SU379886A1 - DIGITAL DEVICE FOR DETERMINING DYNAMIC MOTOR MAGNETIZING LOOP - Google Patents

Description

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The invention relates to the field of measurement technology and can be applied to determine the dynamic loop of magnetization of magnetic materials by points, in particular, any points of interest on the dynamic loop of the magnetization reversal can be determined. The obtained measurement results can be used to calculate other parameters of magnetic materials characterizing the behavior of the latter in alternating magnetic fields.

Instruments for imaging and recording dynamic loops of magnetization reversal of magnetic materials, operating according to the oscillographic and stroboscopic method, are based on using the dependence of the coercive force on the phase shift between the magnetic field strength and the induction in the sample.

However, ferrographs depict a loop of magnetization reversal only on the oscilloscope screen, and strobe installations are quite complex devices, which prevents the obtained results from being used for direct automatic processing. The capabilities of these devices are limited to measuring only one point on the dynamic loop of magnetization reversal, moreover, provided that the magnetic field is sinusoidal. In addition, the dependence of the coercive force on the phase shift between the magnetic field strength and the induction in the sample is nonlinear.

The purpose of the invention is to improve the measurement accuracy in comparison with the oscillographic method, simplify the circuit in comparison with the stroboscopic method and create a more versatile automatic device for determining points on the dynamic loop of magnetization reversal of magnetic materials.

This is achieved by compensating for the magnetization reversal vector.

n Uff (f) Us (f)

compensating vector

, {+ iUfCs (f),

where Unit) is the instantaneous value of voltage, proportional to the instantaneous value of the magnetic field strength;

B (t) is the instantaneous value of voltage proportional to the instantaneous value of induction in the sample; Kpf (t) are the instantaneous values of the composition UKB (I) of the compensating vector.

The frequency of rotation of the compensating vector is many times less than the rotation of the magnetization vector, i.e.

  (

The compensation principle is shown in FIG. 1 and 2 for determining the TI point.

Compensation at this point is judged for simultaneous compensation for both components. The law of change of the compensating vector is determined by the purpose of measurement and the shape of the dynamic loop of magnetization reversal.

FIG. 3 shows a block diagram of the device.

The proposed device works as follows.

The test sample 1 is re-magnetized by the magnetizing winding 2 supplied from the AC source 3. The voltage UH. (T), proportional to the magnetic field strength, is removed from the resistor 4, and the voltage proportional to the first derivative of the induction in the sample is taken from the measuring winding 5. At the output of the integrator 6, a voltage UB (t) is obtained that is proportional to the induction Used the sample. The parameters of the output voltage of the alternator are determined by the software device .7, which also controls the law of variation of the components of the compensating vector at the outputs of the generators 8 and 9 of the compensating voltage. (The form of voltages at the outputs of the comparators W and // is shown in Fig. 2). In the shaper 12 and 13 pulses, the differences of these voltages are converted into needle pulses, which are fed to the input of the comparison circuit 14. At the moment of compensation, the two pulses coincide in time with each component and a pulse appears at the output of the comparison circuit, giving the command to convert

the instantaneous values of the compensating voltages of analogue converters — code 15 to 16-c for recording the indicator device 17 directly in units of induction and magnetic field strength.

With a sinusoidal change in induction, it is possible in the proposed device to increase the measurement accuracy of the analog integrator 6 to replace the digital delay circuit connected to the output of the pulse former 12, which shifts the pulses coming from the former, out of phase by jt / 2.

Subject invention

A digital device for determining a dynamic reversal loop, containing a source of magnetizing field, a software device, devices for isolating voltages, proportional magnetic field strengths and magnetic induction of the test sample, in order to improve the accuracy, simplify the circuit and automate the measurement process, it is equipped with a circuit for dynamically compensating the magnetization reversal vector, which contains two compensating voltage generators controlled by a programmable circuit stvom, two comparators, one input of each of which is connected to a voltage source proportional to either the induction or field strength

the magnetic field, and the other with an appropriate compensating voltage generator; the outputs of the comparators are connected via a pulse shaper to a coincidence circuit, the output of which is connected

with the control inputs of the analogue converters, the code of the components of the compensating vector.

I ,. , I || I and I | 1 1 i,

and I I 1 | 1m1 1 | l,

| 1P | iHi 11-11 i f

1rig.2

FIG. 3