SU1205068A1 - Method of determining dynamic inductivity of non-linear magnetic circuit - Google Patents

Abstract

The invention relates to electrical engineering, to the field of electrical measurement technology. The purpose of the invention is to improve the accuracy and simplify the implementation of the dynamic inductance of a nonlinear magnetic circuit. In addition to measuring the amplitude values of the current, voltage, and phase angle of the main harmonic component, the same parameters are measured at frequencies that are multiples of the carrier. In the description, a formula is presented which allows the inductance to be determined as a function of the magnetizing current. A device implementing the method comprises an alternating current generator 1, a current sensor 3, a voltage divider 4, filtering units 5, 6, amplitude meters of harmonic components of current 8-10 and voltage 11-13, phase meters 14-16, blocks 17 , 18 calculations and registration block 19. 1 il. i (I to about the joint venture about od cx)

Description

.

The invention relates to electrical engineering, in particular, to measuring equipment, electrical quantities (parameters of electrical devices with ferromagnetic cores).

The aim of the invention is to improve the accuracy and simplify the implementation of measuring the dynamic inductance of a nonlinear magnetic circuit.

The proposed method is based on the established functional dependence of the inductance of a nonlinear magnetic circuit on the magnetizing current L:

WITH

LCi)) t4-)

where 2 (4) Langevin function,

LOT) - & - construction constants.

Using the representation of the function as a power series, we transform (1) to the form

L V. Z- I i.1

bH.4.4 () 7VU

Cr)

Substituted in the equilibrium equation EMF

-. , (3) UU) Tl (t) (t) v

expression (2) and the functions Utt) and i (, t), represented as a harmonic series, are equal to the coefficients in the left and right parts of (3) with the corresponding harmonics and taking into account that in chains with steel are clearly expressed are odd higher harmonics, starting from the third, we get three relationships to determine the parameters LO, Y ifr

B. imi lO

0

five

0

five

0

),

111 1

With certain constants of the construction LO, Y, t g, the inductance is calculated from (1).

The use of the proposed method makes it possible to automate the processing of experimental data by using standard electronic measuring instruments and computing facilities.

The drawing shows a block diagram of a device that implements the proposed method.

The device contains sequentially connected AC generator 1, measurement object 2 and current sensor 3, voltage divider 4, filtering blocks 5 and 6. The outputs of unit 5 are connected respectively 5 to the inputs of meters 7-10 of the amplitude of the harmonic components of the current, and the outputs of block 6, respectively, with the inputs of the meters 11-13, the amplitude of the harmonic components of the voltage. The device also contains phase meters 1A-16, serially connected calculation blocks 17-18 and registration block 19.

The electrical signal from the generator 1 is fed to the object 2 measurement. Signals proportional to the values of the function (t) from the current sensor 3 and and (t) from the voltage divider 4 are fed to the inputs of filtering blocks 5 and 6 J intended to separate the harmonic components with the carrier frequency uJ and with the frequencies

 2LJ, zi); 5uJ.

From the outputs of the filtering unit 5, signals with frequencies of uj, 2 uJ, 3u3, 5 (x) are fed to the inputs of meters 7-10 amplitudes of harmonic components of the current, and signals with frequencies of 10, Z) are fed to inputs of meters 14-16 , 5ui3.

From the outputs of the filtering unit 6 to the inputs of meters 11-13 amgshitud. the harmonic components of the voltage and the inputs of the meters 14-16 phase angle angles receive signals 5 with a frequency of and) 3 and),.

From the outputs of the meters 7-16 signals proportional to the amplitudes of the current i ,,. ij, 1:, 15-, voltage amplitudes U, Uj, Us and phase angles Y, H ,, are fed to the input of calculator 17, consisting of typical multiplication blocks and adders for calculating constants, Y, tg

From the output of the calculating block 17, signals proportional to the LO values are fed to the calculating block 18, from the output of which the signal proportional to the inductance L (i) is fed to the input of the recording block 19,

A standard microcomputer, for example, C5-2I Electronics, operating according to an algorithm defined by the formulas given above, can be used as computational units.

Claims (1)

Invention Formula . The method of determining the dynamic 1 INDUCTIVITY of a nonlinear magnetic Editor A.Lёnnina Compiled by V.Stukan Tehred S.Migunova Order 8523/47 Edition 747 VNIIPI USSR State Committee. for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Branch 1TPP Patent, Uzhgorod, st. Project, 4 circuit based on measuring the amplitude values of the current and voltage and phase angle of the main harmonic component, characterized in that, in order to increase accuracy and simplify the implementation of measuring the dynamic inductance of a nonlinear magnetic circuit, the amplitude values of currents and voltages and the phase angles of the harmonic components at frequencies that are multiples of the carrier, and the measurement results determine the inductance as a function of the magnetizing current using the formula ) (7) where l. / - current in the circuit (. instantaneous value) Bo, I5 are construction constants, Z (pCfH - - Langevin function. Proofreader G. Rezhetnik Subscription