the analog-to-digital converter 12 (ADC), and the second to the second output of the analog-to-digital converter 12 (ADC), the digital-to-analog converter 14 (DAC), the first input of which is connected to the output register 13 (P), and the second with the output of the amplifier 8 (Y), the output of the digital-to-analog converter 14 (DAC) is connected to the second input of the integro-summing amplifier 6 (DUT).

Consider the operation of the device for measuring the characteristics of MMM.

From condition (3) we express R ₂ :

Since R _W << R _n and when the condition k _mu = k _y · R ₁ · R _W , the expression (4) will take the form:

, а следовательно, в это время можно определить активную составляющую R_H сопротивления намагничивающей обмотки 2 как отношение напряжения источника питания 1 (ИП) и тока, протекающего в измерительном шунте 4 (ИШ).With a constant current in the magnetizing winding 2, and therefore in the measuring shunt 4 (IS), the magnetic flux Φ ceases to permeate the magnetizing winding 2, i.e.

and, therefore, at this time, it is possible to determine the active component R _{H of the} resistance of the magnetizing winding 2 as the ratio of the voltage of the power source 1 (IP) and the current flowing in the measuring shunt 4 (IS).

The magnetizing winding 2, deposited on the test sample 3, is fed by a trapezoidal voltage U ₁ (figure 2) from a power source 1 (IP). Part of this voltage from the output of the scaling device 5 (MU) is supplied to the first input of the integro-summing amplifier 6 (IU), and the input of the amplifier 8 (Y) receives a voltage proportional to the current flowing in the measuring shunt 4 (IS), and therefore, the voltage in sample. At the first input of the divider 10 (DL) voltage U ₈ is supplied from the output of amplifier 8 (Y), and the second is supplied with voltage U ₅ from the output of scaling device 5 (MU). The voltage U ₈ from the output of the amplifier 8 (Y) is supplied to the input of the differentiator 9 (DF). At times t ₁ , t _{5 the} current in the magnetizing winding 2 ceases to change. At time t ₂ , t _{6 the} transients in the test sample 3 are completed and the voltage U ₈ at the output of the amplifier 8 (Y) takes a constant value, the voltage U ₉ at the output of the differentiator 9 (DF) takes a value equal to zero, which causes a zero organ 11 (BUT). According to the signal U _{11 of the} null-organ 11 (BUT), the analog-to-digital converter 12 (ADC) starts converting the voltage U ₁₀ , which is inversely proportional to the active component R _{n of the} resistance of the magnetizing winding 2, from the output of the divider 10 (DL) into a digital code. At time t ₃ , t ₇ completes the analog-to-digital conversion and the signal U _12.2 from the second output of the analog-to-digital Converter 12 (ADC), the resulting code is recorded in register 13 (P). The signal from register 13 (P), inversely proportional to the active component R _{H of the} resistance of the magnetizing winding 2, is fed to the first input of the digital-to-analog converter 14 (DAC), the second input of which is connected to the output of amplifier 8 (Y). The voltage from the output of the digital-to-analog converter 14 (DAC), inversely proportional to the active component R _{n of the} resistance of the magnetizing winding 2, is supplied to the second input of the integro-summing amplifier 6 (DUT), which ensures compliance with condition (5). At times t ₄ , t ₈ , after the condition (5) is satisfied, the magnetizing winding 2 starts to magnetize in the opposite direction. The voltage U ₆ at the output of the integrosumming amplifier 6 (DUT), proportional to the magnetic flux, is supplied to the first input of the recording device 7 (RU), the second is the voltage U ₈ from the output of the amplifier 8 (Y), proportional to the magnetic field strength.

The device operates cyclically.

Thus, every half period of the magnetizing current, the expression (5) is corrected.

