SU419821A1 - HYSTERESIS LOSS MEASURER - Google Patents

Description

one

The invention relates to the field of magnetic measurements and can be used in the development of magnetic measuring equipment.

A disadvantage of the known hysteresis loss meters is the laboriousness of obtaining the final result due to the need to preliminarily measure the values of BG, He and their subsequent multiplication and the need to preliminarily determine the static hysteresis loop and its subsequent planning.

The automation of these operations, necessary to obtain the final result, is associated with the complexity of the apparatus. In addition, the known devices have low accuracy.

To improve the accuracy of the automation of the measurement process and obtain the result in a digital code in the proposed meter, the counting input of the reversible counter is connected to the output of the magnetization unit through a key and a voltage-to-frequency converter.

FIG. 1 shows the structural scheme of the described gauge; in fig. 2 - graphs explaining the principle of its work.

The meter contains three blocks; magnetization unit 1, hysteresis loss measurement unit 2 and control unit 3.

2

The magnetization unit is an inductive emf control system. at a given stationary level (in the theory of automatic control, such systems are called automatic stabilization systems of the controlled variable). The magnetization unit includes a voltage regulator 4, the input of which is connected to the output of the control unit, and the output through

the voltage subtraction circuit 5 and the controlled current generator 6 are fed to the input 7 of the magnetizing device 8. The output 9 of the magnetizing device is connected to the second input of the calculating circuit, and the output 10 is fed

the input of block 3 and block 2. The magnetizing device 8 includes an electromagnet II, between the poles of which sample 12 is placed, a measuring winding 13, one end of which is grounded, and the other end serves as an induced emf output, and a potentiometer 14, one end of which is grounded, and the second is fed to the input of the integrator 15, the output of which serves as the output of the magnetization unit. The deposition of UH at the output of the integrator 15 is proportional to the intensity of the magnetic field in the sample. One end of the winding 16 of the electromagnet is grounded, and the other serves as the input of the magnetizing device.

Unit 2 contains a voltage-to-frequency converter 17, whose input is connected

with the output of the block i, and the output through the electronic key ib is connected to the counting input of the reversing counter 1U. The input of the zero-level discriminator 20 is connected to the output of the i-tree, and the output is fed to input 1 of the addition of the trigger of the sign ii2 of the reversible counter, iio the key input and the input of the subtraction 26 of the trigger of the sign of the control unit.

ria FIG. i, a is a structural diagram of one of the possible variants of a magnetizing device, which is used to measure noti on the hysteresis of samples with an open magnetic conductor.

When measuring notii on the hysteresis of toroidal samples, the magnetizing device is made according to FIG. 1.6. In this case, it contains sample 24 with a magnetizing winding 25 and a feedback winding 26. The end 27 of the magnetizing winding 25 serves as the input of the magnetizing device, and the end 26 through the calibrated resistor K is grounded. End 28 serves as the output of a UH pattern, which is proportional to the magnetic field strength. One end of the feedback winding 26 is grounded, and the other end 29 serves as the output of the induced emf. When measuring the hysteresis loss of toroidal samples instead of the magnetizing device shown in FIG. 1, and the points 27, 29, and 28 of the magnetizing device shown in FIG. 1.6. The circuit shown in FIG. 1, a, works as follows.

The signal from block 3 turns on stabilizer 4. Its output voltage is applied as a reference voltage to the subtraction circuit 5, to the other input of which a feedback signal is received. The voltage from the output of the subtraction circuit, equal to the difference between the reference panel and the feedback voltage, acts on the controlled generator 6, the output current of which enters the winding 16 of the electromagnet I. The resulting magnetic field peremagnetizes the sample 12 from -Nt to the limit hysteresis loops (NT is the maximum value of the magnetic field intensity in the sample). An emf induced in the winding 13 is fed as a feedback signal to the subtractor 5. Thus, the magnetization unit provides constant emf. when unchecked, and, as is known, the constant emf means that the induction in the sample varies linearly with time. Simultaneously with the onset of magnetization, the start signal from control unit 3 passes to input subtraction 23 of sign 22 trigger, which sets reversing counter 19 to count down and opens key 18, through which pulses from voltage-to-frequency converter 17 pass to counting input of reversible counter 19. In the process of magnetization reversal of the sample, the induction in it changes in time from -W to, as shown in FIG. 2b, and the time variation of the voltage UH is depicted by the curve in FIG. 2, a (solid line). With a linear in time variation of the induction, the shape of the curve (t) (Fig. 2, a) corresponds to the upstream branch of the limiting hysteresis (since in this case the time axis can be considered the axis of induction). For clarity, FIG. 2, and the dotted line shows the downstream branch of the hysteresis loop. The pairing (t) is fed to the input of the voltage-frequency (FUL) converter 17 (Fig. 1, a), at the output of which the pulse frequency is proportional to UHB, the time ti (Fig. 2, a) the zero level discriminator 20 (Fig . one). Its output signal overturns the sign 22 trigger and thereby switches the reversible counter 19 to a direct account. The number of pulses counted by counter 19, during the time from the beginning of the remagnetization to the moment ti is equal to

N, JlF (i) df, (1)

about

where F (t) is the frequency of the following pulses on the output of the FNP.

Since the PNC performs linear conversion of frequency to frequency, we can write

F {i) k.Uf, (f), (2)

where k (f) is the constant conversion coefficient of the FNP.

Substituting the expression for F (t) from formula (2) into equation (1), we obtain

N, k / {Uff (f) df. (3)

about

The number of pulses iVi is proportional to the area bounded by the curve (t) in the interval from O to / 1 and the time axis, i.e. the area of region I (Fig. 1, a).

In the time interval from ti to tz, the reversible counter counts the pulses in the forward direction. The number of pulses transmitted to the counter during 4-ti time is equal to:

N, k / fUff (i) dt, (4)

 t,

that is, it is proportional to the area bounded by the curve (t) in the time interval from ti to tz and the time axis, that is, to the sum of the areas of regions II and III.

The code written in the counter at the moment -tz will be equal to

, -N,. (5)

The number L is proportional to the difference in area, one of which is equal to the area of areas II and P1, and the second is the area of area I (Fig. 2, a). The area of area P1 is equal to the area of area I and, thus, the number L is proportional to the area of area II, that is, half the area of the hysteresis loop and, due to the symmetry of the loop, is the area of the entire loop, and, as is known, the magnitude of hysteresis losses is proportional to the area of the static hysteresis loop .

Subject invention

A hysteresis loss meter that contains a magnetization unit that provides sample reversal but a limiting hysteresis loop linearly in time

6

a change in induction, a zero-level discriminator, a sign trigger, a key and a reversible counter, characterized in that, in order to improve accuracy, automate the measurement process and obtain a result in a digital code, the counting input of the reversible counter is connected to the output of the magnetization unit through a key and a converter, for example life is frequency.

/ - b

 I

.J

FIG. 2