SU146861A1 - Two-bridge converter - Google Patents

Description

The proposed converter relates to a known type of converters operating with a leading power factor, made on two three-phase bridges and containing two feeding transformers, three-phase balancing reactors, valves and switching capacitors.

A feature of the converter that constitutes the subject of the invention is the connection of the cathode and anode groups of valves of both bridges, in which they, together with three-phase equalizing reactors, switching capacitors and windings of supply transformers, form two compensated converters designed according to the "double star with equalization reactor" and connected on both sides to the load.

In this case, the primary windings of one supply transformer must be connected in a triangle, the other - in a star and the secondary windings of the latter are connected in a zigzag.

Running a two-bridge. The converter is reduced in size and weight compared to a known converter of the same type.

In the drawing, depicting the circuit diagram of the proposed converter (for the case of rectification mode operation), the following symbols are used: Tr-1 and Tr-2 supply transformers, 1-6 and D-6 - valves, U / C, and UK2 - three-phase equalization reactors, Ci - Се - switching capacitors, - cathodic reactor, I - load. The primary windings of the transformer of the Tp-l converter are connected to a star, the secondary windings to a zigzag, which ensures the rotation of the secondary voltage phase relative to the primary phase by 30 °. Primary winding

No. 146861- 2 transformer Tr-2 is connected in a triangle, the secondary windings - in a star. Since the primary phase voltages of both transformers are shifted by 30 °, the additional rotation of the secondary voltage of the Tr-1 transformer by 30 ° provides a shift of the secondary voltage of both transformers by 60 °. Valves operating with a shift of 180 °, i.e. valves / and 2, 2 and 5, 3 and /, 4 and 5, 5 and 6, 6 and 4 are interconnected by a common bus. Each group of three busbars of the same polarity is connected to the DC bus through the corresponding three-phase equalization reactor y / Ci, yKz, between the terminals of which are included capacitors C - C3 and C4 - Sb, respectively.

Each group of valves of the same polarity, i.e., valves /, 2, 3, /, 2, 3 and 4, 5, 6, 4, 5, 6, together with the windings of the Tr-1 and Tr-2 transformers, with three-phase balancing the U. / and CC reactor and the corresponding capacitors form two compensated Pr-1 and Pr-2 converters, made according to the “double star with equalization reactor and connected to the load from two sides.

The shift between the two compensated NR / and PR2 converters by 60 ° and the reduced wiring diagram results in full symmetry of rectified voltages and switching from one valve to another one converter, for example, from valve 2 to valve 3, performed by means of a switching capacitor C, flows simultaneously with the switching of current on the valves of another converter of opposite polarity, for example, from valve 4 to valve 5, carried out with the help of a capacitor C. This ensures complete symmetry of both transducers azovateley from the viewpoint of voltage on switching capacitor. These two circumstances completely exclude equalizing currents between parallel-working converters.

Subject invention

A two-bridge power-supply converter that contains two power transformers, valves, three-phase surge reactors and switching capacitors, characterized in that, in order to reduce its size and weight, the cathode and anode groups of the valves of both bridges are combined in such a way that three-phase equalizing reactors, switching capacitors and windings of supply transformers, form two compensated converters made according to the “double star” scheme with equalization reactor and connected: from two sides to the load, with the primary windings of one supply transformer connected in a triangle. the other has a star and the secondary windings of the latter are connected in a zigzag.