The blocks that make up the device for measuring the characteristics of soft magnetic materials can be performed, for example:

- magnetizing winding 2, measuring shunt 4 (IS), scaling device 5 (MU), integrosumming amplifier 6 (IU), recording device 7 (RU), amplifier 8 (U), as in the prototype;

- differentiator 9 (DF) according to [Falkenberry L. Application of operational amplifiers and linear ICs: Per. from English - M .: Mir, 1985.- S.142-143];

- null-organ 11 (BUT) according to [Falkenberry L. The use of operational amplifiers and linear ICs: Per. from English - M .: Mir, 1985. - S.235-236];

- divider 10 (DL) on the chip 525PS2;

- analog-to-digital Converter 12 (ADC) on the chip K572PV1;

- register 13 (P) on the chip K155IR13;

- digital-to-analog Converter 14 (DAC) on the chip K572PA1A;

- the power supply circuit 1 (IP) is shown in figure 3 and contains: pulse generator 15 (GI), pulse counter 16 (SI), read-only memory 17 (ROM), digital-to-analog converter 18 (DAC), low-pass filter 19 ( Low-pass filter) and power amplifier 20 (UM). In the cells of the permanent storage device 17 (ROM) pre-recorded codes corresponding to the desired form (figure 2) of the signal U _{1 of the} power source 1 (IP), in a step form. Power source 1 (PI) works as follows. The pulse generator 15 (GI) produces pulses of constant frequency, which are fed to the input of the pulse counter 16 (SI). The digital code at the output of the pulse counter 161 (SI) corresponds to the address of the memory cell of the read-only memory 17 (ROM), in which information about the current value of the approximated voltage is recorded, this information is fed to the digital-to-analog converter 18 (DAC), the output of which is a stepwise trapezoidal curve voltage, this curve is smoothed by the low-pass filter 19 (low-pass filter), the power amplifier 20 (UM) is designed to match the power source 1 (IP) with the fed circuit. The device operates cyclically.

The blocks included in the power supply 1 (IP) can be performed, for example:

- pulse generator 15 (GI), as described in [Gutnikov B.C. Integrated electronics in measuring devices. - L .: Energoatomizdat, 1988. - P.154-157];

- pulse counter 16 (SI), as described in [Gutnikov B.C. Integrated electronics in measuring devices. - L .: Energoatomizdat, 1988. - P.167-169];

- read-only memory device 17 (ROM) on the chip KR556RT16;

- digital-to-analog converter 18 (DAC) on the K572PA1A chip.

- low-pass filter 19 (low-pass filter) according to [Falkenberry L. Application of operational amplifiers and linear ICs: Per. from English - M .: Mir, 1985. S.194-196];

- power amplifier 20 (UM) according to [Titz U., Schenk K. Semiconductor circuitry: Per. with him. - M .: Mir, 1982. - S.245-246].

Experimental studies of the layout of the inventive device for measuring the characteristics of soft magnetic materials showed that, compared with a device of a similar purpose (prototype), the inventive device improves the accuracy of measuring the magnetic characteristics of products from MMM by reducing the error caused by a change in the active component of the resistance of the magnetizing winding.

Claims (1)

A device for measuring the characteristics of soft magnetic materials, containing a power supply connected in series, a magnetizing winding applied to the test sample, a measuring shunt, a scaling device, a first input of an integrating sum amplifier, a first input of a recording device, and an amplifier input are connected to the output of the measuring shunt; , the output of which is connected to the second input of the recording device, characterized in that it is an additional o contains a differentiator, the input of which is connected to the output of the amplifier, a divider, the first input of which is connected to the output of the amplifier, and the second to the output of the scaling device, a zero-organ, the input of which is connected to the output of the differentiator, an analog-to-digital converter, the first input of which is connected to the output of the divider, and the second with the output of the zero-organ register, the first input of which is connected to the first output of the analog-to-digital converter, and the second to the second output of the analog-to-digital converter, digital-to-analog conversion Tel, the first input coupled to an output register, and the second - to the amplifier output, output digital to analog converter connected to the second input of the amplifier integrosummiruyuschego.

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