SU935897A1 - Ac voltage control - Google Patents

Description

(54) AC VOLTAGE REGULATOR

one

The invention relates to electrical engineering, in particular to converter equipment, and can be used in the development of converters with transformers or reactors with magnetic conductors of ferromagnets, for example, thyristor-transformer voltage regulators, stand-alone inverters with output transformers and top - Drink with equalization reactors.

. AC voltage regulators (converters) containing a transformer with a branched magnetic circuit, a thyristor switch of the power winding of the transformer, sensors whose output is connected to the input of the control unit, and automatic correction of the magnetisation current of the winding are known, due to which the hysteresis loop of the magnetic circuit Cl2nt21 is subsequently corrected ,

The closest to the present invention is a converter comprising a transformer with a branched magnetic circuit, one power winding of which is via a thyristor switch and the other winding is directly connected to the input and output pins, respectively, of the control unit and automatic correction of the magnetizing current of the power windings, correcting inputs which are associated with the measuring windings of the respective sensors of the derivative of the magnetic flux 3.

to

A disadvantage of the known device is the difficulty of implementation due to the need to have a phase synchronization unit associated with the power part of the device.

15

The purpose of the invention is to simplify the device.

The goal is achieved by the fact that the regulator is equipped with two non-linear converters, the outputs of which

20 are connected, respectively, to the correction inputs of the control unit and automatic correction of the magnetizing current, and their inputs through the filters of the lowest 9 frequencies to measure the windings of the respective sensors of the derivative of the magnetic flux. At the same time, nonlinear converters have monotonic, symmetric with respect to the origin, convex or concave in one of the quadrants of the characteristics, which allows to obtain at the output of non-gang converter the signals that reflect the direction and degree of displacement of the hysteresis loop : water, i.e. the direction and degree of its elevation. FIG. 1, a functional diagram of the regulator of alternating voltage is given; in fig. 2 and 3 are time diagrams that explain the principle of operation of the controller. The circuit contains: transformer with ramified magnetic core 1, primary and secondary power windings of transformer 2, 3 - thyristor switch (triac keys), 4 - control and automatic magnetizing current correction unit, 5 and 6 correction and control inputs of unit 4 , respectively, 7 - sensors of the derivative of the magnetic flux, 8 - measuring windings of the sensors 7 9 - low-pass filters, 1O - non-linear transducers Timing diagrams explaining the principle of the regulator's operation during the remagnetization along the symmetric and The symmetrical cycles of the hysteresis loop are shown respectively in FIG. 2 and FIG. 3, where: a - curves, supply voltage; b - voltage curve on the power primary winding. 2; in - voltage curve on the measuring winding 8; r is the voltage curve at the output of the low pass filter 9; d, e is the voltage curve at the output of the nonlinear converter with its characteristics concave and convex in the first square, respectively. The principle of operation of the device is as follows. The correction inputs 5 of the block 4 are used to correct the asymmetry of the switching pulses of the triac keys 3 and, accordingly, the position of the hysteresis loops, and its control inputs 6 control the voltage setting at the regulator output. Nonlinear 1O converters have monotonic (single-valued derivative) symmetric about the origin (i.e. (-x) - (x), where ij and x are respectively 974, output signals and input signals of the converters), convex (second derivative is negative) or concave (the second derivative is positive) in one quadrant of the characteristic (in Fig. 1 the solid line shows concave in the first quadrant, and the dashed line shows the characteristic in the first quadrant). A small part of the magnetic flux of the transformer 1 passes through the magnetic circuit of the sensor 7, since the magnetic resistance of the magnetic section of the transformer 1 to which the sensor 7 is attached is small, and the magnetic resistance of the two air gaps between the magnetic cores of the transformer 1 and sensor 7 is significant. When the controlled section of the transformer 1 magnetic circuit is saturated, its magnetic resistance increases and the fraction of the magnetic flux branching into the magnetic circuit 7 increases sharply. The EMF of the measuring winding 8 is proportional to the derivative of the branching flow. Measuring winding 8 takes a voltage signal roughly proportional to the derivative of the controlled section of the magnetic circuit, and the output of the low-pass filter 9, which behaves as an integrator at high frequencies, removes the voltage signal (Fig. 2, 3 g), approximately proportional to the intensity of the controlled section of the magnetic circuit. In this case, it is of fundamental importance that, in all modes, in the voltages of both the measuring winding 8 (fig. 2, 3 c) and the output of phytra 9 (fig. 2, 3 g) there is no constant component, which does not allow directly use these voltages to form a corrective action on block 4 to correct the position of the hysteresis loop. When the nonlinear converter 1O is switched on, a voltage is formed between the output of the filter 9 and the correction input 5 of block 4 at the output of this nonlinear converter (Figs. 2, 3, e, e), in which a constant appears only when the hysteresis loop position is shifted control of the land plot. When using a nonlinear converter 10 with a concave characteristic in the first quadrant (solid curve), large values of the input voltage predominate even more at the output of the nonlinear converter. In summary, after nonlinear voltage conversion

(Fig. 3 g) without a constant component, a voltage is obtained (Fig. 3 e) with a constant constant component.

When using a nonlinear transform 10 with a characteristic convex (first line) in the first square, the high voltage values at the input are more weakened at the output than the smaller ones. In the end, after a nonlinear voltage conversion (Fig. 3g), without a constant component, a voltage is obtained (Fig. 3e) with a negative constant component.

When magnetizing the controlled section of the transformer-transformer 1 magnetic circuit along a symmetrical hysteresis loop cycle, all the voltages (Fig. 2, Fig. 2e) have a shape that is symmetrical about the abscissa axis, therefore, all constants have no constant

The constant components from the outputs of nonlinear converters 10 noctynaot to the correction inputs 5 of block 4, which changes the symmetry of the switching pulses of the triac keys 3 until these constant components are eliminated, i.e. Remagnetization of each of the controlled sections of the branched magnetic circuit of transformer 1 along symmetric non-shifted cycles is not yet provided.

Thus, introducing counter-symmetry by incorporating nonlinear 1O transducers into the thyristor switch 3 control circuit (triac keys) basically eliminates the possibility of transformer magnet conductor saturation as it includes the thyristor switch impulses and the load;

Claims (3)

Claim 1. Voltage regulator containing a transformer with a branched magnetic circuit, one power winding through a thyristor switch and the other winding directly connected to the input and output pins, respectively, the control unit and automatic correction of the magnetizing current of the power windings, the correction inputs of which with the measuring windings of the respective sensors of the derivative of the magnetic flux, characterized in that, for the sake of simplification, it is equipped with two The linear converters, the outputs are connected respectively to the correction inputs of the control unit and the automatic correction of the magnetizing current, and their inputs through low-pass filters to the measuring o6MOfKaMH of the respective sensors of the magnetic flux derivative. 2. The device according to claim 1, characterized in that the non-linear transducers are monotonic, symmetrical, relative to the origin, convex or concave in one of the quadrants, characteristics. Information sources, taken into account in the examination 1. USSR Author's Certificate for Application No. 2306275/07, cl. H 02 R 13/16, 1972. 2. US patent number 3697855, cl. H 02 M 7/42, 1973. 3. Lokhov S.P. et al. Methods for controlling thyristor switches on the primary side of a multiphase transformer in variable voltage controllers. -In pr. Modern tasks of converting equipment, part 2, Kiev, 1975.