SU665379A1 - Static ac-to-ac converter - Google Patents

Description

one

The invention relates to a converter technique, namely to static converters made on the basis of a sequential autonomous inverter, and can be used, for example, in installations for the induction heating of metals.

Known static converters, made on the basis of a standalone serial inverter.

One of the well-known static converters contains two valve bridges, each of which has a switching circuit in the diagonal of alternating current and filter chokes and capacitors in the DC circuit, and the power supply of the inverter is dried from the DC link LIJ.

A static converter based on an autonomous serial inverter is also known, in which a protection element connected to the inverter gate bridge and logic circuits are used to protect the inverter thyristors when the inversion fails by removing control pulses from the thyristors of the DC link rectifier. matches that prohibit the passage of control pulses to the thyristors of the rectifier with the disappearance of the alternating voltage of the inverter 2.

The closest to the technical nature of isooretion is a static converter containing two valve bridges with switching capacitors in the AC diagonal, filter chokes and capacitors in the DC circuit, and a DC link j 5J. The disadvantage of such an inverter is low reliability, since in the event of a breakdown of the inversion, the emergency current reaches a considerable value, which can lead to the output of the thyristors.

The aim of the invention is to increase allegiance. The goal is achieved by inserting two high-frequency power supply units of pulse formers into the static converter, one of which is connected to the switching capacitor of one valve bridge and connected to the first group of drivers and the second is connected to the switching bridge of another valve bridge and connected to the output of the second group of drivers, and the thyristors of the DC link are connected in a bridge circuit, with two thyristors connected to each arm of the bridge The transitions of which are connected to the pulse formers.

The high frequency power supply unit can be implemented, for example, in the form of a high frequency transformer, the secondary winding of which is connected to a bridge rectifier.

The basic electrical circuit of the static converter is shown in the drawing, where:

1 -12 - DC link thyristors;

13-20 - reverse diodes of valve bridges;

21-28 - valve bridge thyristors;

29--32 - auxiliary valves;

33-36 - filter chokes;

37-40 - filter capacitors;

41, 42 - commuting chokes;

43, 44 - switching capacitors;

45.46 — high frequency power supply units of pulse formers;

47, 48 — groups of pulse formers;

49-block synchronization;

50- load.

Static Converter works as follows.

By alternately switching the thyristors of the inverter valve bridges to the switching capacitors 43, 44, an alternating high frequency voltage is created. This voltage is converted by high frequency power supply units 45, 46 to direct current, and is used to power groups of direct current drive thyristors.

The control signal to the drivers comes from the synchronization unit 49.

When overturning at least one of the inverter valve bridges, the high-frequency voltage at the commutator capacitor of this bridge disappears and the supply voltage of the corresponding group of drivers disappears. Thus, the removal of the control

pulses from the thyristors of the DC link and the static converter is protected from emergency currents.

Claims (3)

1.Static AC to AC converter based on an autonomous serial inverter containing two valve bridges with switching capacitors in the AC diagonal, filter chokes and capacitors connected to the DC terminals of the bridges, DC link on the thyristors, control transitions of which are associated with pulse formers, characterized in that, in order to increase the reliability of operation, two blocks of high-frequency power supply of pulse formers, the first of which is connected to the input capacitor of one valve bridge and connected to the first group of drivers, the second is connected to the switching capacitor of another valve bridge and connected to the second rpynine drivers, and the thyristors of the DC link are connected on the bridge circuit, and in each the bridge arm includes two thyristors each, the control transitions of which are connected to the formers of different groups. 2. The transducer according to claim 1, characterized in that the high-frequency block The power supply is made in the form of a high-frequency transformer, the secondary winding of which is connected to a bridge rectifier. Information sources, taken into account in the examination 1. USSR author's certificate number 486439, cl. П 02М 7/537, 10.09.71. 2. USSR author's certificate number 366539, cl. H 02Р 13/16, 03.12.68. 3. USSR author's certificate No. 601790, cl. H 02M 7/515, 10/8/73.