SU928565A1 - Thyristorized converter of ac voltage to ac voltage for active load - Google Patents

Description

one

The invention relates to semiconductor (thyristor) converters m-regulators of alternating voltage and can be used as an actuator of automated industrial electrical resistance heaters in various industries (for example, in construction industry, metalworking, chemistry, etc.).

Known thyristor AC voltage converters containing pairs of parallel-counter thyristors connected between the input terminals and the load are characterized by a low power factor with deep regulation. To increase the energy performance of thyristor AC voltage converters for active loads, load partitioning is used. In such converters, the use of the zone continuous regulation principle allows to significantly increase the power factor throughout the entire control range and at some intermediate points of the regulating characteristic to obtain a power factor value equal to unity 1.

Closest to the proposed invention is a thyristor converter of alternating voltage to alternating for active load, containing two thyristors, the anode of one of which is connected to the cathode of the other and one of the input terminals while the cathode of the first thyristor is connected to the first output to connect the first element (section a) the load, the anode of the second thyristor is connected to the first half to connect the second load cell, the second input lead is connected to the common point of the secondary leads to connect each load element, and between the first terminals for connecting the first and second

the load elements included a thyristor chain, forming with the first and second thyristors a closed loop in the driving direction. The regulation characteristic of a known converter consists of two parts ijtoB. In the first section, the angles of unlocking of two main thyristors are changed while the third thyristor is closed, and in the second section, the angles of unlocking the third thyristor, unlocking the two main thyristors at the moments of their natural commutation, are changed. At the boundary of the sections of the regulating characteristic, the power factor is equal to the unit -2.1.

A disadvantage of the known converter is the low power factor in the areas of the regulating characteristic, a small control range with the available power factor.

The purpose of the invention is to increase the overall power factor of the converter, expanding the range of adjustment of the converter.

The goal is achieved by the fact that the thyristor chain contains n horizontally connected thyristors, the common points of which form the terminals for connecting additional load elements.

FIG. 1 is a schematic diagram of the proposed thyristor converter; in fig. 2 and 3 line diagrams of currents in the second and third sections of the regulation characteristic.

The converter contains two ti ristors 1 and 2 which are connected by one anode and a second cathode to the input terminal (clamp) of the device and two elements (sections) of the load 3 and connected in series with thyristors 1 and 2 and connected by their common point to the second input terminal, Between the common points of thyristors 1 and 2 and load sections 3 and t (in the bridge diagonal containing these elements) there is a thyristor chain consisting of thyristors 5 and 6 sequentially connected to each other. Thyristors 1, 3, 6 and in their conducting direction form a closed loop. The common point of the thyristors 5 and 6 is connected to the common point | 1 of the load section 3 and i via the additional load section 7. The thyristors 1 and 2 are unlocked by the system

control 8. Thyristors 5 and 6 - control system 9. In the first part of the adjustment characteristic, only thyristors 1 and 2 are opened, similar to the prototype. In the second section of the adjustment characteristic by the control system 9 on one half-period - the thyristor 6 (Fig. 2); the thyristors 1 and 2 open at the corners of their natural commutation. In this case, the network current in one half period i is equal to the sum of the currents of sections 3 and 7 (i3) to the second half period 12 to the sum of the currents of sections 4 and (4 7) to the end of the second adjustment section (d.- 0) the power factor is equal to one.

In the third section of the adjustment characteristic for one half period, the thyristors 1 and 5 open at the natural switching angle, and the power consumption is regulated by changing the angle of unlocking the thyristor 6; in the second half-period, thyristors 2 and 6 are opened at the angle of natural commutation, and the power is regulated by changing the ugg of the thyristor 5. At each of the half-periods, the current of the network i and i is equal to the sum of the currents of all load sections (). At the end of the third section (Fig. 3) at oLy О, the power factor is equal to one — the power consumed is maximum. The proposed converter can be made on the basis of a commercially available single-phase converter containing four valves.

The positive effect of the proposed alternating voltage thyristor converter circuit for active loads compared to the known one is achieved by increasing the power factor, increasing the number of sections of the regulating characteristic, at the boundaries of which (sections) the power factor is one. At the same time, in the proposed addition of one section of the regulating characteristic, the minimum complication of the converter circuit is achieved by increasing by one the number of thyristors.

Claims (2)

1.Gelman M.V., Lokhov, SP Thyristor variable voltage regulators. M., Energie, 1975, p. 58, fig. 18. 2. Authors certificate of the USSR W 682987, cl. H 02 M S / O, 1979. f 1